i Bus Priority Signal Design and Control at Unconventional Intersections: A Simulation-Based Study in Jönköping Master’s thesis in Infrastructure and Environmental Engineering AUTHORS: HAYDER ALSHIBLY AND MOHAMMAD MEZHER. DEPARTMENT OF ARCHITECTURE AND CIVIL ENGINEERING ii iii Master’s thesis 2024 Bus Priority Signal Design and Control at Unconventional Intersections: A Simulation-Based Study in Jönköping HAYDER ALSHIBLY AND MOHAMMAD MEZHER Department of Architecture and Civil Engineering Division of Geology and Geotechnics Urban Mobility Systems Chalmers University of Technology Gothenburg, Sweden 2024 iv Bus Priority Signal Design and Control at Unconventional Intersections: A Simulation-Based Study in Jönköping HAYDER ALSHIBLY AND MOHAMMAD MEZHER. © HAYDER ALSHIBLEY, MOHAMMAD MEZHER, 2024. Supervisor: Jiaming Wu, Chalmers University of Technology and Mattias Tell, Tyréns AB Examiner: Jiaming Wu, Chalmers University of Technology, Division of Urban Mo- Bility Master’s Thesis 2024 Department of Architecture and Civil Engineering Division of Geology and Geotechnics Urban Mobility Systems Chalmers University of Technology SE-412 96 Gothenburg Telephone +46 31 772 1000 v Abstract This thesis evaluates the efficacy of traffic management strategies at the Museirondellen and Södra Strandgatan intersections in Jönköping, Sweden, emphasizing bus prioritization and geometric design modifications. Due to their significant traffic volumes and complex designs, these intersections pose key challenges in terms of congestion and safety. Advanced traffic simulation tools are employed to assess current conditions and to explore the impacts of proposed geometric changes under various traffic scenarios, including increases of 10%, 15%, and 20% in traffic volumes. The study incorporates a survey of local drivers to gather firsthand insights into the current traffic issues and perceptions of the proposed changes, complemented by detailed geographical data and signal timing information from local databases. A new intersection design was proposed and tested through simulations, demonstrating its potential to alleviate congestion and enhance public transport efficiency. The research aims to analyze existing traffic inefficiencies, evaluate the effectiveness of bus prioritization, and assess the new geometric design's impact on traffic flow and safety. The findings are intended to provide evidence-based recommendations that could influence urban planning and policy-making in Jönköping and other cities with similar challenges. The significance of this study extends to its approach to integrating bus traffic within urban intersections and optimizing intersection geometries to foster sustainable traffic systems. Expected outcomes include improved urban mobility, enhanced road safety, and actionable insights for future enhancements in traffic management in urban settings. vi Acknowledgment We would like to extend our heartfelt appreciation to Jiaming Wu, our examiner at Chalmers, for his expert guidance and unwavering support during our master’s thesis. Our thanks also go to the team at Tyréns AB, particularly Mattias Tell our supervisor and Viktor Åkesson, the manager of the road department, for their indispensable contributions and support in providing resources and expertise essential to our research. We are particularly grateful to Jönköping Municipality for allowing us access to their data, which was crucial for our study. Lastly, our profound gratitude goes to our families and friends. Their constant support and encouragement have significantly eased the challenges of this academic endeavor. vii viii Table of Contents 1 Introduction .............................................................................................................................. 1 1.1 Aim ................................................................................................................................... 2 1.2 Research questions ........................................................................................................... 2 1.3 Data collection .................................................................................................................. 3 2 Site Description ........................................................................................................................ 4 2.1 Geographical Context and Layout .................................................................................... 5 2.2 Public Perception and Media Attention ............................................................................ 7 2.3 Surrounding Environment ................................................................................................ 8 2.4 History .............................................................................................................................. 9 3 Literature review .................................................................................................................... 11 3.1 Fundamentals on Signalized Intersections ..................................................................... 11 3.2 Throughabouts ................................................................................................................ 13 3.3 Bus Prioritization ............................................................................................................ 15 3.4 Challenges in Intersection Design .................................................................................. 19 3.5 Case Study Relevance .................................................................................................... 21 3.6 Research Gap .................................................................................................................. 22 4 Methodology .......................................................................................................................... 23 4.1 Simulation Model Development .................................................................................... 23 4.1.1 Advanced Traffic Signal Analysis .......................................................................... 24 5.1.2 VISVAP FLOW CHART ............................................................................................... 26 4.2 Survey ............................................................................................................................. 27 5 Results .................................................................................................................................... 30 5.1 Traffic Simulation for Current Situation ........................................................................ 30 5.1.1 Speed Link Segment ............................................................................................... 30 5.1.2 Density Link Segment ............................................................................................ 32 5.1.3 Queuing Length Link Segment .............................................................................. 33 5.1.4 Node Data Analysis ................................................................................................ 34 5.2 Survey ............................................................................................................................. 37 5.2.1 Driving Frequency and Experience in the Area ..................................................... 38 5.2.2 Perception of Safety and Confusion ....................................................................... 40 5.2.3 Challenges in Navigation ....................................................................................... 41 5.3 Need for and Type of Improvement ............................................................................... 42 ix 5.3.1 Analysis .................................................................................................................. 42 6 A New Design and Control Solution ...................................................................................... 44 6.1 New Geometric Design .................................................................................................. 44 6.1.1 Design Standards and Implementation ................................................................... 45 6.1.2 3D Visualization ..................................................................................................... 48 6.1.3 Comparative Analysis ............................................................................................ 50 6.2 Simulation ...................................................................................................................... 53 6.2.1 New Dsign Signal controlling ................................................................................ 53 6.2.2Density Link Segment .................................................................................................... 54 6.2.3 Speed Link Segment ............................................................................................... 56 6.2.4 Queuing Link Segment ........................................................................................... 57 6.2.5 Node Results .......................................................................................................... 58 7 Discussion .............................................................................................................................. 63 7.1 Discussion of results ....................................................................................................... 63 7.2 Discussion of new design ............................................................................................... 65 7.3 Limitations and challenges ............................................................................................. 66 7.4 Future research ............................................................................................................... 67 8 Conclusion .............................................................................................................................. 68 References ...................................................................................................................................... 69 Appendix A .................................................................................................................................... 74 Appendix B .................................................................................................................................... 76 Appendix C .................................................................................................................................... 77 Appendix D .................................................................................................................................... 80 x Table of Figures Figure 1: Museirondellen and Södra Strandgatan intersections (Minkarta, 2024) .......................... 4 Figure 2: Jönköping and site location (Google earth 2024) ............................................................. 5 Figure 3: Museirondellen surrounding streets (Minkarta 2024) ...................................................... 5 Figure 4: Södra Strandgatan surrounding streets (Minkarta, 2024) ................................................. 6 Figure 5: Newspapers talking about the confusing of Museirondellen and Södra Strandgatan intersections. ..................................................................................................................................... 7 Figure 6:Color coding of surrounding buildings .............................................................................. 8 Figure 7: Site area in 1975 (Länmateriet, 2024) Site area in 2024 (Länmateriet, 2024) ............................................................................................................................................... 10 Figure 8: Throughabout (Zakeri and Chaupani 2021) .................................................................... 13 Figure 9: Detailed signal plan ........................................................................................................ 25 Figure 10: Simplified version of a more complex VISVAP chart .................................................. 26 Figure 11: Current visualization speed ........................................................................................... 31 Figure 12: Current visualization density ........................................................................................ 32 Figure 13: Current visualization queue length ............................................................................... 33 Figure 14: Node results for 3 scenarios at Östra Strandgatan ........................................................ 34 Figure 15: Node results for 3 senarios at Odengatan ..................................................................... 35 Figure 16: Node results for 3 senarios Södra Strandgatan ............................................................. 36 Figure 17: Survey result for Question 1 ......................................................................................... 38 Figure 18: Survey result for Question 2 ......................................................................................... 39 Figure 19: Survey result for questions that covers perception of Safety and Confusion ............... 40 Figure 20: Surcey result for question that cover challenges in navigation .................................... 41 Figure 21: Survey results that cover questions for reflecting on public opinion ........................... 42 Figure 22: Proposed design drawing .............................................................................................. 45 Figure 23: Type of vehicle frequenting the intersections (Trafikverket; RÅD-VGU, 2022) ......... 46 Figure 24: Lane dimension (Trafikverket, RÅD - VGU, 2022) ..................................................... 46 Figure 25: Inspired Drop refuge (Trafikverket, KRAV-VGU, 2022) ............................................. 47 Figure 26: Ri &Ry, roundabout dimensions (Trafikverket, KRAV-VGU, 2022) ........................... 47 Figure 27: Infraworks visualization from south to north view ....................................................... 48 Figure 28: Infraworks visualization from north to south view ....................................................... 49 Figure 29: The existing design of the Södra Strandgatan intersection ........................................... 50 Figure 30: The New design of the Södra Strandgatan intersection ................................................ 51 xi Figure 31: New design signal control ............................................................................................ 53 Figure 32: Proposed solution link segment density result .............................................................. 55 Figure 33: Proposed solution link segment speed result ................................................................ 56 Figure 34: Proposed solution link segment queue length result ..................................................... 57 Figure 35: Östra Strandgatan current scenario vs proposed solution scenario ............................. 58 Figure 36: Odengatan current scenario vs proposed solution scenario ......................................... 59 Figure 37: Södra Strandgatan current scenario vs proposed solution scenario ............................. 60 Figure 38: Plan drawing for existing detector data ........................................................................ 74 Figure 39: Existing signal timing ................................................................................................... 75 Figure 40: The complete VISVAP chart ......................................................................................... 76 Figure 41: New design plan drawing ............................................................................................. 80 xii Introduc-on 1 1 Introduction Urban traffic management stands at the forefront of sustainable urban planning, directly influencing the economic vitality, environmental sustainability, and quality of life in cities. The advent of rapid urbanization has escalated challenges such as congestion, air pollution, and traffic-related accidents, pressing city planners to devise intelligent traffic management strategies (Litman, 2020). Effective urban traffic control is not only about managing the flow of cars but also involves optimizing signalized intersections, integrating various modes of transportation, and ensuring the safety and efficiency of public transit systems through strategies like bus prioritization (Rodier et al., 2019). Signalized intersections are critical nodes within urban traffic networks, where the design and operational strategies can significantly impact traffic flow and safety. These intersections use traffic signals to manage the movements of different streams of traffic, including vehicles, pedestrians, and cyclists, making them complex but essential components of urban infrastructure (Garber & Hoel, 2018). Properly implemented, these systems reduce delays and accidents, and when coupled with bus prioritization measures, they can significantly enhance the efficiency and appeal of public transportation. Bus prioritization at signalized intersections, such as giving buses advanced green lights or dedicated lanes, helps in reducing travel times for public transit and making it a more competitive choice compared to private vehicles (Cervero & Guerra, 2011). The city of Jönköping, Sweden, with its significant challenges at key intersections like Museirondellen and Södra Strandgatan, provides a practical context for this study. These intersections are not only high-volume traffic areas but also incorporate complex designs that include signalized configurations and extensive bus traffic. This research focuses on evaluating and optimizing these intersections through innovative traffic management strategies, including the prioritization of buses and the assessment of geometric modifications to improve traffic flow and safety. The Museirondellen and Södra Strandgatan intersections are characterized by their design and function, incorporating elements like a signalized throughabout and adjacent non-signalized intersections. These features create a complex traffic management scenario characterized by frequent congestion, navigational challenges, and significant bus traffic flows. Addressing these challenges through effective traffic management strategies is crucial for improving traffic flow and enhancing road safety. The primary objectives of this thesis are to conduct an in-depth analysis of current traffic conditions at these intersections to identify primary areas of congestion and key safety issues; evaluate the effectiveness of bus prioritization strategies at the Museirondellen throughabout in improving bus Introduc-on 2 travel times and reducing general traffic delays; assess the impact of proposed geometric changes at both intersections on improving navigational clarity, reducing driver confusion, and enhancing safety; and explore the long-term effects of these traffic management strategies on meeting the growing demands of urban traffic and assess their sustainability in the context of Jönköping’s urban development. The significance of this research lies in its potential to provide insights that could influence future urban planning and policy-making in Jönköping and other cities with similar traffic challenges. By offering evidence-based recommendations, the study aims to contribute to the broader field of traffic engineering and urban planning, advocating for innovative solutions to enhance urban mobility and quality of life. The findings from this study are expected to provide valuable guidelines for urban traffic management, particularly in optimizing the integration of bus traffic within busy urban intersections, and designing intersection geometries that improve traffic flow and safety. Ultimately, this research seeks to contribute to the development of smarter, more efficient urban traffic systems that can adapt to future challenges. 1.1 Aim The primary aim of this thesis is to evaluate the traffic management strategies at the Museirondellen and Södra Strandgatan intersections in Jönköping, Sweden, with a particular focus on the effectiveness of bus prioritization and geometric design modifications. This study seeks to assess how these strategies influence traffic flow, safety, and overall efficiency, aiming to provide evidence-based recommendations for future urban planning and traffic system enhancements. By integrating advanced simulation tools and empirical data analysis, the thesis focus on: • Analysis of the current traffic patterns and identify key areas of congestion and safety concerns at these intersections. • Evaluate the effectiveness of proposed geometric changes in enhancing navigational clarity and reducing driver confusion. • Explore the long-term sustainability of the implemented traffic management strategies in light of urban growth and increased traffic demands. 1.2 Research questions 1. How does the current traffic configuration and the geometric design at the Museirondellen and Södra Strandgatan intersections in Jönköping, Sweden, affect speed, density, and queue length, and what implications do these factors have on overall traffic flow? 2. How do potential traffic volume increases impact queuing, delays, and overall efficiency in the studied area? Introduc-on 3 3. In what ways does the current geometric design of the non-signalized intersection at Södra Strandgatan contribute to driver confusion, and what potential modifications could enhance navigational clarity and traffic safety? 1.3 Data collection The data collection process for the traffic simulation model validation at the Museirondellen and Södra Strandgatan intersections in Jönköping is extensive and thoroughly planned to ensure high fidelity in modeling real-world conditions. This process begins with acquiring baseline traffic data, which includes traffic counts, vehicle classifications, and traffic patterns, primarily focusing on peak traffic periods. This data is sourced from Jönköping municipality and Trafikverket NVDB databases, which provide a foundational understanding of the traffic dynamics at these intersections. Additionally, Jönköping municipality supplied a detailed DWG map of the area. This map is crucial for accurately representing the geographical layout and infrastructural specifics of the intersections in the simulation model, enhancing the contextual accuracy of the traffic analysis. The municipality also provided crucial detector data, signal plans, and signal data in the form of PDF files. This information is instrumental in understanding the existing signal timing and coordination, which directly influences traffic flow and control strategies at these intersections. For further investigation for the data refer to Appendix A Figure 38 and Figure 39. Field observations complement these data sources and add a layer of granularity to the traffic assessment. On February 29, 2024, detailed video recordings of traffic flow were captured during a peak period from 4:00 PM to 5:00 PM. These observations are critical for understanding real- time traffic behaviors, including lane usage and turning movements, which are not always apparent from database information alone. Further enhancing the data collection, a comprehensive field study was conducted during evening rush hour. This study not only involved counting vehicles but also focused on observing the interactions among different types of road users and the operational impact of traffic signals on traffic flow and safety. These field studies provide high-resolution data that captures the complex behaviors and interactions within the traffic system, offering valuable insights into the actual operating conditions at the intersections. Site Descrip-on 4 2 Site Description This thesis delves into the distinctive traffic configuration in Jönköping, Sweden, with a particular focus on the interconnected intersections of Museirondellen, a signalized roundabout (throughabout), and an adjacent intersection at Södra Strandgatan (see Figure 1). Figure 1: Museirondellen and Södra Strandgatan intersections (Minkarta, 2024) i Site Descrip-on 5 2.1 Geographical Context and Layout Jönköping, situated in the central southern part of Sweden, boasts a population of 146,000 residents as reported by the Jönköping Municipality in 2023. The Museirondellen and the Södra Strandgatan intersections are located in the city’s heart, a bustling urban center (see Figure 2) Figure 2: Jönköping and site location (Google earth 2024) The Museirondellen is distinguished by its unique design featuring a split central island, deviating markedly from traditional roundabout designs (see Figure 3). Figure 3: Museirondellen surrounding streets (Minkarta 2024) Site Descrip-on 6 This roundabout is a convergence point for six streets: Södra Strandgatan, Slottsgatan, Odengatan, Parking house Atollen, Lillsjöplan, and Öster Strandgatan. Its design also integrates two bus lanes. The combination of these streets and the roundabout's novel layout results in a complex traffic flow pattern. Adjacent to Museirondellen is a crucial intersection on Södra Strandgatan (illustrated in Figure 4). This intersection interlinks four streets and includes access points to the Smedjan parking house and bus lanes originating from Slottsgatan and Södra Strandgatan. The intricacy of this intersection, coupled with the proximity to the roundabout, creates a multifaceted navigational challenge for drivers. Figure 4: Södra Strandgatan surrounding streets (Minkarta, 2024) The ingress and egress points of the Smedjan parking house, in particular, presents a notable complexity in the traffic design of the area. Located in close proximity to the bus lanes, this entrance creates a challenging navigation scenario, as drivers must navigate through the mixed traffic flows while also contending with the specific demands of entering and exiting the parking structure. Site Descrip-on 7 2.2 Public Perception and Media Attention The Museirondellen and Södra Strandgatan intersections have not only captured the attention of local media but have also been featured in international news outlets. A notable instance is the coverage by the Danish newspaper B.T., which reported on the roundabout on April 10, 2015, following its inauguration (see Figure 5). B.T. highlighted the confusion and disorientation experienced by drivers, especially during instances when snow concealed the red lanes designated for buses. For more details on this coverage, see the article "Rundtosset: Er dette den mest forvirrende rundkørsel, du har set?" by B.T link: Rundtosset: Er dette den mest forvirrende rundkørsel, du har set? | BT Utroligt men sandt - www.bt.dk. Figure 5: Newspapers talking about the confusing of Museirondellen and Södra Strandgatan intersections. Similarly, Sweden's Television (SVT) addressed the complexities of navigating the newly opened roundabout in a segment titled "Confusion in the new roundabout in Jönköping," broadcast a few days after its opening on November 14, 2014. The local newspaper, Jönköping Posten, has also consistently covered the intersections, providing insights into the community's reactions and adjustments to the new traffic layout. Further details can be found in SVT's coverage link: Förvirring i nya rondellen i Jönköping | SVT Nyheter https://www.bt.dk/utroligt-men-sandt/rundtosset-er-dette-den-mest-forvirrende-rundkoersel-du-har-set https://www.bt.dk/utroligt-men-sandt/rundtosset-er-dette-den-mest-forvirrende-rundkoersel-du-har-set https://www.svt.se/nyheter/lokalt/smaland/forvirring-i-nya-rondellen-i-jonkoping Site Descrip-on 8 Furthermore, Aftonbladet, a widely circulated Swedish daily tabloid, has featured articles about these intersections. Known for being one of the largest daily newspapers in the Nordic countries, Aftonbladet's coverage underscores the significance and widespread interest in the traffic dynamics and design of these intersections in Jönköping. More information can be found in the article "Jönköpings nya rondell har blivit en nationell snackis" from Aftonbladet link: Jönköpings nya rondell har blivit en nationell snackis (aftonbladet.se). This extensive media attention from both local and international sources reflects the public's keen interest and the challenges posed by these intersections, particularly in terms of driver adaptation and traffic management. The coverage serves as a testament to the intersections' impact and the broader implications for urban traffic design and navigation. 2.3 Surrounding Environment The intersection at Museirondellen and Södra Strandgatan, is surrounded by a diverse urban environment. This is detailed in a map using a color-coded system, see Figure 6. The area is important for understanding the city's complex and varied urban layout. Figure 6:Color coding of surrounding buildings Three key parking areas - Atollen, Smedjan, and the library parking - are shown in cyan color on the map. These parking places are essential for managing the large number of vehicles in this area. https://www.aftonbladet.se/nyheter/a/KvaBr5/jonkopings-nya-rondell-har-blivit-en-nationell-snackis https://www.aftonbladet.se/nyheter/a/KvaBr5/jonkopings-nya-rondell-har-blivit-en-nationell-snackis Site Descrip-on 9 The Smedjan parking, near the bus lanes, is particularly notable. Its position creates traffic challenges, especially for drivers entering and leaving the parking. In close proximity to these parking areas, the historic Göta Court, color-coded in gold or sand yellow, stands as a testament to the city's rich cultural heritage. This esteemed building encompasses the original 1650 court structure and a 19th-century archive addition, marking a significant historical footprint in the landscape. The map shows the Jönköping County Museum in maroon color. This museum is important for the culture of the region, showing local history and art. Nearby, the Jönköping Library is marked in deep blue, indicating its role as an important place for learning and community information. Significantly, areas combining Banks, Companies, Shopping Stores, and Gyms are represented with a pattern of striped orange and gray. This color scheme signifies the dynamic and multifunctional nature of these spaces, blending various aspects of urban life. The map also highlights other important urban features. Shopping centers, businesses, and restaurants are indicated in purple with green highlights. This shows areas of commercial activity and social gathering. Hotels are marked in royal blue, pointing out the city's hospitality services. Residential areas are in beige or light brown, showing where people live within the city. Areas that mix shopping, restaurants, and residences are uniquely shown using a red to yellow. This illustrates the lively and diverse nature of these mixed-use areas. This color-coded map of the Museirondellen and Södra Strandgatan intersection encapsulates the essence of urban complexity. It blends cultural, commercial, and infrastructural elements, each contributing to the area's unique challenges in traffic management and urban planning. Such a detailed representation underscores the necessity for innovative and thoughtful approaches in city development, ensuring a balance between preserving historical heritage and accommodating modern urban needs. 2.4 History The development of the Museirondellen and Södra Strandgatan intersections, which was officially opened on November 12, 2014, represents a pivotal moment in the evolution of Jönköping City's traffic management and urban planning. This intersection's construction in 2014 marked a significant transformation from its previous state. Looking back to 1975, the area was considerably different, with notable changes occurring over the years, particularly in terms of building development. A substantial increase in the number of buildings, especially shopping stores and restaurants, has been observed, indicating a shift towards a more commercial and vibrant urban landscape. See Figure 7. Site Descrip-on 10 Figure 7: Site area in 1975 (Länmateriet, 2024) Site area in 2024 (Länmateriet, 2024) Prior to the 2014 redevelopment, the intersection functioned with a traffic light system. At that time, there were no designated bus lanes, nor was there any prioritization for buses in the intersection. This aspect of the intersection's design highlights the evolution of urban transport infrastructure, catering to the increasing demands of public transportation. Furthermore, the traffic demand in the area has escalated significantly compared to the past. Before the 2014 reconstruction, the volume of traffic was considerably lower, reflecting the urban growth and increased mobility needs of the city over the years. The transformation of the Museirondellen and Södra Strandgatan intersection from a conventional traffic light junction to its current state underscores the dynamic nature of urban development. It reflects the city's response to changing transportation needs and the evolution of its urban landscape, demonstrating a shift towards more sophisticated traffic management and urban planning methodologies. Literature review 11 3 Literature review This section looks closely at how signalized intersections have changed and how they affect city traffic control, focusing on Throughabouts and their implementation, buss prioritization, and challenges in intersection design. It starts by looking at the history of these intersections, from their start in the early 1900s to their modern forms. These intersections are key in managing traffic and improving road safety and have developed a lot to keep up with growing city needs. Then, the review examines different intersection designs, from usual signalized ones to newer ones like throughabouts. It checks how well these designs work for managing traffic and supporting public transport, which is particularly important in city planning today. It gives special attention to how these intersections fit into cities, with examples like a signalized roundabout that helps buses, to show how they work in real life. In the end, this review aims to give a full picture of signalized intersections. It investigates their technical progress and how important they are for modern city planning and traffic engineering. By doing this, the review hopes to offer useful knowledge, especially for improving city movement and traffic control in fast-changing urban areas. 3.1 Fundamentals on Signalized Intersections The concept of signalized intersections appeared with the advent of motor vehicles. As early as the 1860s, gas-lit signals were used in London to control the flow of horse-drawn carriages. However, the first electric traffic signal was installed in Cleveland, Ohio in 1914. This innovation marked the beginning of modern traffic control systems (Garber & Hoel, 2018). Over the years, the design and technology of signalized intersections have evolved significantly, incorporating advanced sensors, computerized control systems, and adaptive algorithms to optimize traffic flow. Signalized intersections typically consist of several key components: traffic lights, detection systems, controllers, and pedestrian signals. Traffic lights are the most visible element, displaying assorted colors (red, yellow, and green) to direct traffic. Detection systems, such as inductive loops and cameras, provide real-time data on traffic conditions, which are used by controllers to adjust signal timings. Pedestrian signals ensure safe crossing opportunities for foot traffic. It utilizes traffic lights to control the movement of vehicles and pedestrians. These intersections are typically found at junctions where two or more roads meet, and traffic flow is too heavy or complex to be managed by less controlled means like roundabouts or stop signs. The primary purpose of signalized intersections is to facilitate the orderly movement of traffic, prevent the stream of traffic from one direction from continuously blocking other movements, and ensure a balanced distribution of green time to various traffic movements (Coates, Yi, Koganti, & Du, 2012). Literature review 12 One of the key benefits of signalized intersections is the enhancement of safety. By dictating the right of way, these intersections reduce the likelihood of conflicts that could lead to accidents. Signalized intersections are particularly beneficial in managing high-traffic areas, where the volume of vehicles and pedestrians necessitates a more regulated approach to ensure safety and efficiency. The signals enforce a systematic sharing of the intersection, which helps in reducing the potential for collisions, particularly angle and left-turn collisions (Alshayeb, S., Stevanovic, A., Stevanovic, J., & Dobrota, N, 2023). The installation and operation of signalized intersections are guided by various standards and best practices. In the United States, the Manual on Uniform Traffic Control Devices (MUTCD) sets forth guidelines for the design and use of traffic signals. Additionally, the American Association of State Highway and Transportation Officials (AASHTO) provides design specifications for roadways, including signalized intersections. These standards ensure consistency, safety, and efficiency in traffic management across different jurisdictions (AASHTO, 2018). Signalized intersections also play a critical role in intelligent transportation systems (ITS). They can be integrated with other ITS components, such as advanced traveller information systems and emergency vehicle preemption systems, to create a more efficient and responsive traffic network. For example, signal priority can be given to buses in a bus rapid transit (BRT) system to improve public transportation efficiency (Agafonov, A., Yumaganov, A., & Myasnikov, V, 2023). Despite their benefits, signalized intersections also present challenges. Incorrectly designed or poorly timed signals can lead to increased congestion and delays. Additionally, intersections are often sites of vehicle-pedestrian and vehicle-vehicle conflicts, leading to safety concerns. As such, ongoing research in traffic engineering focuses on optimizing signal timings, improving pedestrian and cyclist safety, and integrating emerging technologies like connected and autonomous vehicles into intersection management (S Cheng, C., Du, Y., Sun, L., & Ji, Y, 2016). Signalized intersections come in diverse designs, each tailored to the specific requirements of the location. The most common design is the traditional crossroads configuration, where two roads intersect at right angles. However, other designs include T-junctions, staggered junctions, and multi- arm junctions, each offering unique advantages depending on the traffic patterns and physical constraints of the location (Coates, Yi, Koganti, & Du, 2012). An integral aspect of signalized intersections is signal phasing and timing. Phasing refers to the grouping of traffic movements given the right of way simultaneously during a signal cycle. Efficient signal phasing is essential to maximize the capacity of an intersection and minimize delays. For example, a simple two-phase system might have one phase for north-south movements and another for east-west movements. More complex intersections might have additional phases for protected left turns or pedestrian crossings (Coates, Yi, Koganti, & Du, 2012). The timing of these phases is equally crucial. The signal cycle length and the distribution of green time among phases must be carefully calibrated based on traffic volumes, patterns, and the specific Literature review 13 needs of the intersection. Effective timing can significantly reduce delays and improve the overall efficiency of the intersection (Alshayeb, S., Stevanovic, A., Stevanovic, J., & Dobrota, N, 2023). Advancements in technology have led to the development of adaptive signal control systems, which adjust signal timings in real-time based on current traffic conditions. These systems use sensors to detect traffic volumes and adjust the signal phases, accordingly, thus improving the responsiveness of the intersection to dynamic traffic patterns. Adaptive signal control systems can significantly enhance the efficiency of signalized intersections, particularly in areas with fluctuating traffic volumes (Feng, Y., Head, K. L., Khoshmagham, S., & Zamanipour, M., 2015). Signalized intersections also have notable environmental and economic implications. Efficient signal timing can lead to reduced idling and shorter travel times, which in turn can lower vehicle emissions and fuel consumption. This not only contributes to better air quality but also offers economic benefits in terms of reduced fuel costs and enhanced productivity due to less time spent in traffic (Coates, Yi, Koganti, & Du, 2012). 3.2 Throughabouts Throughabouts represent a change in thinking in roundabout design, a concept innovatively introduced by Zakeri and Choupani (2021). This design is characterized by a split central island, a feature that fundamentally differentiates it from traditional roundabouts see Figure 8. Figure 8: Throughabout (Zakeri and Chaupani 2021) The central idea behind throughabouts is to streamline traffic flow while simultaneously accommodating Bus Rapid Transit (BRT) systems more effectively, an aspect explored in-depth by Literature review 14 researchers like Levinson et al. (2002) and Cervero (2006). The distinct configuration of throughabouts facilitates a more organized segregation of traffic, allowing for a smoother flow of vehicles and a more efficient transit of BRT systems, thereby addressing some of the most pressing challenges in urban traffic congestion. The adaptability of throughabouts to various urban landscapes, as emphasized by Ma et al. (2017) and Elhassy et al. (2020), highlights their versatility in managing traffic under different conditions, from high-density urban centers to suburban areas. The implementation of throughabouts is a complex process that involves careful consideration of various factors. One of the most critical aspects is the integration of advanced traffic signal systems. These systems, as studied by Li et al. (2015) and Zakeri & Choupani (2021), need to be meticulously synchronized with larger urban traffic networks to ensure an uninterrupted and efficient flow of traffic. This synchronization becomes particularly vital in areas where BRT systems are predominant, as highlighted in the research by Hidalgo and Gutiérrez (2013), who stress the growing significance of BRT systems in urban transport infrastructures. In designing throughabouts, the safety and accessibility for non-motorized users, such as pedestrians and cyclists, must be given paramount importance. The design must incorporate comprehensive pedestrian crossings, cycling paths, and various safety measures to ensure an inclusive environment for all forms of traffic. This consideration, detailed in the work of Sisiopiku & Akin (2003), is critical for building roundabouts that are not only efficient for vehicular traffic but also safe and accessible for pedestrians and cyclists. The advantages of throughabouts extend to various aspects of urban life. They significantly improve the efficiency of public transportation systems, especially BRTs (Bus Rapid Transit), by minimizing delays and enhancing punctuality, thereby contributing to a more reliable public transportation network (Aakre & Aakre, 2017). Additionally, through the reduction in vehicular congestion and smoother traffic flow, throughabouts can contribute to a decrease in CO2 emissions, underlining their role in promoting environmental sustainability in urban transportation. Despite these benefits, the implementation of throughabouts comes with its own set of challenges. Key among these is the management of traffic signals in such a way that they complement the new traffic patterns. Another significant challenge is ensuring public compliance and understanding of these new traffic layouts. As Gitelman & Korchatov (2021) point out, educating the public and adapting driver behaviour to new traffic configurations is crucial for the successful functioning of throughabouts. In comparison with traditional intersections, throughabouts offer marked improvements in both efficiency and safety. Research by Retting et al. (2002) and Daniels et al. (2010) has demonstrated that traditional intersections are often less efficient and more prone to accidents. Throughabouts, with their enhanced traffic flow and safety features, present a compelling alternative, especially in areas struggling with high traffic volumes and safety concerns. Looking at the broader picture, the success of throughabouts is contingent upon their acceptance by the community. The importance of public education and behavioural adaptation to new traffic systems, as emphasized by Taubman et al. (2007), is integral to the smooth transition to these new Literature review 15 arrangements. Programs focusing on public awareness, driver education, and the use of simulation- based training methods (Kay et al., 2009) are essential in acclimatizing the public to throughabouts. As cities continue to expand and face new traffic management challenges, throughabouts emerge as a crucial tool in shaping sustainable, efficient, and safe urban traffic systems. In the realm of traffic management and urban planning, throughabouts have been subject to various studies and implementations, shedding light on their practical applications and efficacy in diverse contexts. Notably, the research conducted by Zakeri and Choupani (2021) stands out as a significant case study that offers detailed insights into the operational evaluation of throughabouts, particularly emphasizing their role in prioritizing public transport in standard roundabouts. In their study, Zakeri and Choupani (2021) conducted a thorough investigation into a throughabout's impact on traffic flow and public transportation efficiency. This research is pivotal as it provides empirical evidence on how throughabouts can significantly improve travel time for both public and private transport. The study's location in Shahrood, Iran, provides a unique context, yet the findings have broader implications, resonating with urban centers globally experiencing similar traffic challenges. The research employed advanced microsimulation tools, specifically AIMSUN software, to model traffic flow and assess the throughabout's performance under various traffic volumes. This methodology allowed for a detailed analysis of travel times, queue lengths, and overall traffic efficiency, offering a comprehensive understanding of the throughabout’s impact in real-world scenarios. The study's findings revealed that throughabouts improved travel times and maintained steady traffic flow at various volume levels. This improvement was not limited to public transport; private vehicles also benefited from the smoother traffic flow facilitated by the throughabout design. Importantly, the study highlighted the throughabout's ability to keep traffic flowing, even under high-volume conditions, which is a critical consideration for urban areas grappling with congestion issues. The research by Zakeri and Choupani (2021) thus provides a valuable case study in understanding the practical implications and benefits of throughabouts in urban traffic management. 3.3 Bus Prioritization Bus prioritization in urban transportation planning is a concept that revolves around optimizing the flow of buses through intersection designs and signal optimizations (Wahlstedt, J., 2011). This approach is driven by the growing necessity to manage urban traffic congestion, environmental concerns, and the demand for efficient public transportation systems. The fundamental principle of bus prioritization is to enhance the operational efficiency of bus transit by reducing travel time and improving service regularity, thereby making public transport a more attractive option for commuters. This concept is integral to the strategic planning of urban transportation, emphasizing the critical role of buses in the mobility network (Hamurcu, M., & Eren, T, 2020). Literature review 16 The rationale for bus prioritization is deeply rooted in the challenges faced by urban transportation networks. With the dramatic increase in vehicle population and the lag in road infrastructure development, cities worldwide are grappling with severe traffic congestion. This congestion not only leads to increased travel times but also contributes significantly to environmental pollution through greenhouse gas emissions (Zhao, J., & Zhou, X.,2019). As a social group-based transport mode, public transport, particularly buses, is seen as an effective method to alleviate congestion and reduce traffic pollution. Buses require less road space per capita compared to private vehicles, and they can transport a larger volume of passengers with higher efficiency. Therefore, enhancing the operational efficiency of buses through prioritization measures is pivotal in addressing urban traffic challenges (Zhai, X., Guo, F., & Krishnan, R., 2023). The concept of bus prioritization is not new; it has evolved over the years with advancements in traffic engineering and urban planning. Historically, the approach to bus prioritization was straightforward – dedicating specific lanes for buses and adjusting traffic signal timings to favor bus movements. However, as urban traffic conditions became more complex, the need for more sophisticated bus prioritization techniques became evident (Zhao, J., Yu, J., Xia, X., Ye, J., & Yuan, Y., 2019). Today, bus prioritization encompasses a range of strategies, from physical infrastructure changes like exclusive bus lanes to advanced traffic signal control systems that dynamically respond to bus transit needs (Zhao, J., & Zhou, X., 2019). Bus prioritization directly impacts urban mobility by improving the reliability and efficiency of public transport (Wahlstedt, J., 2011). By reducing delays at intersections and along routes, buses can maintain more consistent schedules, which is crucial for commuters who rely on timely service. Furthermore, by making bus travel faster and more reliable, bus prioritization can entice commuters to shift from private vehicles to public transport, thus reducing the overall number of vehicles on the road. This shift not only alleviates road congestion but also contributes to environmental sustainability by reducing vehicular emissions. The success of bus prioritization in improving urban mobility hinges on a well-thought-out design that considers the unique characteristics of each urban area, the specific needs of the bus transit system, and the overall traffic flow in the city (Qing-fang, Y., & Biao, Z., 2011). The implementation of bus prioritization strategies involves a multifaceted approach that includes both infrastructure and operational changes. One common strategy is the designation of exclusive bus lanes. These lanes are reserved solely for buses, allowing them to bypass traffic congestion, particularly in high-density urban corridors. The effectiveness of exclusive bus lanes is evident in their ability to reduce delays and improve the punctuality of bus services (Qing-fang & Biao, Year Needed). Another critical strategy is Transit Signal Priority (TSP), which involves modifying traffic signals to extend green phases or reduce red phases when buses are present (Halbach et al., 2022). Literature review 17 TSP strategies can be passive, active, or real-time, depending on the specific operational needs of the bus system. Passive priority strategies operate continuously, regardless of whether buses are present, while active strategies only prioritize specific transit vehicles upon request. Real-time TSP strategies optimize signal timings with the consideration of performance criteria such as person delay, transit delay, and vehicle delay (Zhai, Guo, & Krishnan, 2023). While the benefits of bus prioritization are clear, implementing these strategies is not without challenges. One of the main challenges is the potential negative impact on other traffic movements, especially at intersections where bus priority measures might disrupt the flow of other vehicles (Gross, Lyon, Persaud, & Srinivasan, 2013). Therefore, careful planning and design are required to ensure that bus prioritization contributes to the overall efficiency of the transportation network without significantly disadvantaging other road users (Saccomanno, Cunto, Guido, & Vitale, 2008). Additionally, the success of bus prioritization depends on several factors, including the existing urban infrastructure, the volume of bus traffic, and the behaviour of other traffic participants. In designing bus prioritization strategies, transportation planners must consider these factors to create an optimized and balanced traffic system (Khwais & Haddad, 2017). Bus prioritization is an innovative approach in urban traffic management, aimed at enhancing the efficiency and effectiveness of bus services within congested city environments. This methodology employs a diverse array of techniques and technologies, each crafted to optimize bus transit and more seamlessly integrate it into the urban transportation network. Its primary goal is to improve bus travel times, reliability, and overall service quality, thus encouraging a shift from private vehicles to public transportation. The subsequent sections explore the myriad of techniques and technologies utilized in bus prioritization, shedding light on their functionalities, benefits, and considerations for implementation (Furth & Muller, 2000; Kakooza, Luboobi, & Mugisha, 2005). A cornerstone of bus prioritization is the implementation of exclusive bus lanes. These lanes provide buses with a segregated roadway, free from the typical congestion encountered in mixed-traffic lanes, allowing for consistent speeds and more reliable schedule adherence. The design of these lanes varies, including configurations such as center, offset, curb side, and contraflow lanes, each tailored to specific urban layouts and traffic conditions. Center transit lanes, located in the middle of roadways, are especially effective in urban areas with frequent bus services, as they reduce conflicts with turning vehicles and blockages by parked or stopped vehicles, and are often paired with specialized boarding platforms for efficient passenger transitions (Zhao & Zhou, Year Needed). Meanwhile, offset lanes, positioned between curb side parking and general traffic lanes, balance accessibility and traffic flow. In contrast, curb side lanes, situated adjacent to sidewalks, offer easy access but are more susceptible to obstructions from parked vehicles and loading activities (Zhao, Yu, Xia, Ye, & Yuan, 2019). Literature review 18 Transit Signal Priority (TSP) forms another vital aspect of bus prioritization, enhancing the efficiency of intersections for buses. TSP adjusts traffic signal phases to minimize delays for buses, employing various strategies such as passive, active, and real-time approaches. Passive strategies, which operate continuously irrespective of real-time bus presence, are common in areas with frequent bus services (Guler, Gayah, & Menéndez, 2016). Active strategies, conversely, are activated by transit vehicles on-demand, offering a more targeted and efficient approach. The most advanced, real-time TSP strategies, leverage real-time data on traffic conditions and bus locations to dynamically optimize signal timings, considering factors like transit delay and overall intersection efficiency (Wahlstedt, Year Needed). An innovative concept in bus prioritization is the Dynamic Exclusive Bus Lane (DBL) design. This approach allows for multipurpose use of the exclusive bus lane at intersection exits, including facilitating left-turn movements of buses. This design enhances the running efficiency of left-turn buses, optimizes lane utilization, and alleviates traffic demand on normal lanes. The DBL design synergistically integrates lane markings, signal timings, and median opening locations to minimize person delay and maximize the efficiency of both buses and private vehicles (Gu et al., 2021). Sweden's approach to bus prioritization stands as a hallmark of success in the realm of public transportation. The country's initiatives in optimizing bus transit, particularly in cities like Stockholm, demonstrate the effective implementation of bus prioritization techniques and technologies. These examples not only highlight the practicality of such strategies but also their positive impact on overall traffic management and public transit efficiency. Stockholm, the capital city of Sweden, has been at the forefront of implementing bus prioritization strategies. One notable example is the use of the PRIBUSS (Prioritizing of Busses in Coordinated Signal systems) method. This method, standard in Sweden, is a comprehensive approach to bus prioritization in coordinated traffic signal systems. The PRIBUSS method is designed to enhance bus movement through intersections by modifying traffic signal timings to favour bus transit. Research and studies conducted in Stockholm using this method have shown considerable benefits for bus passengers, including significant reductions in travel times (Wahlstedt, 2011). These benefits are achieved with minimal negative impacts on other traffic, highlighting the effectiveness of carefully planned and implemented bus prioritization strategies. Looking ahead, the future of bus prioritization lies in the integration of advanced technologies and data-driven approaches. With the advent of intelligent transportation systems, there is potential for more dynamic and responsive bus prioritization strategies. For instance, real-time data on traffic conditions and bus locations can be used to adjust traffic signals more effectively, ensuring optimal Literature review 19 flow for buses while minimizing disruption to other traffic (Xiaoguang, 2010). Additionally, the use of simulation tools and predictive analytics can aid in the design and evaluation of bus prioritization measures, allowing for more informed decision-making and effective implementation (Saccomanno, Cunto, Guido, & Vitale, 2008). As urban areas continue to grow and evolve, bus prioritization will remain a key component of sustainable and efficient urban transportation planning. The deployment of automated and connected vehicle technology, including the prioritization of automated shuttles in V2X public transport systems, is an emerging field that demonstrates significant potential for enhancing the effectiveness of bus prioritization strategies (Halbach et al., 2022). Furthermore, the exploration of online optimal bus signal priority strategies to equalize headway in real-time exemplifies the ongoing advancements in this area, aiming to balance the needs of buses with overall traffic efficiency (Zhai, Guo, & Krishnan, 2023). These innovative approaches signify a move towards more adaptable and intelligent urban traffic systems, where bus prioritization not only improves the efficiency of public transport but also contributes to the holistic management of urban mobility. 3.4 Challenges in Intersection Design The design and management of road intersections are pivotal in urban planning and traffic engineering, representing a nexus of various challenging elements that directly influence traffic flow efficiency, road safety, and urban mobility. The complexity of intersection design is notably pronounced in managing diverse and often conflicting traffic flows. According to Hwan NamGung et al. (2020), the simultaneous movement of different modes of transportation – motor vehicles, pedestrians, and bicycles – creates a dynamic environment where safety hazards and operational inefficiencies are prevalent. These challenges necessitate the implementation of multifaceted strategies, such as the segregation of traffic modes through dedicated lanes and signal phases, to ensure the safety and smooth flow of all users. Intersections present unique safety challenges due to the convergence of different traffic movements. The design and operation of these intersections, whether signalized or non-signalized, significantly influence the occurrence and severity of accidents. A seminal study by Retting et al. (2002) demonstrated that converting traditional intersections to roundabouts in the United States led to a marked reduction in injury crashes, emphasizing the safety benefits of certain design choices. In contrast, signalized intersections, while effective in managing traffic flow, have been associated with a higher incidence of certain types of collisions, such as rear-end crashes, as highlighted by Bonneson and Zimmerman (2004). These findings underscore the need for careful consideration of safety aspects in intersection design, balancing the advantages and risks of different configurations. In urban settings, particularly in densely populated areas, 4-leg intersections present additional layers of complexity. Saeed et al. (2023) highlights the exacerbation of congestion and the heightened risk of accidents in these environments, primarily due to high Literature review 20 traffic volumes and the intricate interaction of diverse traffic movements. This congestion not only impacts travel time and fuel consumption but also contributes to environmental degradation through increased vehicle emissions. Addressing these challenges requires a comprehensive approach that includes optimizing traffic signal timing, utilizing intelligent traffic management systems, and redesigning intersections to improve traffic flow efficiency. For example, the introduction of dedicated turning lanes and advanced signaling systems can significantly reduce traffic bottlenecks and enhance safety. The study by Pan et al. (2021) delves into the realm of unconventional intersection designs, such as Continuous Flow Intersections (CFIs) and Parallel Flow Intersections (PFIs), which are increasingly being considered in areas plagued by heavy traffic. These designs represent innovative solutions to traditional traffic flow problems by altering standard traffic signal phases and patterns, thus facilitating smoother vehicle movements, and reducing overall congestion. However, the implementation of such unconventional designs demands an in-depth understanding of traffic dynamics, as well as a careful consideration of the impact on all road users, including pedestrians and cyclists. The study emphasizes the importance of designs that minimize conflict points and integrate advanced traffic signal systems capable of adapting to real-time conditions, thereby enhancing the safety and efficiency of these complex intersections. Beyond the immediate challenges of traffic flow and safety, intersection design in the modern urban landscape must also adapt to rapid technological advancements. The integration of intelligent transportation systems, autonomous vehicles, and smart city infrastructure requires a forward- thinking approach that anticipates future developments. This involves the incorporation of sensors, smart traffic signals, and data analytics into intersection design, allowing for dynamic traffic management and improved safety. However, these technological integrations also pose challenges in terms of cost, maintenance, and ensuring compatibility with existing infrastructure. Intersection design also has profound environmental and societal implications. Non-signalized intersections, for example, can contribute to reduced vehicle idling, thereby mitigating air and noise pollution – a concern highlighted by Wigan (2006) in his analysis of urban traffic impacts. Additionally, the integration of pedestrian and cyclist needs in intersection design is a critical challenge. The work of Zegeer et al. (2002) emphasizes the importance of designing intersections that are safe and accessible for non-motorized road users, a crucial aspect often overlooked in traditional intersection design. Moreover, as urban areas continue to grapple with issues such as air pollution and noise pollution, intersection designs must contribute to environmental sustainability. This includes promoting non-motorized transportation, implementing green traffic signal timing strategies to reduce idling and emissions, and incorporating green spaces within intersection designs to aid in urban cooling and provide aesthetic benefits. The research by Pan et al. (2021) underscores Literature review 21 the need for traffic simulation models to evaluate the environmental impacts of different intersection designs, ensuring that they not only address immediate traffic concerns but also contribute positively to the broader urban environment. 3.5 Case Study Relevance The comprehensive literature review on signalized and non-signalized intersections has direct relevance to my case study of the two interconnected intersections at Museirondellen in Jönköping, Sweden. This case study presents a unique scenario: one intersection is a signalized roundabout (throughabout) with traffic lights that prioritize buses, and the other is a non-signalized intersection also designed with bus prioritization but poses challenges in terms of its design and drivability. The insights gained from the literature on the evolution and effectiveness of throughabouts provide a valuable context for analysing the signalized intersection at Museirondellen. The study highlights the importance of such designs in managing traffic flow and prioritizing public transport, which is directly applicable to evaluating the success and efficiency of the signalized roundabout in my case study. On the other hand, the non-signalized intersection at Museirondellen, with its design challenges, resonates with the gaps identified in the literature regarding the safety and functionality of such intersections. The difficulties experienced by drivers at this intersection reflect the need for a more nuanced understanding of intersection design, particularly in how it affects driver behaviour and safety. The literature's focus on public perception and the integration of different modes of transport provides a framework for assessing and potentially reimagining the design of this non-signalized intersection to enhance its usability and safety. Additionally, the case study's emphasis on bus prioritization in both intersections aligns well with the literature's discussion on the importance of public transport efficiency in urban planning. This aspect of the study is crucial for assessing how well the intersections serve public transport needs and the overall traffic management system in Jönköping. Literature review 22 3.6 Research Gap The literature review has elucidated the dynamics of both signalized and non-signalized intersections, highlighting crucial insights into their design, management, and the specific challenges they present. In examining the Museirondellen and Södra Strandgatan intersections in Jönköping, Sweden, several significant research gaps have been identified that our thesis aims to address include: 1- Integration and Impact of Throughabouts with Bus Prioritization: There is a scarcity of empirical research exploring the combined impact of throughabouts and bus prioritization on traffic flow and public transportation efficiency in urban settings. Our research could investigate how throughabouts, when integrated with bus prioritization systems, influence both public transport dynamics and overall traffic efficiency, particularly in mixed traffic environments. 2- Challenges and Efficacy of Signalized Intersection Designs in Urban Areas: While the literature explores various designs of signalized intersections, there is a limited understanding of their efficacy and challenges in densely populated urban areas. Research is needed to evaluate how different signalized designs, including innovative ones like throughabouts, manage high traffic volumes and complex traffic movements, and their implications for urban traffic congestion and safety. 3- Real-World Application and Public Perception of Throughabouts and Bus Prioritization: There is a need for more case studies that examine the real-world application, effectiveness, and public perception of throughabouts combined with bus prioritization strategies. Such studies would provide insights into the acceptance and operational challenges of these systems, contributing to improved designs and implementation strategies in urban traffic management. These gaps underscore the importance of our research in contributing to the body of knowledge on effective intersection design and management, particularly in complex urban settings like Jönköping. Addressing these gaps through empirical studies could provide significant benefits in terms of traffic efficiency and safety enhancements. Methodology 23 4 Methodology In this section of this study, we delineate the systematic procedures and analytical techniques employed to investigate the traffic dynamics at Museirondellen and Södra Strandgatan intersections. This includes a detailed description of the simulation tools and data collection methods used, ensuring replicability and providing a robust framework for evaluating the effectiveness of proposed traffic management strategies. The adoption of PTV Vissim 2024, a powerful microsimulation tool, enabled an in-depth analysis of traffic behavior, including flow efficiency, safety metrics, and congestion management. This tool was pivotal in modeling urban traffic dynamics and evaluating traffic management strategies. Collectively, these methods underscore a commitment to developing sustainable and efficient traffic solutions for Jönköping, preparing the intersections to meet current demands and future traffic growth. That blend ensures that the designs achieve high standards of precision and functionality. The primary designs were developed using AutoCAD Civil 3D, complemented by Autodesk InfraWorks to enhance visual assessments and environmental impact analyses through dynamic 3D modeling. This facilitated a clearer visualization of traffic movements and pedestrian flows. This methodological framework address the redesign of the Södra Strandgatan intersection and analyze the traffic dynamics at both the Museirondellen and Södra Strandgatan intersections in Jönköping. The methodology synthesizes advanced engineering tools with authoritative guidelines and microsimulation techniques. The methodology adheres to the Trafikverket VGU guidelines, ensuring all design elements meet Swedish national standards for safety, efficiency, and environmental sustainability. 4.1 Simulation Model Development The refinement of the simulation model began with foundational data provided by Jönköping municipality, including traffic signal timings, detector information, and initial map signal models. These elements formed the basis for subsequent modifications to enhance model accuracy and relevance. A critical aspect of this enhancement was the adjustment of the VISVAP logic, tailored to accurately reflect the specific traffic dynamics at Museirondellen and Södra Strandgatan intersections. The recalibration process involved meticulous mapping of lane configurations to mirror the actual road layouts. This included a detailed representation of bus lanes, marked distinctly to highlight their role in the traffic system and to facilitate analysis of their impact on overall traffic flow. Bus lane dynamics, such as frequency, dwell times, and interaction with general traffic, were closely Methodology 24 simulated to assess their efficiency and priority within the traffic network. Advanced traffic signal algorithms were integrated to mirror real-world timing and operations. These algorithms are based on Vehicle Actuated Programming (VAP) which dynamically adjusts to the changing traffic volumes, ensuring that traffic flows as smoothly as possible. The simulation also extended to pedestrian crossing synchronization with adjacent traffic lights, offering a realistic portrayal of traffic behavior across the entire network. This enhanced simulation model serves as a vital tool in urban planning and traffic optimization efforts in Jönköping, providing a more precise and realistic evaluation of potential traffic management strategies and their impacts. 4.1.1 Advanced Traffic Signal Analysis In the context of urban traffic management, strategically placed detectors are pivotal for optimizing the flow of vehicles in the area of Musemrondellen and Strangatan area see Figure 9. Here, we explore the justification for the placement of various detectors within a specified signal plan, examining their roles in ensuring efficient traffic control and safety. The location of detectors D 5 and D 6, positioned south of the roundabout to monitor the approaching traffic, is critical. These detectors facilitate the adaptive control of signal 7, allowing it to respond dynamically to traffic volumes. This placement is justified by the need to prevent congestion and streamline the flow of vehicles entering the roundabout, thereby reducing the likelihood of accidents and delays. Detectors D 7, D 8, and D 9, installed within the southern segment of the roundabout and linked to signal 3, play a significant role in the internal management of the roundabout's traffic dynamics. Their purpose is to directly manage the traffic flow within the roundabout, enhancing the coordination between entering and exiting traffic. This strategic placement is essential for maintaining continuous movement within the roundabout, minimizing stop-and-go traffic, which can lead to inefficiencies and increased collision risks. The placement of detector D 10 adjacent to Smedjan parking house on the east side serves to regulate traffic related to entrances and exits from the Smedjan parking house area. Controlling signal 4 based on the real-time data collected by this detector ensures that traffic delays are minimized and that pedestrian safety is prioritized, particularly in areas with potentially high pedestrian activity. Detector D2, situated west of Smedjan parking house, is strategically placed to manage the flow of traffic that interacts with entrances, exits, and possibly parking access points associated with Smedjan parking house. This detector’s role in controlling signal 1 is crucial for facilitating smooth transitions onto main roads, thereby avoiding back-ups that could extend onto busier arteries. The positioning of detector D 3 inside the roundabout, tasked with monitoring and managing the traffic exiting the roundabout, is justified by the need to enhance traffic decongestion efforts post- roundabout navigation. By controlling signals 6 and 5, this detector ensures that traffic is efficiently distributed onto subsequent roads, thereby reducing potential bottlenecks. Lastly, detector D 4’s location south of the roundabout and its association with signal 8 highlight its role in managing Methodology 25 downstream traffic flows. This strategic placement aids in the smooth merging and transitioning of vehicles from the roundabout to southern routes, crucial for preventing traffic accumulation and facilitating a steady flow of vehicles. Figure 9: Detailed signal plan Methodology 26 4.1.2 Visvap flow chart Figure 10: Simplified version of a more complex VISVAP chart The flowchart presented in Figure 10 is a simplified version of a more complex VISVAP chart, designed to provide a clearer and more straightforward explanation of the traffic signal control system based on bus detection. It outlines the fundamental steps and signal groups involved in managing traffic lights at intersections, focusing on optimizing traffic flow and prioritizing bus movements. The process initiates with a "Check for Detectors" phase, where the system scans for the presence of buses using specialized detectors. If no buses are detected during this initial check, the system defaults to Signal Group 1, where all signals for cars are set to green. This allows for normal traffic flow until a bus is detected. If a bus is subsequently detected from the north, the Methodology 27 control system transitions to Signal Group2. In this scenario, all signals for cars turn red, except for car signal number 4, which remains green to allow cars from specific directions to proceed. This setup minimizes the disruption to overall traffic flow while giving priority to the northbound bus. The system continuously monitors for further bus detections. If a southbound bus is detected during this phase, the system then shifts to Signal Group 3. If buses from both directions are detected, it advances to Signal Group 5. Signal Group 3 is specifically for handling a bus detected from the south. Similar to Signal Group 2, it turns all car signals red except for car signal number 4. The continuation into Signal Group 4 occurs if further detection from the south is noted, with the system maintaining the green signal for car number 4 unless a bus is also detected by detector 10, which would cause all signals to turn red. Signal Group 5 is a critical phase where buses from both directions have been detected. In this state, all car signals are turned red to completely halt vehicle traffic, allowing buses free passage from both directions. The system remains in this mode until no further buses are detected, at which point it resets to the initial detection phase. Overall, this flowchart illustrates a responsive and adaptive traffic management system designed to prioritize bus traffic at busy intersections while balancing the needs of regular vehicular flow. The system's ability to adjust based on bus detection and directionality ensures that traffic disruption is minimized, and safety is maintained. For the interest in a more detailed and technical depiction of this traffic management system, the complete VISVAP chart done by us based on the provided data such as the detector data, signal plan and signal data that are provided from Jönkoping muncipality refer to the appendix B. 4.2 Survey To enhance road safety and optimize traffic flow, a detailed survey was conducted targeting drivers navigating the intersections at Museirondellen and Södra Strandgatan. This area, known for its complex traffic patterns, has been a focal point of concern for both city planners and daily commuters. The objective of the survey was to gather firsthand information from drivers to better understand their experiences, perceptions, and suggestions for improvements. Google Forms was used to facilitate data collection in this survey and the following link refers to the conducted survey (https://forms.gle/vDMsd2c97ZwQgiGU7). The survey encompasses a range of questions designed to delve into various aspects of driving experience in this specific area. These aspects include the frequency of drivers’ use of these intersections, their experiences of confusion or clarity while navigating, their perception of safety, and incidents of misrouting. Additionally, the survey aims to evaluate the ease of accessing key locations such as Parkeringshus Smedjan, the effectiveness of current road designs, and the potential benefits of proposed changes such as redesigning the intersections or improving signage. https://forms.gle/vDMsd2c97ZwQgiGU7 Methodology 28 Drivers’ input on these matters is crucial for developing a data-driven approach to enhancing road safety and efficiency. The responses will provide valuable insights into current issues and will be instrumental in guiding future urban planning and traffic management decisions in the area. Below in Table 1 is a structured summary of the survey questions, outlining the key topics and the specific areas each question addresses: Table 1: Summary of the survey questions Question Description Frequency of Using the Area How often drivers travel through Museirondellen and Södra Strandgatan: daily, several times a week, occasionally, or rarely. Experience of Confusion Frequency of feeling confused while driving through the area: often, sometimes, or never. Perception of Safety Drivers' sense of safety in the area, ranging from completely safe to very unsafe. Incidents of Wrong Routing Whether drivers have mistakenly taken the wrong route in the area. Ease of Navigating to Parkeringshus Smedjan. How easy or difficult drivers find navigating to Parkeringshus Smedjan for parking. Clarity and Safety of Road Design Rating of the road design at Museirondellen and Södra Strandgatan from very clear and safe to extremely confusing and unsafe. Benefits of Redesigning for Safety Opinions on whether redesigning the intersections would improve safety. Impact of Better Signage Whether improved signage could make driving in the area easier and safer. Suggestions for Improvements in Södra Strandgatan Suggestions for changes in Södra Strandgatan, including redesign, area improvements, enhancing signage and road markings, or maintaining current design. Need for Changes in Geometric Designs If altering the geometric designs of Museirondellen and Södra Strandgatan would improve traffic flow and safety. The survey responses will play a crucial role in shaping the proposed solutions for the intersections at Museirondellen and Södra Strandgatan. By analyzing drivers’ experiences and perceptions, we aim to pinpoint specific areas for improvement, whether in design, signage, or signal optimization. This feedback, when combined with the data from traffic simulations, will guide us in identifying Methodology 29 key focus areas for our proposed changes. For instance, if a significant number of drivers report confusion at certain points, this could indicate a need for clearer signage or re-evaluation of the current geometric design. Similarly, concerns about safety or frequent wrong routings might suggest the need for modifications in traffic signal timings or lane arrangements. This comprehensive approach ensures that our proposed solutions are not just technically sound but also address real-world challenges faced by drivers, leading to more effective traffic management. Results 30 5 Results This section provides a thorough analysis of our network infrastructure's current performance by exploring individual link segments and node output capacities. Utilizing a blend of recent survey findings and simulation results, we aim to identify critical bottlenecks and pinpoint areas where traffic congestion is notably severe. This detailed evaluation serves as a foundational step in planning enhancements and ensuring the reliability and scalability of our infrastructure to meet future demands. 5.1 Traffic Simulation for Current Situation This section presents an analysis of traffic patterns based on simulations carried out using the PTV Vissim software, focusing on the average outcomes derived from multiple runs. These simulations, conducted ten times each for an hour, were initiated from the 900-second mark to the 4500-second mark of the total 3600 seconds, avoiding the initial and final fluctuating conditions to ensure the stability of traffic flow. The results are represented as average visualizations from these runs, providing insights into vehicle speeds, densities at a complex junction, and queue lengths along critical stretches of the road network. The analysis is divided into two distinct parts: the first part discusses the link segment results, which include metrics such as density, speed, and queue length. The second part delves deeper into the node results for the artery road, examining more intricate aspects of traffic flow and interactions at key intersections. This structured approach allows for a comprehensive understanding of both the general traffic behavior along the links and the specific dynamics at the nodes. 5.1.1 Speed Link Segment Figure 11 is a representation from a traffic simulation model, which illustrates the average speeds on different links of a road network that appears to be a complex junction or interchange. Results 31 Figure 11: Current visualizaCon speed The color scheme employed in the figure serves as an indicator of the traffic speeds, with a range starting from red, representing the lowest speed areas, to dark green, signifying the parts of the network where traffic moves at higher speeds. Upon analyzing the figure, it is observed that the segments running from north to south (Södra Strandgatan to Östra Strandgatan) are predominantly marked in green, which indicates that vehicles traveling in these directions tend to maintain a higher speed, suggesting a smoother traffic flow. In contrast, there are segments, possibly oriented east to west (towards Odengatan), that show yellow and orange color, signifying a reduction in speed. This pattern of speed reduction could be due to several factors such as the physical design of the road, traffic density, and intersections that require vehicles to decelerate. The red segments, which reflect the slowest speeds, are crucial for detailed examination as they may highlight congestion points or bottlenecks within the interchange. These areas could be experiencing low speeds due to high traffic volumes, traffic control signals, or due to the merging and diverging maneuvers that typically occur at such junctions. The transitional areas from red through to green—where speeds are seen to incrementally increase—illustrate the zones where traffic begins to disperse and accelerate, possibly after passing through the congestion or a traffic control device. Results 32 5.1.2 Density Link Segment In Figure 12, different colors show how dense the traffic is on various parts of the interchangeroads where vehicles merge, diverge, and cross paths. Figure 12: Current visualizaCon density Light green indicates areas with the least traffic, suggesting that vehicles are likely moving freely at the posted speed limits. These low-density areas are what we aim for in traffic planning because they mean roads are being used efficiently and safely. As colors shift from light green to yellow and then to red, they show where traffic gets heavier. Yellow hints at more cars on the road, but they're likely still moving at reasonable speeds. However, where the map turns red, traffic density is high and there are more vehicles than the road can handle comfortably, leading to slower speeds. The darkest red areas East Road (Odengatan) are of particular concern as they signal congestion, where traffic could be stop-and-go or even at a standstill. Upon closer inspection, the highest traffic density appears to be concentrated around the parts of the interchange where vehicles are joining or leaving the main flow. These are challenging spots in any road system because vehicles are changing lanes and speeds, which naturally leads to more Results 33 congestion. It's common for these areas to require careful analysis and targeted solutions to improve traffic conditions. In professional traffic analysis, understanding where and why congestion occurs is crucial. This simulation helps to do that by highlighting problem areas. For example, if the map shows consistently high density from the north, thus it might conclude there’s a heavy inflow of traffic from that direction. If it’s lighter from the south, this could mean fewer vehicles are entering the interchange from there, or the design allows for smoother merging. In essence, this Figure 12 .gives us a clear picture of which parts of the interchange are working well (the green areas) and which parts are not (the red areas). This kind of analysis is a vital step in creating road systems that serve the needs of drivers, improve safety, and keep traffic flowing, which is the ultimate goal of traffic engineering. 5.1.3 Queuing Length Link Segment Figure 13 shows the analysis of queue lengths at key arterial roads within the simulation model indicates significant congestion issues that can be attributed to suboptimal geometric designs. Figure 13: Current visualizaCon queue length Results 34 Specifically, the data reveals a queue length of 108.71 at East Road (Odengatan) and 144.88 at South Road (Östra Strängatan), suggesting excessive vehicle accumulation due to inadequate road geometries. The Factor of a poorly designed intersections may be contributing to these bottlenecks. 5.1.4 Node Data Analysis The traffic simulation has highlighted significant issues within our system, particularly in terms of extensive queuing and delays. These challenges are evident during peak traffic periods and suggest inefficiencies in the current traffic light configurations and overall traffic management. As part of our approach to addressing these problems, we conducted simulations under three scenarios with incremental increases in traffic data of three arterial roads, enhancing the traffic volume by 10%, 15%, and 20% respectively. This detailed investigation of the node results will allow us to understand the specific contributions of each intersection and junction to the overall traffic dynamics and identify targeted solutions to improve the system's efficiency. 5.1.4.1 Östra Strandgatan The traffic data for östra strangatan shown in Figure 14 provides an illustrative look at how increasing traffic volumes contribute to congestion along this specific lane. Figure 14: Node results for 3 scenarios at Östra Strandgatan 144.88 155.72 198.86 239.05 59.88 60.19 61.6 124.35 26.02 26.31 27.95 60.46 0 50 100 150 200 250 300 Current Scenario Scenario 1- 10% Scenario 2- 15% Scenario 3- 20% Östra Strandgatan Qlen Max Max Vehdelay Max Stop delay Results 35 The maximum queue length (QLENMAX) exhibits a consistent growth through the scenarios. Starting at 144.88 vehicles in the current scenario, it stretches to 155.72 vehicles in Scenario 1 and further to 198.86 vehicles in Scenario 2. The trend continues, peaking at 239.05 vehicles in Scenario 3, which underscores the lane's limitations in coping with high traffic volumes.Regarding delays, the maximum vehicle delay (Max VEHDELAY) initially shows a minimal increase from the current scenario’s 59.88 seconds to 60.19 seconds in Scenario 1. However, as traffic volume continues to rise, we witness a more notable delay of 61.6 seconds in Scenario 2. The delay reaches its apex in Scenario 3, with a staggering 124.35 seconds, more than doubling the initial figure and indicating severe congestion.The maximum stop delay also experiences a gradual increase from Scenario 1to 26.31 seconds to Scenario 2 to 27.95 seconds, and then a significant spike in Scenario 3, reaching 60.46 seconds. This indicates that at higher traffic volumes, the duration for which vehicles remain stationary increases dramatically, pointing to substantial congestion at stops, possibly due to oversaturation.In sum, the progression from the current scenario to Scenarios 1, 2, and 3 with respective traffic increases of 10%, 15%, and 20% clearly demonstrates the compounding effect of additional vehicles on congestion levels. 5.1.4.2 Odengatan The traffic data for Odengatan provided in Figure 15 show a compelling narrative of the impact of increased traffic on congestion within this particular lane. Figure 15: Node results for 3 senarios at Odengatan 108.71 150.15 239.63 309.02 41.37 59.79 109.09 146.92 21.07 25.32 39.51 57.84 0 50 100 150 200 250 300 350 Current Scenario Scenario 1- 10% Scenario 2- 15% Scenario 3- 20% Odengatan Qlen Max Max Vehdelay Max Stop delay Results 36 For the maximum queue length (QLENMAX), there is a progressive increase across the scenarios. It begins at 108.71 vehicles in the current scenario, advances to 150.15 vehicles in Scenario 1, and then climbs to 239.63 vehicles in Scenario 2. This growth trajectory peaks at 309.02 vehicles in Scenario 3, marking a troubling trend that signifies the lane's substantial struggle to cope with an increasing number of vehicles without succumbing to severe congestion. Turning to the maximum vehicle delay (Max VEHDELAY), there is an initial increase from 41.37 seconds in the current scenario to 59.79 seconds in Scenario 1. This trend of increasing delays continues, becoming more pronounced with a delay of 109.09 seconds in Scenario 2. The delay escalates further in Scenario 3, reaching 146.92 seconds. This progression indicates that as the volume of traffic increases, the delays encountered by vehicles grow significantly, leading to longer waiting times and a reduced level of service. Similarly, the maximum stop delay also increases as traffic volumes rise, starting at 21.07 seconds in the current scenario, moving to 25.32 seconds in Scenario 1, escalating to 39.51 seconds in Scenario 2, and finally peaking at 57.84 seconds in Scenario 3. These increments in stop delays reflect the compounding effects of traffic volume on congestion, with each scenario presenting a more challenging environment for traffic flow, resulting in longer and more frequent stops. 5.1.4.3 Södra Strandgatan The traffic data for Södra strandgatan in Figure 16, which is characteristically a road with low congestion levels, reveals the effects of incremental traffic volume increases on its traffic dynamics. Figure 16: Node results for 3 senarios Södra Strandgatan 12.49 13.01 13.6 14.68 18.53 21.33 23.11 25.13 10.59 11.94 12.4 13.1 0 5 10 15 20 25 30 Current Scenario Scenario 1- 10% Scenario 2- 15% Scenario 3- 20% Södra Strandgatan Qlen Max Max Vehdelay Max Stop delay Results 37 The maximum queue length (QLENMAX) shows a similar pattern, beginning at 12.49 vehicles for the current scenario. It climbs gradually to 14.68 vehicles in Scenario 3, suggesting that while the road is well-suited to handle its usual traffic volumes with minimal delay, there is a noticeable though not yet critical rise in the number of vehicles during peak conditions as traffic volumes increase. Maximum vehicle delay (Max VEHDELAY) starts at 18.53 seconds in the current scenario, escalating to 25.13 seconds in Scenario 3. These increases are relatively contained, indicating that even as traffic volume grows, the delays remain within a manageable range for a road not characterized by heavy traffic.The maximum stop delay also sees a steady but unspectacular increase from 10.59 seconds in the current scenario to 13.1 seconds in Scenario 3. This slow growth in delays at stops underscores the fact that Södra strangatan generally remains uncongested, even as it absorbs higher traffic volumes.In summary, the analysis from the current scenario through Scenarios 1, 2, and 3 demonstrates that Södra strangatan, typically free from significant congestion, exhibits only slight increases in queue lengths and delays as traffic volume progressively increases. The data underscores the importance of traffic management to maintain this uncongested state, despite the gradual rise in vehicle numbers. For a more detailed presentation of the node-specific results derived from the PTV Vissim simulations, please refer to Appendix C. This appendix contains extensive data and analysis concerning the traffic flows and interactions at crucial intersections within the simulation model. It includes tables that provide an in-depth view of variables such queue lengths, max queue length , vehicle delay ,and stop delay. This additional data is critical for understanding the complexities of traffic management and for evaluating potential improvements within the traffic network. 5.2 Survey To gain deeper insights into the public’s experience with these intersections, a survey was conducted. The survey aimed to ascertain whether drivers indeed find navigating these intersections confusing, as suggested by the media coverage. The responses, which were numerous and varied, provide valuable data for understanding the user experience and safety implications of the intersection design. Results 38 5.2.1 Driving Frequency and Experience in the Area Figure 17: Survey result for QuesCon 1 Results 39 Figure 18: Survey result for QuesCon 2 Figure 18 shows survey results for question 1&2 which demonstrate a significant regular interaction with Museirondellen and Södra Strandgatan, as evidenced by 34.3% of respondents driving through the area sev