At-grade Intersections Research Articles

Addressing Infrastructure Design Challenges In Constructing At-Grade Rail Crossings Near Road Intersections

At-grade rail crossings, where railway tracks intersect roadways at the same level rather than being separated by bridges or tunnels, are crucial elements of transportation infrastructure. However, these crossings create significant challenges for rail operations, particularly regarding safety and efficiency. Locating an at-grade rail crossing near a road intersection is generally discouraged due to the increased risk of train delays, reduced visibility for train operators, and the potential for train-road conflicts. While these issues are undesirable, they are sometimes unavoidable when rail infrastructure must be near or across road intersections. This study examines the design challenges of constructing at-grade rail crossings near road intersections. It provides a comprehensive review of the safety and operational concerns, including delays, conflicts, and the potential for accidents. The study also discusses existing guidelines and design practices to mitigate these challenges, offering insights into improving the efficiency and safety of at-grade rail crossings near road intersections.

Roundabout Safety Benefits, Design Considerations and Safety Evaluation Techniques

Roundabouts are increasingly replacing conventional signalized intersections due to their potential to enhance traffic safety and operational efficiency. This paper examines and reviews the safety benefits, design considerations, and evaluation methods for roundabouts. Studies consistently show significant reductions in crashes at roundabouts relative to other at-grade intersection control systems, particularly severe injury crashes, with reductions ranging from 37% to 88%. Roundabouts reduce conflict points, lower vehicle speeds, and improve safety for both motorized and vulnerable road users. The methodology for this paper involved a comprehensive review of literature on roundabout design and safety evaluation techniques. Data from global studies were analyzed to identify key design elements such as geometric layout, signage, and pedestrian provisions, which contribute to roundabout safety. Various safety evaluation methods, including crash data analysis, traffic conflict techniques, and surrogate safety measures, were also assessed for their effectiveness in evaluating roundabout performance. Findings indicate that proper geometric design, clear signage, and the use of innovative features like right-turn bypass lanes and roundabout metering systems can enhance safety and traffic flow. Based on these findings, the paper recommends integrating these design elements, prioritizing the safety of vulnerable users, and utilizing advanced safety evaluation techniques, including simulation modelling and intelligent transportation systems (ITS) to further optimize roundabout performance.

Use of Historical Road Incident Data for the Assessment of Road Redesign Potential

Drivers’ safety and overall road functionality are key triggers for deciding on road interventions. Because of the socioeconomical implications of traffic incidents, either fatal or no, continuous research has been dedicated over the previous decades on the assessment of factors contributing to crash potential. Apart from the behavioral aspects of driving, which are commonly studied through simulation and advanced modelling techniques, the road infrastructure status is of equal or even higher significance. In this study, an approach is presented to discuss the road redesign potentials based on the evaluation of network-level historical incident records from road crashes in Greece. Based on total and fatal crash records, the following infrastructure-related aspects were assessed as critical for the discussion of the road redesign potential needs: the status of road’s surface (i.e., dry, wet, etc.), the issue of improving driving conditions near at-grade intersections, the presence and suitability of signage and/or lighting, and the consideration of particular geometric design features. Overall, it is deemed that intervention actions for at least one of these pillars should aim at enhancing the safety and functionality of roadways.

Comparison of E-Scooter and Bike Users’ Behavior in Mixed Traffic

This study aims to investigate the different behaviors with respect to safety measures related to the interaction of e-scooters and bikes with cars in mixed traffic. E-scooters are relatively new vulnerable road users, and their behavior is still not fully understood. For this purpose, an observational study was carried out at an unsignalized at-grade intersection in the city of Catania, Italy. A total of 128 interactions between cars and e-scooters and 89 interactions between cars and bikes were detected. Specifically, two surrogate measures of safety were used, the time to collision (TTC) and post encroachment time (PET), which relate to the “crossing” and the “following” interactions between cars and bikes/e-scooters. The results show that 50% of the “crossings” involving bikes were close interactions with low TTCs representing high risk (TTC < 1.5); meanwhile, for the “crossing” interactions between cars and e-scooters, the same threshold of TTC relates to percentiles of more than 80%. In addition, more than 60% of interactions between cars and e-scooters were characterized by PET values representing a potentially high risk (PET < 1.0 s). The results provide a useful starting point for the elaboration and adaptation of new regulations for mixed traffic conditions including e-scooters that are currently being introduced in several countries with different rules. It should be noted that e-scooters are an intrinsically different transport mode from a bicycle, mainly because their interactions in mixed traffic show that they are prone to a higher risk of closer interactions.

A Performance Analysis of a Two Way Stop Control (TWSC) Intersection under Mixed Traffic Conditions

Intersections are road traffic infrastructure on highways installed to help settle directional movement that could result in conflict while vehicular trips are made. Evaluation of the challenges faced by different automobile users at the Araromi junction (A three Leg at-grade Intersection) located in Akure is the main objective of this paper. To achieve this objective, traffic flow data were collected on the spot by video recording and then the data were manually counted. While, the highway Capacity manual 2010 methodology was adopted to analyse The entry flow rates, Potential Capacities, Movement Capacities, Movement Control Delay, Approach Intersection Control and 95th Percentile Quene Length of the intersection. Findings shows that an average entry flow rate of 357 pc/h occurs for all the legs of the intersection, the North bound left turning movement of the intersection was not within the allowable limit, the average potential capacity by lane for the intersection is 445 pc/h, and the average movement capacity by lane 473 Pc/h, the various legs of the intersection has a level of service of ‘A’ and ‘C’ except the left turning minor street movement that has an ‘F’ LOS. Due to the influence of high traffic flow around the intersection, the analysis of the real-time traffic flow results reveals the need to diverge the high right turning movement into other route to cater for low left turning movement causing delay and poor LOS and a need to introduce Signal on the intersection in other to improve on her functionality.

The Feasibility and Operational Performance of Implementation Median U-turn Intersections: A CRITIC Method

Currently, a growing number of cities are adopting the Median-U-Turn (MUT) intersection design to enhance road capacity and traffic efficiency. The critical question in selecting the right intersection design is how significantly the implementation of MUT can enhance intersection performance, focusing on three key aspects: intersection efficiency, capacity, and the environmental impact of the design. To address this question, an evaluation of operational performance under various prevailing conditions (roadway and control) was conducted using VISSIM, a microscopic simulation platform. This evaluation involved five scenarios: conventional intersections (with increased cycle length, grade separation with a signalized at-grade intersection, grade separation with a roundabout), MUT, and signalized crossover MUT at a dense urban arterial intersection in Amman, Jordan's capital. The performance was compared using several metrics: average control delay, number of stops, average travel speed and time, average stopped delay, Carbon Monoxide (CO) emissions, fuel consumption, and vehicle safety. The Criteria Importance Through Intercriteria Correlation (CRITIC) technique was subsequently used to select the optimal design. The findings indicate that the existing intersection configuration is the least effective, while the MUT with signals at the crossing U-turn points is the most efficient solution.

Contribution of the IATSS research projects to disseminating modern roundabouts in Japan

Until early 2000s, modern roundabouts (RABs) were poorly understood in Japan and were not fully recognized as a form of at-grade intersections. The RAB research projects of the International Association of Traffic and Safety Sciences (IATSS), which began in 2009, started with examining the applicability of RABs in Japan and have steadily progressed to various stages of field experiments, social implementation, and dissemination promotion activities. These RAB research projects, which lasted for approximately seven years, are considered to have played a significant role in the practical application of RAB in Japan. This paper provides a chronological overview of the history, content, and development status of these projects and records and discusses the role that IATSS research projects played in the early days of RABs in Japan.

The Effect of Barzan Highway Improvements on the Traffic Stream Parameters

The rapid economic growth in Duhok City has resulted in high traffic volumes, increased the flow of stream traffic, and decreased the speed of running. Therefore, over the last few years, many roads have suffered from non-uniform traffic flow, traffic jams, and increased traffic accidents. There are several causes for the development carried out by the Duhok Governorate on the Barzan Highway, where signalized at-grade intersections were replaced by bridges and tunnels to prevent conflicts between vehicles on the highway. This study will evaluate how much improvement has been made to the Barzan Highway's main parameters after the improvements have been made. Based on the results of the study, it can be concluded that the underpasses have contributed to the creation of safer roads by reducing the accident rate by 47%, decreasing the average traffic flow from west to east (Imam Hamza underpass to Farmanda underpass) by 32%, and decreasing the average traffic flow from east to west by 10%, reducing travel time from west to east by 48%, and from east to west by 45%; moreover, the density improved from west to east by approximately 60%, while from east to west by 63%.

Performance analysis, evaluation, and improvement of selected unsignalized intersection using SIDRA software – Case study

Abstract Significant social, economic, and environmental costs are associated with traffic congestion. The effectiveness of intersections makes a substantial contribution to the effectiveness of entire road networks. The three-leg at-grade Al-Husainea intersection, located 20 km from the center of holy Karbala city in Iraq, is subjected to serious congestion, resulting in an increase in delay time, reduction in capacity, and bad level of service (LOS). Therefore, it is essential to use advanced software tools to ensure that the current intersection can be controlled, evaluated, and improved. So, the major goal of this study is to use SIDRA, an acronym for signalized and unsignalized intersection design and research aid, software to evaluate the LOS of the Al-Husainea intersection, in which the traffic is assessed using the current LOS. LOS, delay time, and degree of saturation were the criteria utilized to evaluate the traffic flow performance. SIDRA is also used to assess benefits as a result of suggested changes in the design of particular junctions. The first stage is to gather field data regarding traffic volumes utilizing a method of traffic volume gathering. From 7 am to 6 pm, the SIDRA program gathered data for a full 7 days. The results showed that the LOS for the Al-Husainea intersection in the Al-Husainea arm is F, with an average delay of 52 s per vehicle and a saturation level of 0.86 v/c. Finally, it was determined that the Al-Husainea intersection needs additional improvements based on the study and findings from the SIDRA program, and some remedies are suggested in this study to improve the intersection traffic flow.

The role of traffic conflicts in roundabout safety evaluation: A review

The roundabout is one type of at-grade intersection commonly seen in many countries. The evaluation of roundabout safety is usually counted on conflict analysis of the roundabout traffic due to random and limited records of real accidents. This paper surveyed published papers and reports that investigate the role of traffic conflicts in roundabout safety evaluation. It summarized the definitions and observation methods of roundabout conflicts and classified the attributing factors of roundabout conflicts and the countermeasures to control the conflicts. This study found that although unique traffic flow movements at roundabouts create special patterns of roundabout conflicts, the methods of roundabout conflict analysis used in most existing studies were inherited from the studies of highway or cross-intersection conflicts, including conflict definitions, conflict measurements, and thresholds of conflict severity. Special or improper designs of roundabout configurations or basic geometry elements could arouse roundabout conflicts. The most common vehicle-to-vehicle conflicts were entering-circulating conflicts, sideswipe conflicts, and exiting-circulating conflicts. The conflicts among vehicles and vulnerable road users (VRUs) easily evolved into serious collisions, but these conflicts did not get deserved attention in previous studies. Drivers’ familiarity with roundabouts also affected road users’ safety. Traffic signs and pavement markings were commonly used to control roundabout conflicts, while traffic signals were more effective methods for the roundabouts with uneven distribution of approaching traffic or high traffic volume. Based on the analysis of existing studies, this paper pointed out seven future directions of further research in term of conflict measurement, data collection, infrastructure and access management, geometry, drivers and VRUs, signal control, and vehicle control.

Development of a Photovoltaic-Based Module for Harvesting Solar Energy from Pavement: A Lab and Field Assessment

The concurrent worldwide energy crisis has become a strong incentive for researchers, governments, and industry professionals to focus on sustainable energy solutions. Consequently, pavement photovoltaic energy harvesting technologies, as one of the most common sustainable energy solutions, have recently seen a significant improvement, especially in the new innovative designs of pavement solar panels. In this study, an innovative design for a prototype energy harvesting system was proposed based on thin-film photovoltaic solar panels. In addition, the feasibility of utilizing the generated power of the proposed system to illuminate a pedestrian crosswalk to enhance the safety of an at-grade intersection was also analyzed. The designed prototype consists of a thin-film solar panel, a transparent cover to protect the solar panel, and a wooden frame to support the panel and distribute the load. Different materials for the transparent covering plates were investigated, including polycarbonate with varying thicknesses, textured GlassGrit, and textured float glass with corundum skid-resistant coating on the surface. Finite element analysis was also conducted to analyze the behavior of solar panel-incorporated layered asphalt pavement subjected to dynamic wheel loading. The results showed that the suggested model could sustain the structural loads of a moving wheel without failure. Experimental results of the study showed that considering the seven hours of operation on a typical sunny day, the proposed system could generate approximately 699 Watt-hour of power during 7 h of operation (9 a.m.–4 p.m.) from the 304.8 mm (12 inches) × 304.8 mm (12 inches) pavement solar panel.

Comprehensive Review on Capacity Analysis of Rotary Intersection

Rotary intersection, which is a special type of at-grade intersection, where all converging vehicles are forced to move round a central island in clock-wise direction. Increasing trends of traffic in urban area is a major concern in all the cities in India. The heterogeneous traffic are more diverse in nature due to lane changing and lack of lane discipline characteristics of driver’s in India. The rotary intersections are of the most vital components of urban roadway network. Intersection is one when either three or more road meets or intersects each other. It has been observed that the entry capacity of vehicles become comparatively lower at intersection than that of the straight portion of the road due to reduction in speed. The traffic flow characteristics at rotary intersections are study to observe the performance of intersection. The capacity of the roadway rotary depends on the flow at different legs approaching the rotary. The present traffic scenario is usually used to characterize the present traffic condition to access the different parameters at different types of intersection. The crossing of vehicles is avoided by allowing all vehicles to merge into the streams around the rotary and then to diverge out to the desired radiating road. Thus the crossing conflict is eliminated and converted into weaving maneuver or a merging operation from the right and diverging operation to the left. In this paper, an comprehensive review is presented on capacity analysis of rotary intersection.

Are facilities to support alternative modes effective in reducing congestion?: Modeling the effect of heterogeneous traffic conditions on vehicle delay at intersections

Multimodal facilities are being built in a majority of urban areas to accommodate both motorized and non-motorized traffic. The resulting transportation system is susceptible to complex interactions between different modes and users. These complex interactions are hard to quantify and capture on a regular basis. There is a need to rely on a microsimulation platform to replicate such real-world scenarios and forecast future conditions. This study focuses on assessing the effect of heterogeneous traffic conditions involving multiple modes like light rail transit (LRT), walking, bicycling, and motorized traffic on vehicle delay at intersections using Vissim traffic simulation software. A 2.5-mile urban arterial corridor comprising of seven at-grade and two grade-separated signalized intersections along US-29 route in the city of Charlotte, NC, USA was chosen for analysis and modeling. Base simulation model was developed by replicating the traffic scenario for the year 2018 (without LRT and non-motorized traffic). External controllers like VisVAP and Viswalk were used to assign signal priority and model heterogenous traffic conditions. The vehicle operational performance of the corridor improved along the major street after the addition of the LRT. An increase in vehicle delay on the major street was observed with an increase in the non-motorized traffic. Contrarily, the operational performance of the cross-streets at at-grade intersections did not see any significant change due to the addition of non-motorized traffic. The proposed framework assists planners to assess the impact of adding a new transit system like LRT and associated non-motorized traffic on the urban corridor.

Safety Analysis and Level of Service (LOS) Evaluation for At-Grade Intersections along the Metro Rail Corridors in Smart City Pune

Abstract: Infrastructure development is key for economic growth of a country. However, poorly planned and deficiently designed infrastructure facilities becomes hazardous to the public. This leads to frequent fatalities in densely crowded cities like Pune. To minimizing fatalities by improving existing infrastructure facilities is game changer to overcome this problem. In India and around the globe many crowded cities are transforming with Metro rail networks to make urbanites life easy. In this study we have analyzed safety measures and evaluated Level of Service (LOS) for At-Grade intersections, along metro rail corridors in Pune city. This study gives good to fare idea about current safety situation of At-Grade junction based on various parameters viz. Junction Design, Pedestrian Facilities, Public Transport Facilities, Impact of Metro Infrastructure etc. The data used in this study is mostly open sourced data from Mappls RealView 360, Google Street View and site inventory. This study can be used for wide scale implementation for crowded cities, which may helpful in multimodal infrastructure development.

SAFETY ANALYSIS AND LEVEL OF SERVICE (LOS) EVALUATION FOR AT-GRADE INTERSECTIONS ALONG THE METRO RAIL CORRIDORS IN SMART CITY PUNE

Infrastructure development is key for economic growth of a country. However, poorly planned and deficiently designed infrastructure facilities becomes hazardous to the public. This leads to frequent fatalities in densely crowded cities like Pune. To minimizing fatalities by improving existing infrastructure facilities is game changer to overcome this problem. In India and around the globe many crowded cities are transforming with Metro rail networks to make urbanites life easy. In this study we have analyzed safety measures and evaluated Level of Service (LOS) for At-Grade intersections, along metro rail corridors in Pune city. This study gives good to fare idea about current safety situation of At-Grade junction based on various parameters viz. Junction Design, Pedestrian Facilities, Public Transport Facilities, Impact of Metro Infrastructure etc. The data used in this study is mostly open sourced data from Mappls RealView 360, Google Street View and site inventory. This study can be used for wide scale implementation for crowded cities, which may helpful in multimodal infrastructure development. Key Words: Level of Service, LOS, Safety Analysis, At- Grade Intersection, Junction Design.

Experimental Test of Turning the At-Grade Intersection for Articulated Buses

Experimental Test of Turning the At-Grade Intersection for Articulated Buses

Driver’s Perceived Satisfaction at Urban Roundabouts—A Structural Equation-Modeling Approach

In recent years, the use of roundabouts in road networks has reflected a sustainable and modern solution for traffic intersections. Their implementation, integrated design, and proper evaluation are a necessity to achieve their beneficial results. According to the latest edition of the Highway Capacity Manual (HCM) and the Highway Capacity and Quality Service (HCQS), a comprehensive evaluation of a roundabout is based on the interchangeable use of the LOS (level of service) and QOS (quality of service). Both manuals describe the LOS criteria, which are the same as those currently used for unsignalized at-grade intersections, while the QOS methodological description and criteria are not specifically defined. The quality of service, which corresponds to road users’ perceived satisfaction, is determined by identifying and evaluating certain factors that have an impact on users. While the previous work on evaluating the quality of roundabouts is limited, this work aimed to present and evaluate the concept of QOS for urban roundabouts in Greece and to assess the factors that affect drivers’ perceived feeling of comfort. The methodology used for the research, included data collection via an on-line questionnaire addressed to the users of the Greek road network and a statistical analysis based on the performance of six latent variables named quality components (exploratory factor analysis). A structural equation model (SEM) was used to determine the causal relationship between primary factors and quality components. It was noted that the SEM cannot predict the travel behavior but it has ability to express relationships between unobserved and observed variables. The results of the revealed model are of great value for the development of: (a) a comprehensive conceptual framework of the QOS and (b) a critical analysis of the parameters that should be considered for the assessment of the QOS of a roundabout. Identifying the factors that influence road users’ perception in terms of safety and comfort (quality of service) leads to a better knowledge and understanding of the road network characteristics that are important to road users and that influence their behavior and level of satisfaction.

FACTORS AFFECTING STOPPING BEHAVIOUR AT SUBURBAN INTERSECTIONS

This study focused on how drivers dealt with intersections controlled by a stop sign at suburban in Al-Husn city at Irbid governorate, Jordan. The videotape was used at eight unsignalized intersections for one complete peak hour on weekdays. Any at-grade intersection that is not controlled by a traffic signal is defined as an "unsignalized intersection." The results showed that 48% out of 1,208 drivers took the decision to stop completely compared to 52% who chose to keep driving. Female drivers (75%) were observed to stop at intersections more frequently than male drivers. In terms of vehicle type, drivers of buses stopped more frequently than drivers of small passenger cars, which are road car, other than a motorcycle, that is designed to transport passengers. Driver age and compliance to a stop sign were found to be directly proportional to each other, but as the number of passengers in the vehicle increased, the rate of non-compliance also increased. Compliance was highest among leading vehicles, followed by following vehicles, and lowest among single vehicles. A binary logistic model showed that age, vehicle occupancy, and arrival pattern significantly affected stopping the behaviour. Gender and vehicle type were not significantly related to stopping the behaviour.

Assessment of Risk-Taking Behaviour of Young Motorcyclists at Un-Signalised Intersections – A Partial Least Square Structural Equation Modelling Approach

At un-signalised at-grade intersections or roundabouts, motorcyclists have to make a quick decision to manoeuvre and avoid crash. Many studies show that risk-taking behaviour is the major cause of accidents in young motorcyclists. In this study, we analysed various factors that are involved in the risk-taking behaviour of young motorcyclists at un-signalised intersections. Online questionnaires were distributed among university and college students in Islamabad and Rawalpindi. The data of 490 respondents were collected to test the research model. Partial least square structural equation modelling approach was used to evaluate the measurement model, structural model and importance-performance map analysis. In this study, we assumed that risk-taking behaviour of young motorcyclists at un-signalised intersections could be influenced by several factors, i.e., demographic, past crash involvement, and peer influence. The results revealed that past crash involvement, confidence level, and peer influence were the significant factors that affect the risk-taking behaviour. Peer influence has the highest effect on the risk-taking behaviour. The person whose friends encourage them to take risk and accept challenges is more likely to exhibit the risk-taking behaviour. Those people who are more confident while riding a motorcycle are more likely to take risks.

A novel method for the detection of road intersections and traffic rules using big floating car data

The information of road intersection and traffic rules plays an essential role in transportation system especially for people travelling to large, unfamiliar cites. Moreover, cities are growing fast and it is difficult to keep up with the changing frequency of road network information although road map is periodically updated to provide reliable information. In order to tackle this problem, an automatic method to detect road intersection and traffic rules using a floating car trajectory dataset is proposed. The turning trajectories using a newly proposed algorithm employing flexible spatial, temporal, and logical constraint rules were first extracted. Then a Two-trajectory Intersect Angle-based (TIA) method was proposed to locate the candidate points at road intersection. Finally the intersections (junctions) were detected using a cluster-based technique. Furthermore, turning rules at road intersections were extracted automatically by clustering the angles both before and after making a turn. The effectiveness of our method was demonstrated using big floating car trajectory dataset collected in Fuzhou, China. Additional comparisons and analysis were also conducted to confirm identification results. Our findings showed that a total 333 at-grade intersections were detected automatically with more than 94% in accuracy, and turning rules identification reached 85% in accuracy by manually comparing the results.