Browsing by Subject "Intersections"

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Advanced LED Warning Signs for Rural Intersections Powered by Renewable Energy
(Minnesota Department of Transportation Research Services Section, 2010-12) Kwon, Taek Mu; Weidemann, Ryan
A majority of intersection-related fatal crashes occur at rural, through/stop intersections. At these intersections, sight restrictions caused by vertical and horizontal curves negatively affect a driver’s ability to safely accept a gap in the traffic stream. Static advanced warning signs are sometimes installed at these intersections to warn drivers on the main, through approaches that an intersection is ahead. These warning signs appear to be ineffective. A new Advanced Light-Emitting Diode (LED) Warning System was developed and deployed at a rural, through/stop intersection with limited intersection sight distance due to a severe vertical curve. This warning system actively detects vehicles on all approaches and activates LED blinker warning signs for the conflicting movements. The research project included analysis of driver behavior obtained through video data and a survey of local residents and frequent users of the intersection. This report describes the development, implementation, and evaluation results of this new warning system.
Advanced LED Warning System for Rural Intersections: Phase 2 (ALERT-2)
(Minnesota Department of Transportation, 2014-02) Kwon, Taek M.; Ismail, Husam
This report presents findings of the second phase of the Advanced LED Warning System for Rural Intersections (ALERT) project. Since it is the next generation of the same system, the second phase system is referred to as the ALERT-2 system while the first system is referred to as the ALERT-1 system. The ALERT systems demand use of four basic Intelligent Transportation Systems (ITS) technologies: LED-based signs, renewable energy, non-intrusive sensors, and wireless communication. Use of these four basic technologies remained the same for both phases of the system. In the first phase, the data showed that the ALERT-1 system reduced vehicle speeds on the main approach, increased STOP wait time on minor approaches, and eliminated roll-throughs for vehicles on minor approaches when a conflict existed in the intersection. However, when no conflict exists in the intersection, an increase in roll-throughs for vehicles on the minor approaches was observed. The ALERT-2 system was redesigned to mitigate this increased roll-throughs. With respect to technological advances, the ALERT-2 system improves many aspects of the basic technologies, providing higher system reliability, easier installation and maintainability, and better self-sustainability through redesign of the renewable energy application. To assess the driver behaviors at the test site, 13 moths worth of video data and a survey of local residents were collected. This report describes the system development, implementation, and analysis of the video and survey data.
Cooperative Intersection Collision Avoidance System – Stop Sign Assist: Experiments to Validate Use of an In-Vehicle Interface Design
(Center for Transportation Studies, University of Minnesota, 2012-04) Becic, Ensar; Manser, Michael; Creaser, Janet; Donath, Max
The three studies included in the current report examine the transition from an infrastructure-based rural intersection crossing assist system to one located inside a vehicle. The primary goals of the first study, conducted in a simulator, were to examine the effect of potentially confounding factors, such as the drivers’ familiarity with the assist system and the impact of cognitive load on the drivers’ performance. Next, we examined the efficacy of several different designs of such system to determine the optimal interface design to be used for the in-vehicle system. Finally, the optimal design of the system was examined in the third study, as a field test. The results showed that the use of the system under cognitively demanding conditions did not result in any adverse consequences, which suggested that the processing of the system required minimal cognitive resources. Additionally, the results showed that the benefits of the assist system, such as reduced probability of accepting a critical gap were exhibited under the limited visibility conditions when the perceptual task of determining an appropriate crossing gap became overly demanding. The results from the field study showed that the use of the assist system resulted in improved intersection crossing performance exhibited in increased likelihood of making a complete stop at the stop sign and showed a strong trend toward a decreased probability of accepting critical gaps. Additionally, the impact of the in-vehicle CICAS-SSA was equivalent for older and younger drivers; that is, both age groups benefited from the use of the system.
Criteria and Guidelines for Three-Lane Road Design and Operation
(Minnesota Department of Transportation, 2023-02) Davis, Gary A.; Hourdos, John; Gao, Jingru
A 4-3 conversion involves changing a four-lane undivided road into one with two general travel lanes separated by a two-way left turn lane. A commonly-used guideline states that a 4-3 conversion can be considering as long as the road’s average annual daily traffic (AADT) volume does not exceed 15,000 vehicles/day but opinions vary, from lowering the AADT threshold to 10,000 vehicles/day to anecdotal evidence for successful 4-3 conversions with AADTs as high as 20,000. The main objective of this project was to identify conditions where 4-3 conversions might be feasible at AADTs greater than 15,000. After reviewing the literature, we conducted simulation studies on three different roads to identify combinations of major and minor road flow where three-lane configurations provided acceptable levels of service. Eight intersections, with 16 approaches, were then selected to represent our findings. These results were presented as summary tables that practitioners could use to make initial assessments regarding 4-3 conversion feasibility.
Establishing a Repeatable Method for Presenting Nontraditional Traffic Treatments to Maximize Stakeholder Support
(Minnesota Department of Transportation, 2023-08) Morris, Nichole L.; Schwieters, Katelyn R.; Craig, Curtis M.; Tian, Disi
A novel infrastructure design known as the J-turn intersection reduces the risk of serious and fatal crashes at thru-STOP intersections through decreasing points of conflict at an intersection by restricting crossing movements from the minor road. Despite their demonstrated safety efficacy, J-turns have not been met with uniformly positive support. In this research, we first examine novice driver baseline attitudes and driving behaviors on J-turns using a driving simulator study. Results demonstrate that critical errors are decreased with driving exposure to the J-turn; however, attitudes toward J-turns are not improved by exposure alone. A series of studies then evaluates the efficacy of various messaging strategies and educational materials on improving attitudes toward J-turns. The findings from these studies identify that the use of both educational materials and persuasive and customized messaging strategies is an effective method for increasing acceptance of J-turns across diverse resident populations (i.e., rural, suburban, and urban) and among stakeholders in Minnesota. This work demonstrates the importance of the role of proactive educational programs and community initiatives in promoting the acceptance and buy-in toward novel roadway treatments, such as J-turns, among diverse drivers, communities, and stakeholder groups.
Examining Optimal Sight Distances at Rural Intersections
(Minnesota Department of Transportation., 2019-07) Morris, Nichole L.; Craig, Curtis M.; Achtemeier, Jacob D.
Decisions made regarding driver sight distance at rural intersections are complex and require considerations for safety, efficiency, and environmental factors. Sight distance, cross-traffic velocity, and vehicle placements significantly affect driver judgment and behavior atthese intersections. A series of rural, two-lane thru-STOP simulated intersections with differing sight distances and traffic speeds were created and then validated by county and state engineers. Experimental data from 36 participants in a time-to-collision (TTC) intersection crossing judgment task and a rural highway thru-STOP intersection driving simulation task was analyzed to clarify the influence of rural thru-STOP intersection characteristics on driving performance and decision-making. Results demonstrated that longer sight distances of1,000 ft. and slower crossing speeds (i.e., 55 mph) were more accommodating for participants attempting to select gaps and cross from the minor road, corresponding with (1) lower mental workload, perceived risk, difficulty, and anxiousness, and (2) better performance in terms of estimated crash rate, and larger TTCs. Second, longer distances of 1,000 ft. appear to aid drivers’ responsiveness on the main road approaching an intersection, specifically when another driver on the minor road runs the stop sign. Minor road drivers positioned close tothe roadway at the stop sign, compared to standard stop bar placement, tended to help reduce the speed of main road drivers. Overall,results demonstrated a systematic improvement in the performance of both minor and major road drivers with the implementation of a1,000-foot sight distance at rural thru-STOP intersections.
Improving intersection safety through variable speed limits for connected vehicles
(Center for Transportation Studies, University of Minnesota, 2019-05) Levin, Michael; Chen, Rongsheng; Liao, Chen-Fu; Zhang, Tab
Autonomous vehicles create new opportunities for innovative intelligent traffic systems. Variable speed limits, which is a speed management systems that can adjust the speed limit according to traffic condition or predefined speed control algorithm on different road segments, can be better implemented with the cooperation of autonomous vehicles. These compliant vehicles can automatically follow speed limits. However, non-compliant vehicles will attempt to pass the moving bottleneck created by the compliant vehicle. This project builds a multi-class cell transmission model to represent the relation between traffic flow parameters. This model can calculate flows of both compliant and non-compliant vehicles. An algorithm is proposed to calculate variable speed limits for each cell of the cell transmission model. This control algorithm is designed to reduce the stop-and-go behavior of vehicles at traffic signals. Simulation is used to test the effects of VSLs on an example network. The result shows that VSL is effective at reducing the energy consumption of the whole system and reduce the likelihood of crash occurrence.
Innovative Technology Workshop on 3D LIDAR
(Center for Transportation Studies, University of Minnesota, 2016-06) Davis, Brian
The use of LIDAR is becoming more common among state, county, and local agencies. It presents a means for collecting a great deal of information about the geometry of a road, its surrounding area, and depending on the sensors used, real-time 3D information about vehicle, cyclist, and pedestrian movements. The main focus of this project was to develop and conduct two workshops in Minnesota for public DOT and GIS professionals to provide information on the state of the art in mobile LIDAR scanning. Topics included the basics of LIDAR operation, an overview of currently available hardware, as well as current and future applications of the technology. Additionally, the workshops featured a live demonstration of a Velodyne HDL-64E 3D LIDAR scanner. A sample application was developed to both demonstrate and better understand the capabilities of a real-time 3D LIDAR scanner. This work focused on developing a system capable of automatically collecting vehicle trajectories through intersections using 3D LIDAR data. This application showed that LIDAR might be a suitable tool for collecting traffic data and provided valuable information about the strengths and limitations of such a system. This project was designed to provide transportation and GIS professionals with accurate, current, and applicable information about LIDAR systems. To accomplish this, existing LIDAR knowledge was combined with market survey research as well as with new information gathered through the process of creating a sample application. This knowledge was aggregated and used to create a workshop that was informative and well received by participants.
Intersection Control Through Video Image Processing: Executive Summary
(Minnesota Department of Transportation, 1992-07) Michalopoulos, Panos
Among the most promising and innovative concepts today for alleviating urban traffic congestion is the use of video imaging for vehicle detection, automatic surveillance, and advanced control strategies. Because of its conceptual appeal, research in this area was initiated in the mid 70's in the United States and abroad. A system for vehicle detection through video imaging was recently developed at the University of Minnesota and is being implemented on the 1-394 and l-35W freeways in Minneapolis, Minnesota for incident detection. The Minnesota system, called AUTOSCOPE (TM), emulates loop detectors, a large number of which can easily be placed within the field of the camera's view through interactive graphics. In recent tests its performance matched or exceeded that of loops in vehicle counting, speed measurements, and extraction of certain measures of effectiveness. Evaluation tests of the AUTOSCOPE (TM) were very encouraging, thus the system was installed at a traffic intersection to demonstrate the effectiveness of this new technology as a replacement for loop detectors.
Pedestrian Control at Intersections - Phase III
(Minnesota Department of Transportation, 1998-04) Masoud, Osama; Papanikolopoulos, Nikolaos P.
This report presents a real-time system for pedestrian tracking in sequences of grayscale images acquired by a stationary CCD (charged-coupled devices) camera. The research objective involves integrating this system with a traffic control application, such as a pedestrian control scheme at intersections. The system outputs the spatiotemporal coordinates of each pedestrian during the period the pedestrian remains in the scene. The system processes at three levels: raw images, blobs, and pedestrians. It models blob tracking as a graph optimization problem and pedestrians as rectangular patches with a certain dynamic behavior. Kalman filtering is used to estimate pedestrian parameters. The system was implemented on a Datacube MaxVideo 20 equipped with a Datacube Max860 and on a Pentium-based PC. The system achieved a peak performance of more than 20 frames per second. Experimental results based on indoor and outdoor scenes demonstrated the system's robustness under many difficult situations such as partial or full occlusions of pedestrians.
Stopping Behavior at Real-World Stop-Controlled Intersections with and without In-Lane Rumble Strips
(Minnesota Department of Transportation, 2006-11) Harder, Kathleen A.; Bloomfield, John R.; Chihak, Benjamin
This was the third in a series of studies investigating various aspects of rumble strips. In this study, to determine the effect of rumble strips on the real-world stopping behavior of drivers, we used a radar gun to collect speed data from over 400 vehicles on the approaches to ten intersections selected from a sample of 274 approaches. We found that, after drivers encountered the first set of in-lane rumble strips, they slowed down earlier on real-world approaches With Rumble Strips than on real-world approaches Without Rumble Strips—the difference was, on average, 2.0 mph to 5.0 mph (depending on vehicle category and type of approach). In addition, speeding outliers were more likely to slow down earlier on approaches With Rumble Strips. The effect of the presence of in-lane rumble strips on stopping behavior was greater for approaches where the driver’s view of traffic on the major road is obscured on one or both sides of the road. The study suggests that stop-controlled intersections at which cross-traffic is obscured by manmade structures and/or vegetation on one or both sides of the intersection would be good candidates for implementing in-lane rumble strips. It is worth noting that while in-lane rumble strips are likely to reduce crashes, they cannot eliminate them. Some drivers might still run stop signs and others might misjudge gaps.
Using a Smartphone App to Assist the Visually Impaired at Signalized Intersections
(Intelligent Transportation Systems Institute, Center for Transportation Studies, University of Minnesota, 2012-08) Liao, Chen-Fu
The blind and Visually Impaired (VI) rely heavily on walking and public transit for their transportation needs. A major challenge for this population is safe crossing of intersections. As a result of the American with Disabilities Act (ADA), Accessible Pedestrian Signal (APS) systems at signalized intersections have improved significantly since 2000. However, these systems still have shortcomings for both users and municipalities, and new approaches are needed to adequately serve pedestrians with low vision. As part of our ongoing effort to develop a prototype Mobile Accessible Pedestrian Signal (MAPS) application for the blind and VI, we interviewed ten blind and lowvision people to better understand what types of information they use at intersection crossings and to identify information types that could assist them. With these survey results, a MAPS prototype was developed that provides signal and intersection geometry information to Smartphone users at signalized intersections. User interaction is via simple tactile input (single or double-tap) and Text-To-Speech (TTS) technology. A MAPS prototype was developed and tested to evaluate the functionalities of providing signal and orientation information to the visually impaired travelers at signalized intersections. This proposal will build upon the developed MAPS and investigate how blind and low-vision individuals gain their spatial knowledge surrounding an intersection and how the MAPS can be used to support their decision-making strategy at intersection crossings.
Using Detailed Signal and Detector Data to Investigate Intersection Crash Causation
(Intelligent Transportation Systems Institute, Center for Transportation Studies, University of Minnesota, 2013-01) Davis, Gary A.; Chatterjee, Indrajit
Traffic crashes may not always result in severe or fatal injuries, but they can still have nontrivial impacts on system performance, particularly during heavy traffic conditions. One way toward reducing the frequency of such incidents is to first identify the necessary circumstances that resulted in the collision. However, road crashes, particularly intersection related crashes, are complex phenomenon and often result from different combinations of causal factors. Recently, methods for recording high-resolution arterial traffic data have been developed, and it is important for traffic safety engineers to explore such high-resolution data to understand the causes of crashes. In this research one such integrated event based system, known as SMART SIGNAL, which collects and stores detailed loop detector and signal activity, was used to identify the events leading to a crash or a potential crash and illuminate the mechanisms by which traffic conditions and driver decisions interact to produce those events. Two specific event types, a signal violation crash and vehicle pedestrian crash, were evaluated. For the signal violation crash study, SMART SIGNAL data were used to identify the incident and the vehicles involved in the crash. It was then shown how high-resolution data could support a traditional reconstruction of this crash. For vehicle pedestrian interactions, detector and signal activity data were used to predict pedestrian crash risk in the absence of clearance interval at three signalized intersections. A simulation-based method was used to first estimate crash probabilities, and then a counterfactual approach to calculate the probability of the absence of the all-red phase as a necessary condition for the occurrence of the crash provided an alternate estimate of crash-reduction factors for the all-red phase.

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