Download or read book Evaluation of Dynamic Speed Feedback Signs on Freeway Interchange Ramps written by Md Shakir Mahmud and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dynamic speed feedback signs (DSFS) are promising countermeasure to reduce curve speeds and subsequent lane departures at freeway interchange ramps, although their use in such contexts has been limited. Consequently, the impact of DSFS on driver performance at interchange ramps has remained unproven. To that end, research was performed to determine the effect of DSFS installed at freeway interchange ramps on measures of driver behavior, particularly vehicular speeds approaching and entering the ramp curve. To accomplish this objective, a series of field evaluations were conducted at six freeway interchange ramps possessing significant horizontal curvature. Several factors were tested during these evaluations, including: DSFS messaging strategy, positioning of the DSFS with respect to the start of the curve and side of the ramp, physical characteristics of the DSFS, radar detection range, interchange type, and temporal effects. Speed data were collected using one of these three techniques selected based on the site characteristics and types of data desired: 1) a series of high-definition video cameras, 2) handheld LIDAR, and 3) a speed-trailer. Several measures of effectiveness including speed at different locations, speed of drivers at different speed percentiles, and initial braking location were analyzed using appropriate regression techniques. Considering all phases of the field evaluation, it was concluded that DSFS are an effective countermeasure for reducing the speeds of vehicles approaching and entering horizontal curves on freeway exit ramps. The most critical aspect influencing the effectiveness of the DSFS as a speed reduction countermeasure was the longitudinal positioning of the sign relative to the ramp curve. Overall, the presence of a DSFS positioned near the start of the curve resulted in curve entry speeds that were, on average, 1.5 mph to 5.3 mph lower than without a DSFS present at the site. When the DSFS was present near the start of the curve, the lowest curve entry speeds were observed for cases where the feedback message activated when vehicles were within 250 to 400 ft of the start of the curve. Regarding DSFS lateral position, both the right-side-mounted and forward-mounted (i.e., ramp gore area) installations resulted in similar curve entry speeds. Furthermore, there were no discernable differences in curve entry speeds between 15-inch and 18-inch display panels, nor were speeds impacted by the inclusion of an advisory speed panel. In terms of feedback message, the most effective strategy was to display the measured speed alternating with a SLOW DOWN message. The effects on driver behavior associated with the DSFS were consistent between system interchanges and service interchanges, and across all vehicle types. The DSFS was equally effective irrespective of the mainline speed limit or ramp advisory speed. However, more pronounced speed reduction effects were observed for faster drivers (i.e., those within the highest quantiles) compared to the slower or average drivers. Furthermore, there was no evidence of temporal changes in driver behavior during the initial 14 months of operation of the permanent DSFS installation evaluated here. Finally, message activation did not show any significant effect on the speeds of mainline (i.e., non-exiting) vehicles. These findings were subsequently utilized towards the development of guidelines and recommendations for future use of DSFS at freeway interchange ramps.
Download or read book Evaluation of Dynamic Speed Feedback Signs on Curves written by Shauna L. Hallmark and published by . This book was released on 2015 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lane departure crashes are a significant safety concern. The majority of lane departure crashes occur on rural two-lane roadways, with a disproportionate number of these crashes on horizontal curves. Curve-related crashes involve a number of roadway and driver causative factors. A primary driver factor is speeding. Dynamic speed feedback sign (DSFS) systems are one method to reduce vehicle speeds and, consequently, crashes on curves. These systems show promise but they have not been fully evaluated on curves. The Center for Transportation Research and Education at Iowa State University conducted a national demonstration project to evaluate the effectiveness of two different DSFSs in reducing speed and crashes on curves at 22 total sites on rural two-lane roadways in seven States. The goal is to provide traffic safety engineers and other professionals with additional tools to manage speeds and crashes on rural horizontal curves more effectively. Data were collected before and at 1, 12, and 24 months after installation of the DSFS. On average, most sites had decreases in mean speeds, with decreases up to 10.9 miles per hour (mph) noted for both the point of curvature (PC) and center of curve (CC). Most sites experienced changes in 85th percentile speed of 3 mph or more at the PC, with the majority of sites having a decrease of 2 mph at the CC. The numbers of vehicles traveling 5, 10, 15, or 20 mph over the posted or advisory speed limit were also compared. Large reductions in the number of vehicles traveling over the posted or advisory speed occurred for all of the after periods at the PC and CC, indicating that the signs were effective in reducing high-end speeds, as well as average and 85th percentile speeds. A before-and-after crash analysis was also conducted, and crash modification factors (CMF) were developed. CMFs ranged from 0.93 to 0.95 depending on the crash type and direction of the crash.
Download or read book An Evaluation of Freeway Ramp Speed Advisory Signs for Trucks written by P. L. Olson and published by . This book was released on 1991 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evaluation of Ground Mounted Diagrammatic Entrance Ramp Approach Signs written by Helmut T. Zwahlen and published by . This book was released on 2000 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: Highway-freeway interchanges can be a source of confusion to unfamiliar drivers. Typically, freeway entrance ramp information is provided by means of trailblazer assemblies (interstate or highway shield, cardinal direction, and a small white arrow on a blue shield). Trailblazer assemblies are generally located right at the interchange location, giving unfamiliar drivers very little advance notification as to the proper lane choice needed to gain access to the freeway entrance. Advance located ground mounted diagrammatic guide signs provide this much needed information well in advance of the interchange entrance, thus giving drivers more time to change lanes, if needed. Diagrammatic signs have been used in Europe for many years with great success. The present study investigated the effectiveness of ground mounted diagrammatic signs in the context of urban multi-lane arterials leading to a freeway. The diagrammatic sign layout was designed as part of this project in collaboration with ODOT. Six highway-freeway interchanges were selected in the Greater Columbus, Ohio, area to determine the effectiveness of the diagrammatic signs in the field. Traffic flow video footage was collected at the selected sites before the diagrammatic signs were installed. The finalized diagrammatic sign designs were then installed and the traffic flow videotaping was repeated. The collected video footage was automatically analyzed with Mobilizer PC. The resulting vehicle count, speed, and headway data was used as input to a closed form analytical model to determine the probability that drivers could successfully change lanes as needed, prior to reaching the gore of the freeway entrance. The theoretical analysis indicated a much higher probability that an unfamiliar driver could execute a required lane change when diagrammatic signs are used. ODOT/FHWA evaluators visited the six interchange sites and provided their input and opinions as to the use of diagrammatic signs. The vast majority of the evaluators fully embraced the idea of diagrammatic signs. Eye movement recordings were performed at night at the six sites in order to determine if the presence of the diagrammatic signs was distracting. The results of the eye movement analysis indicate that the diagrammatic signs are not looked at excessively often or excessively long. The overall median first look distance to the diagrammatic signs was found to be 125m. An evaluation with unfamiliar test drivers corroborated the findings of the theoretical model analysis, in that drivers were able to execute a needed lane change much earlier when diagrammatic signs were provided. A set of application guidelines for diagrammatic signs is provided.
Download or read book Evaluation of Dynamic Speed Display Signs DSDS written by Elisabeth R. Rose and published by . This book was released on 2003 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dynamic speed display signs (DSDS), devices that detect and display a vehicle's current speed back to the driver, have been shown to have a significant speed-reducing effect in temporary applications such as work zones or neighborhood speed watch programs. In this report, researchers examined the effectiveness of DSDS installed permanently in several locations that were experiencing speed-related problems. Seven sites were evaluated, including a school speed zone, two transition speed zones in advance of a school speed zone, two sharp horizontal curves and two approaches to signalized intersections on high-speed roadways. Data were collected before the DSDS were installed, about one week after installation to determine initial effects of the signs upon vehicle speeds, and again about four months after installation to determine how well the initial speed reductions were maintained. Researchers analyzed average speeds, 85th percentile speeds, percent of the sample exceeding the speed limit and standard deviations of the samples. Also, least square regression analyses between the speed of a vehicle upstream of the DSDS and that vehicle's speed measured again at the DSDS were performed to determine whether the sign affected higher speed vehicles more than lower speed vehicles. Overall, average speeds were reduced by 9 miles per hour at the school speed zone. Elsewhere, the effect of the DSDS was less dramatic, with average speeds reduced by 5 mph or less, depending on the location tested. As expected, the influence of a DSDS was found to differ depending on how fast a motorist approached the DSDS. Those motorists traveling faster than the posted speed did appear to reduce their speed more significantly in response to the DSDS than did motorists traveling at or below the posted speed limit. The results of this project suggest that DSDS can be effective at reducing speeds in permanent applications if appropriate site conditions apply.
Download or read book Guidance for Implementation of the AASHTO Strategic Highway Safety Plan written by and published by Transportation Research Board. This book was released on 2003 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Policy on Design Standards interstate System written by and published by Aashto. This book was released on 2005 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Speed Management written by European Conference of Ministers of Transport and published by OECD Publishing. This book was released on 2006-10-13 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: Speeding is the number one road safety problem in a large number of OECD/ECMT countries. It is responsible for around one third of the current, unacceptably high levels of road fatalities. Speeding has an impact not only on accidents but also on the ...
Download or read book Managing Speed written by and published by Transportation Research Board. This book was released on 1998 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt: TRB Special Report 254 - Managing Speed: Review of Current Practices for Setting and Enforcing Speed Limits reviews practices for setting and enforcing speed limits on all types of roads and provides guidance to state and local governments on appropriate methods of setting speed limits and related enforcement strategies. Following an executive summary, the report is presented in six chapters and five appendices.
Download or read book Guide for the Planning Design and Operation of Pedestrian Facilities written by and published by AASHTO. This book was released on 2004 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evaluation of Ramp Meter Effectiveness for Wisconsin Freeways written by and published by . This book was released on 2004 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Guidelines and Recommendations to Accommodate Older Drivers and Pedestrians written by L. K. Staplin and published by . This book was released on 2001 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Roadside Design Guide written by American Association of State Highway and Transportation Officials. Task Force for Roadside Safety and published by . This book was released on 1989 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Transportation Decision Making written by Kumares C. Sinha and published by John Wiley & Sons. This book was released on 2011-09-09 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt: This pioneering text provides a holistic approach to decisionmaking in transportation project development and programming, whichcan help transportation professionals to optimize their investmentchoices. The authors present a proven set of methodologies forevaluating transportation projects that ensures that all costs andimpacts are taken into consideration. The text's logical organization gets readers started with asolid foundation in basic principles and then progressively buildson that foundation. Topics covered include: Developing performance measures for evaluation, estimatingtravel demand, and costing transportation projects Performing an economic efficiency evaluation that accounts forsuch factors as travel time, safety, and vehicle operatingcosts Evaluating a project's impact on economic development and landuse as well as its impact on society and culture Assessing a project's environmental impact, including airquality, noise, ecology, water resources, and aesthetics Evaluating alternative projects on the basis of multipleperformance criteria Programming transportation investments so that resources can beoptimally allocated to meet facility-specific and system-widegoals Each chapter begins with basic definitions and concepts followedby a methodology for impact assessment. Relevant legislation isdiscussed and available software for performing evaluations ispresented. At the end of each chapter, readers are providedresources for detailed investigation of particular topics. Theseinclude Internet sites and publications of international anddomestic agencies and research institutions. The authors alsoprovide a companion Web site that offers updates, data foranalysis, and case histories of project evaluation and decisionmaking. Given that billions of dollars are spent each year ontransportation systems in the United States alone, and that thereis a need for thorough and rational evaluation and decision makingfor cost-effective system preservation and improvement, this textshould be on the desks of all transportation planners, engineers,and educators. With exercises in every chapter, this text is anideal coursebook for the subject of transportation systems analysisand evaluation.
Download or read book Traffic Control Systems Handbook written by and published by . This book was released on 1976 with total page 670 pages. Available in PDF, EPUB and Kindle. Book excerpt: This handbook, which was developed in recognition of the need for the compilation and dissemination of information on advanced traffic control systems, presents the basic principles for the planning, design, and implementation of such systems for urban streets and freeways. The presentation concept and organization of this handbook is developed from the viewpoint of systems engineering. Traffic control studies are described, and traffic control and surveillance concepts are reviewed. Hardware components are outlined, and computer concepts, and communication concepts are stated. Local and central controllers are described, as well as display, television and driver information systems. Available systems technology and candidate system definition, evaluation and implementation are also covered. The management of traffic control systems is discussed.
Download or read book Driver Expectancy in Highway Design and Traffic Operations written by Gerson J. Alexander and published by . This book was released on 1986 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: Expectancy relates to a driver's readiness to respond to situations, events, and information in predictable and successful ways. This report describes the concept of driver expectancy in the context of the driving task, and provides examples of expectancy and expectancy violations. It includes a procedure for identifying general and specific expectancy violations to enable engineers to develop remedial treatments to deal with expectancy problems.
Download or read book Strategies for Work Zone Transportation Management Plans written by Leverson Boodlal and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the ways a state department of transportation or other transportation agency can address work zone safety and other impacts is to develop and implement a Transportation Management Plan (TMP). The TRB National Cooperative Highway Research Program's NCHRP Research Report 945: Strategies for Work Zone Transportation Management Plans provides a practitioner-ready guidebook on how to select and implement strategies that improve safety and traffic operations in roadway construction work zones. Supplemental materials to the report include NCHRP Web-Only Document 276: Evaluating Strategies for Work ZoneTransportation Management Plans; fact sheets on ramp meter, reversible lane, and truck restrictions; and guidebook appendices.
