Download or read book Evaluating Safety at Oregon s Isolated High speed Signalized Intersections written by Neil Kopper and published by . This book was released on 2010 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: Isolated approaches at signalized intersections with posted speed limits of 45 mph or greater generally experience large numbers of rear-end and angle collisions. A combination of less attentive drivers, high operating speeds, and less than ideal intersection characteristics can result in crash frequencies well above expected rates. A number of treatment options are available to target specific safety concerns at intersections, but it can be difficult or time-consuming to determine when an intersection is experiencing abnormal crash trends. The Oregon Department of Transportation (ODOT) does not currently have a system in place for evaluating safety at isolated, high-speed, signalized intersections (IHSSIs). This thesis describes the development of a method for efficiently evaluating safety and determining potential treatment options for IHSSIs. Specifically, this method identifies data collection requirements, determines expected crash frequencies based on intersection configuration, and provides a list of safety treatment options. This information is packaged into a safety evaluation template to allow for efficient and effective IHSSI evaluations.

Download or read book Evaluating Safety and Operations of High speed Signalized Intersections written by Karen K. Dixon and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Evaluation of Safety Strategies at Signalized Intersections written by Raghavan Srinivasan and published by Transportation Research Board. This book was released on 2011 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: TRB’s National Cooperative Highway Research Program (NCHRP) Report 705: Evaluation of Safety Strategies at Signalized Intersections explores crash modification factors (CMFs) for safety strategies at signalized intersections. CMFs are a tool for quickly estimating the impact of safety improvements.

Download or read book Developing Safety Performance Functions for 4 leg Single lane Roundabouts Based on Oregon Data written by Jianfei Zheng and published by . This book was released on 2013 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt: Roundabouts have become an alternative for traditional intersections due to the safer operational performance. Previous research has provided crash modification factors (CMFs) as a criterion based on before-after studies as to evaluate the safety performance of roundabouts. One drawback of assessment based on crash modification factors, however, is that a before-after study includes too many variations at a time that it only provides a general idea of the safety performance for roundabouts. Since the industrial world is interested in the safety outcome of converting traditional intersections to roundabouts, safety performance functions (SPFs) will provide more specific details on estimating crashes than that of crash modification factors. This thesis will adopt a similar methodology that has been used in the current Highway Safety Manual (HSM) to develop safety performance functions for roundabouts based on Oregon data. The outcome of this thesis will help the Oregon Department of Transportation (ODOT) to evaluate existing roundabouts in the State of Oregon. Furthermore, this thesis will function as an additional case study from Oregon to contribute to the national effort of evaluating the safety performance of roundabouts.

Download or read book NCHRP Report 705 written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Safety at High speed Intersections written by and published by . This book was released on 2010 with total page 2 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Safety at Half Signal Intersections in Portland Oregon written by and published by . This book was released on 2015 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: The safety at half-signalized intersections in Portland, Oregon is analyzed in this thesis using 10 years of crash history and analysis of video that was collected at a subset of intersections. A half-signalized intersection has a standard red-yellow-green traffic signal for automobiles on the major road, a stop sign for motorists on the minor road, and a pedestrian signal with actuation for pedestrians and/or bicyclists on the minor road. Although prevalent in Canada, this type of intersection control is not typically found in the United States because the MUTCD explicitly prohibits its use. Half-signal use is limited mostly to two cities in the Pacific Northwest. In Portland, Oregon there are forty-seven intersections where half-signals are used but the last installation was in 1986; Seattle has over 100 intersections with half-signals and installs these in new locations where warranted. To explore the safety records of these intersections in Portland, crash data from 2002-2011 was analyzed. A total of 442 crashes over the ten-year period at half-signals were observed. Sixteen of these 442 crashes involved pedestrians. In the crashes involving pedestrians, significant differences were found between the approach street of the vehicle and whether the pedestrian or driver was at fault. In the crash error reports, it was found that significantly more of the crashes involving pedestrians were the fault of motorists departing from the minor road who collided with pedestrians crossing the major street. Further crash analysis at half-signals was performed by developing matched comparison groups of minor stop controlled and fully signalized intersections. Crash rates were 0.158 and 0.178 crashes per million entering vehicles for 3-leg and 4-leg half-signals and these rates did not differ significantly from the minor street stop controlled and signalized comparison groups. Results from the matched comparison showed that the half-signalized group had more rear-end crashes when compared with the minor stop controlled group. This was the only result that held significance when crash rates were considered. It was also observed that the minor stop controlled group had a higher proportion of angle crashes when compared with the half-signal group but this did not influence the crash severity. Pedestrian crashes were more prevalent in the half-signal group when compared with the fully-signalized group. Pedestrian volumes were not available which would be used to determine if this significant measure is a result of higher pedestrian use at half-signals. In addition to crash analysis, video was captured at five half-signalized intersections totaling 180 hours. Traffic volumes, pedestrian and bicycle volumes, and signal actuations were collected over a twenty-four hour period. Over this twenty-four hour period the five intersections averaged daily counts of 18613 vehicles on the major street, 591 vehicles on the minor street, 263 pedestrians crossing the major street, 285 pedestrians crossing the minor street, 52 bicycles on the major street, 37 bicycles on the minor street, and 126 signal actuations. Twenty-four hour observations from each of the intersections were used to study conflicts and compliance. No conflicts were observed that reflect the left-turning from the minor street pedestrian crashes that were identified in the crash history. Compliance of the half-signal by vehicles and pedestrians was comparable to compliance at fully-signalized intersections found in other studies with one exception. Across the intersections where video was collected, consisting of four 4-leg intersections and one 3-leg intersection, seven left turn on red violations were observed which had a significant impact on the time after red that red light violations were made. It is hypothesized that at half-signals vehicles on the major street make a left turn on the red signal very late into the red phase because there is not a risk of colliding with a vehicle traveling on the minor street since traffic volumes on the minor street are comparably low. The observed left turn on red violations did not put pedestrians at risk since by that point into the signal pedestrians were already clear of the intersection. Finally, a stop compliance logistic regression model was developed at four four-leg intersections to see what factors had an effect on minor street vehicle stop compliance. All 166 hours of video were used to observe vehicles that arrived at the half-signal during the pedestrian phase. The dependent variable collected was whether a vehicle came to an acceptable stop. Independent variables collected included the vehicle's queue position, if it was the peak school period, if there was a vehicle across the street on the minor road, if a vehicle was stopped at the signal on the major street, if a pedestrian was present when the vehicle arrived, and the movement that the vehicle made from the minor street. Independent variables used in the model included the vehicle's queue position, if a vehicle was stopped at the signal on the major street, if a pedestrian was present, and if the vehicle made a right turn at the signal. Pedestrian presence and right turning vehicles had a positive impact on stop compliance. Vehicles being further back in the queue and cars stopped at the signal on the major street had a negative impact on stop sign compliance. In the model, pedestrian presence had the largest positive impact on stop compliance. When pedestrians were present, a motorist on the minor street was four times more likely to stop at the sign.

Download or read book Improved Safety Performance Functions for Signalized Intersections written by Karen Dixon and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dilemma Zone Protection on High speed Arterials written by Bhaven Naik and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Driver behavior within the dilemma zone can be a major safety concern at high-speed signalized intersections, especially for heavy trucks. The Nebraska Department of ROADS (NDOR) has developed an implemented an Actuated Advance Warning (AAW) dilemma zone protection system. The AAW system has been documented as being effective at improving traffic safety at isolated signalized intersections. However, the system is yet to be used at signalized intersections operating in the coordinated mode. This study tested the feasibility of deploying the system on arterials where the signals are closely spaced and operate in a coordinated mode. A microsimulation approach -- integration of traffic microsimulation and surrogate safety performance measures -- was developed to assess the potential benefits (safety and operation) in-lieu of observed traffic and crash data. The analysis of conflicts indicated that, on average, there were 30%, 7%, and 30% reductions in the number of rear-end, lane change, and crossing conflicts respectively when the AAW system was used. In terms of the relative productivity of the system, the number of vehicles that were processed during a specified analysis period revealed that there were generally more vehicles processed when the AAW system was not in place. Also, the overall link travel times were slightly higher when the system was in place" (page viii).

Download or read book Safety Evaluation of Corner Clearance at Signalized Intersections written by U. S. Department Of Transportation and published by Createspace Independent Publishing Platform. This book was released on 2018-07-18 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: Safety evaluation of corner clearance at signalized intersections /

Download or read book Evaluation of Safety Strategies at Signalized Intersections written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Safety Evaluation of Multiple Strategies at Signalized Intersections written by Thanh Le (Highway engineer) and published by . This book was released on 2018 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: Evaluates multiple low-cost safety improvements at signalized intersections for bacis signing, pavement marking, and signal enhancements.

Download or read book Assessment of Statewide Intersection Safety Performance written by Christopher Michael Monsere and published by . This book was released on 2011 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Intersection Safety Evaluation Using High Resolution Traffic Signal Data written by Natanael. D. Vall and published by . This book was released on 2013 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Research Project Work Plan for Assessment of Statewide Intersection Safety Performance written by Christopher Michael Monsere and published by . This book was released on 2008 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Assessment of Statewide Intersection Safety Performance written by and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Proactive Evaluation of Safety for Vulnerable Road Users at Signalized Intersections written by and published by . This book was released on 2020 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: Continued emphasis on active transportation has led to a proliferation of vulnerable road users (VRUs) such as bicyclists and pedestrians at intersections. Intersections are critical locations as many crashes occur due to mixed traffic flow and various conflicting patterns between road users. Intersection safety has primarily relied on historical crash data. However, due to several limitations including unpredictability and irregularity of occurrence of crashes in real environment, quantitative and qualitative determination of crashes may not be accurate. This study explores alternative measures to the traditional safety analysis known as surrogate safety measures (SSMs). SSMs such as Time to Collision (TTC), Post Encroachment Time (PET) and a variant of TTC, Relative Time to Collision (RTTC) were used to evaluate safety at ten signalized intersections in the city of San Diego. The analysis was conducted in two main parts: proactive safety evaluation for VRUs at signalized intersections by comparison of SSMs and predicting critical bicycle-vehicle conflicts at signalized intersections. In part one, frequency of each SSMs was estimated to identify critical intersections for VRUs and then a comparative study of each SSMs were conducted. It was found that RTTC alone was insufficient to accurately identify critical conflicts. Furthermore, safety evaluation results showed that a single SSM was not reliable but a combination of different SSMs was necessary to ensure the reliability of evaluations. In part two, logistic regression model was developed in R to predict critical conflicts based on PET measure. Bicycle-vehicle kinematics data were monitored for certain period before predicting critical conflicts. Several scenarios were analyzed considering different combinations of PET threshold value and monitoring period, and it was found that a scenario with PET threshold value of 3s and monitoring period of 2s led to the best model based on its statistical performance. Of the many input variables investigated, velocity of the conflicting objects and minimum relative approach velocity were found to be statistically more significant. The model was tested under two cases; sensitivity maximization and maximum overall accuracy, and it was found that sensitivity maximization was more suitable as it ensured accurate prediction of critical conflicts.