Mohammad Jalayer

Background: Several previous studies, based upon wrong-way driving (WWD) crash history, have demonstrated that partial cloverleaf (parclo) interchanges are more susceptible to WWD movements than others. Currently, there is not a method available to predict WWD incidents and to prioritize parclo interchanges for implementing safety countermeasures for reducing WWD crashes. Objectives: The focus of this manuscript is to develop a mathematical method to estimate the probability of WWD incidents at exit ramp terminals of this type of interchange. Methods: VISSIM traffic simulation models, calibrated by field data, are utilized to estimate the number of potential WWD maneuvers under various traffic volumes on exit ramps and crossroads. The Poisson distribution model was implemented without field observation and crash data. Results: A comparison between the field data and simulation outputs revealed that the developed model enjoys an acceptable level of accuracy. The proposed model is largely sensitive to left-turn volume toward an entrance ramp (LVE) than stopped vehicles at an exit ramp (SVE). The results indicated that potential WWD events increase when LVEs increase and SVEs decrease. Also, the probability of WWD event decreases as road users are more familiar with the facility. Conclusion: The proposed method can diminish one of the challenges in front of transportation engineers, which is to identify high WWD crash locations due to insufficient information in crash reports. The results are helpful for transportation professionals to take proactive steps to identify locations for implementing safety countermeasures at high risk signalized parclo interchanges.

Stipulating a space headway is a pivotal concern in traffic engineering. Although consideration of a larger headway leads to safer traffic movement, consideration for a smaller headway can serve more traffic volume, which is significant from an economic standpoint. Implementation of a smaller headway, however, could lead to the tailgating phenomenon (short distances between two vehicles), which is perceived as troublesome and dangerous. Evaluating the space headway provides a reasonable approach to understanding the operational benefit for safety and traffic concerns. Using probabilistic analysis to account for uncertainty can be one of the best applicable methods because the headway data are not deterministic and are treated as random variables. More specifically, by emphasizing the reliability analysis, it is feasible to determine the appropriate space headway. The objective of this paper is to present a state-of-the-art approach for the evaluation of the statistical parameters of the headway by utilizing the reliability analysis. Several data sets among entire states were obtained from the Federal Highway Administration (FHWA) in 2012 and utilized in an analysis of a more pragmatic approach.

Past studies indicated that interchange configurations, access control, and geometric design are related to Wrong-Way Driving (WWD) and minor ramp geometric changes can be effective in reducing the number of wrong-way entries onto freeways. In this paper, access management techniques and geometric elements, which are capable of discouraging wrong-way maneuvers, are identified and discussed. Additionally, every aspect of these elements and their relationship to WWD is investigated. These geometric elements include interchange types, exit ramp terminals, frontage roads, raised medians, channelizing islands, and control radius. The aforementioned elements should be given a special consideration during the design stage of interchanges and intersections.

ABSTRACT For many years, state departments of transportation (DOTs) and local agencies have collected and maintained highway inventory data (HID) to assist the decision makers at different levels. In light of the implementation of the recently published Highway Safety Manual (HSM) in 2010, many state DOTs have sought to tailor the various safety measures and functions to evaluate the safety in their jurisdictions. Insufficient HSM-required HID in many current DOTs’ databases, however, necessitates the collection of the absent features. To obtain these data, various techniques for different purposes have been used, including field inventory, photo and video log, integrated Global Positioning System/geographic information systems (GPS/GIS) mapping systems, aerial photography, satellite imagery, terrestrial laser scanners, airborne light detection and ranging (LiDAR), and mobile LiDAR. Among many data collection methods, the photo and video log is widely employed by DOTs due to its simplicity and low cost. Therefore, the focus of this article, which is a timely and needed research effort, is to evaluate the capability of the photo and video logging method to collect HID for supporting HSM implementation through a comprehensive literature review, a nationwide survey, and a field trial. The results of this study demonstrate that the photo and video log can provide worthy and relevant HSM data sets with acceptable accuracy.

Stipulating a space headway is a pivotal concern in traffic engineering. Although consideration of a larger headway leads to safer traffic movement, consideration for a smaller headway can serve more traffic volume, which is significant from an economic standpoint. Implementation of a smaller headway, however, could lead to the tailgating phenomenon (short distances between two vehicles), which is perceived as troublesome and dangerous. Evaluating the space headway provides a reasonable approach to understanding the operational benefit for safety and traffic concerns. Using probabilistic analysis to account for uncertainty can be one of the best applicable methods because the headway data are not deterministic and are treated as random variables. More specifically, by emphasizing the reliability analysis, it is feasible to determine the appropriate space headway. The objective of this paper is to present a state-of-the-art approach for the evaluation of the statistical parameters of the headway by utilizing the reliability analysis. Several data sets among entire states were obtained from the Federal Highway Administration (FHWA) in 2012 and utilized in an analysis of a more pragmatic approach.

This publication is developed in the framework of an executive summary of various case study examples that provide transportation practitioners with a good understanding of RwD safety countermeasure effectiveness. In addition to bringing available information together in one document, a contact person(s) is suggested for each case study example.

This publication is developed in the framework of an executive summary of various case studies that aim at providing transportation practitioners with a good understanding of WWD incidents and emerging safety countermeasures. In addition to bringing available information together in one document, a contact person(s) is suggested for each case study to help readers get at least additional the complementary information about each countermeasure they are considering.

Background: Several previous studies, based upon wrong-way driving (WWD) crash history, have demonstrated that partial cloverleaf (parclo) interchanges are more susceptible to WWD movements than others. Currently, there is not a method available to predict WWD incidents and to prioritize parclo interchanges for implementing safety  countermeasures for reducing WWD crashes.
Objectives: The focus of this manuscript is to develop a mathematical method to estimate the probability of WWD incidents at exit ramp terminals of this type of interchange.
Methods: VISSIM traffic simulation models, calibrated by field data, are utilized to estimate the number of potential WWD maneuvers under various traffic volumes on exit ramps and crossroads.The Poisson distribution model was implemented without field observation
and crash data.
Results: A comparison between the field data and simulation outputs revealed that the developed model enjoys an acceptable level of accuracy. The proposed model is largely sensitive to left-turn volume toward an entrance ramp (LVE) than stopped vehicles at an exit ramp (SVE). The results indicated that potential WWD events increase when LVEs increase and SVEs decrease. Also, the probability of WWD event decreases as road users are more familiar with the facility.
Conclusion: The proposed method can diminish one of the challenges in front of transportation engineers, which is to identify high WWD crash locations due to insufficient information in crash reports. The results are helpful for transportation professionals to take proactive steps to identify locations for implementing safety countermeasures at high risk signalized parclo interchanges.

The severity of roadway departure crashes mainly depends on the roadside features, including sideslope, fixed-object density, offset to fixed objects, shoulder width, etc. Collision with fixed object is identified as the first harmful event in runoff road (ROR) crashes. Common engineering countermeasures regarding roadside safety include: cross section improvements, hazard removal or modification, and delineation. It should be noted that it is not always feasible to maintain object-free roadside clear zone as design guidance recommends. Currently, clear zone width and sideslope are used to determine roadside hazard rating (RHR) to quantify roadside safety for rural two-lane roadways using 1 to 7 discrete levels. Since these two variables are continuous and can be treated as random variables, using probabilistic analysis to account for uncertainty can be an alternative applicable method. To be more specific, by emphasizing on the reliability analysis, it is possible to quantify the roadside safety level by treating clear zone width and sideslope as two continuous variables, rather than discrete variables. The objective of this manuscript is to present an approach to define the reliability index for measuring roadside safety on rural two-lane roads. The segments were randomly selected from three counties in Illinois and utilized in the analysis for a more pragmatic approach. Based on the obtained results, the reliability indices can serve as the indicators to measure the level of safety, showing the greater the reliability indices, the less the ROR crash rate.