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• Safety effectiveness of pedestrian hybrid beacons (PHB) was examined. • Significant crash reductions for all, rear-end, and pedestrian-related crashes. • PHBs with a raised median or pedestrian refuge island had fewer total crashes. Introduction: The pedestrian hybrid beacon (PHB) is a traffic control device used at pedestrian crossings. A recent Arizona Department of Transportation research effort investigated changes in crashes for different severity levels and crash types (e.g., rear-end crashes) due to the PHB presence, as well as for crashes involving pedestrians and bicycles. Method: Two types of methodologies were used to evaluate the safety of PHBs: (a) an Empirical Bayes (EB) before-after study, and (b) a long-term cross-sectional observational study. For the EB before-after evaluation, the research team considered three reference groups: unsignalized intersections, signalized intersections, and both unsignalized and signalized intersections combined. Results: For the signalized and combined unsignalized and signalized intersection groups, all crash types considered showed statistically significant reductions in crashes (e.g., total crashes, fatal and injury crashes, rear-end crashes, fatal and injury rear-end crashes, angle crashes, fatal and injury angle crashes, pedestrian-related crashes, and fatal and injury pedestrian-related crashes). A cross-sectional study was conducted with a larger number of PHBs (186) to identify relationships between roadway characteristics and crashes at PHBs, especially with respect to the distance to an adjacent traffic control signal. The distance to an adjacent traffic signal was found to be significant only at the α = 0.1 level, and only for rear-end and fatal and injury rear-end crashes. Conclusions: This analysis represents the largest known study to date on the safety impacts of PHBs, along with a focus on how crossing and geometric characteristics affect crash patterns. The study showed the safety benefits of PHBs for both pedestrians and vehicles. Practical Applications : The findings from this study clearly support the installation of PHBs at midblock or intersection crossings, as well as at crossings on higher-speed roads. [ABSTRACT FROM AUTHOR]

As the demand for additional capacity on urban freeways continues to increase, there is a need to better understand how to optimize the lane and shoulder configurations so as to improve capacity without adversely impacting operating speed. The overall objective for this research effort was to identify the operational implications of using reduced lane and shoulder widths on freeways. The operational analysis found speeds 3.5 km=h (2.2 mph) higher for a 3.7 m (12 ft) lane as compared to a 3.4 m (11 ft) lane. The authors developed an equation that can be used to predict speeds per lane for freeway locations with boundary conditions similar to those present in the study database. [ABSTRACT FROM AUTHOR]

Left-turn gap acceptance at an unsignalized intersection is dependent on many factors. The Highway Capacity Manual (HCM) uses a single value of critical gap for all types of intersections; however, this may be oversimplistic and lead to inaccurate estimates of left-turn delay and capacity. Most existing studies also do not differentiate between gap and lag when evaluating gap acceptance. In this paper, binary logit models were developed to estimate the probability of accepting or rejecting a given gap or lag for a left-turning vehicle from a major road at an unsignalized intersection considering a number of potential influencing factors. Gap acceptance behavior was found to be influenced by the type of gap presented to the driver (gap or lag). Gap duration, total wait time, time to turn, distance to next signal downstream, and median type were found to be significant factors in predicting the probability of accepting or rejecting a gap. In the model for lag acceptance lag duration, time to turn, crossing width, speed limit, and distance to next signal downstream were found to be significant. Equations for estimating the critical gap and lag were developed. Critical gap and lag were found to be varying over a wide range of values depending on the type of intersection. The range was smaller for critical gaps than lags. The findings from this study can improve operational analysis of left turns at unsignalized intersections by using different critical gaps for different traffic and geometric conditions. [ABSTRACT FROM AUTHOR]

The transportation profession is seeking to better understand the features that influence roadway speeds. Engineers need an appreciation of which roadway design features, or the values for the features, clearly relate to the speed performance on a facility. This study utilized free-flow speed data collected at 79 tangent sites in suburban/urban and rural areas in seven cities located in six states. Key variables used to select sites included functional classification (arterial, collector, and local), edge treatment (curb and gutter versus shoulder), and speed limit. Technicians collected speed data at the midpoint of long straight sections during daylight conditions. For each site, roadway and roadside characteristics were collected such as number of access points within the study section, roadside development type, lane width, and others. Statistical testing revealed that posted speed limit was the only statistically significant variable at a 5% alpha level. Access density was next with an approximate 20% alpha level. Several variables other than posted speed limit and access density showed signs of influence on the 85th percentile free-flow operating speed, including: median type, parking along the street, and pedestrian activity level. A followup cluster analysis revealed the following noteworthy features: pedestrian activity, parking, centerline, median treatment, roadside development, area type, and signal density. [ABSTRACT FROM AUTHOR]