Evaluating Driver Response to Bridge Deck Warning Systems During Winter Weather Conditions
Transportation Research Record2024
Warning signs are often deployed at bridge overpasses during winter to warn motorists of potentially icy surface conditions on the bridge, although the effectiveness of these signs is questionable. One potential improvement to the standard signage methods is the bridge deck warning system (BDWS), which activates a flashing warning sign border or beacon when conditions warrant based on real-time weather and bridge surface data. However, BDWSs have not been broadly implemented in the United States, and consequently, their effectiveness as a safety countermeasure is not well established. To address this knowledge gap, a series of winter field evaluations were performed along three freeway bridge overpasses in Michigan to assess the effectiveness of various BDWS strategies as a speed reduction countermeasure for motorists approaching a potentially icy bridge.
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Examining the Relationship between Connected Vehicle Driving Event Data and Police-Reported Traffic Crash Data at the Segment- and Event Level
Transportation Research Record2024
Police-reported crash data have been the de facto element used by the transportation agencies in developing and implementing traffic safety projects. This approach is reactive in nature and can lead to suboptimal investment decisions owing to inherent challenges in crash data analysis. Because of their large-scale and near real-time availability, connected vehicle (CV) driving event data have emerged as a promising means of addressing these challenges. This study utilized CV event data for three different event types, namely, acceleration, braking, and cornering at three severity levels (easy, normal, and harsh), to examine the viability of using these data in traffic safety analysis. The results showed a strong correlation between crash frequency and CV driving event frequency. CV event data also improved the goodness-of-fit of crash frequency models.
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Effects of Speed Feedback Trailer Positioning and Police Enforcement on Vehicular Speeds in Freeway Work Zone Lane Closures
Transportation Research Record2024
This field study sought to evaluate select strategies for improving compliance with work zone speed limits, which included a speed feedback trailer (SFT) and active police enforcement. The initial evaluation included an SFT positioned at the start or end of the taper within a freeway single-lane closure to determine which position provided the most favorable speed reductions. Positioning the SFT near the end of the taper caused the speed reductions to be sustained over a greater distance into the work zone compared with when the SFT was positioned near the start of the taper. With the SFT positioned near end of the taper, the average speed was 1.5 mph lower at the end of the taper and 0.8 mph lower 1,350-ft beyond the end of the taper compared with when the SFT was inactive.
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Motor Vehicle Crashes Involving Railroad Crossing Signal Masts and Guardrails
Transportation Research Record2019
The installation of “active” warning devices, such as crossing signals and gates, is a principal element of state and federal railroad crossing safety programs, and their effectiveness in preventing vehicle–train collision is well documented. While most active crossings are occupied by trains only a few minutes each day, non-crashworthy items are frequently present at active crossings including crossing signal masts, crossing gate mechanisms, cantilever supports, and signal controller bungalows. Various agencies utilize longitudinal guardrail systems to protect errant motorists from striking non-frangible crossing signal hardware. This study sought to determine whether such guardrails influence the prevalence and severity of motor vehicle strikes involving crossing hardware. A review of 10 years of police crash-report narratives in Iowa, United States (U.S.) indicates an average of 15.6 crashes per year at 1,853 crossings involving signal masts, signal guardrails, or related infrastructure.
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Examining Safety on Two-Lane and Multilane Highways in Consideration of Access Spacing
Transportation Research Record2019
Access management strategies, such as the introduction of minimum access point spacing criteria and turning movement restrictions, have been shown to be important elements in optimizing the operational and safety performance of roadway segments. The relationship between safety and these types of access policies is a complex issue, and the impacts of such features on traffic crashes is critical to the development of appropriate access management strategies. The purpose of this study was to provide a quantitative evaluation of how crash risk on multilane and two-lane highways varies with respect to access spacing in support of the development of a revised access management policy. Data were obtained for approximately 1,247 and 5,795 mi of segments across multilane and two-lane highways, respectively. Crash data were obtained for a five-year period from 2012 to 2016 and a series of random effect negative binomial regression models were estimated for each facility to examine the association between crash frequency, access point spacing, and traffic volume.
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