Vulnerable road users, anyone interacting with the roadway facility without the protection of an automobile, experience greater risk for more severe crash outcomes. Multimodal roadway facilities oftentimes provide less separation and more points of conflict between different types of road users. To promote vulnerable road user safety, transportation agencies across …
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Vulnerable road users, anyone interacting with the roadway facility without the protection of an automobile, experience greater risk for more severe crash outcomes. Multimodal roadway facilities oftentimes provide less separation and more points of conflict between different types of road users. To promote vulnerable road user safety, transportation agencies across the world provide a variety of additional roadway treatments. This dissertation studied the effects of three such safety treatments: flashing blue and amber-white lights on paving equipment and a 20-mph school zone flasher. The fundamental goal of these three traffic control devices is to provide an additional layer of safety leveraging the color, pattern, and presence of flashing lights. The extent of their effectiveness was evaluated based on queries raised by State and County transportation agencies. Evaluation of the traffic control devices provides planners and engineers a better understanding of their effectiveness and will facilitate more informed decision making on implementations to improve road users’ safety. The effectiveness of flashing blue, amber, and amber-white lights installed on paving equipment for harmonizing speeds inside work zones during mobile nighttime operations was studied. Paving operation requires that the highest density of workers on the roadway will be located in close proximity to the paving equipment (paver). In a partial lane closure work zone, the condition considered in this study, there is rarely protective separation, e.g., a hard barrier, between workers and vehicles on high-speed Interstate roadways. This condition warrants effective traffic control devices to draw the attention of the drivers and promote compliance with temporary speed reduction. Using portable traffic sensors, 11-12 nights of data were collected. Flashing blue light installation on the paver showed a statistically significant 2.7 to 16 mph speed reduction. Speed reduction during the nights flashing lights were on ranged from 3 to 7 mph. The Oregon Department of Transportation in coordination with contractors and law enforcement established a provision to allow flashing blue lights on Pavers supported by the results of this study. Flashing yellow and amber lights are popular and have been used since the 1950s on construction work-related vehicles. A study using a similar methodology as described in the previous paragraph did not find evidence of the effectiveness of installing flashing amber lights on the Paver in reducing speed. However, alternatingly flashing amber and white light was determined to significantly reduce speed (2.5 to 10.1 mph) from at-paver and downstream of paver locations. The margin of speed reduction showed a greater reduction (1.5 to 4.1 mph) during the flashing operation. Based on the outcome of this study, the use of alternatingly flashing amber-white lights on the paver to increase visibility and reduce speed near the vulnerable workers near the paver was recommended. A School zone 20 mph flasher was studied for at-grade crosswalks in front of two schools in a driving simulator experiment. Forty-six participants successfully completed the experiment. Flashing sing operation correlated with greater speed reduction. When two children and one child and one adult were present at the crosswalk, speed reductions were greatest. The two children pedestrian level during the flashing operation received the largest amount of visual attention. Yielding rates were higher during the flashing operation. As a result, it was recommended that the flashing lights be used under low vehicle and pedestrian volumes. The three experiments described in this dissertation have produced recommendations for traffic planners and engineers to make informed decisions that improve existing safety issues.
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