Effect of Bulb-outs at Intersections on Speed Reduction and Visibility Conditions in Tempo–30 Zone

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Effect of Bulb-outs at Intersections on Speed Reduction and Visibility Conditions in Tempo–30 Zone

July 2, 2021 Engineering 0

Tempo–30 zones are increasingly being used as a traffic-calming measure. They are primarily intended to cause drivers to reduce their speed to an expected value and to improve traffic safety. Drivers in Tempo–30 zones must pay special attention to vulnerable road users (VRU), who can cross the street at any time. The specific street and junction geometry, as well as the street furniture, warn drivers of the traffic-calmed area ahead of them, compelling them to slow down. One of the most common design measures for junctions in Tempo– 30 zones is to narrow the junction legs and extend their corners. Reduced driving speed expands the driver’s central vision area, allowing for quicker and easier detection of pedestrians about to cross the road. Bulb-outs (also known as build-outs) at intersection corners along the intersection legs shorten the pedestrian crossing distance and provide a better view of oncoming vehicles. They are typically combined with on-street parking lanes reserved for local residents. Taking the foregoing information into consideration, the author conducted speed measurements on a selected downtown street located in a Tempo–30 zone. Several speed measuring devices were used in the survey to automatically measure and record the operating speed and volume of traffic at various locations. At the same time, intersection legs At least one hundred (100) speed measurements were taken per measurement location and traffic direction. The weather was dry during the survey, as was the pavement surface. Statistical analyses were performed on the results. The statistical inference portion of the research included, among other things, a nonparametric test of independence and a median test to confirm the null hypothesis H0 that measurement results are independent of measurement site location. The alternative hypothesis – H1 – was confirmed in almost all cases, indicating that the speed distribution parameters are indeed affected by the location of the measurement site. The measurement sites were chosen with the traffic direction, bulb-out location, and approach and departure conditions in mind. The measurement data and statistical test results confirmed that bulb-out corners have an actual effect on speed reduction on the approach to the junction in Tempo–30 zones, enhancing the driver’s ability to spot any pedestrians about to cross the street. The analysis of speed data revealed that raising the pavement by 7 cm along the traffic-calming street in the Tempo–30 zone had only a minor traffic-calming effect. With the bulb-outs in place, the vehicles parked before the junction do not obstruct the pedestrian’s central vision area, thereby enlarging the pedestrian’s field of vision. improving their ability to detect any approaching vehicles

Author (S) Details

Alicja Sołowczuk
West Pomeranian University of Technology, 50 Piastów Ave., 70-311 Szczecin, Poland.

View Book :- https://stm.bookpi.org/NAER-V4/article/view/1879


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