The developing benefits of the advance space line (ASL) systems for planning safer traffic light intersections

Abstract

The safety of the road vulnerable users is the subject of recent research, considering not only different strategies applied to priorities but also to road geometries, with particular reference to crossings and waiting areas adjacent to traffic light lanterns. This document presents an exploratory study of bicycle boxes considering some European and American case studies. The bicycle boxes, also known as advanced stopping lines or advanced stopping boxes, have been installed to increase the visibility of the cyclists and reduce the conflicts between motor vehicles and cyclists, in particular in the potential situations of "right hooking". A bicycle box is a space of the traffic light intersection located between the walkway, and the stop line of the vehicle used to supply the cyclists a dedicated space to wait for the signal during the red light intersections. In this area the positioning of the cyclists in view of the vehicle stop improves visibility and reduces conflicts between all users. They also provide cyclists with an initial advantage cross the intersection, which helps make cyclists turn difficult and improves safety and comfort due to the difference in acceleration rates between bicycles and motor vehicles. It allows a cyclist to be in front of motor vehicles, which is not the case it only improves the visibility and awareness of motorists, but allows cyclists to "reclaim the lane" if desired. Both the reversal of motor vehicles and bicycles in pedestrian crossing decreased significantly at the points where the bicycles were located compared to the control intersections. Bike boxes have had mixed effects on the invasion of motorists on the bike path. The number of conflicts observed at the pit stations has decreased, while the total number of cyclists and motor vehicles has increased, promoting a safer crossing. Starting from the comparison of case studies examined in the literature of the last 20years, an attempt was made to define the benefits and criticalities produced by this implementation, reporting all of them to a SWOT analysis useful in the preliminary design phase but also a simple control tool.