Advanced Stop Line - Safety Aspects

Safety Aspects

Based on Danish research, it is argued that an ASL should have the general stop line 5 m back from the main traffic signal. The reasoning is that this puts cyclists clearly into the view of HGV (heavy goods vehicles) drivers, who have a blind spot up to 4 m directly in front of the cab. According to an OECD review, ASLs are also advocated as way of improving pedestrian safety at crossings by increasing the separation between crossing pedestrians and waiting motor vehicles.

Although waiting cyclists might be safer out in front of HGVs, concerns have been expressed about nearside cycle lanes approaching such intersections may encourage cyclists to "creep up" on the inside of turning HGVs. Collisions with turning HGVs are strongly associated with a high risk of death and serious injury. The 1997 edition of Cyclecraft by John Franklin advises cyclists that they should use such feeder lanes only if the traffic signal is red. If the signal is green, cyclists are advised that the best way to minimize danger may be to stay within the main traffic stream. If the lights change while the cyclist is still approaching, the advice is to negotiate their way back into the main traffic stream if possible. Advice produced by RoSPA regarding cyclists and lorries (large trucks) cautions cyclists that even though a junction has an ASL it may be better to hang back if there is a lorry (large truck) present.

Portland, Oregon has implemented these "bike boxes" as they call them, to which bicyclists have claimed useful in aiding safety. The main goal is to prevent collisions between motorists turning right and cyclists going straight. Research performed by the Oregon Transportation Research and Education Consortium showed that motorists and cyclists alike appear to understand and comply with the boxes. Nearly three quarters of motorists stopped behind the bike box and roughly the same percentage of cyclists stopped at the proper location ahead of the motor vehicle stop bar. In addition, the number of conflicts at the intersections decreased and drivers yielded more to cyclists after the boxes were installed. User perceptions of safety also improved.

A leaflet produced by the UK Department for Transport notes:

ASLs have been used successfully at sites with motor vehicle flows up to 1000 vehicles per hour, and with two-lane approaches. In Bristol they have been used on the approach to a signalised roundabout. Success will depend on cars not blocking the cycle lane or encroaching on the reservoir, and on signal timings which ensure that cyclists are not frequently stopped.