Advanced stop line

An advanced stop line (ASL), also called advanced stop box or bike box, is a type of road marking at signalised road junctions allowing certain types of vehicle a head start when the traffic signal changes from red to green.

Straight-on cyclists can adopt and maintain a prominent position for transiting the junction safely within the main traffic stream.

An ASL will also help reduce the exposure of such cyclists at junctions with nearside (i.e. left in the UK and Ireland, right in USA, etc.)

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 heavy goods vehicle (HGV) drivers, who have a large blind spot directly in front of the cab.

Federal Motor Carrier Safety Administration (FMCSA) however estimates this spot to be 6 metres (20 ft) long.

Success will depend on motorists not blocking the cycle lane or encroaching on the reservoir, and on signal timings which ensure that cyclists are not frequently stopped.