An investigation of the capacity implications of installing Advanced Stop Lines (ASLs) has been carried out by TRL Limited as part of a project entitled Cycling Facilities and Engineering, commissioned by the Charging and Local Transport Division of the Department for Transport. The study included a review of previous research into ASLs in the UK and in the Netherlands; an examination of the theoretical capacity implications of installing ASLs using OSCADY (Optimised Signal Capacity and Delay) the signal-controlled junction modelling computer programme and saturation flow formulae; ‘before’ and ‘after’ video surveys of modified junctions, and questionnaires to examine the attitudes of cyclists. This report of the study concludes with several recommendations.