SINGLE-LEVEL INTERCHANGES, OR - SPLITTING A SIGNALISED INTERSECTION

With increases in traffic flow, large inter-urban and semi-urban intersections generally reach a stage where further geometric improvements are impractical and the construction of an interchange is considered. A method of splitting one of the cross-roads into two one-way stretches, thereby creating two linked-signalised intersections, is presented and discussed. It is shown that the normal four-phase signal program can be changed to a linked three-phase program, allowing for all directional movements. Calculation of total delays according to data, taken from an intersection so changed, showed a reduction of about 55 per cent in total vehicle delay in morning peak hour and of 33 per cent in off-peak hours. /TRRL/