Current emphasis in highway capacity research conducted at Nanyang Technological University in Singapore is to develop traffic models on an area-wide, link-based and intersection-based scale. The area-wide traffic model relates total inbound and outbound flow rates across the Restricted Zone cordon to average journey speed. The model predicts an area capacity of around 67,300 veh/h. Speed-flow relationships for open expressway sections suggest capacity close to 3000 pcu/h/lane. A tunnel capacity of 2600 pcu/h/lane was found although results appear to be not conclusive as tunnel flows are uncongested even during peak periods. On arterial road segments, our results indicate a capacity of about 800 veh/h/lane. capacity of about 800 veh/h/lane. There also appears to be a non-linear trend between speed and density for both expressway and arterial road sections. Saturation flows between 1600 to 2500 pcu/h/lane have been recorded at signalised intersections; saturation flows of nearside (leftmost) lanes are lower than those of non-nearside lanes. (A)
Abstract