Validity of Reversible Flow Lanes between Kandy Road Flyover and New Kelani Bridge Roundabout along A01 to Accommodate Peak Traffic Flows

Abstract

This paper examines ways of enhancing road capacity by improving lane efficiency along Colombo-Kandy Road (A01) at Colombo city entrance by introducing reversible traffic flow lanes between Kandy road flyover at Pattiya junction and New Kelani Bridge roundabout, to cater for peak traffic flows. A traffic study was conducted between Pattiya junction and New Kelani Bridge roundabout to find out the benefits and any losses, if reversible traffic flow lanes are introduced along this stretch of road during peak traffic flows in mornings and evenings. Two options of lane assignment were considered for the heavy flow direction during peak hours. Option ( i ) by adding one extra mixed traffic lane towards the heavy flow direction while reducing a lane from the opposite direction, and option ( ii ) adding an additional lane exclusively for buses towards the heavy flow direction while reducing a lane in the opposite direction. These two options were considered for both morning and evening peak traffic flows. By using Davidson’s model the benefits or any losses in travel time was computed for the two options separately for both directional peak traffic flows. The study proved that by the introduction of reversible flow lanes along the considered section, during morning and evening peak traffic flows, the benefits obtained by far outweigh the losses due to minor reduction in road capacity in the opposite directional traffic flows. It was also found that introduction of designated lanes for ‘buses only’ further improves the overall efficiency of the system with higher benefits. If ‘buses only’ lanes are introduced it is of the utmost importance to implement these lanes only for buses, as expected.