Abstract:
Traffic congestion is one of the most imperative problems in almost all countries. Flyovers are usually used all over the world to address the traffic congestion, especially at intersections. Advantages of grade separation are; less interruption to traffic flow, higher speed and reduces the scope for accidents. In Sri Lanka also flyovers are used to address the delays and the safety risk at highly congested intersections. Dehiwala intersection was also replaced by a flyover in order to eliminate the traffic congestion. However, congestion and accident trends have not been reduced yet. There are many factors that contribute to increased congestion levels especially during peak periods and the issues behind the increase in accidents at Dehiwala junction. Engineering solutions based on traffic and highway engineering principles can effectively be used to improve the traffic flow and reduce traffic accidents at this location. Accident data analysis, speed and travel time surveys were used to compare the conditions at present and before construction of the flyover. Moreover vehicle movement pattern, road geometry and adjacent land use activities can be used to evaluate the impact to the Dehiwala flyover. Geometry of the road need to be improved as it will not generate significant speed difference between two adjacent sections as well as not generate bottlenecks at the entrances of the flyover. Stopping of buses within 75m from the junction and vehicle parking within 50m range from the intersection need to be discouraged by using regulatory methods.
