Study of left-turn-green-arrow (ltga) traffic scheme at signalised junctions

The Land Transport Authority of Singapore (LTA) has implemented the traffic control Left-Turn-Green-Arrow (LTGA) at signalised junctions since 1996 to improve the conditions of the left-turning traffic. To date, there are many junctions with LTGA all over Singapore and the Authority may introduce such control to more junctions in future. The objective of this project is to study the operational and safety factors pertinent to LTGA traffic control, particularly on the conflict issue between effectiveness of LTGA traffic scheme to reduce motorists’ delay and the safety concerns resulting from it. Three signalised LTGA T-junctions located in Jurong area were selected for a field study. A compliance study was done on road users, both motorists and non-motorists, to find out the proportion of left-turning vehicles and pedestrians violating the red signal. A study was also done on the vehicle movements to assess the degree of recklessness of the non-compliant vehicles. In addition, interactions between vehicle-vehicle and vehicle-pedestrian were also examined. This was done to study the safety concerns of the LTGA traffic scheme. The analysis revealed that the LTGA traffic scheme is effective in giving left-turning vehicles additional opportunity to turn. The compliance study shows that non-compliancy for both vehicle and pedestrian exists. Examination of the vehicle manoeuvres indicated that most of the vehicle movements for non-compliant vehicles were either fast or slow and this can be dangerous. Furthermore, it was found that there were more unsafe interactions as compared to safe interactions for both vehicle-vehicle and vehicle-pedestrian interactions. Various suggestions and recommendations are included in this report.Bachelor of Engineering (Civil