Traffic operations at the approaches to the highway checkpoint sites

Abstract

In recent years, more use of security and traffic safety checkpoints on Iraqi highways were made. Add to this, the huge increase in the numbers of vehicles using these highways (with increased numbers of heavy goods vehicles). This situation could lead to traffic congestion, higher delays and higher operational costs to motorists and also could lead to an increase in the rate of traffic accidents. This study tries to investigate the traffic operations at the approaches to the highway checkpoint sites in the Southern of Iraq (in Basrah Governorate) and focuses on some of the parameters that affecting both safety and capacity. For the purpose of this study, field data have been collected by using camcorders from two highway sites, each site has three lanes with a checkpoint. Both sites were at highway 31 near the interchange between highway 6 and highway 31. Several traffic parameters were observed such as traffic flow, average speed, lane utilization, speed differential, traffic congestion and queuing. The observations revealed that for both sites the traffic flow condition was free to moderate, ranging from 750 to 1750 (pcu/hr), with an average speed ranging from 70 to 120 (km/hr). Lane utilization behavior has also been observed for both sites and the results suggest that there is similarity between both sites with lower traffic flow in the nearside lane in comparison with the other lanes (i.e. middle lane and offside lane). For both sites, the lane utilization for the nearside lanes was around 10% – 20%, whereas, the lane utilization for the middle lane and offside lane were around 40% – 50%. Traffic congestion and queuing have been observed as well and the results suggest that there are some differences in queuing length between two sites. In addition, an increased number of speed differentials amongst motorists and late merging with accepting smaller gaps behavior have been observed for both sites. Other site observation is represented by a very lack implementation of traffic management measures (such as traffic schemes and signage) at the checkpoint sites.