Effect of Longitudinal Joints on Vehicle Positioning

Motorists generally follow the guidance provided by pavement markings, which are normally marked in coincidence with the longitudinal construction joint, when the joints are necessary. At some locations, however, there may be a mismatch between joints and markings, which may lead the motorists to follow joints instead of pavement markings. In the absence of detailed studies on this topic, an effort was made in this study to evaluate the effects of unmatched longitudinal construction joints and pavement markings on the lateral positioning of vehicles. Sites with such characteristics were identified, and detailed data were collected at one of the sites, using video camera techniques to capture movements of vehicles for longer durations. The video tapes were later reduced to extract necessary information. Distance to the centerline of each vehicle, vehicle type, presence of vehicles in the adjacent lane, traffic volume, and vehicle movement were the main data parameters gathered while reducing the data. Statistical analysis was carried out using Student’s t-test to see the differences, if any. Several comparisons were made for various types of vehicles traveling under different weather conditions and vehicles going straight and turning right immediately after passing the location. The analysis results indicated that the distance to the center line of vehicles traveling in the target lane was statistically different from the expected lateral positioning of the vehicles if they were not affected by the joints. Based on the analysis of field data, drivers’ lateral position seems to be affected by unmatched joints and pavement markings. It might be advisable to make efforts to avoid such occurrences.