Field studies were designed to measure the effects of pavement markings on driver behavior at freeway lane drop exits. Number and location of lane changes and erratic maneuvers upstream of three lane drop exits were the measures of effectiveness used to describe driver behavior. The data from two sites directly revealed-and the data from a third site indicated-that drivers are moving into or out of the exiting lane further upstream of the lane drop gore in the after period than in the before period. The before-and-after studies also revealed that the number of erratic maneuvers within the entire study segment decreased with the installation of the markings. The largest decrease was in the number of one-lane lane changes through the gore.

A lane drop exit occurs when one or more lanes are eliminated from a freeway at an exit. This treatment is used when traffic demand decreases or when high volumes are exiting to another facility. Lane drop exits can cause driver confusion when the driver does not expect the lane to exit; rather, the driver expects the lane to continue with the freeway main lanes. Without proper notification of the impending exit, drivers can find themselves performing erratic maneuvers to prevent exiting at undesirable locations. Exit-only signs are the predominant type of traffic control device used to communicate the existence of a lane drop exit. A pavement marking treatment is included in the national and Texas Manual on Uniform Traffic Control Device (1, 2) as an optional MUTCD treatment. Because of interest in determining more effective methods of communicating lane drop exits to motorists, the Texas Department of Transportation (TxDOT) commissioned a study (3) to determine the effects of pavement markings on motorists. The pavement markings, which are generally known as lane drop markings, consist of larger-width lane striping that begins approximately 0.8 km (0.5 mi) in advance of the theoretical gore point and a solid white channelizing line 203 mm wide (8 in.) extending approximately 91.5 m (300 ft) upstream from the theoretical gore point. The larger-width lane striping is 203 mm wide by 0.9 m long (8 in. wide by 3 ft long) separated by 3.7-m (12-ft) gaps. White pavement marking arrows can also be included as part of a pavement marking treatment. Previous studies on pavement markings at exit and entrance ramps focused on the effectiveness of different color markings and on raised pavement markers. One study (4) specifically investigated signing and pavement markings at lane drop exit locations. The study compared the lane changes and erratic maneuvers occurring within 152.5 to 213.5 m (500 to 700 ft) of the gore on a matched 15-min interval basis. The results were mixed; one site showed improvements in all times studied, whereas the other two sites