Improved Communication of a Left Exit Lane Drop Using Pavement Markings (1232-27)

This project investigated the operations and safety characteristics of left exit lane drops. As generally recognized, constructing left exits is to be avoided; however, when present, suggestions on methods to improve safety and operations are valuable. One alternative for better communicating to motorists the presence of a left exit lane drop is with pavement markings. Lane drop pavement markings, pavement arrows, and raised pavement markings were evaluated at one site to determine their effectiveness during daytime and evening operations.|Erratic maneuvers were reduced by 40 percent during daylight operations, and by 34 percent during evening operations. The predominant type of erratic maneuver within 300 ft (91.5 m) of the gore was the lane change through the gore area. The most common type of erratic maneuver upstream of the gore area was the two-lane change.|The study site, which was 1240 ft (378 m) in length, experienced a 31 percent reduction in lane changes (64 percent for the 300 ft (91.5 m) nearest the gore) between the before and after periods during daylight operations. Examining the data by zone (which were typically 100 ft (30.5 m) in length) showed a significant reduction in lane changes per hour in the 700 ft (231.5 m) nearest to the gore, with fluctuations in the remaining zones (between 700 and 1200 ft (213.5 and 366 m) upstream of the gore) for both daylight and evening operations. The data indicated that motorists performed their lane changes, into or out of the exit-only lane, further upstream of the gore in the after period than in the before period.