Abstract:
Left turns into and out of driveways within about 30 meters (100 feet) of an intersection are a leading cause of crashes. Interviews with state DOT traffic engineers in the southeast U.S. suggest that easy-to-implement countermeasures are seen as either hazardous in themselves or else ineffective. One countermeasure could be a narrow raised device, or series of small devices, installed along the divider line as a median. This paper reviews alternative median treatments and recommends development of a prefabricated raised median of 90 mm (3.5 inches) height and 305 mm (1 foot) width. It could be retrofitted to arterials with two-way left-turn lanes, at intersection approaches, without widening the road or narrowing the lanes. Its cross-section complies with AASHTO standards for mountable curbs, but is lower than AASHTO's 100 mm height, which might drage the undersides of some vehicles. Prototype designs should be field tested under controlled conditions for effectiveness and safety.
