Abstract
The Federal Highway Administration (FHWA) proposed highway design guidelines to increase safe driving ability of older drivers, but little empirical evidence exists to support these guidelines. Using kinematics measures from an instrumented vehicle and on-road evaluations, the authors examined the safety effects of improved versus unimproved intersections in older (65-85) and younger (25-45) drivers. Kinematics measures showed that 4 maneuvers had significantly poorer lateral stability for the unimproved conditions, and significantly greater speed for the improved conditions. Behavioral measures showed that drivers had significantly fewer errors for 2 improved left-turn maneuvers, and fewer total errors overall, with older drivers having a higher mean number of errors. These findings suggested that the FHWA guidelines for safe road conditions result in safer driving by older and younger adults.