The objectives of this research project were to establish relationships between traffic performance and accident probability on two-lane rural highways; to develop an experimental design for field testing the effectiveness of conventional and novel delineation treatments; to evaluate the effect of selected delineation treatments on traffic performance and associated accident probability; and to make recommendations for the design and use of delineation treatments. In the first phase of study, regression analysis was used to correlate delineation-related accident potential to a few systematically derived speed and lateral placement measures. In the second phase of study, additional accident and traffic performance data were collected to test the correlation models and to evaluate the safety effectiveness of 21 unique delineation systems. This Executive Summary provides an overview of the experimental approach utilized in meeting the four project objectives. The two validated lateral placement hazard indicators -- off-center driving and longitudinal change in placement variance -- are briefly decribed. Lastly, recommendations are made for the immediate implementation on two-lane rural highways of a 10:30 broken centerline pattern, narrower edgelines, and the selective use of retroreflective raised pavement markers and post-mounted delineators. (Author)
Samenvatting