Although much has been learned about a relatively large number and variety of barrier systems installed on straight and level alignments, there has been a total lack of information on vehicle and barrier behavior and curved-superelevated-sloped alignments. Some recent catastrophic accidents on freeway off ramps have suggested that a better understanding of barriers mounted on these types of alignments was in order. Accordingly, a test program was designed to evaluate the performance of three barrier configurations mounted on a curved, superelevated structure with a downgrade. The objective of this project was to evaluate the performance of the three barrier configurations by using three vehicle types for comparison. The project included full-scale tests of three basic barrier installations:(a) concrete safety shape with vertical orientation,(b) concrete safety shape installed perpendicular to the superelevated roadway, and (c) tubular Thrie-beam and collapsing tube retrofit. Crash tests were conducted by using three vehicle types impacting a 40 mph (65 km/h) and a 15 deg angle (as measured from curve tangent). The three vehicle types were (a) 1800-lb (820-kg) mini-compact car (Honda Civic),(b) 2250-lb (1020-kg) subcompact (Vega), and (c) 20000-lb (9070-kg) school bus (1970 66-passenger Ford/Wayne). All three barrier systems contained and redirected the full range of test vehicles. In terms of vehicle stability and acceleration, the tubular Thrie-beam retrofit was superior. However, there was some barrier damage in the bus test of this system.(Authors)