W-BEAM GUIDERAIL TRANSITION FROM LIGHT TO HEAVY POSTS.

A transition between light- and heavy-post W-beam guiderail was evaluated through two full-scale crash tests. The transition consisted of lowering the rail height from 30 to 27 in. and reducing the spacing of the light posts as the heavy-post section is approached. The crash-test impacts were just upstream of the heavy-post section using 1800- and 4500-lb sedans. Tests results were generally acceptable in terms of NCHRP criteria. Although the exit trajectory of the 4500-lb sedan exceeded the recommended threshold limits, the vehicle was not judged to present a significant threat to other vehicles.