Test Level 4 Noise Wall for Attachment to Concrete Traffic Barriers

A new transparent noise barrier system was developed for use on rigid bridge railings and other rigid structures. The crashworthy noise barrier system incorporated specially designed, strategically located structural hardware into a noncrashworthy noise barrier system. The noise barrier system was anchored to the back face of a reinforced concrete parapet with vertical steel posts. Transparent sound panels surrounded by a metallic frame were dropped between the spaced posts to create a noise barrier. Three horizontal rails were used to prevent errant vehicles from penetrating into sound panels, snagging on the support posts, or both. The test installation consisted of a 34.56-m-long Paraglas Soundstop TL-4 noise barrier system supported by 18 steel posts. Two full-scale crash tests-one with a single-unit truck and one with a pickup truck-were conducted and reported in accordance with the requirements specified in NCHRP Report No. 350: Recommended Procedures for the Safety Performance Evaluation of Highway Features. The safety performance of the transparent noise barrier system was determined to be acceptable according to Test Level 4 evaluation criteria specified in NCHRP Report No. 350.