Case Studies: Cushion Stacking

By: Roads & Bridges

Construction zones are high-risk areas for not only construction workers but also for drivers. In 2004, while Hempt Brothers Inc., Mountain Top, Pa., worked to rebuild state Rte. 114 south of Harrisburg, Pa., it devised a plan for protecting drivers.

Three intersections, divided by cement barriers, were created along Rte. 114 to provide access to businesses off the roadway. Hempt Brothers had six Smart Cushion Innovations (SCI) attenuators installed at the end of each barrier, offering protection for oncoming traffic.

The SCI attenuator is a speed-dependent attenuator that stops vehicle resistance during impact. Designed to withstand impacts of up to 62 mph, the SCI attenuator allows lighter and slower-moving vehicles to have longer ride-down distances and lower ride-down g-forces, while ramping up for heavier and faster-moving vehicles.

Also, it is easy and cost efficient to reset it after an impact. Unlike traditional attenuators, the SCI attenuator only requires two shear bolts. The SCI attenuator saves money by reducing time and labor required to reset the attenuator.

According to Jim Payne, project superintendent, Hempt Brothers, the SCI attenuators were hit about 25 times over the course of the project during 2005. About 85% of them required no replacement parts.