Design and Testing of Tie-Down Systems for Temporary Barriers

Abstract

Two tie-down temporary barrier systems were developed and crash tested according to the safety performance criteria provided in NCHRP Report 350: Recommended Procedures for the Safety Performance Evaluation of Highway Features. Both tie-down systems were designed to reduce barrier displacements and to retain deflected barriers on the bridge deck edge. The first system consisted of a steel tie-down strap concept for use with the Iowa F-shape temporary concrete barrier. At each barrier joint, the trapezoidal-shaped strap retained the vertical pin and was attached to the concrete bridge deck using two drop-in anchors. An acceptable fullscale vehicle crash test of the tie-down strap concept was conducted according to the Test Level 3 (TL-3) impact safety standards in NCHRP Report 350. The second tie-down system was developed for use with Iowa’s steel H-section temporary barrier. A new barrier connection was developed to simplify barrier attachment and to accommodate deviations in horizontal and vertical alignment. It consisted of two steel shear plates positioned within an opening on the adjacent barrier section and held in place with two steel drop pins. Four steel angle brackets were welded to the barrier’s base to allow for rigid attachment to the concrete bridge deck with drop-in anchors. Two full-scale vehicle crash tests were conducted on the steel H-barrier system according to TL-3 impact safety standards found in NCHRP Report 350. After an unacceptable first test, the system was successfully tested with minor design modifications.