InTrans / Aug 14, 2018

Railing systems for longitudinal timber deck bridges

Bridge railing systems in the United States have historically
been designed based on static load criteria
given in the American Association of State Highway
and Transportation Officials (AASHTO) Standard
Specifications for Highway Bridges. In the past
decade, full-scale vehicle crash testing has been recognized
as a more appropriate and reliable method of
evaluating bridge railing acceptability. In 1989,
AASHTO published the Guide Specifications for
Bridge Railings which gives recommendations and
procedures to evaluate railings by full-scale vehicle
crash testing. In 1993, the National Cooperative Highway
Research Program (NCHRP) published Report
350, Recommended Procedures for the Safety Performance
Evaluation of Highway Features, which provides
criteria for evaluating longitudinal barriers.
Based on these specifications, a cooperative research
program was initiated between the University of
Nebraska-Lincoln and the Forest Products Laboratory,
and later the Federal Highway Administration, to develop
and crash test several bridge railings for longitudinal
wood decks. This paper describes the successful
development and testing of nine resulting railing systems
in accordance with the AASHTO Performance
Level 1 and 2 (PL-1 and PL-2) requirements, and the
Test Level 1 and 4 (TL-1 and TL-4) requirements of
NCHRP Report 350.