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Development of a TL-1 Timber, Curb-type, Bridge Railing for use on Transverse, Nail-Laminated, Timber Bridges

REPORT NUMBER

TRP-03-211-09

AUTHORS

Scott Rosenbaugh, Christopher Benner, Ronald Faller, Bob Bielenberg, John Reid, Dean Sicking

PUBLICATION DATE

2023-12-07

ABSTRACT

This report has been revised as of 12/7/2023.

Historically, transverse, nail-laminated, timber bridge decks have been used in the State of West Virginia on rural lowspeed, low-volume roads. Although many of these bridges have standard roadway widths of 32 ft (9.8 m) or more, some bridges are configured with widths of only 12 to 14 ft (3.7 to 4.3 m), as measured curb to curb. Since several narrow bridges exist, there is a need for a low-profile railing system to allow for the passage of large trucks and house trailers across these bridges. Several low-profile, curb-type, bridge railing systems have been developed for longitudinal, glue-laminated, timber deck bridges. However, no low-height railings have been developed for transverse, nail-laminated, timber decks. The research objective was to develop a bridge railing for transverse, nail-laminated, timber decks in order to satisfy the Test Level (TL-1) safety performance criteria found in proposed Update to the National Cooperative Highway Research Program (NCHRP) Report No. 350, now referred to as the Manual for Assessing Safety Hardware 2008 (MASH-08). The new, curb-type railing system was adapted from an existing, low-profile, timber railing system that was developed for longitudinal timber decks and evaluated according to TL-1 of NCHRP Report No. 350. Design modifications were made in order to increase railing strength as well as railing height. Several static tests were performed to evaluate the structural capacity of the rail supports utilizing different shear transfer hardware. One full-scale crash test was successfully performed with a 2270P, 1/2-ton, Quad cab, Dodge pickup truck. The curb-type, timber bridge rail attached to a transverse, nail-laminated, timber bridge deck was deemed acceptable according to the TL-1 evaluation criteria specified in MASH-08.