Design and testing of two bridge railings for transverse nail-laminated timber deck bridges

Nail-laminated timber deck bridges represent an economical and convenient solution for rural low-volume roads, but a need exists to develop effective railing systems for this type of roadway structure. This paper describes the development of two bridge railings that are specifically designed for transverse nail-laminated timber deck bridges and that meet the requirements for Test Level 1 (TL-1) of the Manual for Assessing Safety Hardware (MASH) and TL-2 of NCHRP Report 350. The design for each of the railing systems was based on retrofit modifications applied to existing bridge railings that were previously successfully tested: one for a longitudinal glue-laminated timber deck and the other for a transverse glue-laminated timber deck. For both railing systems, component testing was performed to investigate the behavior of the proposed design and the potential advantage of various solutions. A full-scale crash test assessed the safety performance of the TL-1 curb-type railing under the new MASH criteria, while dynamic component tests were deemed sufficient for the assessment of the steel railing under TL-2 conditions for NCHRP 350.