Chapter 4: Temporary Bridge Railing
Anchor: #CIHEJHIDSection 1: Overview
Anchor: #i998877Introduction
Temporary bridge railing is installed on existing bridges during widening and on new bridges during stage construction.
Anchor: #i998887Occupant-Hazard Protection Requirements
AASHTO has no specific design criteria for the required strength of temporary bridge railing. The AASHTO “Roadside Design Guide”1 broadly states that temporary longitudinal barriers are “usually justified for bridge widening and to separate two-way traffic on a normally divided roadway.”
Texas is moving toward full implementation of NCHRP Report 3502, which provides two occupant hazard tests for what it classifies as work zone traffic control devices:
- TL-2: 1973-lb. small car at 43 mph and at an angle of impact of 20 degrees.
- TL-3: 1973-lb. small car at 62 mph and at an angle of impact of 20 degrees.
Report 350 states that “for Test Level 3, tests should be conducted at speeds between 22 and 62 mph if there is a reasonable potential for such tests to be more critical than those recommended.” Because penetration of temporary bridge railing is a critical concern, assume that the required test for TL-3 should be at 62 mph.
Report 350 does not specify a strength test for work zone traffic control devices.
Anchor: #i998927Strength of Temporary Railing
Base required strength of temporary railing on engineering judgment.
Anchor: #i998937Other Factors in Selection of Temporary Bridge Railing
The following site- and project-specific factors influence the selection of appropriate temporary bridge railing:
- Traffic volume and mix (for example, percentage of truck traffic)
- Posted speed within the work zone
- Width of temporary lanes, number of lanes, and shoulder width if any
- Alignment of the bridge (that is, curves and grades)
- Duration of construction.