Rail Type Selection
Rail Type Selection
Use the greater of the posted speed or design speed at the bridge location to determine the test level required for the railing on the bridge.
All bridges with speeds above 45 mph must have railings that meet TL-3 criteria or greater. Bridges with speeds of 45 mph and below must have railings that meet TL-2 criteria or greater.
The AASHTO LRFD Bridge Design Specifications describes Test Level 4 as "taken to be generally acceptable for the majority of applications on high-speed highways, freeways, expressways, and Interstate highways with a mixture of trucks and heavy vehicles." Based
on this recommendation, bridge railings rated TL-4 as per MASH 2016 are required for new construction and for bridge railing upgrades of all bridges carrying the main lanes of Interstate highways and divided highways. Bridge railings rated TL-4 are recommended for other routes that carry a mixture of trucks and heavy vehicles.
Additional guidance on rail type selection can be found in Appendix A.