TTI Research Supervisor:
William F. Williams, P.E.
Texas Transportation Institute
Texas A&M University System
College Station, Texas 77843-3135
(979) 862-2297 [email protected]
Pooled Fund Technical Representative:
Assistant Bridge Design Administrator
Bridge and Structural Design Section
Louisiana Transportation Center
1201 Capitol Access Road
P.O. Box 94245
Baton Rouge, LA 79084-9245
(225) 379-1323 [email protected]
A complete bridge rail retrofit was needed. The Lake Pontchartrain Bridge supports two 12‑ft roadway lanes with 3 ft shoulders. The total roadway width is 30 ft. The existing bridge rail consists of two 5-inch by 8-inch precast concrete rail members supported by cast-in-place 10‑inch by 10-inch concrete posts. The concrete posts are spaced 8-ft-9-inches on centers. The posts are cast on top of a 9‑inch high by 18-inch wide concrete curb.
The US 11 Lake Pontchartrain Bridge crosses over Lake Pontchartrain just northeast of New Orleans in Orleans Parish, Louisiana. This bridge is approximately 4.72 miles in length and was constructed in the late 1920s, and is shown in Figure 1. This bridge rail was badly damaged during Hurricane Katrina, as shown in Figure 2.
Several bridge rail retrofit designs have been developed at Texas A&M Transportation Institute (TTI) for a host of different states, as well as for the Federal Highway Administration (FHWA). In addition, hundreds of crash tests have been performed at TTI on various Test Level 3 (TL-3) bridge rail designs.
For this project, TTI reviewed several different TL-3 bridge rail designs that meet the performance requirements of NCHRP Report 350. The Illinois 2399-1 bridge rail was a good candidate for this project and was considered for the retrofit design. Details of this design are shown in Figure 3.
The objective of this project was to develop a new retrofit bridge rail design to be used for the US 11 Lake Pontchartrain Bridge that meets the current AASHTO LRFD strength and NCHRP Report 350 performance requirements. Some of the existing reinforcement in the existing bridge rail has deteriorated due to weathering in a marine environment. In addition, the bridge railing was damaged from the high water surge forces from Hurricanes Katrina and Rita, as shown in Figure 2, and deterioration in the reinforcing steel in the bridge rail was evident. A new retrofit bridge rail was designed and developed for this project. Details for the design are provided in Figure 4. This retrofit bridge rail was installed successfully and is currently in use on the structure.