Engineers at Texas A&M’s Traffic Institute plan to begin crashing trucks into a metal railing specially designed for the Lake Pontchartrain Causeway next week, hoping the new design will keep large trucks from toppling over the railing while cushioning the impact of smaller vehicles.
The tests, which will take place at an abandoned airfield near College Station, Texas, will replicate tests begun in December on two other railing prototypes. In the tests, three vehicles — a large panel truck, a pickup truck and a small sedan — are driven into the railing at high speed, with the impacts filmed for later study.
The goal of the tests is to make sure the rails can prevent each type of vehicle from going over the barrier — solving a problem that often proves fatal when a vehicle goes over the side of the Causeway and into Lake Pontchartrain.
Officials commissioned the study after a rash of “overboards,” crashes in which a vehicle goes over the Causeway’s railing and into the lake. The problem is far more acute on the bridge’s older, southbound span, where the concrete railings stand only 25 inches high. That may have been high enough in 1956, when the bridge was opened, but is not sufficient today, when more than half of the vehicles on the bridge are high-profile vehicles such as pickups or SUVs.
The numbers make clear the danger: Since 1994, there have been 14 overboard crashes on the Causeway, 13 of them on the southbound bridge. Eleven people have died in those accidents.
The latest proposed design — a two-rail, 22-inch-high steel railing — would raise the total height of the southbound span’s railing to 47 inches.
It differs from an earlier design in that it would be connected to the current concrete barrier by a flat plate that sits on top of the concrete. The first design used a bent plate that attached to the top and front of the concrete.
While the first design’s two rails did a great job of holding the large panel truck on the bridge, the front part of the plate snagged the smaller sedan’s bumper, causing the car to decelerate too fast, which could injure passengers, according to Causeway General Manager Carlton Dufrechou.
The two-rail design is similar to rails widely used in Texas and Pennsylvania, said William Williams, the Texas A&M engineer heading up the project.
“We are adjusting those designs for the Causeway,” he said.
If the tests proceed as expected, Williams could be ready to present his final report to the Causeway Commission at its May meeting.
If that happens, Causeway officials will face an even bigger problem: funding.
Initial projections have put the cost of mounting the railings on both spans at somewhere around $50 million. The Causeway Commission — officially, the Greater New Orleans Expressway Commission — receives $16 million annually in tolls, which cover operating revenue, and another $4.5 million per year from the state to service the commission’s debts.
Causeway officials have applied for federal and state grants, but so far they have come up empty. Dufrechou said he now plans to apply for federal Transportation Infrastructure Finance and Innovation Act funds for major infrastructure projects.
Officials also have discussed raising the tolls on the bridge, which were $2 for a round trip when the span was opened. With a toll tag, the round trip is still $2, though the cash toll has risen to $3. No decision on an increase has been made, but Dufrechou has repeatedly urged the commission to consider every option necessary to make the bridge safer.
“We have to consider all the funding options,” he said. “We have to. It’s the right thing to do.”