The general contractor building the South Jersey light rail line said Tuesday poor design led to the toppling of a rail bridge in April.

"In layman's terms, it was top-heavy," said Walker Kimball, project director for the South Jersey Rail Group, the partnership building the line for NJ Transit.

He said Archer Steel of Hightstown devised the plan to erect the bridge on a barge between Riverside and Delanco and bears responsibility for its fall. Archer Steel declined to comment.

Kimball declined to provide details, including who, if anyone, reviewed Archer's plans.

"There will be litigation," he said. "There are millions of dollars at stake."

He said the important thing is that "no one was killed or suffered disabling injuries. We can find new parts and fix the bridge. That's what we do. We can't replace lives."

On April 6, the bridge, a 210-foot span under construction on a barge in Rancocas Creek, listed and fell toward the Riverside shore, sending five workers diving for safety.

The bridge now rests on its side at a 45-degree angle.

The rail group, a limited partnership between the Bechtel Company, a construction giant, and Bombardier, the company building the rail cars, has hired a California firm to right the bridge.

That firm, Rigging International, plans to do so by using land winches.

The winches, three on each side of the creek, will be bolted to 180-ton concrete blocks installed to anchor the winches.

Sariah Tambre, an engineer for Bechtel, said cables attached to the top of the bridge will be used to pull from one side and restrain from the other.

A device called a slider will be attached near the bottom of the structure to pull it toward the shore and away from a pier in the creek as the structure is righted.

If the weather cooperates, Kimball said, the bridge could be righted as early as the first week in July.