Files Seized From Tunnel Contractor : Metro Rail: Federal agents serve search warrants on the offices of Shea-Kiewit-Kenny. The inquiry reportedly centers on the use of wood wedges blamed for ground sinkage.

In a widening criminal investigation of the troubled Los Angeles subway project, federal agents Tuesday served search warrants on the contractor building the subway tunnel and hauled away boxes of documents relating to construction defects in the multibillion-dollar project.

The warrants were served on the joint venture of Shea-Kiewit-Kenny, which was hired by the Metropolitan Transportation Authority to dig the tunnels under Hollywood Boulevard and Vermont Avenue.

Agents of the U.S. Department of Transportation’s inspector general, the MTA inspector general and the U.S. Marshals Service loaded a truck with documents from the contractor’s field office at Barnsdall Park, near a giant sinkhole that appeared in the street above the project a few weeks ago.

The investigation reportedly centers on the contractor’s use of less-expensive wood wedges rather than steel bracing in the tunnel.

Engineers working for the MTA allowed the contractor to use the wood wedges.

Use of the wedges came under fire after portions of Hollywood Boulevard sank up to 10 inches last year, shutting down the project for nearly five months. The sinkage prompted federal officials to suspend funding for the region’s largest public works project and resulted in hundreds of claims and lawsuits by businesses along the route.

The federal government has provided about half the funding for the subway, the largest share of the $5.8-billion construction cost.

An engineering firm retained by the MTA concluded that the wood was installed improperly and that the required concrete material was not placed around it. Representatives of the inspection-management firm of Parsons-Dillingam last year also accused the tunnel builder of deliberately concealing deficient work from inspectors.

Shea-Kiewit-Kenny officials have declined to comment publicly. But in a letter to MTA board members last year, the contractor’s top executive faulted Metro Rail officials for not requiring the use of soil-stabilizing grout typically used to minimize surface sinkage.

Officials with the U.S. attorney’s office in Los Angeles declined to discuss the warrants, which were sealed.

John F. Shea, president of J.F. Shea Co., promised to cooperate fully with investigators.

“SKK has provided all pertinent information to the MTA’s representatives months ago and because of our continued cooperation is surprised by the need of a search warrant in this matter,” he said in a statement, declining further comment. A warrant also was served on Shea’s headquarters in the San Gabriel Valley.

Franklin E. White, the MTA’s chief executive officer, declined to comment on the investigation except to say, “I and the board from time to time have asked the inspector general to look into various matters, and that’s what he’s doing.” The MTA inspector general did not return calls.

Sen. Richard Polanco (D-Los Angeles) applauded the investigation. “It looks like someone finally might be held accountable for their actions,” he said.

The U.S. Department of Transportation’s inspector general met with local transit officials in October to launch an audit of the costs and management of the subway project.