Nevada transportation officials are investigating claims by a construction worker who says a new highway bridge south of Reno is unsafe because he was ordered to use substandard concrete to save money building it.

David Lee said he did the shoddy work earlier this year at the direction of his foremen at C.C. Myers, a California-based subcontractor on one of five major bridges that are part of a $600 million highway project connecting Carson City and Reno.

"I personally won't allow my family to drive on these bridges until it is fixed because I believe it could cause catastrophic failure," Lee told The Associated Press. "If that bridge fell apart and I didn't say anything, I couldn't live with myself."

Lee, 49, said he took his concerns to the Nevada Department of Transportation after he was among several workers laid off in October,

Transportation Department assistant resident engineer Kenneth Oates confirmed the state is investigating Lee's allegations. Oates said if any work was substandard, inspectors likely would have detected it during the final checkoff. But he said Lee marked on the blueprints exactly where he claims to have patched weak links.

A company spokeswoman said an internal investigation found no substandard work. "We checked out the claims that were made and in the investigation found no evidence to substantiate them," Beth Ruyak said from Rancho Cordova, Calif. Ruyak said the Nevada Transportation Department's probe was going to be even broader.

"At this point, we understand they have not found anything either but we are told their investigation is still open," she said.

Lee, a third-generation construction worker who moved from Sacramento four years ago, said he was told to use a stucco, sand-cement mix to patch the concrete imperfections in the bridge supports instead of the more-expensive, extra-strength material required under building specifications for the Galena Forest Bridge.

He said a foreman told him to do the work when onsite Nevada Department of Transportation inspectors went to lunch at the 919-foot-long bridge, the second longest in the series along the 8.5-mile stretch of highway. "They were more worried about the money instead of public safety," Lee said.

Oates said the contractor would be held accountable if the patches are found to be inadequate. C.C. Myers was notified of the concerns and already has conducted its own inquiry, he said.

The I-580 bridge is part of a huge transportation project that when finished will complete the last continuous stretch of the freeway linking Reno and Carson City. But it has been fraught with cost overruns and delays.