Federal lawmakers are questioning whether state and local governments are misusing their red light cameras to nab more drivers and boost their revenues.

Transportation officials across the country have been illegally shortening yellow lights after ignoring calls to lengthen the warning signals, according to testimony at a hearing held by a subcommittee of the House Transportation Committee on Wednesday.

Committee chairman Rep. Peter DeFazio, D-Ore., criticized the National Highway Traffic Safety Administration for using lax standards in handing out federal grants to help fund red light camera programs.

"If people are going to use federal funds to establish these programs, shouldn't there be standards or guidelines?" DeFazio asked a panel of transportation officials attending the hearing.

Local officials in D.C., Maryland and Virginia — where nearly 300 cameras are located — have penciled millions into their budgets in expected traffic camera income this year. Arlington County installed four red-light cameras last month, and Prince George's County won state approval in April to expand its camera program.

DeFazio suggested the federal government require proof that states attempted to increase road safety at problem intersections before considering red light cameras.

The chairman modeled his recommendations after a new Georgia law requiring longer yellow lights at state and local intersections.

"We found abuse by local governments and a lack of regulation and standardization," Georgia Rep. Barry Loudermilk said of his state's 10-year-old camera program.

Officials found some of the highest revenue-generating intersections were experiencing an uptick in accidents, and some cities were shortening yellow lights to below the federal minimum.

Three months after Georgia enacted the new law, red light violations were cut in half and 12 cities dropped their camera programs for not generating enough revenue, Loudermilk said.

NHTSA officials and local government representatives insisted on the effectiveness of the traffic cameras in slowing cars and saving lives.

Howard County Police Department Capt. Glenn Hansen said he used a federal grant to test red light cameras in Howard and found crash reductions at every site where cameras were installed.

A study of 132 intersections in Baltimore, Howard County, Montgomery County, and three jurisdictions in California showed red light cameras reduced right-angle crashes by 25 percent and increased rear-end crashes by 15 percent, according to the Federal Highway Administration.

Editor's note: This article has been updated to correct a statement incorrectly attributed to Rep. Reagan. The statment in question was made by Rep. Barry Loudermilk.