WASHINGTON -- American truck regulators are considering a proposal to require trucks with automatic transmissions and buses to have installed technology that prevents unintended acceleration.

The National Transportation Safety Board says it's concerned over incidents involving drivers who press down on the accelerator instead of, or in addition to, the brake pedal and asked the National Highway Traffic Safety Administration to write up a rule.

It wants NHTSA to require the installation of brake transmission shift interlock systems (BTSI) in newly manufactured heavy vehicles with auto transmissions and other transmissions susceptible to unintended acceleration associated with pedal misapplication when starting from a parked position.

The board also urged NHTSA to analyze pedal configurations in heavy vehicles, including designs to determine the effect of pedal design on the driving task, examining pedal error, reaction time, driver acceptance, and driver adaptation.

Once this report is complete, NHTSA should publish pedal design guidelines for designers and manufacturers, says the board.

The board began its investigation in 2005 after a school bus accident in Liberty, Missouri. Pedal misapplication was found to be a factor in the accident as well as four additional accidents involving heavy vehicles up to 2008.

The board cites a 1989 NHTSA study involving light vehicles, which concluded that pedal misapplication is the most probable explanation for sudden acceleration in which no vehicle malfunction is evident; and, in cases where vehicle malfunctions occur, pedal misapplications are often the direct cause of high engine power.

However, the board acknowledges that in the five heavy vehicle accidents it investigated, all the drivers involved reported a loss of braking power or were observed by vehicle occupants to be unsuccessfully attempting to stop the vehicles.

The board concludes, though, that there was no evidence of braking system failure in any of the cases.