WASHINGTON -- The National Transportation Safety Board recommended this week that the DOT explore making several heavy-duty vehicle safety technologies mandatory, including fatigue monitoring systems.

The recommendations come in response to an October 2005 accident on I-94 in Wisconsin where a tractor-trailer rolled over and a motorcoach ran into the wreckage. Four passengers and the bus driver had fatal injuries, and 35 other passengers were injured.

The investigation revealed that the truck driver was fatigued and fell asleep at the wheel.

Possible technologies that could have helped in this instance, the NTSB noted, included lane departure warning systems, driver monitoring systems such as PERCLOS (which measures the rate of eyelid closure), and electronic onboard recorders.

In a letter, NTSB said to the Federal Motor Carrier Safety Administration that it should "develop and implement a plan to deploy technologies in commercial vehicles to reduce the occurrence of fatigue-related accidents," as well as "develop and use a methodology that will continually assess the effectiveness of the fatigue management plans implemented by motor carriers, including their ability to improve sleep and alertness, mitigate performance errors, and prevent incidents and accidents."

"Both active braking and ESC technologies represent opportunities for significant enhancement of CWSs' capabilities to prevent (or mitigate) commercial vehicle accidents," said Mark Rosenker, acting NTSB chairman, in his letter to NHTSA.