In the pre-dawn hours of a summer morning, a bus traveling from New York to Pittsburgh traveled off the right side of the roadway near Burnt Cabins, Pa., where it struck the back of a parked tractor-trailer. Pushed forward, the tractor-trailer hit the side of another parked truck. The bus driver and six passengers were killed; 16 bus passengers and the two occupants of the first truck were injured.

At the National Transportation Safety Board (NTSB), we identified three safety issues in this accident: operator fatigue, bus crashworthiness and the inadequate federal oversight of bus operators.

That crash occurred on June 20, 1998.

Thirteen summers later, on another pre-dawn morning, a bus bound for New York City crashed near Doswell, Va., killing four passengers and injuring several others. Last month’s crash followed the horrific bus rollover in the Bronx in March that killed 15 people and injured 18 more. Two days after that tragedy came two more bus crashes, a fatal accident in New Jersey killing two people and a crash in New Hampshire that injured all 25 onboard. The NTSB is investigating all of these crashes.

Since the 1998 crash, the NTSB has launched 36 investigations into bus accidents. Again and again, we see the same failings: a fatigued driver, poor occupant protection in a crash and marginal operators that are put out of service only after a fatal accident.

Crashes on our nation’s roadways are senseless tragedies. NTSB investigations identify opportunities to prevent these accidents and save lives.

Let me distill the more than 100 recommendations we have made over the years to improve bus safety into three main categories:

1) Better federal oversight of motorcoach operators. This is to ensure the safety of the vehicles and their drivers. Unfortunately, our investigations have regularly identified businesses that should not have been operating buses. In an August 2008 accident in Sherman, Tex., in which 17 people were killed, the bus operator previously failed its compliance review but applied as a new carrier with a new name and obtained another Transportation Department operating number. The accident happened under the “reincarnated” carrier’s new name.

After a January 2008 crash in Victoria, Tex., we learned that the operator had been unable to obtain insurance because of a previous accident so it had used another operator’s authority to operate its buses. The NTSB has recommended that the Federal Motor Carrier Safety Administration improve its detection of unscrupulous operators and ensure that all bus operators have the required operating procedures to safely transport passengers before being granted operating authority.

2) Improved occupant protection. The lack of crashworthiness significantly contributes to the severity of bus accidents. For decades, we have called on the National Highway Traffic Safety Administration (NHTSA) to develop standards to increase window glazing and roof strength, improve seating compartments to keep passengers protected and in their seats, and improve window emergency exits on motorcoaches.

3) Implement advanced vehicle technologies. Technology such as lane-departure warnings, electronic stability control and forward-collision warning systems are commercially available and can help prevent accidents due to fatigue or distraction. For 10 years, the NTSB has recommended that the NHTSA require forward-collision warning on commercial vehicles to decrease collisions. Technologies that provide information about the vehicle’s condition, such as tire pressure monitoring systems, are standard equipment on many passenger vehicles manufactured today but are not required for commercial vehicles. They should be.

A bus safety bill is pending in the Senate. The Motorcoach Enhanced Safety Act of 2011 was introduced in the wake of tragic bus accidents in 2007 and 2008 involving constituents of Sens. Sherrod Brown (D-Ohio) and Kay Bailey Hutchison (R-Tex.). The legislation would implement many of the NTSB’s long-standing recommendations to make bus travel safer.

Increasingly, we are seeing the same sorts of tragic bus crashes, over and over again, with the same absence of actions to prevent this needless loss of life.

Let’s not wake up to another tragic bus crash. Make the needed changes now.

The writer is chairman of the National Transportation Safety Board.