WASHINGTON -- Federal investigators say they now know what caused the bus crash that killed five Bluffton University baseball players last March. They're pointing to confusing highway signs, driver mistakes and a bus that lacked safety features. The National Transportation Safety Board is recommending changes based on the findings.

At a meeting Tuesday, the NTSB focused on the actions of the bus driver and the Georgia Department of Transportation. Investigators say the bus driver thought he was getting on an HOV lane when he drove onto an elevated exit ramp instead. They said the Georgia DOT should have had two signs--one indicating the HOV exit, another indicating where the HOV lane continued on the highway. Instead, the signs were staggered.

They also said the 65 year old driver should have reacted more quickly to the stop sign at the top of the exit ramp. The crash killed the driver and his wife and injured 28 others.

The NTSB also took a close look into the safety features of motorcoaches-- an issue the parents of several of the students killed are fighting to change.

John Betts lost his son David in the crash and says his son would still be alive today if there were more safety regulations on motorcoaches. He made the trip to Washington with about a half dozen other family members to hear the report in person.

"These lives that were lost was absolutely preventable. That's the most frustrating piece for any of the family members is that this was preventable. Not the accident--accidents will occur; HOV lanes can be corrected; my son can not be brought back," said Betts.

Dana Arend's son was also killed and he says it's a crime these buses don't have seatbelts.

"People ask us would Zachary survive if he had a seatbelt? We'll never know because he never had the opportunity. There are no seatbelts on the buses so he never had the opportunity and that really upsets us," said Arend.