His 20-year-old son, David, was crushed to death in March 2007 in another rollover accident in Atlanta during a bus trip with his college baseball team.

That bus, like the one in the Sherman accident, was not equipped with safety belts, except for the driver's seat. Most of those who died were ejected from their seats. Some were crushed.

Now a safety activist, Mr. Betts obsesses about when federal regulators will end 40 years of inattention and order seat restraints that he believes would have prevented David's death and almost all deaths in commercial bus accidents.

"The pain does not need to continue," he said Saturday. "There is no need for people to keep dying in these motor coach rollovers."

Historically, the 30 to 50 people killed each year in bus accidents have paled in comparison to the 40,000 to 50,000 deaths recorded in automobile collisions.

But when multiple deaths have occurred on buses, it has usually been a rollover accident where passengers were ejected from their seats. Sherman police said many of the approximately 40 casualties in Friday's accident appeared to have "crushing wounds" sustained when the bus blew a tire, slid off U.S. Highway 75 and dropped down an embankment.

Survivors reported that some people were tossed around inside the bus. Some passengers landed on top of each other inside the bus while others were ejected through the windows and crushed when the bus fell on them.

Jason Noel, who visited the family of a fellow church member at Wilson N. Jones Medical Center in Sherman on Saturday, said the lack of seat belts was worrisome.

"Absolutely, that could have saved a lot of lives," he said.

Mr. Noel is far from alone in his opinion. Among those who concur is Jim Hall, chairman of the National Transportation Safety Board from 1994 until 2001.

Now a safety consultant in Washington, Mr. Hall said Saturday that the lack of seat restraints on passenger buses is "the biggest gaping hole in transportation safety today."

While other countries have had seat belts in buses for at least a decade, the non-responsiveness from the U.S. Department of Transportation, Mr. Hall said, "is past being a disappointment. It's to the point of almost being criminal."

The safety board has urged the U.S. Department of Transportation since 1968 to require bus manufacturers to install safety belts to keep passengers in their seats. Board members renewed that call as recently as last month, when they used their findings in the Atlanta bus crash to issue a sharp denunciation of the National Highway Traffic Safety Administration's inaction on seat belts.

Board member Debbie Hersman told reporters Saturday at the site of the Sherman bus crash that it was too early to tell if restraints would have mattered.

NHTSA officials have said there is not sufficient evidence to prove safety belts are needed in passenger buses. The agency also has resisted doing research.

"Given the overall safety record of motor coaches and school buses, I think the approach has generally worked," agency spokesman Rae Tyson said in a previous Dallas Morning News interview about seat belts .

NHTSA officials could not be reached for comment Saturday.

There have been recent signs that NHTSA's icy view of seat restraints on buses may be melting. Earlier this year, the agency conducted crash tests in Mr. Betts' home state of Ohio. The results of those tests have not been released.

Last year, Transportation Secretary Mary Peters endorsed the idea of installing seat belts in school buses, although rules to implement that change have stalled.

There is also a movement in Congress to enact legislation that would force the government to improve commercial bus safety. The legislation is co-sponsored by Sen. Kay Bailey Hutchison, R-Texas, and Sen. Sherrod Brown, D-Ohio.

Their bill, which is scheduled for a hearing before the Senate Transportation Committee on Sept. 18, grew out of the Atlanta crash that killed Mr. Betts' son and six others, and a bus fire near Dallas that killed 23 Hurricane Rita evacuees in 2005.

In addition to ordering seat belts and stronger seating systems, the legislation would require glazing on windows to prevent passengers from being ejected.

The motor coach industry, which includes more than 3,700 operators around the country, has not publicly opposed the bill. But representatives have said they want any legislation to be rooted in scientific fact.

Mr. Hall attributed the government's historical inaction on seat belts to successful lobbying by the bus industry, which he accused of putting profits ahead of safety.

The cost of installing seat belts has been estimated by some experts as less than 1 percent of the total cost of manufacturing a bus. Motor coaches, which typically carry about 60 passengers, cost around $500,000 to make.

Houston attorney Tom Brown, who represented several clients in a charter bus crash near Waco in 2003, said he believed manufacturers don't see a need to change.

Mr. Brown was the lead plaintiff's attorney in a lawsuit against Motor Coach Industries, the maker of the bus that crossed the median on Interstate 35, collided with two cars and fell over on its side during a church trip to Dallas.

The $17.5 million verdict, which is pending before a state appeals court, reflected an unprecedented decision by a jury to hold a bus manufacturer liable for not installing seat belts and glazed windows even though the government did not require them.

MCI also manufactured the coaches involved in Friday's crash in Sherman and the 2005 bus fire near Dallas.

Mr. Brown said he continues to be baffled by the bus industry's reluctance to make what he believes is an easy fix. He said he is convinced that change will not come unless the Congress or regulators force it upon the manufacturers.

Calls to the headquarters of two industry groups, the United Motor Coach Association and American Bus Association, were not returned on Saturday.

Mr. Hall said he remains haunted by his inability to persuade federal regulators to require buses to have seat belts.

"Hopefully," he said, "this tragedy will be the tipping point for the federal government to take action."

It's the same hope he said he's had after every bus crash.

The National Transportation Safety Board will hold a news conference at 2 p.m. today in Sherman to discuss its investigation into the bus crash.

Staff writers Kim Horner and Matthew Haag contributed to this report.

•The cause of the crash remains under investigation, but it is known that the right front tire blew out. It was a recapped tire, and using such tires on the front of the bus is a violation of federal safety rules.

•The bus, manufactured in 2002, had three citations for bad brakes in the last 18 months.

•Angel Tours, owned by Angel de la Torre, owned the bus. Angel Tours was shut down by federal officials in June. A few weeks earlier, Mr. Torre started a new company, Iguala Busmex, which took possession of the bus, but the bus wasn't authorized to operate across state lines. On Friday, it was headed to Missouri.

•In the six months before Angel Tours was shuttered, company drivers were taken out of service six times for violations including not having the proper licenses and not keeping proper logs. Thirty vehicle inspections also found numerous violations.

•A Federal Motor Carrier Safety Administration compliance review of Angel Tours in May cited the company for three critical errors: required drug and alcohol tests weren't performed on drivers; two of the company's drivers were found to have expired medical certificates; and 27 of 28 required inspection reports were missing.

•The bus driver, Barrett Wayne Broussard, 52, was convicted in 2001 of driving while intoxicated. He also has convictions for misdemeanor assault, criminal trespass and unlawful use of human services funds, a felony.

•Mr. Broussard's blood was drawn to test for the presence of illegal substances, but there is no indication that alcohol played a part in the crash.

•Mr. Broussard's medical certification was set to expire in May 2008.

Reporting by Matthew Haag, Michael A. Lindenberger and Steve McGonigle