The National Transportation Safety Board found that so-called curbside bus companies, which pick up riders on sidewalks rather than in terminals, were involved in fatal accidents at seven times the rate of traditional carriers like Greyhound.
Curbside buses, which first gained popularity in the Chinatown districts of Manhattan and Boston by offering frequent rides between major cities for as little as $1 a seat, also were cited for violations related to driver fatigue and training at a higher rate than their conventional cousins.
In general, the report found that low-cost bus companies were a safe mode of travel and that accidents happened infrequently. In fact, among bus carriers that operate on regular schedules, the low-cost buses recorded proportionally fewer accidents than their share of the market.
But when those accidents occurred, they were far more likely than those involving traditional carriers to result in serious injury or death. (In a not particularly reassuring footnote, the report said that “most of the deaths in fatal motor coach accidents are occupants of other vehicles.”)
The report, the most extensive study of the curbside motor coach industry undertaken by the federal government, was prompted by a bus crash in the Bronx in March that killed 15 passengers returning from a casino trip.
“This industry has been growing so exponentially,” said Representative Nydia M. Velazquez, whose office requested the review. “We have to be a step ahead of them and make sure we implement the types of safety measures that are necessary.”
Senator Charles E. Schumer, who spoke at a news conference on Monday unveiling the report, described it as “a wake-up call” and asked federal officials to create a more rigorous regulatory system for the industry.
In a statement, the Transportation Department, which has oversight of the motor coach industry, said it had nearly doubled its safety inspections on buses in the past five years. It also recently issued rules banning bus drivers from talking on cellphones or sending text messages while driving.
But the agency did not dispute the findings that federal regulators can often be stymied by the unique nature of the low-cost bus industry.
Because the buses do not park in traditional terminals, officials must make inspections on crowded street corners, which they said could be logistically difficult. Regulators are also barred from inspecting buses in the middle of a scheduled trip, which can reduce the element of surprise.
Many drivers and owners of low-cost bus companies do not speak English, and their records are often kept in other languages, which investigators described as frustrating. Officials say they are concerned that the language barrier means some owners do not fully understand every federal regulation.
Another challenge is a practice that officials called “reincarnation” — when bus companies with safety violations simply start a new concern under a different name and reuse the vehicles and drivers. That tactic has been used by the company involved in the fatal Bronx crash, World Wide Travel, which is still running its buses through two other companies connected to the owner.
Ms. Velazquez, a Democrat whose district includes Chinatown, acknowledged that curbside bus companies contributed to the economic and social activities of her constituents.
“But we have a responsibility to make sure that cannot be at the expense of the lives of those who are using it,” Ms. Velazquez said. “The focus of our effort is not to punish this industry, or impose unnecessary regulation. It is to restore travelers’ confidence.”