WASHINGTON D.C. Although fires in motorcoaches usually draw heavy media attention, very few of them result in injury or death to passengers, a new federal report has found.

The study also revealed that coaches receiving out-of-service orders during roadside inspections are almost twice as likely to be involved in a fire later than buses that pass inspections.

"The magnitude of probabilities may be small, but the odds ratio is substantial and appears to be growing, as the out-of-service rates of fire-involved motorcoaches diverge from those of the general motorcoach population," the study warns.

Matthew Daecher, president of Daecher Consulting Group, called the out-of-service finding the most significant in the study.

"Though the sample is relatively small, this somewhat confirms that proper and thorough maintenance has a significant effect on preventing fires, regardless of the presence of warning or suppression systems," said Daecher.

Still, the study suggests that the severity of bus fires could be reduced by almost three-quarters with the use of electronic devices to detect and suppress fires; expanded inspection programs, and improved pre-trip and post-trip checks by drivers.

Those and other findings and conclusions are included in the extensive study, titled Motorcoach Fire Safety Analysis, which was developed for the Federal Motor Carrier Safety Administration by the Volpe National Transportation Systems Center.

Results of the study and its recommendations are expected to help federal regulators and the motorcoach industry come up with policies and practices aimed at reducing or eliminating coach fires, which now cause an average of about $65,000 damage to each bus involved in a fire.

Bus safety experts like Daecher say the study confirms what many of them knew from their own studies of fire origins, and known and suspected causes.

"It did statistically confirm some suspected underlying causes for fires, such as engine evolution and design," said Daecher.

Federal regulators and the industry have been hampered in earlier efforts to study motorcoach fires because no one has collected or maintained detailed records of fires. Instead, most of the reports on fires listed them only as accidents, grouped them together with buses of all types, and usually lacked critical information about their causes.

"Reporting criteria for motorcoach fires are less clear and less enforceable, compared with the criteria for other types of roadway incident reporting," the researchers noted in a 95-page report on the study.

899 bus fires studied

Still, using a variety of information collected between 1995 and 2008 by a number of federal and state agencies and private safety organizations, as well as news media accounts, they were able to find and examine records of enough fires 899 of them to conduct the study.

Zeroing in on passenger injuries, the researchers found they were rare except for one exception the so-called Hurricane Rita coach fire in Texas four years ago that killed 23 and injured 15 elderly and disabled people who were being transferred from a nursing home to escape the approaching hurricane.

Eliminating the Texas fire, which was considered anomalous, the researchers concluded that only about 5 percent of coach fires result in any type of injury or death to passengers, a finding that flies in the face of public perception that fires on buses usually injure a large number of people.

The researchers also discovered there may be far fewer fires than the industry has long thought, and that the number of fires appears to be stable from year-to-year rather than increasing.

Using data from the years in which the most information was available 2004 to 2006 they determined there are about 160 fires on motorcoaches each year. Thats in sharp contrast to claims by some in the industry who have suggested that motorcoach fires occur on a daily basis.

"Although it has been estimated that motorcoach fires occur nationwide with at least daily frequency, study data indicates a lower rate," the study contends.

However, it cautioned that because of the poor record keeping in the past, there are reasons to suspect that actual fire occurrence is likely greater than the number of records collected each year would suggest.

"The database contains a sample of verifiable incident records but is not a precise sampling of all reportable incidents," the study notes. "Accordingly, we can surmise only that complete and accurate reporting by all sources would yield an average occurrence rate of at least 160 fires per year."

Where fires start

The two places where most of the fires 70 percent started were the engine compartments and the wheel wells, areas where multiple sources of combustible materials and ignition are present.

Another 9 percent were traced to the battery compartment, the transmission, the baggage storage area, the interior of the bus or the fuel system. The researchers were unable to determine the starting point in the remaining 21 percent of the fires.

The study findings also noted that the age of a coach plays a role in fires. There was a pattern of few fires in older models, a significant increase beginning with 1997 models that continued with the 2003 models and a sharp drop with more recent models.

The pattern corresponds with the increased complexity of engines built to provide greater power and fuel efficiency for larger and heavier buses that were introduced in the 1998-to-2002 time period, according to the researchers. They said some of the engine design changes also were due to efforts to meet new mandatory government emission standards.

The study also identified makes and models of coaches and engines that were involved in fires during the 13-year study period.

Motor Coach Industries Inc., which has the most coaches on the road, topped the list with 490, followed by Van Hool with 109 and Prevost with 83. The MCI model 102DL3 had 186 fires to lead individual models. Coaches with Detroit Diesel engines recorded the most fires with 411, while Cummings had 50 and Caterpillar 8.

Reducing fires

To reduce the number of fires, the study delivered a host of recommendations topped by the need to develop more accurate fire data by improving reporting methods and promoting the importance of everyone in the industry adhering to them.

The study also held that fire warning and suppression systems currently available for tire and turbocharger malfunctions could prevent 42 percent of all motorcoach fires, while engine-compartment detection and suppression systems could help reduce the risk of an additional 36 percent of them.

"If used together on every motorcoach, they might be able to prevent or reduce the consequences of wheel-well and engine fires, which account for 70 percent of all fires in the database," the report emphasizes.

The researchers pointed out that although such systems would only marginally reduce injuries and fatalities, they could provide major life-saving benefits for the rare catastrophes, such as the Texas fire. That fire started in a wheel well and was discovered too late for the driver and others to evacuate all of the elderly and disabled passengers.

The study also called for increasing and improving roadside motorcoach inspections and repair and maintenance procedures.

"Motorcoach fire prevention efforts could become more effective through revised inspection criteria, with an emphasis on inspector training," it stresses.

Researchers suggested that the out-of-service criteria be expanded to include heightened attention to areas where fires might start such as brakes, electrical systems, wheels and hub bearings, fluid lines, air conditioner compressors, engine components and exhaust systems.

More driver responsibility

They said, too, driver pre-trip and post-trip inspections conducted by drivers should be expanded to include a set of specific fire prevention checks on parts and accessories critical to fire-safe operation. And, those checks that cannot be done by the driver should be added to the periodic inspection program managed by the companys service department.

Daecher noted that modifying inspection criteria to include identifying known fire-causing conditions on a motorcoach recently was added to the Commercial Vehicle Safety Alliance out-of-service criteria, although he cautions that it will take some time to get inspectors trained on visually identifying and inspecting these newly established items.

Manufacturers can help, too, the study emphasized, by making major design changes on their vehicles.

Among them are replacing dual tires with wide-base single tires; improving wire/cable routing, including eliminating troughs that could expose wires to water; relocating the air intake to reduce smoke entering a bus interior due to engine fire; using heat-shielding turbocharger covers; using more effective electrical shielding and insulation; using heat-resistant hub/wheel seals and axle flange gaskets; and replacing oil-lubricated wheel bearings with those that are grease-lubricated.

Daecher agreed with the researchers that the use of fire detection technology to prevent and fire suppression to mitigate fire outcomes would help.

"I believe prevention through detection is the best answer and fleets would be wise to deploy reliable technology designed to identify fire hazards," he added.

However, he emphasized that the recommendation for training drivers and maintenance personnel on the causes and mitigation of fire risk is critical, too, and would benefit carriers regardless of the technology deployed on their coaches.

Daecher also noted that there was too little mentioned of vehicle design.

"We know that time is of the essence in a fire situation; the more time we have, the more likely the possibility of evacuating all passengers," he said. "Reviewing vehicle design to delay the effects of a fire is a basic line of defense which can be present no matter the state of the components or various systems that are on the bus."