WASHINGTON -- A lack of data and limited enforcement options are inhibiting federal oversight of ground passenger transportation accessibility requirements of the 1990 Americans with Disabilities Act.

That's the gist of a new report from the U.S. Government Accountability Office to a U.S. House of Representatives subcommittee on appropriations.

The report particularly noted the lack of data from private bus operators that are not complying with annual ADA reporting requirements. Barely more than one in 10 coach operators submit the reports.

The report covers all modes of ground transportation and public rights of way, including over-the-road or commercial buses, plus privately run transportation operations that are open to the public, such as airport shuttles and taxis.

According to recent estimates there are some 50 million people in the United States with disabilities that include spinal cord injuries or other mobility impairments, and who may use a wheelchair or some other aid.

Others are visually impaired who may need assistance or may have hearing disabilities that make it difficult or impossible for them to hear announcements.

Since ADA requirements became effective, the report states, access to surface transportation in the U.S. has improved. Various reports indicate that more public and private transportation vehicles are accessible than before the law was passed.

"While data indicate accessibility is improving for public transit, the extent of ADA compliance for other modes of transportation and public rights-of-way is unknown due to a lack of reliable data," the GAO says.

Where's the data?

The GAO notes that the Federal Motor Carrier Safety Administration solicits compliance data from registered commercial bus companies, but the response rate was only 13 percent in 2006. U.S. Department of Transportation rules require commercial bus carriers to supply compliance data to the FMCSA.

Even so, the FMCSA has not even bothered to verify any of the skimpy data it receives, the report states. Agency regulations require the FMCSA to analyze the data it collects.

Still, the report says the agency has developed a preliminary strategy for doing so and plans to finish its analysis by next year.

The report also notes that federal agencies face specific difficulties in overseeing and enforcing ADA compliance. The lack of data, for example, limits the USDOT compliance efforts.

"Without the necessary information on the extent of compliance, agencies are not able to target their enforcement efforts where most needed or to evaluate the effectiveness of their efforts," the GAO says.

In addition, USDOT officials regard their enforcement options, such as withholding grant money, as a lengthy and complex process and would not be undertaken lightly. DOT officials say the authority to impose fines, an option they lack, would be more useful.

The GAO report, sought by and addressed to Rep. John Oliver, D-Mass.,

chairman of the Appropriations Committee Subcommittee on Transportation,

Housing and Urban Development, and Related Agencies, notes that some

transportation providers, including commercial bus drivers, "have

refused to accommodate service animals, such as guide dogs, as required

by law."

Few complaints but ...

The report says the USDOT and the Department of Justice have data on

ADA-related complaints for all modes of transportation, and while the complaints are relatively few, that alone is not considered a good indicator of ADA compliance.

FMCSA has an ongoing court case that points to a shortcoming in the system. The agency has the authority to penalize commercial bus companies for safety violations, but it cannot withhold operating authority or issue civil penalties for ADA violations.

The GAO recommends that USDOT develop a legislative proposal that would give the agency the authority to impose civil penalties for noncompliance.

Although FMCSA shares information with the U.S. Department of Justice, the report says there is no formal mechanism for coordination. "As a result," the report states, "there appear to be gaps in oversight and enforcement for -- commercial buses."

What's more, USDOT has the option to refer cases to the Justice Department for investigation, but has done so only twice, the GAO says.