The U.S. Transportation Security Administration is one of those federal agencies that tends to inspire intense reactions among the traveling public. It's a bureaucracy that interacts with millions of passengers each day, requiring their shoes, jackets, laptops—and time.

Virtually all this occurs at airports, with about 80 percent of the agency's $7.4 billion budget spent on aviation security. Only 2 percent of the TSA's funding goes to surface transportation, according to a report by the Office of Inspector General earlier this month. Congress is looking to change that.

Several U.S. senators want the TSA to focus more attention and resources on rail, highway, and marine transportation, which would mean greater security oversight at such places as Amtrak stations and Megabus coach stops. A bipartisan bill introduced Thursday by Senator John Thune (R-S.D.) would require the TSA to use a risk-based security model for these transport modes and to budget money based on those risks. It would require a wider use of the agency's terrorist watch list by train operators and more detailed passenger manifests along with tighter screening of marine employees. The legislation also would increase the TSA's canine use by as many as 70 dog-handler teams for surface transportation.