A proposal in the Senate version of a six-year transportation bill gives states broad authority to levy tolls on interstate highways, the Washington Post reported this week. The Senate bill allows states or transportation authorities "to toll any highway, bridge, or tunnel, including facilities on the interstate system, to manage high levels of congestion or reduce emissions," after informing the secretary of transportation. The proposal has set off a fierce lobbying battle involving a host of powerful groups. Opposed to the proposal are AAA, the American Trucking Associations, the American Farm Bureau, and the American Highway Users Alliance. Supporting the changes are coalitions representing state highway departments, road-building groups, the US Conference of Mayors, leading environmental organizations such as Environmental Defense, and the Reason Foundation, which advocates free-market solutions to economic and social problems. Since the passage of the Federal Aid Highway Act in 1956, travel on the interstate system has been largely free. But several factors are combining to cause Congress to reconsider the policy, such as using electronic sensors to levy fees. The technological advances created intriguing possibilities for alleviating heavy traffic by giving motorists the option of paying to enter fast-moving, congestion-free lanes similar to high-occupancy vehicle, or HOV, lanes. Some jurisdictions, such as San Diego, are experimenting with the use of fast lanes at rates that change every few minutes, depending on traffic. An even bigger factor for legislators is the possibility that tolls could raise billions of dollars over the next six years for transportation. Revenue for transportation programs is derived mainly from the federal gasoline tax, which neither Congress nor the White House wants to increase in an election year, the Post reported. But the administration has indicated that it supports the tolling proposals in the Senate bill, signaling a possible way out of the funding impasse. House language, championed by Representative Mark Kennedy, Republican of Minnesota, is more restrictive. HOV lanes, viewed as underused, could be converted to toll lanes. Otherwise, tolls could be imposed only on new lanes or roads, and the tolls would cease when the highway bonds were paid. Several powerful groups back the House approach. A spokesman for the American Trucking Associations said the organization worked with Kennedy on the proposal's language.