Maine and Vermont senators have won preliminary approval of a measure to permanently allow 100,000-pound trucks on state interstates.

The measure, pushed by Sen. Patrick Leahy of Vermont and Sen. Susan Collins of Maine, was included in the annual transportation funding bill that the Senate Transportation Appropriations Subcommittee approved Tuesday.

Collins is the ranking member of the subcommittee and Leahy is a senior member.

"My provision to permanently change federal law would advance all of those goals by allowing the heaviest trucks to travel on our federal interstates in Maine rather than being forced to use secondary roads and downtown streets," Collins said in a press release.

Approval is expected today in the full Senate Appropriations Committee, where Leahy is number two in seniority. The bill's fate in the full Senate is unclear.

To become law, a similar provision would have to be introduced into the House version of the budget bill, which so far has not happened. Maine Rep. Mike Michaud said he was working on the issue through a separate bill he has sponsored.

Last month, Maine Sen. Olympia Snowe introduced a bill that would allow states to bypass Congress and seek individual waivers of the interstate restrictions from the U.S. DOT.

A Maine Department of Transportation report last fall concluded allowing trucks on all interstates would "increase traffic safety, improve the environment, increase business competitiveness and reduce transportation infrastructure costs at no cost to the taxpayer." It also noted that trucks use less fuel on the Interstate than on secondary roads.

Last December, a one-year federal pilot program allowing the heavier trucks to use all Maine's interstates lapsed.

Parents Against Tired Truckers and the Truck Safety Coalition criticized the move, calling the subcommittee's actions "irresponsible and with complete disregard for the safety of families sharing the road with these overweight trucks."

According to the coalition, the initial weight exemption was passed as a pilot program in the Consolidated Appropriations Act of 2010, and it included a requirement for an evaluation of the pilot program and report to Congress.

The TSC says it was able to obtain limited information about the pilot project impacts by sending a Freedom of Information Act request to the Federal Highway Administration and a Freedom of Access Act request to the Maine Department of Transportation. According to the group, these requests for information revealed that "FHWA has concluded that the margin of bridge safety is reduced on Maine and Vermont Interstate Highways where the heavier vehicles operate. The use of heavier axle loadings on the Interstate highways in Maine and Vermont will reduce the pavement life, especially with an increase in the number of heavy trucks and the allowance for axle loadings that exceed current federal standards."

As to the contention that allowing the heavier trucks on interstate highways will help keep them off off more-dangerous secondary roads, where they are currently allowed, the safety advocates contend the trucks should not be on any highways.

To read more about this issue, see "Supporters of Higher Truck Weights Hope that Now is Their Time" from December 2010.