PORTLAND – A U.S. Senate panel in Washington has agreed to require testing of 15-passenger vans for rollovers and weight loading.

The vans have come under scrutiny in Maine because one was involved last September in the worst traffic fatality in state history, which killed 14 people.

“Fifteen-passenger vans are popular vehicles for tourists, schoolchildren and church outings, but they can also be dangerous if overloaded with either passengers or cargo,” U.S. Sen. Olympia Snowe, R-Maine, a member of the Transportation Committee, said Thursday. “Steps must be taken now to prevent deadly accidents.”

Snowe sponsored the legislation adopted as part of federal transportation policy that Congress is debating this year. The full Senate is expected to consider the bill in July and the House is working on its own version of the legislation.

Van safety gained the spotlight in the state when 14 forestry workers from Guatemala and Honduras died Sept. 12, 2002, when their van plunged off a one-lane bridge across the Allagash Wilderness Waterway in northern Maine. A 15th passenger swam to safety after kicking out a rear window.

The National Highway Traffic Safety Administration had warned in a study the previous April that the vans may become top-heavy and weighted to the rear when fully loaded. The vans are nearly three times more likely to roll over when they carry at least 10 people, according to the study.

Since 1990, more than 420 people have died in more than 260 van rollover accidents nationwide, and hundreds more have been injured.

Snowe’s portion of the bill would require the National Highway Traffic Safety Administration to include vans in a rollover-testing program that is now being created for cars and light trucks, although not previously for 15-passenger vans. The vans also would be tested at various load levels, to quantify rollover risks that now apply to vehicles carrying 10 passengers or fewer.

The bill also requires the agency to evaluate, in conjunction with van manufacturers, technological systems such as stability programs and rear-view mirror warnings, to help drivers keep control of the vans.

Snowe was unable to get the committee to accept another provision dealing with schools buying vans, but said she would pursue it as an amendment on the Senate floor.