Two lanes closed on Longfellow Bridge

Large trucks banned from span completely

Federal highway officials, dissatisfied with the state's oversight of truck restrictions on the deteriorated Longfellow Bridge, shut down two lanes effective today, narrowing a major thoroughfare between Boston and Cambridge.

The Federal Highway Administration also asked the state to ban large trucks from the bridge completely - rather than barring them only from the inner lanes. As of today, the Longfellow can no longer be used by 18-wheelers and other large trucks, though pickup trucks, duck boats, and delivery vans can still cross it.

The closures will remain in effect until repairs to the bridge are complete, possibly in the fall.

The Longfellow, a main thoroughfare over the Charles River, will now be squeezed from four lanes to two, affecting the commutes of roughly 50,000 vehicles a day.

The federal order was the latest expression of concern for the Longfellow, which is long overdue for an overhaul and which gained new attention after a Minnesota bridge collapsed last August.

Since that time, inspectors and repair crews have been working on the bridge almost nightly to restore worn steel components and ensure the Longfellow's integrity while awaiting a major bridge renovation project. The full bridge overhaul is not expected to start until at least 2011.

But the flow of bad news has only continued along with repairs. Earlier this month, officials announced that their engineering consultants could not determine whether the sidewalks along the Longfellow would be safe for a large crowd. As a result, pedestrians are banned from the bridge for the upcoming Fourth of July celebration.

In January, the state Department of Conservation and Recreation, which owns the bridge, restricted large trucks from the passing lanes to limit the weight traveling over some of the most corroded parts. The inner two lanes abut the MBTA's Red Line tracks.

A seam between the two leaves space for rainwater to enter and corrode steel components below. Repairs have focused on the areas below those seams, but the reduced rating was imposed to protect the bridge in the meantime.

But this week, Federal Highway Administration officials meeting with state officials visited the Longfellow and found signs that prohibited large truck traffic had been removed. Trucks were freely using the left lanes.

They determined it is impossible to enforce a truck ban in only one lane, and the Conservation Department agreed to prohibit trucks weighing 20 tons or more from the bridge completely, said Richard K. Sullivan Jr., department commissioner.

Asked whether the federal restriction indicates a vote of no-confidence in the bridge, Sullivan said: "It certainly shows that we did not have the ability to ensure safety because we were not able to ensure the posting limits that were up there and the limitations that were on the bridge.

"We have to go to the next step so I can ensure people who use the Longfellow that it's safe for their purposes. The only way to truly do that is to restrict traffic from that lane."

Since last summer, DCR has spent more than $1 million on inspections and $4.5 million on repairs to the bridge.

The repairs are only 60 percent complete, and the bridge requires a full renovation expected to cost some $250 million.

Stephanie Ebbert can be reached at ebbert@globe.com.