The bridge supports are exposed and show the deterioration. DOT officials say bridge repair work should begin within the next two years.

The Providence Journal / Kris Craig

PROVIDENCE — State transportation officials Thursday imposed weight limits that exclude many trucks, school buses and other heavy vehicles from five bridges in four communities.

The state Department of Transportation said the postings are based on inspections and are needed to preserve the bridges and keep them safe until they can be replaced or rehabilitated. Some of the work will begin this summer but some has no timetable, the agency said.

The bridges are in Bristol, East Providence, Narragansett and Richmond. The DOT said that their average age is more than 45 years and that bridges typically need rehabilitation at that age.

Kazem Farhoumand, the DOT’s chief engineer, said the postings reflect the department’s inability to keep up with bridge maintenance because of a lack of money.

Only heavy vehicles are affected, with the restrictions varying from bridge to bridge, and their impact depending on the number of axles the vehicles have. It wasn’t clear whether the response time of heavy emergency equipment, such as fire trucks, will be affected, as has been the case in some previous bridge postings.

“Unfortunately,” Farhoumand said, “there is going to be an impact on school buses.” He said they weigh roughly 12 tons empty and 18 or 19 tons when full of students. In some cases, he said, even empty school buses may be affected when they must go from the end of one trip to the start of another.

DOT Director Michael P. Lewis apologized for the inconvenience the weight limits will cause, but said they aren’t optional. “Safety is our number-one priority,” he said. “Setting weight limits are not desirable actions by the department, but are necessary ones we must take based on the findings of our bridge inspections.”

The bridges affected and the weight limits are:

Bristol — The bridge carrying Colt Drive over Mill Gut Lake in Colt State Park, posted at 18 tons.

East Providence — Two bridges in the Taunton Avenue interchange with Route 195. One carries traffic from the off-ramp from Route 195 East at Exit 4 (Riverside) to Veterans Memorial Parkway. It’s posted at 14, 19 and 29 tons for two-, three- and five-axle vehicles, respectively. (Traffic using the same exit to reach Taunton Avenue isn’t affected.) The other bridge affected at the interchange carries traffic from Veterans Memorial Parkway to Route 195 West. It is posted at 10, 13 and 21 tons for two-, three- and five-axle vehicles.

Veterans Memorial Parkway itself already has a 5-ton weight limit, DOT spokesman Charles St. Martin said, so the two East Providence bridges should see only limited use by trucks anyway. The DOT said rehabilitation for both East Providence bridges is being designed and that work is expected to begin in the next two years. The DOT said vehicles over the weight limits should use the Warren Avenue, Pawtucket Avenue or Broadway interchanges to get on or off Route 195.

Narragansett — The bridge carrying traffic from Route 108 (Point Judith Road) to Route 1 North, adjacent to the intersection of Point Judith Road and South Pier Road. The bridge is now posted at 14, 24 and 29 tons for two-, three- and five-axle vehicles. The DOT said it has established a short detour for trucks by following Route 108 North to the Dillon Rotary and using a ramp there to Route 1 North.

The DOT said that bridge, along with the nearby bridges that carry Route 1 over Point Judith Road, will be repaired using funds from the federal economic stimulus program, the American Recovery and Reinvestment Act of 2009. Construction should begin later this summer, the DOT said.

Richmond — The bridge carrying Kings Factory Road over the Pawcatuck River is now posted at 12, 14 and 25 tons for two-, three- and five-axle vehicles. Kings Factory Road is a rural road connecting Route 91 to Route 1, and the DOT said trucks can use either Route 216 or Route 112 as alternate routes. The agency said it has no timetable for repairs to this bridge.

blandis@projo.com