State transportation officials are warning of backups on Route 128 this weekend as they close portions of the highway near exits in Needham to demolish the old Highland Avenue Bridge.

“We’re concerned about traffic, but we don’t see it as a super catastrophe,’’ Walter Heller, a highway director at the state’s transportation department, said at a news conference Thursday.

The shutdown would be the first time in recent memory that state transportation officials have closed a section of Route 128/Interstate 95.

From 8 p.m. Friday until about 2 p.m. Saturday, northbound drivers will need to exit 19A to cross Highland Avenue and connect to the northbound on-ramp via a temporary paved connection, as crews close about 4,000 feet of the roadway during the demolition process.

From about 1 p.m. Saturday to Sunday afternoon, southbound drivers traveling on the highway through Needham will need to exit 19B to cross Highland Avenue and connect to the southbound on-ramp through a temporary paved connection.

Traffic on Highland Avenue will be rerouted through local routes to allow the highway detour.

Heller said about 5,000 vehicles travel through the area during weekend peak hours, and the detours only have the capacity for about 4,000. So drivers should avoid the area or expect delays.

Workers have built a new version of the Highland bridge beside the old one, which now must be torn down. The Highland Avenue Bridge, which connects Newton and Needham over Route 128, was built in 1931 and rebuilt in 1953.

Highway officials said the detour will mark one of the final milestones for a long-running expansion of the highway.

The shutdown coincides with work on the Massachusetts Turnpike to remove toll plazas, but officials say they aren’t worried about catastrophic traffic at either location.

Nicole Dungca can be reached at nicole.dungca@globe.com.