Updated 3 p.m. Friday: Ramps from northbound Central Expressway to the Bush Turnpike will remain open this weekend.

Central Expressway will be shut down in both directions in parts of Plano and Richardson this weekend as crews take out an overpass as part of a $37 million project to improve the Bush Turnpike interchange.

The Texas Department of Transportation plans to divert all main-lane traffic to access roads from 2 a.m. Saturday until 5 a.m. Monday.

The shutdown of U.S. Highway 75 between Renner Road in Richardson and 15th Street in Plano is needed to remove the Plano Parkway overpass, which sits nearly atop the southbound exit to the Bush Turnpike.

Traffic moves on U.S. Highway 75, Central Expressway, under the Plano Parkway bridge. Central Expressway will be closed this weekend in both directions in southern Plano and northern Richardson for the partial demolition of the second half of the Plano Parkway bridge. (Jae S. Lee / Staff Photographer)

Bush Turnpike exits from southbound Central Expressway are within the closed section and will not be accessible. Turnpike exits to Central will also be closed.

The turnpike access roads do not cross Central. The nearest north-south turnpike exits are at Alma Road, Plano Road/Avenue K and Jupiter Road. All connect with 15th Street to the north and Renner to the south for access to Central Expressway.

Also closed this weekend is the northbound Central HOV lane from LBJ Freeway to Galatyn Parkway in Richardson. An HOV lane on the southbound side, from Bethany Drive in Allen to Park Boulevard in Plano, has been closed long-term as part of the ongoing project.

The interchange project will continue through early 2019, according to TxDOT. More than 258,000 vehicles per day use the stretch of Central Expressway, TxDOT officials said, and the interchange is among the busiest in the Dallas-Fort Worth area.

When the segment of the turnpike opened in late 1999, the tolled road had plenty of space between Plano and Richardson. But the interchange was a forced fit between existing exits on Central, and growth in the area intensified the backups.

The project includes moving existing Central Expressway retaining walls to make room for additional lanes near Plano Parkway.

On the northbound side, those lanes will allow TxDOT to change the traffic pattern one exit north at 15th Street. Currently, motorists who exit at 15th have to cross the path of traffic entering Central from the turnpike. The 15th Street exit will instead be combined with the Plano Parkway exit.

Southbound on Central, the exit to 15th is being relocated and the entrance ramp at 15th is being separated from traffic exiting at Plano Parkway.

It will be the second consecutive weekend for a full freeway shutdown in North Texas, as TxDOT took out the Eighth Street bridge over Interstate 35E in Oak Cliff on Sunday as part of the $666 million Southern Gateway project.

Wednesday, TxDOT announced an unrelated overnight shutdown on U.S. Highway 75, 20 miles farther north in Collin County. Southbound lanes of the freeway will be closed between Melissa Road and Mantua Road in Melissa between 9 p.m. Friday and 6 a.m. Saturday. Workers will connect new entrance and exit ramps during the closure.