ST. LOUIS (AP) A key Mississippi River bridge between St. Louis and Illinois closed July 20 for at least four months of roughly $16 million of improvements.

Crews are expected to remove the Martin Luther King Bridge’s deck, replace the middle truss span and make structural steel repairs and paint, the St. Louis Post-Dispatch reported. Eastbound lanes of the bridge, which links St. Louis to East St. Louis, Ill., have been closed overnight in recent weeks so crews could install scaffolding for the project.

Drivers accustomed to using the span should use the Stan Musial Veterans Memorial Bridge as a detour, said Jeff Church, an Illinois Department of Illinois project implementation engineer in Collinsville, Ill., just east of St. Louis.

“We want to make sure people understand to give themselves some extra time, because undoubtedly there will be some delays especially during the rush hour,’’ he said.

IDOT said 26,700 vehicles use the King bridge each day, and the Missouri Department of Transportation said about 40,000 drivers travel the Stan Musial bridge.

The bridge opened as the Veterans Memorial Bridge in 1951 as an East St. Louis-built toll bridge for $10.5 million. It later was renamed for the late Rev. Dr. Martin Luther King Jr., and tolls were eliminated in 1987, when Illinois took control of the bridge.

IDOT had planned last summer to shut down the bridge for months so crews could rebuild its decks, but a bid to do that work came in about $3 million higher than the agency expected, and the project was stalled, Church said. Doing the work in the summer lowered the project’s cost because expenses such as painting in cold weather could be trimmed, he said.