Big changes are headed to Santa Barbara’s State Street undercrossing at Highway 101.

On Tuesday, the City Council is set to approve $11 million in contracts for a massive transformation of the underpass in the 300 block of State Street.

The project will narrow the four-lane street to one vehicle lane in each direction and reconfigure the turning lanes at Gutierrez and Yanonali streets.

In addition, sidewalks are to be widened on each side of the street to about 15 feet from eight. The bike lanes will expand to seven feet from five, along with a two- to three-foot protected buffer.

Crews also will install safety lighting and new protective railings; demolish and reconstruct nonstructural columns; and replant the upper planters.

The plan calls for the removal and replacement of trees, and modifications to the Gutierrez and Yanonali intersections to reduce crossing distances for pedestrians.

“The new underpass project will serve as a stepping stone for the gateway to downtown,” said City Councilman Oscar Gutierrez, whose district includes the undercrossing.

“The project is a much-needed improvement of that area of State Street.”

The undercrossing was originally built in 1991 as part of the Highway 101 improvement project that, among other changes, eliminated the traffic signals at several streets that crossed the freeway.

The new changes are part of the city’s Vision Zero strategy that aims to eliminate all vehicle crashes and fatalities.

About $6.5 million of the project will go to C.A. Rasmussen Inc. of Ventura for the road construction.

Another $1.7 million is proposed for David Shelton Inc. of Santa Barbara for the installation of pedestrian railing and light poles.

“Shelton is uniquely qualified to fabricate and install the project’s ironwork,” according to the staff report written by supervising transportation planner Jessica Grant.

The project is funded primarily by a Caltrans Active Transportation Program grant and Measure C capital funds.

“It will complement the newer 100 and 200 blocks of State and, hopefully, influence the rejuvenation of the 300 and 400 blocks, as well as serve as an anchor for the State Street Master Plan moving forward,” Gutierrez said.

The council meeting is at 2 p.m. at City Hall, 735 Anacapa St.