The new Randolph Road underpass Credit: State Highway Administration

The State Highway Administration is preparing to open Saturday morning a major portion of its $40 million interchange project at the intersection of Georgia Avenue and Randolph Road in the Glenmont area.

The agency announced Tuesday that a new lane shift will begin at 6 a.m. Saturday to enable drivers on eastbound Randolph Road to access a portion of the new tunnel underneath Georgia Avenue.

Charlie Gischlar, a spokesman for SHA, said Tuesday the tunnel opening will eliminate part of the at-grade intersection where Randolph meets Georgia Avenue.

He described it as one of the busiest intersections in Montgomery County.

A diagram showing how the completed underpass will look. Via SHA

Crews have been working on the underpass and adding additional lanes to Georgia Avenue since the interchange project began in 2014. Gischlar said work will continue on the underpass until the mid- to late-summer, and will focus on completing the next section of retaining wall for the underpass and other portions of the project, such as landscaping.

SHA warned drivers of possible traffic delays approaching the new lane configuration this weekend and urged drivers to exercise caution.

Drivers on eastbound Randolph Road who want to turn onto Georgia Avenue will have to bear right to avoid entering the through lanes that are part of the new underpass.

The intersection next to Glenmont Shopping Center has been prone to lengthy traffic backups, particularly during rush hour.