Construction of a roundabout and other improvements will shut down the intersection of Md. 180 and Mount Zion Road for eight weeks, beginning June 20.
While some preliminary work has already begun, the $3 million project will really begin with closing the road once Frederick County schools have let out for the year.
The intersection is used by about 4,000 vehicles per day, according to the State Highway Administration.
Drivers on Md. 180 will be detoured onto U.S. 340, which runs parallel to Md. 180. Drivers on Mount Zion Road will be detoured to Stone Road to Teen Barnes Road to Md. 180 and back to Mount Zion Road.
The project is being handled by Concrete General Inc., of Gaithersburg.
The construction of a roundabout at the intersection was a contentious issue at an informational meeting that SHA officials held with residents in Jefferson in February 2018.
Officials say they dramatically reduce the number of crashes, especially so-called angle crashes, which cause more injuries than sideswipes or rear-end crashes.
Statistics show 20 crashes at the intersection between 2012 and 2018, according to SHA.
There were eight police-reported crashes at the intersection in 2018, SHA spokesman Charlie Gischlar said in an email Friday.
The state had been looking at the intersection for several years, SHA District Engineer John Concannon told the 2018 community meeting.
Officials had tried changing marking, signage, and lighting, but the crashes continued, he said.
Since the state began installing roundabouts in 1994, there have been no intersection-related fatalities, according to the State Highway Administration.
James Robinson, who works at Engineered Construction at Md. 180 and Mount Zion Road, said he has heard crashes from the window of his office.
He said SHA has kept them informed of what to expect during the construction.
The work will be inconvenient, but it could possibly save lives, he said.