East Lyme ― It will become a common sight in less than two weeks.

A line of state police cruisers and heavy-duty trucks with blinking arrows coming to a slow, controlled stop as they direct all Interstate 95 traffic off the highway here to make way for a sporadic, weeks-long blasting operation.

The detours will occur twice daily from Monday through Thursday as both sides of the highway are shut down for roughly 15 minutes each time. State Department of Transportation spokesman Josh Morgan said a blast operator from Maine Drilling and Blasting will be using explosive charges to dislodge chunks from 800 feet of rock ledge between exits 74 and 75.

The blasting project is slated to take six to eight weeks to complete once it starts with a bang on Aug. 1. The plan is to widen the highway to accommodate auxiliary lanes that will give drivers more time to get up to speed and so cars traveling just one exit will be able to get off without ever having to merge into another lane of traffic.

The work is part of a four-year, $148 million construction project at the Exit 74 interchange of I-95 that began in March.

Morgan said the closures will happen sometime between 9 a.m. and 1:30 p.m. But the exact timing won’t be known until a half hour before the explosives are detonated.

“Unfortunately, we can’t say it will be every day at 9:30 or every day at 12:30, just because so much is dependent on conditions in that moment,” he said.

Text alerts will go about 30 minutes prior to each blast. Travelers can sign up for the alerts via a form on the project website at i-95eastlyme.com.

The northbound detour will direct vehicles off exit 74, onto Route 161, and then onto Route 1 so they can get back on the highway at the exit 75 interchange. The southbound detour will send drivers onto Route 1 at the exit 75, to Route 161, and back on at the 74 interchange.

One hundred property owners in a 500-foot radius of the blast zone were notified of the plans, according to Morgan.

The project will begin on the east end of the ledge, closer to exit 75, and will move toward exit 74. Morgan said the plan is for material to fall forward onto the ledge instead of onto the highway.

Drivers can expect to see the first visible signs of the work next week as cranes and drilling equipment are carried in via a temporary road to give crews access to the rock ledge on the northbound side of the highway.

Morgan said six officers from the East Lyme Police Department will be available along the detour route.

The department is also authorized to take part in the rolling roadblock on the highway if there aren’t enough state troopers available at any given time.

East Lyme police Chief Mike Finkelstein, whose department typically has no more than three officers working a shift, said the extra staffing will have no local budget impact because the costs are picked up by the state.

The original plan for the blasting called for one closure per day instead of two. Morgan acknowledged it’s going to be an inconvenience for drivers who get caught up in the detour but said it would cut down the duration of the project significantly.

“Two smaller operations instead of one larger one will mean it gets done quicker and also that it’s a little bit safer,” he said, citing fewer charges in each operation and less debris in the roadway.

Morgan asked for patience from motorists.

“We’re hopeful that these are going to be short, 15-minute closures in each direction and it’s a pretty quick detour,” he said.

e.regan@theday.com