Groton — Essentially reversing the setup that has been in place since April, the southbound travel lanes of Interstate 95 over the Gold Star Bridge will be shifted to the left side of the bridge beginning Dec. 8, the state Department of Transportation said in a news release.

In total, three left lanes of travel will be operational while the rightmost lanes will be blocked off for construction.

According to the DOT, those who come from the Bridge Street on-ramp will have to merge left into the right travel lane. The right travel lane will remain an exit-only lane for Exit 82 to Route 32, so those who do not wish to exit the highway will have to merge one additional lane to the left.

Those who come from the state Route 184 on-ramp will be dumped into the leftmost travel lane and will not have to merge unless they need to get over to Exit 82.

All entrance and exit ramps will remain open during construction, but additional lanes may be closed during off-peak hours, the release said.