WESTPORT — A project to improve traction on the road surface will require daytime closures of the Merritt Parkway’s Exit 42 ramps this week, the state Department of Transportation has announced.

“Crews will be applying a high friction surface treatment to the off-ramp pavement.” the DOT says. “The HFST requires warmer air and surface temperatures for proper placement which may only be possible during the daytime to complete.”

When the treatment is installed, the affected ramp will be closed to traffic.

Ramp closures will begin at 6 a.m. and could continue to 6 p.m. on Thursday and Friday. Message boards will be placed on the parkway and at the ramps to inform motorists of the closings and detours.

Motorists who normally use the off-ramps at Exit 42 will be guided to use the following detours:

Exit 42 southbound off-ramp closure and access to Weston Road (Route 57): Detour will direct motorists to use Exit 41 southbound off-ramp to Wilton Road (Route 33) and return to Exit 42 northbound off-ramp via the Exit 41 northbound entrance ramp.

Exit 42 northbound off-ramp closure and access to Weston Road (Route 57): Detour will direct motorists to use Exit 44 northbound off-ramp to Black Rock Turnpike (Route 58) and return to Exit 42 southbound off-ramp and Route 57 via the Exit 44 northbound entrance ramp.

High friction surface treatment is a pavement treatment intended to restore and maintain pavement friction to reduce crashes. It is a thin layer of polish-resistant aggregate bonded to the pavement surface with polymer resin binder.

Studies have found the treatment can reduce the number of crashes on tight curves and during wet weather by providing more grip on the road.

The work is the final pavement surface treatment on the $56.7 million Merritt Parkway improvement project in Fairfield and Westport.