Only two lanes will be open on the Thruway between exits 23 and 24 as the final phrase of the highway-widening project begins this month.
Work will continue for most of the year.
All traffic will be redirected to the southbound side of the Thruway, which has been restriped to allow two lanes in each direction.
Meanwhile, workers on the closed northbound side will build a third lane to the narrow two-mile portion of the highway.
Concrete barriers will be erected over the next two weeks, and work will begin Mar. 12.
The three-year, $99.7 million project is the largest public construction project in the Capital Region, Thruway officials said.
The general contractor is Rifenburg Construction Inc. of Troy.