The state Thruway Authority said the lane shift will begin Friday for the first phase of its $128 million construction project between Exits 39 and 40, a section of highway that many commuters between Syracuse and Cayuga County use.

Starting Friday morning, all eastbound traffic will shift to a portion of the normal westbound travel lanes for a five-mile stretch. Vehicles will be will be separated by concrete barrier, and two lanes in both directions will be open during peak travel periods.

The project, which will reconstruct the highway in both directions along the 15-mile section, is being conducted in multiple phases. A November 2011 completion date for all of the work is expected.

The Thruway Authority has told motorists to expect delays at times, and if possible, to avoid the Thruway in that area during peak hours.