NYACK - Prep work to build the new Tappan Zee Bridge is affecting drivers overnight this week.

The installation of structural monitors to analyze the test pile program is shutting down one lane of the span every night this week.

One lane on the southbound side of the Thruway between exit 11 and the span will be closed tonight from 9 p.m. to 6 a.m.

Then, starting Wednesday night, work is expected in the northbound lanes during the same times until Saturday.