It will be spring before motorists will be allowed to turn left from Central onto West Street.
Construction of a water line began Monday across one of the city's busier intersections, where officials said nearly 34,000 vehicles pass every day.
Drivers may still turn left from West onto Central until mid-November, when major pavement work at the intersection begins, city officials said.
The work is part of a $7.7 million project to reconstruct West Street between Maple and Central, adding a center left-turn lane, a new drainage system, new water lines and new traffic signals.
The project began in May 2009 and is expected to be completed in mid-2010. Pavement work at Maple and West Street is nearly complete.
Left turns from Maple onto West Street are now open, but left turns from West Street onto Maple are not possible yet because additional pavement work needs to be completed, officials said.