Today, July 6, is the scheduled start of the six-month detour for drivers on Fair Lakes Parkway near its busy junction with the Fairfax County Parkway. The Virginia Department of Transportation is rebuilding the area into an interchange to improve traffic flow. The project is scheduled to be done in 2013.

The first phase of the detour will prohibit through-traffic on the Fair Lakes Parkway at Fairfax County Parkway. Drivers will be directed from Fair Lakes Parkway south to Fair Lakes Circle and then back to Fair Lakes Parkway.

This phase, scheduled to last through the fall, will add five to 10 minutes to a trip through the area, VDOT estimates. The speed limit on Fair Lakes Parkway will be reduced from 45 mph to 35 mph. This does not block access to the Fair Lakes Mall, and the Fairfax County Parkway will remain open.

The next phases of the detour will affect traffic heading from Monument Drive to westbound Fair Lakes Parkway and traffic turning left from Fair Lakes Parkway to Fairfax County Parkway. That’s scheduled to start this fall.

VDOT’s $69.5 million interchange construction project, with some funding from Fairfax County and a big infusion of money from the federal stimulus program, is rebuilding one of the oldest and most congested stretches of the county parkway.

These are the project’s main components:

The Fairfax County Parkway will be widened from four to six lanes from south of I-66 to Rugby Road, a distance of about three miles.

Signals at Fair Lakes Parkway and Monument Drive will be eliminated.

Long ramps will provide separate access to and from Fair Lakes Parkway and Monument Drive.

Shared-use paths and sidewalks will allow for pedestrian and cyclist access at the interchange and also to the Rocky Run Stream Valley Park trail system.