Alexander Street/Road in Princeton and West Windsor will be closed and detoured for six months beginning on Wednesday, Nov. 6 for concurrent Mercer County and NJDOT bridge replacement projects, New Jersey Department of Transportation (NJDOT) and Mercer County officials announced today.

Before the long-term closure goes into effect, Alexander Street/Road will be closed and detoured this weekend starting tonight for utility work in preparation for the bridge replacement.

There are two separate bridge replacement projects involving three bridges near each other that will take place concurrently on Alexander Street/Alexander Road in Princeton and West Windsor.

One is a Mercer County project to replace two bridges and the other is an NJDOT project that will replace one bridge. The road is called Alexander Street in Princeton and becomes Alexander Road in West Windsor at the Delaware & Raritan Canal, which divides the municipalities.

Beginning at 8 p.m. tonight, Friday, Oct. 25 until 5 a.m., Sunday, Oct. 27, Mercer County is scheduled to close Alexander Road between Route 1 and Basin Street for utility work by New Jersey American Water. The work is in advance of removing a 16-inch water main from service for the upcoming bridge replacement project on Alexander Street and is required to be completed prior to the removal of the existing bridge.

While the utility work is taking place this weekend, the bridge will be open to pedestrians. Local vehicular access for residents and businesses also will be maintained between Route 1 and Canal Road this weekend.

Detour signage will be posted

Motorists wishing to travel north on Alexander Road toward downtown Princeton from Route 1 or West Windsor will be directed to use Washington Road (County Route 571) north to Faculty Road. Motorists will be directed to turn left onto Faculty Road and continue through the roundabout at Elm Drive/Lakeside Road, then turn right on Alexander Street.

Motorists wishing to travel south on Alexander Street from downtown Princeton to Route 1 or West Windsor will be directed to turn left onto Faculty Road, continue through the roundabout at Elm Drive/Lakeside Road, then turn right onto Washington Road south  to Route 1.

NJDOT project will replace the bridge over the D&R Canal between Princeton and West Windsor, which was built in 1948 and is in poor condition. The existing structure consists of a three-span, simply supported, timber stringer-type bridge with a timber deck overlaid with asphalt. There is a 6-foot-wide timber sidewalk on each side with continuous, rolled steel beams below.  The existing structure features one travel lane in each direction and no shoulders.

The new bridge will be a single-span consisting of a beam-supported concrete deck on reinforced concrete abutments. The outer edge of the structure and concrete wingwalls will feature a wood façade. Bridge railings and guiderail will meet current standards and the design is respectful of the historic nature of the D&R Canal and surrounding area. The new roadway will consist of two 12-foot lanes, two 5-foot shoulders and two 5-foot wide timber sidewalks with concrete curbs.

The Mercer County project will replace two structures: the bridge over the Stony Brook and the Bridge over Alexander Creek, which are north of the D&R Canal.

The existing truss bridge over the Stony Brook was installed in 1989 as a temporary replacement to the structure in place at the time. Construction of a permanent bridge has now become a priority as the truss bridge has begun to deteriorate and the width is not adequate to accommodate bus and truck traffic.

The county says bridge railings and guiderails will meet current standards and the design is respectful of the historic nature of the D&R Canal and surrounding area.

The bridge just north of Basin Street over Alexander Creek also will be replaced due to deteriorated structural conditions. Both bridges will be built with the same roadway configuration as the new D&R Canal Bridge being constructed by NJDOT.

To minimize the duration of the closure of Alexander Street/Alexander Road, all three structures will be replaced simultaneously. Both NJDOT and Mercer County say they are employing Accelerated Bridge Construction techniques for their respective bridge replacements, which should reduce the required closure time of Alexander Street.  Conventional bridge construction would require approximately 9-12 months to complete. These projects are expected to be completed in less than six months.

Mercer County and NJDOT say they coordinated with regulatory agencies such as the New Jersey Department of Environmental Protection, NJDEP State Historic Preservation Office, D&R Canal State Park, D&R Canal Commission, NJ Water Supply Authority and stakeholders, such as West Windsor, Princeton and Princeton University.  Construction schedules were largely driven by environmental restrictions. The projects are expected to be completed in the spring of 2020, with the detour removed by April 20, 2020.

During the six-month closure, Alexander Street/Alexander Road will be closed and detoured using the same detour listed above.

For the NJDOT Alexander Road Bridge over the D&R Canal, the towpath along the canal will be open during construction except during temporary closures for the safety of path users and construction personnel. However, pedestrians will not be able to access Alexander Road/Street due to safety considerations as these areas will be active construction zones.

Commuters are encouraged to learn the multiple alternate driving routes and public transportation options that are available, and be prepared to try several options in the first days and weeks of the closure to find the route or mode of travel that best meets their needs while minimizing inconvenience.

Travel times for alternate routes will be provided during construction to provide useful information to motorists. In addition, NJDOT is working to optimize traffic signal timing on Route 1 to assist with addressing traffic congestion where possible.

To mitigate congestion during this project, NJDOT has been working with local officials, employers and commuters to promote several strategies including joining a carpool or vanpool, adjusting travel times to leave before or after the peak morning and evening travel periods, or to telecommute or work at other sites that employers may have available. NJDOT also recommends that commuters consider using mass transit.

Motorists will be encouraged to use alternate parallel routes, such as Route 27, Princeton Pike, and Route 206 if possible during the closure. Other routes that may be considered include Quakerbridge Road, Elm Road, Washington Road, Harrison Street, Witherspoon Street and River Road.

Travel Times to be Posted on Message Boards

To assist motorist in choosing an alternative route, NJDOT will provide 11 message boards with travel times to and from Princeton via a variety of alternate routes. The boards will be located on Route 1, I-295, Route 206, Princeton Pike, Alexander Street and near the Princeton Junction train station. Real-time information on traffic conditions is always online at