PRINCETON, NJ --  Mercer County motorists should brace themselves for long-term traffic delays caused by bridge repairs in the heart of the county.  Beginning on Wednesday, Alexander Street/Road, which runs through Princeton and West Windsor, will be closed and detoured for approximately six months.

The long-term road closure is a result of New Jersey Department of Transportation (NJDOT) and Mercer County undertaking concurrent bridge replacement projects involving three bridges near each other that will take place concurrently on Alexander Street/Alexander Road in Princeton and West Windsor.

Construction is expected to be completed in the spring of 2020.

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The NJDOT project will replace one bridge over the D&R Canal that was built in 1948 between Princeton and West Windsor.  The existing structure is now in poor condition and consists of a three-span, simply supported, timber stringer-type bridge with a timber deck overlaid with asphalt. The existing structure can only hold one travel lane in each direction and no roadway shoulders.

Once construction is complete, the new bridge will be a single-span structure 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 while meeting current standards 

The new roadway will consist of two 12-foot lanes, two 5-foot shoulders and two five-foot wide timber sidewalks with concrete curbs.

The towpath along the canal will be open during construction except during temporary closures for the safety of path users and construction personnel.  Pedestrians will not be able to access Alexander Road/Street due to safety considerations as these areas will be active construction zones

Meanwhile, the Mercer County project will replace two bridges – the bridge over the Stony Brook and the bridge over Alexander Creek.  Both structures are north of the D&R Canal.

Installed in 1989, the existing truss bridge over the Stony Brook was intended to be a temporary replacement to the previous structure. Construction of a permanent bridge has now become a priority as the truss bridge has begun to deteriorate.  Currently, it is not wide enough to accommodate bus and truck traffic.  

The bridge just north of Basin Street over Alexander Creek also will be replaced due to deteriorated structural conditions.

The project designs are respectful of the historic nature of the D&R Canal and surrounding area, officials say. Furthermore, the Mercer County bridges will be built with the same roadway configuration as the new D&R Canal Bridge being constructed by NJDOT.

The projects are being undertaken simultaneously to minimize the duration of the closure of Alexander Street/Alexander Road.  NJDOT and Mercer County are employing Accelerated Bridge Construction (ABC) techniques to drastically reduce the required closure time of Alexander Street.

Conventional bridge construction would require approximately nine to twelve months to complete. Under the ABC method, these projects are expected to be completed in less than six months.

Commuters are encouraged to seek alternate driving routes and public transportation options that are available.  To ease the congestion and impact of the road closure, motorists are encouraged to join a carpool or vanpool; adjust travel times to leave before or after the peak traditional morning and evening “rush-hour” travel periods; or telecommute or work at other sites that your employer may have available.

During construction, construction updates and real-time travel information will be available on NJDOT’s traffic information website:

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