By Barbara A. Preston for The Montgomery News | June 25, 2026
The Griggstown Causeway wooden canal bridge is in poor condition and needs to be replaced.
The bridge replacement project will require a full road closure, says the NJ Department of Transportation (NJDOT).
Construction was anticipated to begin in May, with an estimated completion date of Spring 2027. As of June 23, it has not started.
Traffic is expected to increase heavily over the Rocky Hill bridge on Rt 518, Rt 206 in Montgomery, and Rt 27 in Princeton/Kingston while the bridgework commences.
The wooden Griggstown Causeway Canal Bridge will be replaced soon with a single-span steel-plate girder bridge with a concrete deck and timber sidewalk surface, according to the NJ Department of Transportation.
The wooden bridge over the Delaware & Raritan Canal.
Plans also call for a flashing beacon at the Delaware & Raritan Canal State Park trail crossing at Griggstown Causeway. It is a popular spot for hikers, and the location of a canoe-rental business on the canal.
The towpath along the canal is expected to remain open during construction.
The NJ DOT is proposing a detour along Canal Road on the Franklin Township side or Millstone River Road on the Montgomery side. On the Montgomery side, take River Road south to Route 206 to Washington Street (Route 518) in Rocky Hill, then back to Canal Road.
The Griggstown Causeway Bridge was built in 1950 and reconstructed in 1990. Due to the poor conditions of the substructures, the bridge requires replacement to provide a safe and efficient bridge crossing, according to the NJ DOT.
Widening the bridge,
Raising the roadway profile,
Upgrading ADA-compliant sidewalk,
Installing bridge railings, and
Utility Relocation.
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Regulations pertaining to the protection of historic properties require NJDOT to take into account the effect of projects upon historic resources listed in, or eligible for listing in, the National Register of Historic Places.
For information, reference the Advisory Council on Historic Preservation’s “A Citizen’s Guide to Section 106 Review,” available online at: achp.gov/sites/default/files/documents/2017-01/CitizenGuide.pdf.
To sign up for Somerset County Safety Alerts, including county road closures, visit somersetcountynj.gov/about/emergency-alerts.
