It is a state-maintained bridge over Amtrak's Northeast Corridor line in West Windsor.

The route makes a gradual curve to the west off the railroad bridge and passes behind a couple of homes before heading to the south slightly at an intersection.

The original proposal for the highway was to turn the road into a limited-access freeway along its entirety.

[1] This new, 104.00-foot-long (31.70 m) bridge replaced the at-grade crossing on Washington Road,[6] which is now a dead-end.

[7] The state highway law was amended just three years later, with the freeway option removed and the extensions remaining.

[5] The route was truncated from both ends toward Princeton and Hightstown, leaving just the bridge in West Windsor.

[10] Route 31A remained in the state highway statutes for several decades after decommissioning, with a bill in 1991 being proposed.

[12] However, the need for an expressway from Trenton to the Jersey Shore remained, and in the late 1950s, the State Highway Department brought about plans for the Princeton–Hightstown Bypass, a four-lane freeway that would head for 14 miles (23 km) from U.S. Route 206 in Montgomery Township to New Jersey Route 33 in Hightstown.