Phase: Final Design

Purpose And Need: The purpose of the project is to correct structural deficiencies, substandard elements, and improve community/motorist safety along US Route U.S. 206 at the South Broad Street Bridge over Assunpink Creek (County Bridge #140.2) at MP 42.69 located in the City of Trenton in Mercer County.

Existing Conditions: The South Broad Street Bridge is a historic stone masonry arch structure located in the City of Trenton over the Assunpink Creek. The bridge is individually eligible for the National Register of Historic Places. The project site was the location of the Second Battle of Trenton during the American Revolutionary War. Early industrial development in the City of Trenton grew around the bridge site, with Assunpink Creek providing power for various mills. The arch consists of three sections. The two exterior sections have a variable width of approximately 15 feet on each side. These exterior sections date back to a widening that was performed around 1870. The inner section is likely part of a rebuilding program that took place after major floods in either 1822 or 1843. The entire arch is approximately 60 feet wide with an approximate clear span of 45.5 feet. Upstream of the bridge, the creek is channeled by stone masonry foundation walls and is split adjacent to the bridge by a 5-foot-wide stone masonry pier. Downstream of the bridge, the creek flows through a two-cell reinforced concrete culvert then daylighting towards South Warren Street and continues to the Delaware River. There is a second masonry arch structure immediately to the south of the exposed arch which is not visible as it's buried under fill.

Proposed Improvements: The proposed improvements consist of maintaining the approximate alignment of the existing roadway, and a new support structure, constructed over the top of the existing arches, would be built to carry the modern required loads. The existing arches would remain, and preservation activities would be undertaken to stabilize the existing arches. The existing exterior spandrel walls would be retained and rehabilitated, and that new spandrel walls would be constructed just inside of the existing walls. The buried spandrel walls of the original core structure would also have new spandrel walls constructed on both sides. The downstream two-cell reinforced concrete box culvert is proposed to be removed in its entirety, utilities (water mains) carried on this structure will be relocated into the South Broad Street roadway and the stream cross section regraded. It is proposed that the current 36-foot-wide roadway be maintained; however, the existing sidewalk extensions on the east side would be removed, resulting in a narrower width for the overall structure. The roadway over the bridge would be on a tangent alignment which would allow the roadway to have a normal crown shape. Railings that can withstand traffic impact loads will be provided on each side of the structure. The details of the external appearance of the new spandrel walls and railings are to be determined, but will be compatible with the historic character of the structure.

Estimated Schedule:

• Current – Final Design
• November 2025 – Final Design Complete
• December 2025 – Bid for Construction
• March 2026 – Start Construction
• March 2027 – Construction Complete

For further information, please contact: 

Joseph B. Vena, P.E. Assistant County Engineer 

Mercer County Department of Engineering 

Tel: (609) 281-7220 

 jvena@mercercounty.org

Public Information Center Postponed: