Three-sided rigid frame bridge technology allowed Fort Miller to replace Cornwall’s century-old Main Street Bridge on a skewed, curved site without disrupting the gateway to the community.

Three-Sided Rigid Frame Bridge Replacement Over Idlewild Creek

Cornwall, NY

Project Details

• Owner: Orange County
• Engineer: Transit Halmar JV
• Contractor: HVEA Engineers
• Project Completion: 2025

Project Overview

Originally constructed in 1929, the Main Street Bridge (Bridge #2, C.R. 9) over Idlewild Creek in Cornwall, NY had reached the end of its useful life. Orange County, in partnership with HVEA Engineers, selected a three-sided rigid frame bridge as the replacement structure. 

Located adjacent to Chadeayne Circle along County Route 9, the bridge serves as a gateway to Cornwall. Therefore, the project team specified architectural detailing to match its visibility, including sculpted parapet walls, decorative lamp posts, and iron fencing.

Scope and Details

For this project, Fort Miller fabricated the three-sided rigid frame bridge, wingwalls, and bridge rails. The frame bridge was constructed on a skewed span of 43’-6 7/8”, with all units manufactured parallel to traffic. 

Additionally, HVEA Engineers designed the bridge rail (commonly referred to as “Texas rail”) which attaches to the structure via pilasters. Because the bridge sits on a curve, Fort Miller precast the rail on a curve to match the site geometry, while the facia of the bridge units remained straight.

The team connected the pilasters to the bridge using NMB Splice Sleeves, a cast-in coupler system that mechanically joins reinforcing bars between precast elements. Then, Fort Miller suspended the railing slightly between the pilasters, leaving reinforcement protruding underneath to allow a closure pour. This tied together the pilasters, bridge rail, and three-sided frame into a continuous assembly without field welding or extensive cast-in-place formwork at the connection zone.

Impact and Innovation

The bridge sits at a constrained intersection where adjacent businesses left limited right-of-way. This affected staging and delivery logistics throughout construction. To manage tight ROW conditions, Fort Miller fabricated all components offsite in their Greenwich, NY facility, minimizing on-site work time. As a result, general contractor Transit Halmar JV opened the bridge on schedule in late June 2025.

This project combined a skewed frame, curved precast rail, and a pilaster connection system, representing a technically demanding scope for a county bridge replacement. Precast fabrication allowed Fort Miller to resolve frame geometry, rail curvature, and connection tolerances under controlled plant conditions before arriving on site. This approach reduced risk and kept the installation sequence on track.