Proj Overview

Project Overview 

Constructed in the 1910s - early 1920s Bridge 77, a cast-in-place concrete T-beam bridge was deemed structurally deficient due to substandard and deteriorating railings. The scope of this project required replacement of the deck and superstructure to preserve this crucial infrastructure link. 

Innovative and efficient, Bridge 77's superstructure was replaced with precast solid concrete slabs for long-term durability. This modernization optimizes resources and performance on the strong foundation of the existing structure and fulfills the Buy America project requirements. 

Because this route is vital to the area's infrastructure, and there were no options for bypasses or detours, a phased approach was required. A staged and phased approach was necessary to maintain one lane of traffic accessibility during construction by keeping one lane of traffic open at each location. 

Precast Solution

J.P. Carrara & Sons, Inc. played a crucial role as the precast concrete producer for this innovative project. A key component of the project involves the use of eight prestressed concrete solid deck beams, measuring 18" deep x 3'-8 1/2" wide x 37'-6" long. These beams are enhanced with 9" wide reinforced structural closure pours between them, forming a seamless, monolithic deck. 

This cutting-edge approach addressed the pressing need for a more durable deck system while eliminating the complexities associated with traditional transverse post-tensioning. By adopting a monolithic deck design, the project aims to significantly extend the service life of the bridge. Utilizing high-strength materials including 8,000 psi concrete and epoxy-coated reinforcement further enhances durability and longevity. 

The implementation of accelerated bridge construction techniques ensured swift progress while minimizing disruption to traffic. This streamlined approach emphasizes efficiency, with a focus on speed and quality, ultimately resulting in a single, robust bridge superstructure ready to serve the community for many years to come. 


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Project Team


State of Vermont Agency of Transportation (VTrans)

PCI-Certified Precast Concrete Producer:

J.P. Carrara & Sons, Inc. 

Engineer of Record:

State of Vermont Agency of Transportation (VTrans) 

General Contractor:

A.L. ST. Onge Contractor Inc. 

Key Project Attributes

  • Accelerated Bridge Construction
  • Monolithic Deck Design 

Project/Precast Scope

  • (08) 18" deep x 3'-8 1/2" W x 37'-6" L solid deck beams