This award-winning example of accelerated bridge construction replaced two deteriorating 100-year-old bridges with a precast concrete tunnel, forming a key section of a revitalized rail corridor for the community.

Project Details

• Owner: Vermont Agency of Transportation and Town of Middlebury, VT
• Contractor: Kubricky Construction Corp.
• Engineer of Record: VHB
• Completion Date: 2019
• Scope: U-Wall sections, Upper-Wall Units, Fast-Tracked, Tunnel

Project Overview

The Middlebury Bridge and Rail Project is a landmark example of accelerated bridge construction. 

Administered by the Vermont Agency of Transportation (VTrans) in collaboration with the Town of Middlebury, the project replaced two deteriorating 100-year-old bridges with a 360-foot precast concrete tunnel, part of a larger 1,736-foot rail trench.

Through our expertise in precast concrete, Fort Miller helped transform a complex infrastructure challenge into a nationally recognized success, setting a new standard for projects employing accelerated bridge construction. 

Scope and Details:

The original bridges, removed in 2017 due to severe structural deterioration, posed significant issues. Ongoing deterioration had impacted pedestrian zones and falling concrete pieces posed a risk to trains passing below. Drainage problems caused ponding and icing, disrupting rail operations.

Additionally, poor horizontal alignment of the rail line contributed to operational inefficiencies and even a train derailment.

Temporary bridges were installed to maintain traffic flow, but also lacked the vertical clearance for double-stack railcars. 

The project, including the 345-foot-long precast concrete tunnel, replaced the two bridges, and the surface above serves as a continuous roadway, connecting the town’s Triangle Park with the Village Green.

This ambitious project not only addressed these structural deficiencies but also introduced significant advancements in rail operations and urban design:

• Increased Rail Clearance: By lowering the rail bed by four feet, the project achieved a 21-foot vertical clearance, accommodating double-stack rail cars and future-proofing Middlebury’s rail infrastructure.
• Improved Rail Alignment: The redesigned rail trench softened a sharp curve, reducing operational risks and enhancing train movement efficiency.
• Enhanced Drainage Systems: Modern drainage mitigates ponding and icing, ensuring year-round rail functionality.

The Fort Miller Co., Inc. played a critical role in the success of this project, fabricating 422 precast concrete elements, including 295 U-wall sections and 127 upper-wall units. Each U-wall section was cast monolithically, weighing over 30 tons, and assembled on-site with precision and speed.

These precast elements were manufactured off-site, minimizing on-site disruption.

Additionally, the modular nature of the precast components enabled rapid assembly within the project’s aggressive 10-week construction window. 

This approach reduced road closures and allowed the town’s streets and sidewalks to remain largely operational during the construction period, minimizing the impact on residents and commuters.

Impact and Innovation:

Fort Miller played a pivotal role in the project’s success, accelerating the installation and ensuring the project met the aggressive timeline.

This precast concrete solution revitalized Middlebury’s rail infrastructure and reshaped its downtown landscape. By reconnecting community spaces, enhancing rail operations, and safeguarding against environmental risks, the project stands as a testament to the power of innovative engineering and collaboration.

This project demonstrates how accelerated bridge construction and precast solutions can modernize infrastructure while respecting local character and minimizing disruption. 

2022 Precast/Prestressed Concrete Institute Design Winner: Transportation Award for Best Bridge with a Main Span up to 75 Feet