Project Overview

The I-40 Bridge over the Big Sandy River holds a groundbreaking place in U.S. bridge engineering as the first precast, prestressed concrete bridge designed and constructed to be continuous for composite dead and live loads. Inspired by findings from the AASHO/Bureau of Public Roads (BPR) road tests in the early 1960s, the bridge introduced an innovative design approach that has since influenced modern bridge construction.

The tests indicated that when precast concrete beams were butted together at intermediate supports and reinforced with longitudinal steel in the composite slab, a continuous structural action could be achieved. Based on these findings, the Tennessee Department of Transportation (TDOT) Bridge Division developed a novel design methodology. This approach incorporated cast-in-place concrete diaphragms between beam lines at intermediate supports, allowing the structure to function as a continuous system. By analyzing the beams as continuous for composite loadings, TDOT engineers reduced positive moments by establishing negative moments over intermediate supports, enhancing structural efficiency. The pioneering methods used in this design were later publicized in a 1965 Portland Cement Association (PCA) publication, documented by Cliff Freyermouth.

The success of the Big Sandy River Bridge led TDOT to standardize this design approach, ultimately influencing other highway agencies to adopt similar methods. Eventually, these designs were adopted into the AASHTO Bridge Design Specifications. This bridge was the first to successfully implement composite load bridge design for precast, prestressed concrete construction, demonstrating not only improved structural efficiency but also reduced future maintenance needs compared to simple span designs. In essence, the innovations employed in this project significantly advanced precast, prestressed concrete bridge design.

The I-40 Bridge over Big Sandy River was subsequently widened in 1999 by adding an additional beam line to accommodate a full roadway approach template. The design introduced by this bridge led the way to increased service life expectations for similar structures. Despite enduring heavy truck traffic for 60 years, the bridge remains in service with a “Fair” rating, further demonstrating the lasting success of its design.

Precast Concrete Producer:

Construction Products Incorporated of Tennessee, Jackson, Tennessee

Key Project Attributes

• Completed in 1964.
• Widened in 1999 by adding an additional beam line to accommodate a full roadway approach template.

Project/Precast Scope

• It is an example of employing intuition, building on past research, and daring to take responsibility, in expanding the envelope of bridge design practice.
• The Big Sandy River Bridge established, for the first time, success in composite load bridge design for precast, prestressed bridge construction.
• Led to the standardization of this design approach at TDOT as well as prompting other highway agencies to adopt such designs.
• The bridge, which has been subjected to heavy truck traffic for 60-years and is still in service with a rating of “Fair”, demonstrates the success of its design concept.