With an eye toward planning the replacement of downtown Nashville's busy Broadway Viaduct, the Tennessee Department of Transportation (TDOT) has chosen Gresham Smith, a firm based in the capital city, to design the new structure.
The bridge project will replace a viaduct that carries traffic on Broadway/TN Route 1/U.S. Highway 431 and serves as one of the primary gateways into and out of the city's business center, funneling some 26,000 vehicles over five CSX railroad lines, 11th Avenue South and two greenways. It is positioned between the Nashville Yards development on the north and Union Station Hotel on the south.
Ted Kniazewycz, TDOT's structure division director, has referred to the Broadway Viaduct as one of the busiest streets in Nashville.
The transportation agency announced earlier this year that Gresham Smith would conduct surveys for the project. Construction is expected to begin in early 2023, and the projected service life of the future viaduct is at least 75 years, according to TDOT.
Built in 1948, the existing Broadway Viaduct is showing signs of deterioration and needs to be replaced, the agency noted on its website.
The structure is approximately 700 ft. long and 98 ft. wide and is made up of structural steel beams and support columns. The roadway consists of six 10-ft.-wide travel lanes (three in each direction) and one 12-ft. center turn lane with 1-ft. shoulders, curb and gutter, and 10-ft. sidewalks on both sides of the roadway.
TDOT wants the replacement bridge to remain on the same alignment and general width of the existing structure. It will be comprised of concrete pre-stressed box beams and support columns. The new roadway will maintain six 10-ft. travel lanes (three in each direction) and one 12-ft. center turn lane with 1-ft. shoulders and curb and gutter. On the southside, the sidewalk will be 10 ft. wide. On the northside, the sidewalk will be 10 ft. with an additional 4-ft. furnishing zone for a total pedestrian width of 14 ft. to meet local standards.
A pedestrian bridge also has been proposed as part of the development plan with an access point on the future Broadway Viaduct, connecting it to a planned pocket park of irregular dimensions to lie beneath the structure.
Design Firm Planning Different Techniques for Build
Gresham Smith expects the project to be built via the construction manager-general contractor delivery method with accelerated bridge construction techniques put in place to speed the process and cause less impact to downtown traffic.
With the goal of completing the project within three years, this means a guaranteed maximum price for the project will not be negotiated until the project is more than halfway finished, the Nashville Post reported. Gresham Smith will subcontract third-party consultants for geotechnical services and surveying. A request for proposals targeting prospective construction managers will be soon, the news source added.
"We're excited for the opportunity to deliver the design on this critical and complex piece of infrastructure development in the heart of Nashville," explained Andy Lucyshyn, professional traffic operations engineer and leader of Gresham Smith's Middle Tennessee transportation projects division. "Our goal is to provide TDOT with cost-effective, innovative and time-saving solutions to accelerate construction and minimize impacts to the public."
Gresham Smith said its services will include bridge design, environmental compliance, lighting, permitting, roadway design, traffic analysis and utility coordination.
The design firm, which also has an office in nearby Franklin, led TDOT's 2015 "Fast Fix 8" omnibus project, a $62 million series of Interstate 40 bridge rehabilitation projects that replaced four pairs of twin bridges seven months ahead of schedule using only 10 weekend road closures. This was partly accomplished by fabricating steel superstructure units offsite at a bridge farm in an I-40 median, before transporting the materials onsite to install during weekend closures.
The effort earned the team the Grand Iris Award from the American Council of Engineering Companies of Tennessee.
These same accelerated bridge construction techniques will be used on the Broadway Viaduct, the company told the Post.
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