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Almost 22 miles of walking and biking trails are now connected via a new trail bridge crossing the Cumberland River in Nashville, Tennessee.

This project was nominated for a Planning/Design Award as part of the 2008 National Trails Awards, announced at the 19th National Trails Symposium in Little Rock, Arkansas.

 

Cumberland River Pedestrian Bridge links Nashville greenways

Background

As Nashville, Tennessee, works progressively to expand its greenway system, the new Cumberland River pedestrian bridge opened to the public that links 22 miles of walking and biking trails. This $8.5 million structure, designed by CTE for the Metropolitan Board of Parks and Recreation of Nashville and Davidson County (“Metro”), is an essential piece of Metro’s greenway system.

photo of bridge from the air

The new bridge from the air showing trail approaches

Linear corridors of land, greenways are, typically, parks and trails that connect communities to recreation areas, downtowns, schools, and shopping districts. And, most greenways include trails that are accessible by the public that accommodate walking, running, biking, and rollerblading.

In the Nashville area, the Greenways Commission of Metro Parks, along with Greenways for Nashville, is spearheading an effort to increase its system of multi-use paved and hiking trails along the Cumberland, Stones and Harpeth rivers, as well as the Richland, Whites, Seven Mile, and Mill creeks. Eventually, these greenways will form a network of corridors that link together the region’s communities.

This new pedestrian bridge, crossing the Cumberland River where it bends near Briley and Two Rivers parkway, is considered a vital link in Nashville’s impressive and emerging greenway system. Almost 22 miles of walking and biking trails are now connected, via the new bridge, from MetroCenter north of downtown to Percy Priest Dam. In addition, the new Cumberland River bridge now connects the 1,150-acre Shelby Bottoms and Park to the 384-acre Two Rivers Park.

Shelby Bottoms and Park contains ballparks, wetlands, and a nature center, and lies on the west side of the 745-foot-long bridge. A short tunnel and walkway are located on the east side, crossing under Briley Parkway to Two Rivers Park, with its skate park, golf course, and Wave Country water park on the Stones River Greenway, which ends at Percy the Priest Dam.

photo of new bridge

Bridge piers were placed on banks outside of the river channel

 

Design Innovations

To minimize costs and potential obstructions to river traffic, the piers were placed on banks outside of the river channel at normal pool elevation. As the result, the main span is 8 feet above the river and 475 feet long. This arrangement provides unparalleled views of the river and adjacent Shelby Bottoms and Park.

In order to provide a landing point for the west end of the bridge and access to the Shelby Bottoms trail system located 700 feet below, a reinforced earth mound was constructed from material excavated on site. The resulting pit was graded and planted to create a shallow lagoon and wetland for shore birds adjacent to the earthen mound. A spiral paved trail with rest areas and overlooks was built around the mound, which was planted with native grasses.

The bridge consists of three continuous spans of 150,475 and 120 feet of a 12-foot deep (constant depth), trapezoidal box girder composite with a 6-inch concrete deck. The box girder is fabricated from weathering steel to achieve a simple rustic look that is consistent with the surrounding environment and other structures on the connecting trails. Uplift of the short end spans was addressed by placing a hold-down at the west abutment and filling the first 95 feet of the east end span.

The pedestrian/bicyclist railing is composed of continuous horizontal members and vertical pickets painted a deep brown color to complement the weathering steel box girder. Portals, steel towers and suspension cables were detailed to enhance the visual impact of the bridge and to provide the pedestrians and bicyclists with a sense of security and comfort as they crossed. An adjustable system of weights was utilized to keep the suspender cables taut and vertical while allowing for thermal movements and deflection of superstructure.

Photo of horses on the trail

Map showing Nashville's trail system along the Cumberland River

The superstructure is supported by concrete abutments and hollow shaft piers. The east abutment is a stub type with flared wing walls founded on rock bluff, while the west one is a highwall abutment with laid-back parallel wing walls supported by micropiles and the first 46 feet of hollow shaft was filled with concrete to resist impact from floating debris during high water.

The west pier is supported by steel H-piles, while the east entrance portal is founded on drilled shafts. The exposes surfaces of the entrance portals, abutments, wing walls, piers, and edges of deck were all coated with a solid color sealant to provide a uniform appearance and enhance their visual effect.

The superstructure and aesthetic suspension system were extensively modeled and analyzed for wind and pedestrian-induced vibration and flutter. The results indicated that internal tuned mass damper should be provided to preclude any potential for vibrations or pedestrian discomfort that has come to light recently in several high-profile structures after they were opened to the public. In this case, five small dampers were installed— three for vertical and two for horizontal motion.

For more information:

Shain Dennison, Greenways Director
Metro Parks
P.O. Box 196340, Nashville TN 37219-6340
Phone: 615-862-8400
shain.dennison@nashville.gov
http://www.nashville.gov/parks/

Jim Morinec, Vice President
CTE
220 Athens Way, Suite 200, Nashville TN 37228
Phone: 615-313-0356
jim.morinec@cte.aecom.com
http://www.aecom.com/

 

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