Case Studies
Aquila Dock Rail Expansion #117
Project Name
Aquila Dock Rail Expansion
Customer Name
Aquila Dock
Design / Specifying Engineer
Brad Turman, Principal of J.B. Turman Engineering, PLCC (formerly with Foster Supply), in conjunction with Aquila Dock engineers and railroad engineers
Block Manufacturer
Foster Supply, Inc.
Wall Installer
Jeff Frye with J.R. Contractors; Barboursville, West Virginia
Project Location
Kenova, West Virginia
Year Built
2008
Project Scope
By Brad Turman, P.E.
When the Aquila Dock coal handling facility needed to expand its rail lines, construction plans required an additional 15 to 20 ft. of level land. The challenge? The site of the proposed line was located on a steep grade between an existing covered railway bridge and a live Norfolk Southern railway.
This location left Aquila Dock with very few options for creating a level space for the new line, as room for excavation and reinforcing any sort of wall was extremely limited. A 21 ft. high wall was required, but there was no room to bring in equipment for piling, and installing a grid-reinforced wall would have required undercutting the existing railway—causing the rail line to be shut down. Based on these factors, Aquila Dock officials decided that a precast, large block gravity wall would be the best choice for the project.
To provide a solution, Aquila Dock turned to local Redi-Rock manufacturer Foster Supply, Inc. to design the large block wall. The design criteria included creating a 4,500 sq. ft. gravity Redi-Rock retaining wall that would be constructed at the bottom of the slope and backfilled to create an additional 15 to 20 ft. of level ground at the top of the wall. The wall would support an additional track approximately 16 ft. back from the wall face. Train traffic on this section would be slow, about two to five mph.
Redi-Rock walls are made of massive, precast concrete retaining wall blocks that weigh over one ton each. Due to the scale of the blocks, Redi-Rock can build tall gravity walls that often don’t require geogrid and the extensive excavation that goes with it. Redi-Rock was the best solution for this project.
Through the use of various block types, I was able to design a solution that met the height and geometry conditions required by this site. Additionally, for the loading condition I used a 2500 psf strip load surcharge as part of the analysis.
I designed a reinforced concrete leveling pad with a concrete shear key at the toe to help resist sliding forces. The toe of the wall started 18 ft. below an overhang for the adjacent covered rail bridge. To achieve the necessary height, the wall design included 60 In. Base blocks, 60 In. Middle blocks, followed by 9 In. Setback blocks and finished with 28 In. Middle and Top blocks. The wall was completely backfilled with imported ¾ In. limestone on a 1:1 influence beginning at the leveling pad and extending the full wall height.
Using the standard Redi-Rock wall system would have created approximately a 4 degree batter, which meant the top of the wall would have finished under the canopy overhang which was unacceptable. Instead, I recommended the Redi-rock 9 In. Setback block to not only increase the design batter to approximately 26.6 degrees for this gravity structure, but also to ensure the wall cleared the canopy at the top. The 9 In. Setback block enabled us to meet our factor of safety with respect to overturning, and gave the owner the geometry they needed with the bottom and top of wall locations that had already been established.
The preliminary design was presented to Aquila Dock, who approved the design with its own internal engineers. Additionally, the owner received approval from the railroad to proceed with the project.
Installation began in 2008. Redi-Rock installs like giant Legos—each block interlocking with the one above through a system of knobs and grooves. The blocks are installed using a piece of heavy machinery and a small crew. On this project, installation crews had to deal with very limited access to the site. They were only able to access the wall construction site from one location, so there was very little space to stage equipment or store material. Plus, excavation and installing had to take place while the adjacent railway was live. Material had to be stored away from the site and transported onsite in small amounts.
In total, the finished wall is approximately 4500 sq. ft., with the tallest section standing 21 ft. tall and stretching approximately 260 feet long. The completed wall used both Redi-Rock Cobblestone and Limestone textures.
To learn more about Redi-Rock engineering or to find out how you can use Redi-Rock in a railroad application, contact info@redi-rock.com or call 866-222-8400.
