Things look to be progressing very well for the Southern Platte Pass Trail extension. The biggest pain in constructing this project was the excavation for the job and the soil nail retaining wall underneath I-29. A soil nail retaining wall is a wall that uses "nails" to attach the retaining wall to the earth. The friction between the nails and the earth holds the retaining wall in place. A good analogy would be the dirt is a 2 by 4, the soil nails are like nails hammered in, and the retaining wall is the sheetrock holding it all together. Looking at the picture below, the "nails" are really 1-2" diameter reinforcing steel bars covered with green anti-rust material and finished like a screw.
After the nails are installed, a "shotcrete" finish is "squirted" onto the exposed earth. "Shotcrete" is a very liquid but biding concrete mix and when dry is the grey swiss cheese looking stuff. A reinforcing steel mesh is then formed (shown in the left below).
This reinforced mesh connects to the metal plates attached to the soil nails. The metal plates bind the reinforcing steel mesh and concrete together and hold up the wall. After the mesh is complete, wood or metal forms are put up and more traditional concrete is pumped and sets.
The concrete dries or cures and the forms are taken off and the retaining wall is complete.
Another type of retaining wall used in more open areas due to the ease of construction is a "big block" wall. This type of wall is made of out big concrete blocks and are stacked like Legos™. The weight of the blocks offsets the weight of the earth being held up by the blocks. As part of this project, a small "big block" wall is being built along Prairie View Road to provide a sidewalk to the ATA bus stop so people don't have to walk in the ditch to get to the blue bus stop pole. These blocks are about 28" deep by 36" wide and 18" tall and are made at a production plant and trucked to the job site.
Traffic signal modification work is still underway and most of the excavation is done. There is a power pole still in the way in front of Mazatlan which needs to be moved before all the grading is done.
I am purely speculating, but it looks like they are going to be all done by the end of July.
Great to hear about the progress on the Southern Platte Pass Trail extension! The explanation of the soil nail retaining wall construction process is really insightful, especially with the analogy of the "nails" being like screws holding everything together.
Posted by: BAM Shotcrete | 02/24/2024 at 05:55 AM