Egrid 170R Hwy 22 Bridge Abudment
LOCATION: Drayton Valley, AB TIMEFRAME: October 2010 SCOPE OF WORK: An embankment for the new bridge needs to be built to crossover the North Saskatchewan River on hwy 22. PROJECT PARTNERS: Owner: Alberta Transportation Client: MCL Group (sub for Graham Cons) Installation: MCL Group Material supplier: Layfield
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Highway 22 has been experiencing an increasing volume of traffic and the existing bridge, built in 1956, and is no longer sufficient. Due to the current bridge only being 8.5m in width, future plans to twin highway 22 and with the growing maintenance the existing bridge requires, it was determined that a new bridge was required. The new bridge will have a wider 13.4m deck for superior traffic flow and improved safety.
The first phase of the project was to clear the area for the future lanes on the east side of the river, construct the approach leading to the new bridge and build abutment 1 on the east side of the North Saskatchewan. The abutment was to be built up using 12 layers of uniaxial geogrid with 1m of fill in between each layer and a 1.5m overlap of the grids. The neat amount of geogrid required was 30,000m². The challenge was meeting the high ultimate tensile strength required to reduce the impact of settlement.
Layfield’s technical specialist worked with the installing contractor and the supplier to come up with a product that met the unusually high specifications; ultimately choosing E’Grid 170R, an HDPE uniaxial geogrid, choosing only the rolls that exceeded the 175kN/m ultimate tensile strength required. Layfield’s specialist then contacted Alberta Transportation and got the product approved for the project along with bodkin joints. The bodkins are used to join the rolls together to eliminate the extra material required for overlap, saving the contractor from having to order additional material. Layfield was able to supply the 30,000m2 (600 rolls) of E’Grid 170R to the contractor in time for the project to start.
As the weather did not cooperate in 2009, the product was being installed in 2010. Due to concerns with settling, only one layer of geogrid was being deployed a week with 6” of fill being placed at a time until 1m of fill is achieved.
In addition to the E’Grid 170R, Layfield was also able to supply the installing contractor with the necessary erosion control items required for the project. These items included silt fence, wirebacked silt fence, coconut erosion control blankets, and spring berms.