West Creek, BC Arch Shaped Multi Plate Crossing

The Challenge

Temporary emergency repairs were performed, however, the road remained closed as the repairs did not allow for safe vehicular travel. Local residents were forced to take a 15-minute detour to access and leave their properties. The existing road was low volume, however, the Township requested a solution designed to take future increases in traffic without incurring significant expense. Protecting the local ecosystem was also a priority. As one of B.C.’s most sensitive streams, West Creek is a major contributor to the Lower Fraser River’s salmonoid habitat and rearing areas containing over 200 juvenile fish during fish salvage. In addition to using this opportunity to upgrade the capacity of the drainage infrastructure, the Township wanted to recreate the most ‘natural’ scenario for the aquatic ecosystem to benefit the salmonoid population. The final item to consider was service life. The existing structure had lasted 50 years. The Township now required an economical, ‘fish-friendly’ solution that would deliver a 75-year Design Service Life.

The Solution

Various bridge solutions were considered but eventually ruled out due to the high upfront cost and the need for ongoing maintenance. Armtec proposed an arch shaped Multi Plate crossing. This buried Structural Plate Corrugated Steel Pipe (SPCSP) component system would easily accommodate future increases in traffic volume as required by the Township. Its open bottom design also preserved the natural aquatic habitat. The cross-sectional area of the arch shape was sized to prevent washout from future storm events. A cost-benefit analysis of both capital and operating costs showed Multi Plate was the most economical option for the township and its taxpayers. Once installed, the Multi Plate structure was finished with an attractive stone headwall end treatment in order to blend seamlessly with the surrounding environment.

Technical Details