YOHO NATIONAL PARK TRANS-CANADA HIGHWAY WILDLIFE OVERPASS

Built in the 1950’s, the Trans-Canada highway required upgrading to move traffic safely through the park, reduce wildlife mortality, and ensure wildlife migration from one side of the highway to the other for genetic diversity. Therefore, it was determined that a wildlife overpass was required at KM 84.5, and due to the topography of the site, the design called for a 33.4m single span over four lanes of highway.

Global News Article Parks Canada prepares to open largest wildlife overpass of its kind in Yoho National Park

By Sarah Offin, Reporter, Global News

The arch had to be built in a short construction window during peak tourist traffic with minimal highway stoppages. The contractor had limited backfill available to use without resorting to importing expensive engineered material. The area of construction had a very small lay down area and required delivery co-ordination between the contractor and Nilex to ensure smooth work flow. The geometry at the top of the walls was also a unique challenge.

The contractor chose the ARES MSE wall system due to the flexibility of panel size and ease of installation. Nilex initially offered a choice of either the 1.524m x 1.524m panels or the larger 3m x 3m panels. Upon layout drafting it was discovered that due to the unique geometry of the wall’s top, the project would require up to four times the number of smaller panels than the larger ARES panels. The decision was made to reduce the number of panels required to ship, handle and erect by going with the 3m x 3m panels. Nilex’s geogrids proved to be more versatile and worked well with the select backfill material available for the site.

The project called for a total area of 380m2 of face area and a maximum wall height of 8.472m. Using 3m x 3m panels for the headwalls to the sides and overtop of the precast arch, the contractor installed the panels with an excavator and two labourers. For backfilling, the crew included one operator using a compactor or Bobcat, one on a plate tamper, and two labourers colour marking and installing geogrid. Nilex provided onsite assistance throughout the project.

The ARES Retaining Wall System proved to be an efficient choice for the contractor. After the wall portion of the project was completed, the contractor said he was “sold on the full height panels”. Installing less panels with more area per panel, the wall system was fast and efficient. The contractor also liked that he could just set the panels and get to backfilling. The geogrid was found to have very forgiving and flexible backfill requirements.

Nilex is committed to unearthing better results. Whether it’s for a civil, resource or environmental project, we offer the latest engineered and technically superior materials and techniques to save our customers time and money, and minimize the need to move or remove earth, and reduce the need for granular materials.

With over 35 years experience, a long-standing commitment to the environment and highly qualified staff, Nilex delivers the products and technologies that give clients an economic advantage with environmental benefit.