Project Description

The steep terrain on the South Fraser Perimeter Road required the largest quantity of MSE walls on a highway project in British Columbia – over 63,000 m². Different proprietary systems were procured depending on the geography:

• 26,000 m² of rock-faced galvanized steel straps from SSL
• 24,000 m² of rock-faced geogrid straps from Nilex
• 8,000 m² of 70 degree green MSE walls from Nilex
• 5,200 m² of two-staged abutment precast panel MSE walls from Nilex

Typically, select granular quarried aggregate is used as backfill however the project team received over $1 million in savings by using Fraser River sand. The team performed triaxial tests to confirm the sand friction angle. The sand caused a slight increase in the MSE strap length and thus caused greater excavation however; the sand was much more cost effective and allowed for all-weather construction due to its porous nature.

Other cost savings were employed on the MSE walls including:

• Using extensible geogrid in bridge abutments where it is typically not allowed
• Founding true bridge abutments directly on MSE walls as tall as 18 meters
• Designing split grade(tiered) MSE walls to reduce excavation volumes

RAM’s Role

RAM was retained by the joint venture FTG Constructors to manage the MSE wall design, procurement, tendering and construction. A variety of subcontractors and self-perform crews were managed to build the different systems