The Deltaport Causeway Overpass in Vancouver B.C. was the centerpiece of a $45 million upgrade of the transportation infrastructure at Canada’s busiest container port terminal. The project included the design and construction of a curved overpass located on a narrow causeway in an area of highly sensitive soils. The aim of the project was to improve vehicle access to the terminal by separating road and railway traffic at a critical bottleneck junction, and to contribute an additional 200,000 container units of annual capacity at the port.
This paper describes the technical challenges and the engineering solutions that were used to design the structures to accommodate the tight geometric constraints of the site while ensuring minimal impact to terminal operations. The key technical challenges included:
1. The design of very slender bridge columns due to the close proximity of the rail tracks. The
innovative design used small-diameter reinforced concrete columns with an externally-bonded
fiber-reinforced polymer (FRP) wrap. The FRP wrap was designed to confine the concrete core,
and ensure the columns had sufficient ductility to meet the structural design capacity;
2. The design of expanded-base concrete ‘Franki’ piles founded within a zone of stone-column
ground improvement. Franki piles were the preferred piling system because the depth to bedrock
precluded the installation of deep-pile foundations. The Franki piles were constructed by driving
a zero-slump concrete mix out the bottom of a steel casing to form the load-bearing compression
and tension bulbs;
3. The design of a state-of-the-art lightweight-fill solution for the bridge-approach embankments
using expanded polystyrene (EPS) blocks, aka “geofoam”. The lightweight properties of EPS
allowed the approaches to be constructed at a relatively shallow depth, and limited the weight
applied to the load-sensitive foundation soils.
