ISL geometric and structural designers worked together to improve safety by realigning a previously sub-standard on-ramp to be lengthened under the bridge.

Client: BC Ministry of Transportation and Infrastructure

Location: Delta, BC, Canada

Project Type: Transportation

About This Project

The Matthews Interchange retrofit and 80 Street Off Ramp project was a partnering of the Government of British Columbia and the Corporation of Delta to design and construct $7M worth of upgrades to roads along the Highway 99 corridor. The retrofit to Matthews Interchange provides an increase in traffic capacity while enhancing safety for motorists, and the new 80th Street off-Ramp also serves to alleviate traffic congestion at the interchange while providing direct access to the Boundary Bay Airport.

ISL geometric and structural designers worked together to improve safety by realigning a previously sub-standard on-ramp to be lengthened under the bridge. Space for the realigned on-ramp was made by removing the bridge apron and replacing it with a pinned-back vertical retaining wall. The on-ramp then merged with another re-aligned on-ramp in a curvilinear configuration designed to manage vehicle speeds, thereafter providing adequate acceleration length and a
single merge zone. Other design highlights accommodation for future bus lanes, a bus queue jumping lane at the Hornby Drive Intersection, and complex drainage design to account for drainage below sea-level that is managed by pump stations.

As a strategy to fast track the project and achieve construction completion commitments in the fall of 2014, a very tight construction schedule required ISL with the challenge of forgoing preliminary and functional design and preceding straight into detailed design for construction. However, as the 50% geometric design was achieved, geotechnical analysis revealed the area was comprised of unsuitable soils, requiring cost prohibitive ground improvement strategies.
The project was re-scoped by the Ministry to reduce the size of the project and fall within the available funding limit, while still retaining the primary improvements for capacity and safety. Thereafter, ISL reconfigured the design package to accommodate the revised scope of work as well as integrate design drawings and details to include the geotechnical ground improvement solutions.


Lesson’s Learned

The construction time-crunch was mitigated by breaking the project into two contracts, thereby taking advantage of construction staging complexities such that one ground improvement strategy could be contracted for the 80th Street off-ramp in advance of the ground improvement strategies at Matthews Interchange. The two projects were tendered, and construction was completed in the fall of 2014 as intended.

This project provided many ‘Lessons Learned’ components, and truly highlight the importance of proactive communication and instituting strong project management fundamentals. ISL was fortunate to be able to collaborate with an engaged MOTI team that enabled the project to be constructed on schedule.

Integrated Expertise

  • Transportation
  • Municipal Engineering
  • Supporting Services

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