Design Challenges to Accommodate Operations, Maintenance, Rehabilitation, and Construction Considerations of the Neptune Cargill Overpass Extension Project

The Neptune Bulk Terminals in North Vancouver plays an integral role in connecting the Canadian economy with oversea markets by transporting 30 million tonnes of products annually. As part of the approx. $24 million Neptune Cargill Overpass Extension Project to improve access to a growing port terminal in the North Shore Trade Area, Stantec provided engineering design and construction support for the new overpass extension which was completed in 2019. This grade separation offers a direct route into the terminal coal storage yard from Low Level Road and the existing Neptune/Cargill Overpass, improving terminal operations and efficiency in goods movement. The new bridge spans approximately 56m on a curved alignment over a maintenance road entrance to an existing settlement pond, terminal access road, and multiple freight rail tracks. This paper discusses the challenges our team faced to accommodate rail operations, maintenance, rehabilitation, seismic hazards, girder erection, and traffic management.

From the early stages in our design process, integration of operations played an important role. This overpass extension project was actually envisaged at the time of the Low Level Road Project and Neptune/Cargill Overpass original construction in 2013-2014 as part of the next phase in development. Our multi-discipline design team was intimately aware of the community impacts, port operations and site constraints given our previous involvement having worked in the area, and this was valuable to developing an innovative design solution that met the project objectives. Minimizing and avoiding rail operation disruption was a key consideration for the new grade separation, in addition to the adverse soil conditions that included areas of lateral spreading and liquefaction hazards.

While developing designs of the steel bridge girders, we had to consider fabrication and shipment of the superstructure to site which required careful consideration of rail logistics and structure element sizing. The resulting solution of the bridge (steel tub girders acting in composite action with concrete deck) allowed to streamline the construction sequence. The steel components of the superstructure were fabricated out of Province and assembled on site, and then rapidly installed via self-propelled modular transporter (SPMT) units. With close coordination of the designer, terminal operator, railways, and contractor, Accelerated Bridge Construction (ABC) techniques were used to save project costs and enhance safety with minimal overhead works above the live rail envelope.