West Harbour GO Station
Ontario is on the move! Metrolinx’s regional transportation plan, “The Big Move” (bigmove.ca) is expanding the connectedness of the Greater Toronto-Hamilton Area. With billions of dollars committed to this, Metrolinx aims to create effective transit and transportation solutions to “bolster our global competitiveness, protect our environment, and improve our quality of life”.
An important piece of the transit plan is the construction of the West Harbour GO Station in Hamilton, Ontario, which offers train and bus service along the Lakeshore West Line. It is part of the proposed LRT system that will carry passengers throughout the city and connect to the John C. Munro Hamilton International Airport.
Phase 1 of the West Harbour GO Station was completed ahead of the recent Pan Am Games to shuttle athletes, coaches, and spectators to and from Hamilton’s Pan Am Soccer venue.
Several station features were required to be operational in time for the Pan Am Games. This included track and station work including the construction of a 43 m (141 ft) concrete segmental retaining wall running west from the Bay Street Bridge Abutment.
In addition to the tight project schedule, the construction of the new retaining wall was planned in an area of soft, compressible clay at a limited-access site where vibration and impact on adjacent active railroad and site works had to be minimized.
The design team initially considered various foundation support options for the new retaining wall with heights up to 5 meters. Shallow foundations were quickly eliminated because of the soft nature of the site soils and settlement concerns. A driven H-pile solution was initially selected and designed for 40 piles with a structural capacity (ULS) of 1,300 kN. However, the H-pile option was challenged with practical construction issues. These challenges included excessive vibrations, extended working pad laydown area requirements, access issues requiring excessive splicing of battered piles, as well as variations in working grades causing challenges for installation equipment and inefficient pile material usage.
Working closely with the design team, a Ductile Iron Pile alternative was proposed for support of the retaining wall. The Ductile Iron Pile solution consisted of 74 piles with a structural capacity (ULS) of 725 kN. The pile design included a 118/7.5 Ductile Iron Pile section (118 mm outside diameter with 7.5 mm wall thickness) along with a #8 reinforcing bar centered in the pile and 20 MPa grout. The piles were installed to depths ranging from 25 m to 28 m to bear on rock. Design at the site was verified with a full-scale load test performed to 1,036 kN. Maximum (gross) deflection at the maximum test load was limited to 18 mm with much of the deflection occurring as a result of elastic shortening of the pile. GeoSolv installed a total of 39 vertical and 35 battered (3:1) piles in 12 shortened working days. Installation utilizing a medium-sized CAT 315 excavator allowed the crews to work from variable grades, without the need for significant working grade modifications. The modular Ductile Iron Pile sections allowed for battered pile installation without obstruction due to existing adjacent retaining walls. The limited vibration generated with the system significantly reduced potential issues with slope stability or impact on nearby rail activity.
The project is Canada’s largest Ductile Iron Pile installation to date and was successfully completed on schedule. It is a critical part of the successful completion of the West Harbour GO station and Ontario’s overall “The Big Move” plan.