The Ross Street Underpass was a highly anticipated project to allow Salmon Arm pedestrians and motorists to cross under the CP rail tracks in the middle of town.
When Thurber came on board in 2021, a tender package including 50% concept drawings designed by other consultants existed. Thurber identified that the design was risky, expensive and would not be feasible within the allowable timeframe. The initial design involved sheet piles running parallel to the railway tracks with tie-back anchors and a massive open cut to build the bridge.
To improve efficiency, Thurber worked with McElhanney and carried out a full redesign and had it approved by CP between November 2021 – March 2022. The redesign involved adjusting the sheet pile alignment to mostly run perpendicular to the railway tracks to reduce risk, unloading behind the sheets to reduce loading on the walls, and the use of deadman tie-back (consisting of sheet piles) that used the sheet piles as both temporary shoring and permanent retaining walls. We also provided soil corrosion assessment. The construction took only 18 months with much of the project finished in November 2022 and the rest finished in March 2023.
Key design requirements in the tender documents included that the walls be modelled in PLAXIS 3D with which Thurber has extensive experience.
The underpass opened on May 17, 2023 and had quite the turnout of support. In the end, Thurber was able to shave six months off the project and the Mayor, City and public all seemed to be very happy with the project's results.