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Getting Beneath the Surface of the Union Station Revitalization Project

Challenge

The ongoing Union Station Revitalization is set to bring many new enhancements to riders such as a roof and glass atrium over passenger platforms and railway tracks, new staircases, additional vertical access points, and an overhaul of the platforms and station concourses. GO Transit is also expanding its services and infrastructure with a goal to increase ridership, enhance speed and anticipate growing demand. This includes a track reconfiguration between the Don River and Strachan Avenue where existing tracks will be interconnected to various platforms, allowing more riders to access trains.

Because the track had been subject to change and resurveyed multiple times over the years, concerns arose over the accuracy of existing data particularly for subsurface assets: datasets were housed disparately and scattered across multiple platforms. Adding to the challenges was the fact that Go Transit’s interlocking track system is considered one of the most complex in North America and much of the infrastructure is 50-70 years old. Project managers were uncertain of the location of underground utilities within the project area and needed to find a way to capture a precise snapshot of buried infrastructure.

subsurface utility engineering, Union Station

Solution

The SUE process was implemented to get an accurate depiction of all existing public and privately owned utility services including gas, hydro, water, fibre optics, telecommunications and signal cabling. Non-destructive geophysical inspection methods including Ground Penetrating Radar (GPR) and Electromagnetic Induction (EM) were leveraged to detect buried cables and utilities that crossed the corridor. The vertical and horizontal positions of subsurface assets were then confirmed through vacuum excavation. Collected data was referenced against existing maps to reveal anomalies, and information was then stored in a central database. 

Property boundary and topographic data was also gathered and overlaid on a map, to generate a 3D topographic survey. The study resulted in a documented understanding of the Union Station Rail Corridor (USRC) ownership and easements, detailed knowledge of surface infrastructure and the inferred spatial position of all underground utilities targeted by the investigation.

Traditional survey techniques were also combined with LiDAR data to model the corridor in 3D, providing an accurate perspective of corridor dimensions.  As the trains are protected by a clearance envelope through a very narrow tunnel, 3D modelling provided a detailed perspective and better line of sight, allowing project stakeholders to make accurate measurements for corridor routes.