Challenge – Sorting Out the Tangled Web Beneath
Over the next 20 years, 200,000 new residents are expected to move to Ontario. Congestion in the GTHA is a mounting challenge and existing infrastructure will be incapable of supporting projected future growth. As such, Rapid Transit projects including LRTs (Light Rail Transit) and BRTs (Bus Rapid Transit) have become a key priority throughout the GTHA, as a solution to manage growth, ease congestion and prevent urban sprawl. More and more, Subsurface Utility Engineering is playing a key role in this development.
It all began with the Kitchener-Waterloo LRT, the “ION” which will connect the region’s bus rapid transit in Cambridge to the University of Waterloo and Wilfrid Laurier campuses. In Toronto, the Government of Ontario has committed $8.4 billion to support new transit including the Eglinton Crosstown LRT which will run 19 kms, connecting Weston Road to Kennedy Station; the Sheppard East LRT which will add 13 km of new transit along Sheppard Avenue; and the Finch West LRT which will connect the Finch West subway station at Keele Street to Humber College.
On the west end, the Hurontario LRT will bring 20 kms of rapid transit to Mississauga and Brampton and will provide a crucial link between many of the region’s existing transit lines. The Hamilton LRT which will connect McMaster University to downtown Hamilton is part of the largest infrastructure investment in Ontario’s history. Furthermore, the Mississauga Transitway and York Viva BRT projects will provide dedicated bus lanes allowing buses to move out of congested traffic and provide faster, more reliable service.
Solution – Subsurface Utility Engineering
As these Rapid Transit projects are being built through highly congested areas, both above and below ground, one of the most complex challenges involves accurately locating existing utilities during the design phase and discerning whether the utility can be accommodated or if it must be relocated. Decades ago, this process involved simply collecting utility records and assuming that they were accurate and complete with no formal verification process in place. Clearly this process, or lack thereof, included a wide margin for risk.
To close this margin, most large transportation infrastructure projects including Rapid Transit now incorporate Subsurface Utility Engineering (SUE) at the design phase. It provides a standardized process to verify utility records and gauge completeness – removing the guess work and risk. Governed by standard guideline CI/ASCE 38-02, Subsurface Utility Engineering requires a professional engineer to provide oversight for the data acquisition and seal data submittals. This fosters accountability, ensuring that individuals involved in the project are adequately qualified and can provide the professional judgement required to carry out the work.
Comprised of four data quality levels, Subsurface Utility Engineering involves a mix of records research, geophysical methods, vacuum excavation and land survey techniques which converge to reveal utility data that can be counted on as accurate and complete. This data is leveraged to identify potential conflicts which are then documented in a Utility Conflict Matrix, forming the basis of informed decision-making throughout the design phase of a project. From there, a qualified Subsurface Utility Engineering engineer can work alongside municipalities, ministries, private property owners and other stakeholders to review and comment on utility accommodation plans.
Finch West LRT – multiVIEW was retained to map all underground utilities along a 17km stretch of Finch Avenue from east of Yonge Street westward to the proposed Humber College Terminal. Additionally, 5km of utility mapping was completed on side-streets and major intersections to assist with siting layouts for proposed stations, alternative road designs, potential parking and passenger entry/exit structures while identifying utilities in need of relocation. For the Level B study, all utility information was captured by survey-grade GPS measurements and plotted in digital format adhering to CI-ASCE 38-02 guidelines. A Level A study was completed in areas where the design team determined that precise horizontal and vertical definition of underground facilities was required.
Eglinton Crosstown LRT – The focus of this study was to map underground utility conflicts to assist with design services for the proposed twin tunnels including bored tunnels, cut and cover structures, Emergency Exit Buildings, tunnel crossing passages, tunnel boring machine launch shafts and extraction shafts. multiVIEW completed the project in two Phases: Phase 1 involved the physical delineation of storm and sanitary sewer systems, along with water valve surveying and Phase 2 involved designating and mapping locatable underground utilities across the LRT project area. The study included all quality levels; SUE QL-A, at 27 discrete locations, QL-B, QL-C & QL-D.
As LRT and BRT projects are traditionally criticized for schedule and cost overruns, the Subsurface Utility Engineering process helps to mitigate unplanned utility relocation costs and project schedule impacts. A few things to consider for ensuring a successful Subsurface Utility Engineering Program include:
- Relegate Subsurface Utility Engineering management responsibilities to an experienced professional engineer and not a junior or inexperienced team member
- Ensure that technicians carrying out the work are highly trained, have a deep level of technical knowledge and are well versed in using non-destructive technology to capture data on the location and position of underground utilities
- Ensure that your Subsurface Utility Engineering program is coordinated and carried out by a single project team
- Ensure that utility data is collected in strict accordance with CI-ASCE 38-02 standard guidelines
- Leverage utility matrices to manage identified conflicts from the design phase through to construction