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December 15, 2021 Getting Creative to Provide Solutions on Complex Bridge Project

Powerline Plus beats schedule and delivers Gerrard St. East Bridge electrical upgrades early

Toronto Hydro-Electric System Limited (THESL) selected Powerline Plus Ltd. (Powerline) to remove and replace aging electrical infrastructure from the Gerrard St. East Bridge in Toronto, Ontario. Because the existing infrastructure did not have room to expand the electrical to bring enough power to connect customers and neighborhoods on each side of the 140-meter-long bridge, the existing duct structures and primary distribution feeders needed to be replaced.

It was a unique and complex project that required creative thinking to design and construct. Powerline developed a plan and delivered it safely and ahead of schedule.

This particular bridge has a road and light rail track on top of it, and also has a highway (the Don Valley Parkway) and the Don River below. These complexities required Powerline’s team to involve many stakeholders including the customer, the city, the transit agency Metrolinx, and environmental agencies. The plan they developed accounted for all the public safety and environmental needs of the project and Powerline successfully delivered the project in November 2021.

Powerline does many underground projects while working above a river and highway is more unusual for them. The unique solution of working from a suspended platform beneath the bridge was also atypical, but a key to success on the project.

“We are always eager to take on new projects and expand on our existing capabilities. And we will go above and beyond to meet customer and the community’s needs,” the Powerline construction team said.

Designing the Best Solution for Constructing Under a Bridge

Powerline performed structural, electrical, environmental, and traffic design and analysis for the project. The design phase took about a year, beginning with gathering all the information about the scope of work, acquiring documentation of existing infrastructure, and multiple site visits to develop a constructable electrical design and hanger system for the ducts with weight that the bridge could bear.  

The construction phase began April 2021 with removal of the existing duct structures, cleaning all the existing pipes and removing old cables, and cleaning all remnants of bridge rehabilitation work before installing new ducts and pipes and pulling new cable. Powerline also served as a liaison with telecommunications companies to remove and relocate their active cables.

One of the biggest challenges the team had to solve was how to work under the bridge safely and efficiently, and especially over the Don Valley Parkway which could not be fully shut down. Doing all the work tethered and suspended from the bridge would have taken too long, so they sought to find a way to keep crews safe without performing all the work that way. They devised a plan to build a platform underneath that was suspended from the bridge.

Powerline was able to secure single lane closures of the road for a few hours at a time overnight to erect that platform. It took three weeks of these brief lane closures to erect it, and another three weeks when the platform was removed.

The platform had strict weight limits and was inspected daily for safety. Powerline also had to build a second platform on top of the first to distribute the weight and limit the number of workers on it each day. This meant working slower than their normal pace, but still far faster than if they had tried to accomplish all the work tethered to the bridge.

“This project showcased our ability to adapt to all city regulations and site conditions to deliver a successful project,” the team members added.

Planning and Precautions Keep Crews and Public Safe

Powerline is committed to always working safely and takes all measures necessary to protect their people and the public. In this case, working safely required careful planning, extra personal protective equipment including respirators, additional precautions during the removal of existing infrastructure, traffic control, and using lock out tag out of the platform access points.

Removing existing infrastructure required mitigation and protection from exposure hazards because the old pipes were lead and contained asbestos. Workers and the public were protected throughout the dismantling. Powerline implemented a mesh debris containment beneath the work to protect the river and passing traffic from contamination. They also strictly enforced the use of personal protective equipment (PPE) to protect workers from the hazardous materials and implemented ventilation to protect them from car exhaust.

They conducted safety meetings ahead of time so everyone would know the scope of work and hazards to expect, in addition to daily safety meetings. In those daily meetings, the day’s tasks and hazards were discussed, and crews were reminded to take a break if they became dizzy – which can happen quickly to people working on a platform below moving bridge traffic.

These safety measures succeeded, enabling Powerline to complete the project with zero incidents.