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Friday, Dec 22, 2017

Rehabilitation of Toronto’s aging bridge infrastructure extends asset life-span and improves user safety

Toronto bridge rehabilitation

The City of Toronto’s bridges, structures, and expressways are aging. Several bridge elements in 11 locations were identified for immediate rehabilitation, including approach slabs, barriers, abutments, bearings, retaining walls, metal railings, and elevated sidewalks. 

The City retained Associated Engineering as prime consultant to complete repairs for the 11 sites, which was later expanded to 14 sites. Our scope of work included preliminary and detailed design, tendering, contract administration, and post-construction services.

The project team investigated all of the sites to assess the present condition and collect additional data for the anticipated repairs. Since the repairs at the various structures were limited to bridge components, the project team collected field data, measurements and performed limited testing and sampling, as necessary. 

Project Manager, Sarvejit Nagi, tells us, “The project involved many sites, each with its unique issues and problems. We needed to tailor a specific workplan for each site.” 

One of the sites is Dundas Street West at Islington Avenue where the eastern structure approach slab has cracked from the heavy use of public buses turning at the intersection. 

Another site is Dupont Street at CNR/Metrolinx. The existing grade separation is desperately in need of rehabilitation or replacement of the elevated sidewalks and adjoining retaining walls. The sidewalk slab used by pedestrians has evidence of delaminations. A three-metre section has collapsed and a steel plate is in place as a temporary measure to keep the sidewalk open.   

In discussions with the City at the project onset, the project sites were split into two tenders with the first tender comprised of priority sites. The design team prepared preliminary design reports for each site and recommended a repair strategy. Six of the sites have been tendered and the remaining sites are in detailed design and will be tendered in early spring 2018. 

A preliminary design report was prepared to determine a preferred solution for each location. Sarvejit says, “One of the challenges faced by our team was to meet schedule requirements for the first package. We had to ensure that all of the permitting was in place prior to releasing the construction tender for all sites, because if one of the site permits was delayed, it would impact the delivery of the whole tender package.“ The project team secured all of the necessary permits and worked with the permitting authorities to minimize re-submittals.

Pro-active coordination of permits kept project on schedule 
 As part of the rehabilitation design, permitting approvals were sought with City departments and 60% detailed design plans were circulated to utility companies affected through the Toronto Public Utilities Coordination Committee (TPUCC) process. The design team prepared traffic control plans to accommodate the bridge repairs and coordinated the traffic strategy with TTC and Mississauga Transit. We also effectively engaged with the property owners affected and other stakeholders to collectively gain their buy-in for the repairs.
Sustainable approaches include recycling concrete and asphalt from sidewalks, barriers and approach slabs. Trees will be planted to compensate for any injured or removed trees.
Key personnel on the project included Sarvejit Nagi, Geoff Burn, Christian Concolino, Sulaf Zear, Caelin Markarian, Alina Wu, and Roy Gong.