The Highway 401/403/410 interchange in Mississauga, Ontario is one of the two busiest interchanges in North America, carrying well over 400,000 vehicles a day. Recognizing the need to upgrade the 35 year old interchange, in 2017, the Ministry of Transportation Ontario retained Associated Engineering to undertake the rehabilitation of eight structures at the interchange. The project included structural rehabilitation consisting of barrier wall upgrades, bearing seat replacements, concrete repairs, modular joint replacement, ITS (intelligent transportation system) upgrades, LED underpass lighting, pavement upgrades, lidar surveying, and complex traffic management.
The structures located at the Highway 401/403/410 interchange consist primarily of voided slab structures, including the Highway 401 Eastbound-410 Northbound ramp, a ten-span, 555 metre, post-tensioned, slab bridge.
A 3D mobile lidar survey was undertaken to capture the site conditions, supplemented by total station survey. Pavement engineering included over 140 pavement boreholes in support of temporary traffic detouring on shoulders.
The electrical component of the project included AGI32 analysis of the existing underpass structures to support conversion of the existing HPS (high pressure sodium) lighting to LED lighting. In addition to this, Associated’s ITS team designed additional loops, including a Non-Intrusive Traffic Sensor.
Project Manager, Mark Torrie tells us, “The challenges we faced were driven by the structural configuration of the post-tensioned voided slab structures, supported by single post piers. Construction staging analysis was undertaken, accounting for all live and construction loads, including removal of barrier walls. We found that, during the removal of the barrier walls, several of the structures would uplift from some of the bearings. To counteract this uplift, we incorporated ballast loads into the construction staging.” In addition to the uplift potential, the bearing replacements included as part of this contract required time-dependent finite element modelling to account for the additional vertical forces from the post-tensioning in the jacking design.
The project also included replacing the modular joints on Highway 401 Eastbound-410 Northbound. With a length of 555 metres, modular joints were required to accommodate the thermal expansion and rotations at the joint.
Finite element modelling confirmed loads and design of bearing replacements
The project was tendered in two contracts in early 2018; construction of the $20 million project will commence in the summer. Construction of the works on the eastbound structures are anticipated for completion in the fall of 2019. The westbound structures are estimated to be completed in the fall of 2021. Mark advises, “We completed the project on time, in just nine months, and under budget. Kudos go to the project team.”
Key team members include Josh Hubert, Tina Keochanh, Vincent Lam, Tracey Kucheravy, Jordan Frost, Yasser Al-Anany, Christian Concolino, Kerri Hildebrandt, Andrea LaPlante, Dan MacDonald-Lockhart, Caelin Markarian, Josh Trim, Farzad Nikfar, and Rey Rimando.