By John Devine
Special to Ontario Construction News
The design has been revealed for five pedestrian bridges that will be part of the Michigan Interchange component of the new Gordie Howe International Bridge connecting Windsor and Detroit.
According to the design team, the pedestrian bridges are both functional and visually pleasing, and feature a curved steel arch to be constructed of pre-cast concrete.
“The design of the pedestrian bridges is a result of meaningful consultation with the community and other stakeholders. The voices of community members have helped shape the project since early planning days and we will continue to engage and consult as the project progresses through construction and into the operations phase,” said Bryce Phillips, CEO, Windsor-Detroit Bridge Authority.
The pedestrian bridges will be compliant with the Americans with Disabilities Act (ADA) standards, and will include lighting features. They will be located over Interstate 75 (I-75) in Detroit at Solvay Street, Beard Street, Waterman Street, Junction Street and Lansing Street. Bridging North America (BNA) will undertake construction of these pedestrian bridges between 2020 and 2024, when the bridge spanning the Detroit River is expected be open.
It is being built at a cost of about $5.7 billion, and is being financed through a public-private partnership. Construction challenges are daunting, and include the building of two A-frame bridge towers to suspend the cable-stayed structure, one on the Canadian side and the other on the American side, where it will soar 750 feet about Detroit’s skyline.
The massive towers will anchor the bridge stretching 2,799 feet, the longest main span in North America. Preparing the ground for the bridge project is nearly complete, with the full scope of the effort detailed in four separate projects:
- The bridge itself
- The entry point to the bridge in Canada
- The entry point in the United States
- The Michigan interchange that links the bridge to Interstate 75 and delivers six lanes of commercial traffic to businesses on both sides of the border.
The work on the Windsor side includes customs plazas at the port of entry.
“The alignment of the bridge could not be changed,” says Jiri Filipovic, vice president of alternative delivery at AECOM Transportation and a member of the BNA design team. “It was mostly because of the former salt mining. The underground is just fraught with cavities, and significant investigations have been done to make sure that the alignment and any of the foundations don’t hit the mining cavities. So that’s why it was pretty mandatory for everyone to stay on the alignment as we had it.”
The design of the bridge involves a continuous curve, anchored at each end by the towers that suspend the bridge deck with cables across the river. The side spans are each 1,049 feet long, and supported by 27 backstay cables and three pairs of ancillary piers that transfer loads directly to the ground. Other features include:
- The mostly serpentine approaches on each side include two sharp horizontal curves, designed that way because of the difficult ground.
- Remediation work has been extensive. The land is being prepared for 50,000 square feet of buildings, in addition to the bridge.
“We had to do a lot of stability work near the seawall (on the American side) because (drilling subcontractor) Malcolm Drilling’s equipment is so heavy,” says Doug Thornton, general superintendent for the American point of entry. “This work is existing seawall, so we’ve got to drill some shafts in between all the tiebacks and transfer the load to the backside of the anchor cap wall. Then we can clear out all these existing obstructions and be able to drill our shafts for the actual tower. So all that work is going on.”
The project is expected to meet its 2024 completion date. Majority Canadian-owned BNA is the private-sector partner designing, building, financing, operating and maintaining the bridge. The company and its partners have significant experience with infrastructure projects, including the Rt. Hon. Herb Gray Parkway in Windsor, the New Champlain Bridge Corridor in Montreal, Autoroute 30 in Montreal, the Eglinton Crosstown LRT in Toronto, Réseau Express Métropolitain (REM) in Montreal, the Automated People Mover at LAX Airport, the San Francisco-Oakland Bay Bridge, and many other projects.
The design is being conducted by two separate teams to resolve different building standards, but features will be consistent.
“It had to be contemporary, minimalist and welcoming,” said Filipovic. “We wanted to have an openness by the way we used the space. Because of these common themes, both teams needed to work very closely together, and we did. On top of that, to address the various requirements for security, we brought in specialty sub-consultants to supplement AECOM and the other design team members to address the different security requirements (of the Canadian and American border security agencies).”