(BNA/WDBA)

Located at the busiest border crossing in the North American continent, the Gordie Howe International Bridge between Windsor, Ontario and Detroit, Michigan is set to become a new symbol of the important partnership between Canada and the United States of America. Once complete, it will mark the first new major bridge between Canada and the USA in over 60 years.

Approximately 30% of all truck trade between the USA and Canada occurs between the cities of Detroit and Windsor. A study commissioned by the Canadian Government in 2001 identified a need to create redundancy in the system to increase the resilience of this busy border crossing. The answer was found in the construction of a new international crossing which – with its six lanes of traffic – would effectively double the size of the regions’ cross-border pipeline. Furthermore, it would shorten the connection between major highways Interstate 75 in Michigan and Highway 401 in Ontario, resulting in an estimated cumulative time saving for truck traffic of 850,000 hours a year.

This international infrastructure project is being delivered by Windsor-Detroit Bridge Authority (WDBA), a not-for-profit Canadian Crown corporation. In this public-private partnership, WDBA is responsible for overseeing and managing the construction and operation of the new crossing, while bridge ownership is held jointly by the Government of Canada and the state of Michigan.

The procurement process began in July 2015 with six contractor groups initially applying and competing to design and build the bridge. Formal proposals that included design, fixed prices and schedules were submitted in November 2016. All groups were given the liberty to choose between cable-stayed and suspension-bridge typologies. The preferred proponent was announced in July 2018 as Bridging North America (BNA), formed by ACS Infrastructure Canada, Fluor Canada and Aecon Concessions, with their architecture and engineering partner Aecom.

BNA proposed a cable-stayed bridge spanning the full width of the river with towers positioned slightly more than 850m apart, approaching the upper limit of approximately 1,000m for a cable-stayed design. A suspension bridge was an obvious choice for this span but it would have required more material and additional anchorage for its cables, resulting in a more costly option. Cable-stayed bridges are more efficient because bridge deck loads are directly transferred to the ground using multiple stay cables that descend symmetrically from either side of the towers.

Aesthetics and design

(BNA/WDBA)

Beyond its practical value, the Gordie Howe Bridge has already delivered something that the cities of Detroit and Windsor have not seen in more than a generation — a sense of sheer, architectural awe.

Named after the Canadian Detroit Red Wings hockey player Gordie Howe, the bridge pays tribute to two hockey-loving nations who share this great man’s sporting legacy. It is no coincidence that when viewed from certain angles, the form of each tower leg appears to echo the curvature of Gordie’s hockey-stick, mid-slapshot – his most powerful and feared ‘shot’.

The bridge is designed as a gentle curve, anchored at each bank by graceful towers. The two towers with their imposing height of 220m and fan-shaped arrangement of 216 cables (108 on each side) create majestic portals that launch the bridge deck across the river. The deck floats high above the water in a smooth arch and transitions seamlessly into the spans at each side of the river. The side spans are completed by 27 pairs of stay cables and three sets of ancillary piers fitted with tie-downs that transfer the loads directly into the ground. 

The design combines engineering ingenuity and aesthetics in a unique display of elegance. Its aesthetic appeal arises from the extreme slenderness of the deck which, in combination with its stay cables, provides an impression of gravity-defying lightness and transparency. The patterns of the white stay cables create ever-changing moiré effects when viewed from different angles, lending the structure kinetic beauty with a sculptural dimension.

An enormous effort went into the visual quality aspects of this bridge to create a landmark structure that would captivate and inspire. All utilities were concealed inside the enclosed deck and tower structure to keep the form pure and elegant. The architect – who was involved throughout the process – worked closely with the engineers, fabricators and construction teams to carefully mock up every critical detail. The colours and finishes of each component were carefully coordinated and will be further complemented by a bridge lighting system that will add yet another dimension to the project.

Once opened, the 853m span of the Gordie Howe International Bridge will make it the longest cable-stayed bridge in North America and the second longest in the western world, after the 856m-long Pont de Normandie in France. Overall, it will be the tenth longest bridge of its kind, with Russky Bridge’s 1,104m-long main span in Vladivostok holding the record for the longest since completion in 2012.

Construction

Designing and delivering a bridge across two nations poses inherent challenges: from dealing with different engineering codes, unions, regulations and even units of measure, to complying with stringent customs and border crossing requirements.

After adding up US and Canadian compliance as well as requirements from the state of Michigan and the province of Ontario, it meant that there were essentially four different sets of regulations and certifications for the project. Works on either side of the river sometimes required a modified approach and, what’s more, as a border crossing there were additional levels of security as well as the management of two separate supply chains. Materials could not simply be shared across the border but rather had to be procured independently. Indeed, now that the bridge deck is connected, staff working on the project are required to clear customs when leaving the bridge deck.

The installation of foundations deep enough to support the bridge’s two 220m-high towers close to the river’s edge was an early technical challenge for the project. Each of the legs of the two towers are supported by six shafts drilled into bedrock to a depth of 36m and filled with approximately 262,000l concrete. The footings are connected by 1,600m of post-tensioning cables.

A geotechnical survey showed that the ground in the Detroit-Windsor area consists of layers of lumps of rock, clay and sand formed during the ice age. In some parts these had cemented together, creating confining layers of impermeable rock that trapped groundwater. Moreover, the highly toxic, corrosive and flammable gas hydrogen sulphide was also potentially present because of organic debris in the rock, so workers were required to take extra safety measures.

The geometry of the cable towers also presented some hurdles for the construction team, as it changes as the pylon rises. The form starts with a 10° incline at the legs, developing into a curving transition piece to the upper pylon where it then tapers to the tower top. To accommodate these changes in geometry, a custom ‘jump-form’ system was designed and implemented for the works. Vertical access to the jump-form system was provided via a specialised construction elevator cabin fitted with an automatic levelling mechanism that catered to the geometry changes along its traveling path.

The project’s main challenge, however, was the design and erection of an 853m-long span without footings in the water, which required careful planning. The lengthy span itself had to be designed to withstand the strongest potential wind gusts, for which the project team ran multiple wind tunnel tests as the design progressed. Erection plans and engineering details were adjusted as needed to allow for safe construction, which included the identification of the most suitable equipment and installation methods. “Before we could get properly started on site, there were lots of moving pieces, lots of meetings and lots of drawings, iterations and reviews,” says Terry Poole, who led the BNA construction planning in close collaboration with Steve Stroh, chief bridge engineer from the Aecom team.

While barge-mounted cranes are often used for major bridgeworks across water courses, for the construction of Gordie Howe Bridge’s footings, towers and other components BNA instead chose to deploy two 50t-capacity 250m-high Comansa cranes installed on dry land. The deck of the main span was constructed using two 330t crawler cranes on each side of the river, with smaller hydraulic cranes assisting as needed. When wind conditions exceeded maximum allowances, operations ceased in line with the project’s high safety standards and the equipment’s rated and engineered capacities.

The obstacles that were faced in the early days of the project – which included limited water access, deep soft clay and winter weather – led BNA to revisit its original erection method. The team had first planned to build the main bridge deck using the balanced cantilever method, ie building the two 220m-high towers on either side of the river and then building the bridge deck, segment by segment, outwards from either face of the towers. Work would have been in sequence towards both the main-span and side spans in a balanced fashion, until the two 420m-long cantilevers met in the middle. This would have required simultaneously working at both the main span and the side spans during bridge deck construction.

However, by summer 2019, with the prospect of a hard winter closing in and bad weather potentially delaying the build, BNA decided to change track. Instead, the team opted to use an unconventional approach and build the bridge in an ‘unbalanced’ cantilever fashion, combined with a ‘stick-built’ concept for bridge-deck works. This gave BNA the flexibility to build the back-span of the bridge first, supported on temporary steel bents, before having to undertake the more challenging works across the river.  The stick-built for the road-deck works was undertaken using MLC cranes mounted on the decks’ leading-edges.

(BNA/WDBA)

The extreme climate conditions in the area were also a major influencing factor on daily construction activities.  In December and February the wind-chill temperatures would fall below -20°C, with plentiful snow and frozen rain, so it was necessary to implement thermal encapsulation, frost fighters and heating systems. In contrast during July and August, with temperatures high and humidex factors well above 40°C, shifts needed to incorporate breaks of up to 45 minutes per hour. And, from November to May, wind speeds could randomly exceed 12-16m/s, thus halting many crane operations.

The project, like many others, experienced unprecedented disruptions caused by the three-year Covid 19 global pandemic. The disruptions were even more so for this project, given the differing applicable restrictions in the USA and Canada, combined with the ramping up of construction activities in early 2020.

Lastly, the proximity of the site to Black Oaks Woods meant that there was a possibility of birds nesting in the area. The risk of delay to the construction plan from the implementation of the wildlife protection plan – buffering the nesting area until chick fledging – was mitigated through the professional services of a bird of prey and a dog, who regularly patrolled the site to deter nesting.

(BNA/WDBA)

Although the bridge deck is now closed, there is still much work to be done before the official opening to traffic in fall 2025. The crews will need to focus on fine-tuning restressing works and appurtenances installation, including anti-vandalism protection for the stay cables, and continue with the installation of the electrical, lighting, fire suppression and drainage systems. The road-deck surface and multi-use path will also be prepared for traffic with required safety barriers, signage and fencing.

This new border crossing is history in the making and represents an important new monument to optimism for Detroit and Windsor, two cities that have endured economic downturns and other significant challenges since the hay days of the North American auto industry. The project is expected to give a much-needed boost to the local economies on either side of the border.

Erik Behrens is the bridge architect for the project and creative director at Aecom. Jaime Castro-Maier is the construction lead on the Canadian site and construction manager at Aecon Group.

 

Reaching deck closure

Meticulous and diligent geometry control work allowed the construction teams to maintain the required tolerances at the two leading edges of the bridge deck, facilitating the advancement of both bridge-cantilevers until their eventual meeting point in June this year.

The gap separating the two halves of the 2.5km-long Gordie Howe International Bridge had shrunk to just 11m by late May. The 220m-high pylons had been previously completed between August and December 2023, while the construction of the main span segments and stay cables was still under way.

The two halves of the deck grew from both sides of the river, segment by segment, supported by progressively installed stay cables. Each half of the bridge main span comprises 27 pre-designed segments, each 15m long and 37.5m wide, requiring an intense marathon of repetitive construction cycles.

During structural steel installation, the horizontal and vertical alignments of both bridge-decks were carefully surveyed, monitored and corrected with the help of squaring works, while the tension of the stay cables was adjusted as needed. It is worth noting that, at 447.5m in length, the stay cables are the longest in North America.

The vertical alignment of the two bridge decks at different construction stages was kept well within the allowable tolerances, with the transversal alignment at a minimal 10-15mm. This was considered a major achievement in light of the massive unsupported length of the bridge cantilevers.

(BNA/WDBA)

The very last 11m-long bridge-deck section – the mid-span closure segment – was an intense operation. The hot June temperatures and associated material expansion meant bridge engineers had to consider dimensional changes. The Canadian construction crew used temporary hydraulic jacks to offset its half of the deck towards the side-span to enlarge the existing 11m gap by about 250mm. This extra room aimed to accommodate temperature changes in the bridge structure while also facilitating the placement of the remaining mid-segment components, without any last-minute complications.

At 1:00am on Friday 14 June 2024, both the US and Canadian bridge teams began the highly sophisticated mid-span closure within the pre-set gap. The sequence dictated the mid-segment first be connected to the US bridge deck with a standard splice. This was followed by levelling the newly extended US bridge deck with the Canadian bridge deck, and then jacking the Canadian segment to close the residual gap to the mid-segment. Lastly, the two sections at the very last bridge-deck joint – known as the ‘green splice’ – were bolted together.

On the same day, after over 12 continuous hours of united efforts from both sides of the river, the bridge deck became a unified structure.

(BNA/WDBA)

  • Client: Windsor-Detroit Bridge Authority (a Canadian Crown corporation)
  • Contractor: Bridging North America (BNA), formed by ACS Infrastructure Canada, Fluor Canada, Aecon Concessions
  • Architecture and engineering: Aecom