Construction is progressing upward and onwards on the Gordie Howe International Bridge project, and our team, as Owner’s Engineer, is diligently overseeing every step along the way.
Let’s have a look at the remarkable series of milestones that were achieved these past couple of years. Foundations for the bridge were completed and emerged from the ground in the spring of 2020 when both sides of the USA-Canada border were locking down and the teams were learning how to continue operations during a global pandemic. Then began the work on the giant towers, 220m tall, made of cast-in-place reinforced concrete. Much of the design and construction of the towers is driven by a key technical requirement defined by our subject matter experts: 125 years of service life, the longest service life required in comparable bridge procurements. With topics such as climate change, sustainability, and circular economy being top of mind in our industry, maximizing service life appears imperative, and the durability study conducted by our experts revealed that providing a service life of 125 years instead of 75 years had little impact on cost.
Canada Day – July 1, 2020, marked the first footing concrete placement, 1000 cubic meters, to form the first lift of the giant tower footings. Exactly 6 months later, 之前的工作人员回家度假, the last bit of the footings’ concrete was placed, totaling 7600 cubic meters for both towers.
The year 2021 kicked off with the teams’ focus shifted to the tower leg construction. With repetitive operations like tower leg lifts, construction started to accelerate. Geometry control was one of the most challenging aspects of building the legs. The design-builder worked against gravity by different means such as building the legs with a camber and using temporary cross beams. In July 2021, just after the project celebrated 1000 days since the start of construction, another important milestone was reached: Tie-beam construction was completed. This is one of the most critical structural elements for this bridge, balancing the horizontal reaction forces coming from the inclined tower legs. The designer elected to position the tie-beam at grade level, connecting the footings, and to post-tension the element.
So what does it mean for the Owner’s Engineer team when an activity performed by the design-builder is of higher complexity or is more critical? It means risk is higher and therefore our team performs a more detailed oversight exercise. For example, for the high-risk tie-beam post-tensioning work, our team performed a mirrored QC. And for tower geometry control, our survey sub-consultant independently checked tower leg geometry at every lift. The P3 partners focused on decreasing cycle times of the tower leg erection, and by spring 2022, when the legs reached their full height of 135m above ground, the cycle time was as low as one lift per week. Our oversight role was key to promote continuous improvement of the works, helping to ensure that optimizing the tower erection cycle times was not sacrificing quality.
Now is officially the season of steel on the Gordie Howe International Bridge! The very first deck element was lifted into place on March 29, 2022, on the Canadian side. Due to the Bridge site’s proximity to Zug island’s industrial area, the exposure condition of the exterior metallic surfaces is classified as a very high corrosivity environment (ISO 9223 C5). The visible white finish of the structural steel consists mainly of a 3-coat paint system, meant to last 40 years in this environment, as required by our subject matter experts. On July 27, 2022, the first steel anchor boxes, which are fabricated elements that will secure the cables at the tower, were placed on the US tower.
Overall completion of the bridge and opening is planned for the end of 2024. Once complete, the Gordie Howe cable-stayed bridge will have a clear span of 853 meters over the Detroit River, giving it the longest main span of any cable-stayed bridge in North America.