You may notice something different as the towers for the new Gordie Howe International Bridge soar to new heights.
A walkway connecting the jump forms on the north and south tower legs has been installed on the Canadian side of the project.
The walkway, sometimes referred to as a catwalk, currently sits approximately at 40 metres/120 feet above the ground and gives workers access to and from each tower leg during construction. As the jump forms rise, so too will the walkway.
The jump forms are a self-climbing system made of enclosed steel support frames and formwork panels that provide access and a safe platform for workers constructing the towers.
Workers are currently working on the lower pylon of the tower which at 140 metres/460 feet, makes up the longest portion of the tower. The full height of the bridge towers will be 220 metres/722 feet and will rival the height of the tallest building of the GM Renaissance Center in Detroit.
The tower legs support the pylon head housing the cable-stayed system. The cables are strung from the pylon head to the bridge deck which is approximately 42 metres/138 feet above the Detroit River. The current height of the walkway is at the same approximate height of the bridge deck once the project is complete.
The walkway is made of steel components that are welded and bolted together. Initially the walkway is 36.4 metres/119.4 feet long and weighs about nine metric tonnes/19,841 pounds. As the tower legs rise, the length of the walkway will shorten.
Workers gain access to the walkway using a construction elevator that can accommodate six people at a time. It climbs about 40 metres per minute.
The walkway took about a week to assemble on the ground and was lifted into place on the jump forms on a tandem lift with the use of a tower crane and a mobile crane.
A similar structure has been placed on the bridge tower legs in Michigan.
The catwalks will be in place during the entire construction period of the tower legs, which are expected to be complete by the end of 2021.
The construction elevator attached to the tower leg
