01-14-2022

It’s Suspenseful: Thousand Islands Bridge Canadian Crossing

Crews prepare to unreel the new suspender cable by attaching the socket to the tail of the old suspender to be pulled up and over a nest of sheaves installed at the main cable level.
Left: At the main cable level, TIBA crews pull the old and new suspenders up and over a nest of temporary sheaves to get the new suspender cable into position.
Right: The last turn of the reel will deliver the leading and trailing cable sockets at deck level for permanent connection to the superstructure. The old suspender seen on the roadway deck has since been reeled and readied for transport for physical strength testing.

Every year since 1938—when the bridge opened to traffic—engineers from our Bridge Team travel to the Thousand Islands region of New York State and Ontario, Canada, to inspect the Thousand Islands Bridge. Our legacy Steinman team designed the entire international crossing, serving as the engineers for the Thousand Islands Bridge Authority (TIBA) ever since. One of a few intriguing span types, the crossing consists of two suspension bridges: one over the US Seaway channel and one over the Canadian channel.

This year was unique in two ways. First, to cross the international border, we were required to meet stringent Covid-19 protection protocol, including proof of inoculation, a negative Covid-19 test within the past 72 hours, and proof of essential services provided. Second, we supported TIBA staff in removing a fully loaded suspender cable and replacing it with a new one—while under traffic.

The operation consisted of installing the Parsons-designed jacking frames, removing the deck-level connections, pulling the old suspender down using a temporary upper nest of sheeves, and attaching the new suspender to the tail of the old one to unreal it and pull it up and over the main cable. Reconnection at the deck level completed the job. The work was well planned and was accomplished without the slightest deviation from the plan.

Congratulations to our team for the flawless execution of work. The old suspender is currently being sent for ultimate strength testing as part of an ongoing asset management program for these world-class suspension bridge spans.

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