Strength in numbers: Steel girders placed for I-17 bridge project

Strength in numbers: Steel girders placed for I-17 bridge project

By Doug Nintzel / ADOT Communications
November 12, 2020

I-17 and Central Avenue Girder Placement 103120

It is an operation that requires planning, steady hands and a focus on safety. Oh, and let’s throw in another word: measuring. We’re talking about the recent placement of more than 20 steel girders at Interstate 17 and Central Avenue in Phoenix, where the first half of ADOT’s reconstruction of the old freeway bridge continues to advance.

As you can see in our accompanying group of ADOT photos, these are large and heavy girders. Project crews worked earlier in November to lift them into place with cranes, followed by the important work to safely secure them with bracing.

To be a bit more descriptive, these are Continuous Welded Steel Plate Girders. Each of them is 80 to 88 feet long and each tops the scales at between 12 and 15 tons.

For this part of the I-17 bridge project at Central Avenue south of downtown, three girder sections were placed end-to-end in seven rows, also known as girder lines. They will provide the support for what will be the southbound lanes of the freeway when all is said and done in 2021.

These girders are now secured with steel plates that are installed every 16 feet between the side-by-side girder lines. And before you bolt from reading this, give some thought to how many bolts are used in this whole process. Don’t go “nuts” when you learn the answer is more than 6,500 bolts for the entire new structure. It’s all about strength, security and safety.

The focus of this $13.5 million project so far has been on rebuilding the southbound side of the bridge over Central Avenue. The original I-17 bridge was opened to traffic in 1962. Working in phases, crews earlier this year demolished the old southbound structure to make room for the area where these new girders are now located. Freeway traffic is currently shifted and thus temporarily sharing the existing northbound side of the bridge.

ADOT’s project team plans to complete the modernized southbound side of the bridge early next year. That’s when all I-17 traffic in the area will be shifted to the new structure so that reconstruction of the northbound side can move ahead. 

That second major phase in 2021 will include placing an additional 27 of these big girders to provide a wider bridge that will be able to accommodate more lanes along I-17 when future funding is available. So there’s still lots of heavy lifting ahead at I-17 and Central Avenue. 

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