Girders installed for Alabama Highway 75 bridge in DeKalb County

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August 16, 2024

SR-75-girder-seetting-01-2048x1536 — Workers fasten a center section of bridge girder. The old bridge, constructed in 1942, is in the background. (ALDOT Photo)

LAKEVIEW — Cranes hoisted the final girder for the new SR-75 bridge at Lakeview into place Monday morning.

The girders – huge steel beams – will support the future bridge deck spanning Town Creek in DeKalb County, east of the Marshall County line.

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A girder is suspended from a crane sitting next to the bridge. The girder is topped with a U.S. flag. Workers are on top of the girder and on scaffolding hanging from the sides. — The final girder was raised into place Monday morning.

Bigger and better

The $13.7 million bridge will be substantially longer, taller and wider than the old bridge built in 1942. Whereas the 82-year-old bridge is 280 feet long, 29 feet wide, and stands 54 feet above the creek, the new bridge will be 715 feet long, 38.5 feet wide and stand 75 feet above the creek.

The design corrects steep vertical curves on both bridge approaches.

New bridge under construction with three cranes. — The taller bridge and new alignment will significantly reduce vertical curves. The highway’s descent to the old bridge is visible in the background.

Setting girders

During the last two months, contractors installed 32 girders, individually weighing up to 44 tons. Cranes raised each girder into position. Then workers secured it to adjoining girders. Each splice required about 660 bolts.

Workers in safety gear reach out to align a suspended beam. — Workers on the flanges of a girder guide the next beam into position.

Workers in safety gear work from scaffolding hanging from a bridge girder. — Each splice between girder sections is held together by about 660 bolts.

Now begins the tedious, weekslong task of tightening roughly 23,000 bolts to a specified tension.

Following that, contractors will construct the bridge deck and rails and segments of roadway approaching the bridge, before demolishing the old bridge.

Smaller beams installed at intervals between the girders. — Cross braces are installed between the girders.

Few traffic impacts

Because the replacement bridge is being constructed on a new alignment parallel to the old bridge, the old bridge remains open to traffic during construction. Most work items should have little impact on traffic.

ALDOT anticipates completion of the project in about a year.