Five years later, a look back at the US 231 landslide in Morgan County and repairing the bridges

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March 13, 2025

US231_01272021_02-1024x462 — The U.S. 231 bridges opened to the public in September 2020. (ALDOT contributed)

Amidst the trees, a bare mountainside, where a landslide has been excavated. Bridges are under construction. The photo is an aerial view looking south, up the mountain.

LACEY’S SPRING — Five years ago this week, officials with the Alabama Department of Transportation met with concerned residents from several north Alabama counties to unveil an ambitious plan to repair U.S. 231 after a landslide destroyed parts of the highway in Morgan County.

One month earlier, heavy rain triggered the slide on Brindley Mountain, opening large cracks in the pavement as material shifted below. ALDOT shut down the bifurcated northbound and southbound roadways about five miles south of Huntsville.

The highway carried about 15,000 vehicles daily. Those motorists diverted to a roughly 15-mile passenger detour via Union Hill Road. The commercial detour, comprised of only state routes, was more than twice as long.

A cracked runs through a roadway, displacing the pavement. — A large crack that significantly displaced the pavement, rendering the southbound US-231 roadway impassable. Image courtesy of David Cooper, EQB View.

Exploring the mountain, exploring options

During the next few weeks, contractors removed pavement and began preliminary excavation of the slide area. ALDOT secured the assistance of geotechnical consultants Dan Brown and Associates. Drill crews and geotech engineers probed the mountainside for answers. ALDOT explored several potential solutions.

“So much went into investigating the problem and identifying the best way to fix it — not just any repair, but a stable and timely one, but that wasn’t visible,” said North Region Engineer Curtis Vincent. “Understandably, motorists who had been coping with the detour were growing anxious. They wondered not only how we would fix it, but how many years they would have to endure that commute.”

A large crack running along the shoulder of a highway., — One of many cracks that formed in U.S. 231 in February 2020 after heavy rains led to a landslide.

Answers for the public

Before a packed auditorium at Arab High School, Vincent and Transportation Director John Cooper laid out the plan.

ALDOT proposed constructing twin bridges, one for each roadway, spanning the slide area, which would be deeply excavated to reduce the overburden on the slide. The 1,000-foot bridges would be anchored by drilled shafts keyed into the mountain rock below the slip plane to hold the structures fast against continued movement of the slide.

At the time, they estimated the road would reopen about one year from the start of construction.

Against the clock

“A monumental task confronted us,” Vincent said. “But I believed that if we remained determined, we could accomplish it in a much shorter timeframe than initially thought.”

Gov. Kay Ivey’s proclamation of a state of emergency due to February flood damage helped accelerate the project toward construction. Engineers designed the bridge plans for an emergency project letting. Meanwhile, Reed Contracting continued to prepare the site, excavating about 200,000 cubic yards of loose soil and rock.

Reed Contracting deployed many machines to excavate the landslide.

ALDOT also found ways to shrink the anticipated construction timetable. They shaved months by ordering $4.2 million in custom-fabricated materials in advance to reduce the time for materials procurement later. With the plans ready in April, ALDOT placed a six-month deadline on the project and attached up to $2.5 million in incentives for early completion.

In May, ALDOT opened bids and the same day awarded the $14.6-million contract to Brasfield & Gorrie of Birmingham. The winning bid undershot the next lowest bid by $5.7 million. Reed concluded the site preparation just days later, and Brasfield & Gorrie began work June 1.

Workers surround a drill that is drilling into the ground — The drilled shafts that form the bridge foundation are each more than 9 feet in diameter.

Beating the clock

Working around-the-clock seven days a week, the contractor installed most of the 32 drilled shafts by late July. Each drilled shaft is 9½-foot diameter, contains steel reinforcing pipe, and between each pair of shafts is a grade beam, or ground-level strut. Having constructed about half the columns and caps — the above-ground substructure atop the foundations — they also began setting girders, the long horizontal beams that would eventually support the bridge deck.

Equipment moves girders -- long, horizontal bridge beams -- into place — A total of 84 prestressed concrete girders were installed on the bridges.

As summer ended and restrictions brought on by the COVID-19 pandemic eased, and more vehicles returned to the roads. The congestion that made the detour difficult for motorists during the first month of the closure threatened to intensify again.

But the bridge construction reached a timely conclusion. Brasfield & Gorrie built both bridges in less than four months — far ahead of the Dec. 2 deadline. The roadway reopened to the public in late September, providing relief for thousands of motorists.

In all, the repair cost $27.5 million.

“Condensing planning and construction to a matter of months certainly increased the cost,” Vincent said. “But if we put a number on the time and trouble it saved motorists, I think we came out ahead.”