As the Alabama Department of Transportation plans to start work on the long-awaited $3.5 billion Mobile River Bridge and Bayway project to replace an outdated and overused tunnel and bridge along I-10, key archeology work is being completed. (To read part 1 of this story, click here.)

[Above photo courtesy of the University of South Alabama Center for Archaeological Studies.]

While different generations of the project have been on the drawing board for nearly three decades, ALDOT had to yield the site to a team of archaeologists to preserve any significant historical resources of Mobile – a city founded in 1702 that once served as the capital of French Louisiana.

It’s a scene repeated across the country as state department of transportation engineers work side-by-side with archaeologists to preserve the history beneath us before major infrastructure is built.

“All [state] DOTs make every effort to avoid any area with historical sensitivity,” explained Tony Harris, chief of the ALDOT Media and Community Relations Bureau. “When you can’t do that, it’s important to identify the history in the area, explore it and preserve it to the greatest extent possible.”

Because of the significance of the area, ALDOT called on the University of South Alabama Center for Archaeological Studies to manage the exploration. The archaeology team eventually excavated 15 sites, uncovering geographic changes along the Mobile River, long-forgotten buildings, and tons of artifacts, some dating back more than 2,000 years.

“We’re hoping that this project not only gives us a picture of the past, but tells us, ‘How did that past inform the present?’” said Dr. Philip Carr, director of the center. “We’re looking explicitly at that, even at what that past may tell us about the future. Decisions that were made in the 19th century about land filling have a lot to do with why Mobile floods today.”

Erica Schneider – assistant environmental administrator for the Ohio Department of Transportation, who also serves as chair of the Cultural Resources Subcommittee within the Committee on Environment and Sustainability for the American Association of State Highway and Transportation Officials – added that state DOT archaeologists work closely with their states’ historical preservation office to avoid shutting down transportation projects.

“If we find out a project will have an adverse effect on a site, we’ll work to develop mitigation efforts,” she said. “A lot of times, we can do data recovery, so we can go in and excavate the site. There’s often a public education component, too.”

In Alabama, Dr. Carr’s team eventually uncovered more than 400,000 artifacts from the site, including old military cadet uniform buttons, a dinner plate from the French Colonial period, thousand-year-old pottery shards, and Quin Dynasty coins from China. The center has created a website for the public to see some of the treasures.

Dr. Carr also said he received “great cooperation” from ALDOT during the process.

“They have been proactive, they have made sure the resources we needed…fencing, silt fencing, access to the properties, anything, that gave us access to the resources so we could do it right.”

The construction project – the largest in Alabama history – will include a 215-foot cable-stayed bridge, which would be the second-tallest cable-stayed bridge in the country, after the Golden Gate Bridge. Crews also will build a new bayway bridge over Mobile Bay that will be 10 feet taller and carry double the traffic of the old bayway.

A design-build team has been identified, and construction should get underway in 2026. Even though the archaeological work may have kept some construction from being done sooner, Harris said preserving the history of an area is “much more than a requirement” of the environmental process.

Sometimes, as in the Mobile project, work can continue once the cultural resources have been identified, catalogued, and preserved. Occasionally, sites prove to be too significant to be disturbed, and the only option is a no-build option.

Schneider was part of an assessment team in 2015, when Ohio DOT was planning a large corridor project in southwestern Ohio. The project footprint included several Native American sites, including a village that pre-dates European contact.

“It is essentially a multi-component prehistoric habitation, which means people lived there on and off during multiple prehistoric periods over hundreds of years,” she said. “We also know, based on previous excavations by others, that there are burials related to those occupations in this area. Based on geophysical surveys we conducted, we suspected the potential for hundreds of burials in our project area, alone.”

The archaeological finding was a big reason Ohio DOT chose the no-build option. The department later developed smaller, more targeted projects in the region, a decision that wound up serving the transportation needs of the region while respecting the history of the land.

“I think it’s important that we understand or try to understand the history of the people who came before us,” said Schneider, “I think we have an obligation to make that available to the public, to the masses. It’s like any other finite resource. When it’s gone, it’s gone.”

Dr. Carr said he was especially proud that his archaeological team was able to accomplish so much in less than two years of excavation.

“Not slowing down construction – that’s a point of pride for me,” he said. “I’m a Mobilian, and we need a new bridge. I didn’t want to slow it down.”

Before a construction crew can build a road, a transportation archaeologist often must reconstruct the history of the ground it’s being built upon. This is the first of a two-part series that digs into that process.

[Above photo courtesy of the University of South Alabama Center for Archaeological Studies.]

The National Historic Preservation Act of 1966 mandates that states must consider a federally funded transportation project’s effects on any site that is listed or may be eligible for listing on the National Register of Historic Places. Usually, the only way to find out if a site is eligible is through an environmental assessment, which includes a survey of cultural resources.

“We first do a literature review and check the historic preservation office – all states have a historic preservation office,” said Erica Schneider, assistant environmental administrator for the Ohio Department of Transportation. “We’ll go out and do an archaeological survey of the area – that’s called identification. If we find sites, we have to determine if they’re eligible and if they’re significant, and what effect the project would have on the site.”

While this process has been characterized by some as a speed bump to faster project delivery, many of the United States’ artifacts and history would have remained buried if not for state department of transportation archaeologists.

[Editor’s note: Many state DOTs seek to engage the public more deeply in their archeological work. For example, in November 2025, the Georgia Department of Transportation and the Forest Grove Preserve hosted a “Public Archaeology Day” at the historic Harper House in Sandersville, GA, to offer new insights into the daily lives of people who lived and worked in rural Georgia over the past 150 years.]

“There’s a huge value in this, giving us a bigger, broader picture of what’s out there,” explained Schneider, who also serves as chair of the Cultural Resources Subcommittee within the Committee on Environment and Sustainability for the American Association of State Highway and Transportation Officials.

“I think transportation archaeology contributes – and continues to contribute – to archaeology as a whole,” she said.

A few examples of the notable intersections between transportation and archaeology include:

· In 1974, work halted on a planned expansion of U.S. 49 in Mississippi when a midden – an ancient refuse pile – was discovered. Further investigation revealed the pile may date back 6,000 years. Today, the site is known as the Pocohontas Mounds and bears a historical marker erected by the Mississippi Department of Transportation.

· In 2007, 16,000 artifacts from a 19th-century-era homestead were discovered in the path of highway project in Maryland. The findings revealed that the inhabitants of the homestead called on West African spirits to protect their home.

· In 2021, an archaeological dig at an interstate project in Idaho revealed evidence of Kootenai Indian tribal activity thousands of years earlier than first thought. The findings earned the Idaho Transportation Department the 2024 AASHTO President’s Transportation Award for Equity.

· From 2021 to 2023, archaeologists excavated 15 sites at the planned location of the I-10 Mobile River Bridge and Bayway Project in Alabama. The findings tell the story of Mobile from its days under French, Spanish, and British control in the 18th century to Native American communities from 2,000 years ago.

Transportation engineers’ jobs are to plan, build and maintain roads and bridges, and archaeologists’ jobs are to ensure history is not paved over. Occasionally but inevitably, there is a rub between them.

Schneider said conflicts are more likely to occur when state DOTs “are still siloed” but most agencies now encourage divisions to work together as one team.

“One of the things I’ve learned is the importance of communication and working with people in those other worlds, the engineers and the planners, and to communication with them early on,” Schneider said. “We can come in and say, ‘Maybe we can tweak the road just a bit.’ It can be a real challenge, but I think it’s probably gotten better over the years.”

In Mobile, the need for the bridge project was undeniable. The existing tunnel beneath the Mobile River and the adjacent bridge that crosses Mobile Bay were carrying three times the designed traffic capacity of the structures.

But false starts and intermittent opposition kept the project in various stages of planning for nearly 30 years. After Hurricane Katrina in 2005, new Federal Highway Administration guidelines meant the Alabama Department of Transportation would have to raise and replace the 7.5-mile bay bridge instead of simply adding lanes, adding even more costs until the project’s price tag seemed to settle at $3.5 billion.

Then, there was the history.

ALDOT knew the project site was in a culturally significant part of Mobile, the oldest permanent settlement in French Colonial Louisiana. Fort Conde, built by French explorers in 1723, “is a stone’s throw from the mouth of the tunnel,” ALDOT Media and Community Relations Bureau Chief Tony Harris said.

“I think there was every expectation that we’d find something,” Harris said.

The bridge project site temporarily turned into a major archaeological site that eventually would yield surprising insights into Mobile’s history.

In part two of this story, to be published next week, ALDOT details how its work on the I-10 Mobile River Bridge and Bayway Project unearthed interesting history about the region.