Mobile Bayway

MOBILE, Ala. (WALA) – The Alabama Department of Transportation argued Monday that a higher Bayway is necessary for a variety of design and legal reasons.

Some state lawmakers have raised concerns about plans to expand and elevate the Bayway because of cost. Removing the existing Bayway and building the new one at the higher elevation adds about $350 million, or roughly 17 percent of the total $2.1 billion price tag.

ALDOT Director John Cooper has given different explanations over the past two months, fueling opposition to the state’s plan to finance the $2.1 billion project through tolls up to $6 each way.

In a detailed statement, ALDOT sought to eliminate ambiguity over the issue.

“Many factors went into the decision to replace the Bayway with a higher structure as opposed to widening it,” the agency states. “Those factors include storm surge analysis, federal regulations, ALDOT design standards, and cost.”

Under the plan conceived by the state, a six-lane bridge reaching a height of 215-feet would carry traffic over the Mobile River. In addition to a higher elevation, the Bayway also would be widened to eight lanes. And the plan calls for improvements to seven interchanges on Interstate 10.

ALDOT cites four separate regulations to support its plan to elevate the Bayway:

  • 23 CFR 650.115, which states that the design shall be “supported by analyses of design alternatives with consideration given to capital costs and risks, and to other economic, engineering, social and environmental concerns.”
  • 23 CFG 650.115(a)(2), which states that the design for interstate highways “shall not be less than the flood with a 2-percent chance of being exceeded in any given year.”
  • 23 CFR 650(a)(3), which states that the clearance between the lowest part of a bridge and the top of the flood water “shall be provided, where practicable, to protect bridge structures from debris- and scour-related failure.”
  • 23 CFR 650.111, which states that National Flood Insurance Program maps, when available, “shall be used to determine whether a highway location alternative will include an encroachment” on the flood-plain.

ALDOT also pointed to a 2014 order by the Federal Highway Administration requiring the agency to align policies to the threat of climate change.

“Proactive management involves developing engineering solutions, operations and maintenance strategies, asset management plans, and transportation programs that address risk and promote resilience at both the project and systems levels,” that order states.

A 2017 memo by the agency also recommended state metropolitan planning organizations consult with agencies and officials responsible for reducing the risk of natural disasters.

What’s more, ALDOT cited a pair of manuals published by the Federal Highway Administration to be used when designing projects to comply with federal regulations.

One manual published in 2008 requires engineers to evaluate the risk that bridges in coastal areas will be impacted by storm surge and to design alternatives. A manual published in 2016 requires engineers to consider climate change and sea level rise in designing bridges that are resilient to extreme weather.

ALDOT also pointed to guidelines developed in 2008 by the American Association of State Highway and Transportation Officials. Although that is a private organization whose recommendations are not binding, ALDOT notes that the Federal Highway Administration requires states to consider those guidelines, developed in the wake of damage caused by Hurricanes Ivan, Rita and Katrina more than a decade ago.

“Wherever practical, the vertical clearance of highway bridges should be sufficient to provide at least 1 foot of clearance over the 100-year design wave crest elevation, which includes the design storm water elevation,” the AASHTO manual states.

ALDOT reiterated prior analysis that most of the existing Bayway is below the 100-year wave crest elevation and that a 100-year storm even would “catastrophically damage major portions of the existing I-10 Bayway structure beyond repair.”

ALDOT places the odds at 64 percent that a storm would impact the existing Bayway during the 55-year period covering Alabama’s contract with a private investor group that would be selected to build and manage the new bridge.

ALDOT officials said they also have explored strengthening the current Bayway as part of a widening project. That would cost $1.032 billion and it would have to be replaced in 20 years at a cost of $890 million because it will reach the end of its design life in 2037, according to ALDOT.

“To comply with Federal regulations, ALDOT determined replacing the Bayway above the 100year storm surge elevation is in the best interest for the safety of traveling public and is the most cost-effective solution,” ALDOT stated.

All content © 2019, WALA; Mobile, AL. (A Meredith Corporation Station). All Rights Reserved.

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