Tunnels under Atlanta would be smog generators

It's alarming enough that state officials are taking seriously a fanciful proposal to ease metro Atlanta's transport woes by digging a network of double-decker tunnels under the city.

The tunnels would be pricey ($25 billion is an optimistic guess). By treating the city as a donut hole to be driven under, they'd egg on sprawl and possibly air pollution. And because the scheme is unlikely to qualify for federal funds, Georgians would be stuck with taxes and tolls for the entire bill for a whole lot of drilling.

At least, you gotta figure, the tunnels would give Atlanta's neighborhoods some dignity and stay out of sight. You'd be wrong, though. To a surprising extent, the scheme would dot Atlanta's landscape with big, ugly structures meant to pull pollution from the tunnels into the air over Atlanta.

No technical analysis has been conducted for the scheme, which was whimsically proposed by the California-based, libertarian-leaning Reason Foundation. And now, David Doss, chairman of the state Transportation Board Public-Private Initiatives Committee, has started to push the idea as though it were a well-vetted policy proposal.

But no technical analysis needs to be done to understand why Atlanta's neighborhoods should be concerned.

Robert Poole, director of transportation studies for the Reason Foundation, told the Legislature's House Transportation Committee that the tunnels would "avoid any interference with the neighborhoods and land uses" and have "no impact on traffic in any of those neighborhoods." At that meeting, he failed to mention there would be structures to ventilate emissions from the tunnel, but acknowledged in an interview with CL that "there would definitely have to be a ventilation system."

Boston's now-infamous Big Dig, the most expensive municipal public-works project in U.S. history, includes a ventilation system, stretched along nearly eight miles of tunnels. One hundred forty fans work constantly to transfer pollution in the tunnel to the air above Boston, via seven buildings that are up to 280 feet tall and can take up enough space to fill a city block.

In Paris, the A86 West tunnel, which Reason used as the model for its Atlanta ideas, relies on four emissions buildings above 6.25 miles of underground highway.

The three Atlanta double-decker tunnels would run for around 28 miles, much of it under some of the city's most desirable neighborhoods, including Morningside, Virginia-Highland, Edgewood, East Atlanta, Ormewood Park, Midtown and Summerhill.

Without a technical analysis, it's hard to say exactly how many emissions buildings would be needed in Atlanta. The structures could be supplemented with jet fans attached to the ceiling. The tunnels in Boston and Paris both use a combination of the two methods. In both cases, the jet fans save on the need for emissions buildings, but don't eliminate the need.

If the emissions buildings followed the patterns in Paris and Boston, the Atlanta tunnels could require around 21 of the structures.

Despite such questions about the tunnels, Doss seems sure the scheme's dandy. He wouldn't talk to CL about it. But he included a variant on his list of "Big Ideas" for Georgia transportation. According to a WSB-TV report, he's calling for a fair amount of highway infrastructure above ground, including an interchange in Poncey-Highland and a new highway to run aboveground between Little Five Points and I-20.

However pie-in-the-sky the tunnels may seem to some, the idea is rumbling along through Georgia policy-making circles. Doss' Public-Private Initiatives Committee drafted a resolution seeking proposals from private companies willing to build a "comprehensive transportation system," which many view as a first step toward a road-dominated plan that includes tunnels. The full Transportation Board approved that resolution in August.

Freelance writer Joe Winter holds a degree in urban studies and is a board member of Citizens for Progressive Transit.