8:39am

Fri June 27, 2014
Transportation

Tighter curves could minimize impact of new I-81 viaduct

Tighter curves built into a new Interstate 81 through downtown Syracuse could mean fewer buildings along the highway’s path would need to be torn down.

Rebuilding the mile and a half of elevated interstate through the city is one of two options transportation planners are recommending for how to replace the current, aging viaduct.

But a new viaduct would have to be significantly wider than the current one in order to be up to highway standards. It could also be up to ten feet higher.

Mark Frechette, a project engineer with the state transportation department, says they would never build a viaduct as it is now.

Narrow lanes, no shoulders, short on-ramps all help make the I-81, I-690 interchange downtown one of the most risky places to drive in the state. It averages four times as many accidents.

"So that’s one of the things that we definitely want to try to fix, is to create some shoulders, make it so there aren’t accidents," Frechette said. "There are a lot of problems with the weaving lanes; there’s a lot of problems with the movement of traffic."

A new viaduct would be about 82 feet wide, compared to the 66 foot span it has now.

Frechette says the wider viaduct would require 30-40 buildings to be torn down to make way, but it would allow the speed limit to be increased to 55 miles per hour through downtown.

Frechette says tighter curves would limit the footprint of the wider viaduct. Two variations of the viaduct plan reduce the property impact up to 40 percent.

The options are part of plans transportation officials released this week as part of efforts to decide how the I-81 viaduct will be reconstructed. Public comments are being taken through Sept. 2.

The other option still being strongly considered by highway officials is the street-level boulevard, which would re-route I-81 to I-481 east of Syracuse.

The options that have been ruled out for a new Interstate 81 through Syracuse were also the most expensive and difficult to build.

Right now, Interstate 81 through downtown Syracuse travels 20 feet above the ground. Turns out, the opposite - putting it below ground - wouldn’t be a great option.

Two ideas being considered for a rebuilt I-81 were a tunnel or depressed highway.

The ground below the viaduct’s path is too wet, salty and full of city infrastructure, like water mains, Frechette said.

"We anticipate, to build these tunnels, it would take seven to eight years to actually build these tunnel alternatives, which is pretty significant," he said.

One of the tunnel ideas, an 81 foot deep, five mile tunnel, also carried a $3.3 billion price tag.

The new viaduct or street-level boulevard both carry $1 billion-plus price tage.

The elevated section of I-81 through Syracuse is aging and nearing the end of its lifespan.