Lafayette city-parish planners have proposed a major design change for the Interstate 49 Connector, floating the idea of elevating the interstate as it skirts downtown and scrapping plans for two downtown interchanges.

The potential changes address key complaints that a preliminary design by the state Department of Transportation and Development might not be a good fit for downtown and the surrounding neighborhoods.

“For us, we just kind of said, ‘Let’s look at this in a different way,’ ” said city-parish planner Neil LeBouef, who helped introduce the proposal last week to DOTD committees guiding the design of the new interstate.

The proposal, which aims in part to keep the six-lane interstate from dividing the city and fouling local traffic patterns, has quickly gained traction but has yet to be carefully scrutinized by engineers for feasibility.

“There are a lot of rough edges, a lot of things that need to be worked through,” said city-parish Planning, Zoning and Development Director Carlee Alm-LaBar.

The I-49 Connector is the roughly 5.5 miles of planned interstate through Lafayette, part of a larger project to extend I-49 from Interstate 10 to New Orleans.

Estimated to cost at least $700 million, the connector is among the most expensive and complex sections of the route, and DOTD last year launched an outreach effort seeking public comment on how to design the stretch through Lafayette.

The effort met early complaints that DOTD was clinging to a preliminary design for the connector and not open to any significant changes, and earlier this year, the state agency announced an extension of the public comment period to consider new ideas.

City-parish planners and others worried a planned downtown interchange for I-49 at Second and Third streets might send traffic speeding through the Congress Street corridor, an area now being studied for a makeover as a slower route more friendly for walkers, bicyclists and developers.

DOTD’s preliminary design also brought the height of the interstate down to near ground level between the interchange for Second and Third streets and the nearby Johnson Street interchange, creating a possible barrier for pedestrians and not allowing space for the parks and other features proposed for under and around the interstate.

The alternative design unveiled by city-parish planners last week addresses both issues.

The interchange at Second and Third streets would be scrapped, as well as the Johnston Street interchange, and the interstate would be elevated where it skirts downtown.

City-parish planners say removing the large interchanges and raising the interstate near downtown will make it easier for local traffic, pedestrians and bicyclists to move between downtown and areas on the other side of the six-lane interstate and could leave more land open for new development.

“I think it’s great. It addresses several of our concerns,” said Downtown Development Authority CEO Nathan Norris. “It substantially improves the quality of the connectivity between downtown and neighborhoods to the east.”

The plan offered by city-parish officials also envisions redeveloping the Evangeline Thruway near downtown with street parking and wide sidewalks as part of a plan to revive the area.

The planned connector generally follows the path of Evangeline Thruway through Lafayette, but the interstate would veer westward, away from the thruway near downtown.

“All of a sudden, it gives a great purpose and functionality to Evangeline Thruway,” Norris said.

Still undetermined is how drivers coming and going from the downtown area would get on I-49.

City-parish planners have proposed using slip ramps, possibly accessed near Pinhook Road south of downtown and Willow Street to the north.

Slip ramps are generally one-way on and off ramps that mesh into the existing local street pattern, as opposed to the full-blown interchange spread out over several acres.

City-parish traffic engineer Warren Abadie said much work is needed in the coming months to vet the alternative design for the connector, including studies to determine how the changes would affect the ability of the road to move heavy traffic and how on-off ramps would tie-in to the downtown area.

“We feel it has a lot of promise, but right now, it’s just an idea,” Abadie said.