DOT's director says the estimated costs of the boulevard approach appear to be about the same as replacing the seven bridges in the 6-10 Connector corridor.

PROVIDENCE — State transportation officials said Wednesday they are considering a radical redesign of the Routes 6-10 interchange that would entomb Route 10 in concrete walls with a roof covered in dirt over the roadway to create a park-like median from Route 6 to Broadway.

State Department of Transportation Director Peter Alviti Jr. said the boulevard-style redesign is the agency’s preferred approach to replacing seven bridges in the connector corridor, but he cautioned it wasn’t guaranteed until DOT’s engineers refined the numbers, probably next month.

The state intends to spend about $400 million of its own money plus $400 million more in hoped-for federal transportation grants to replace bridges and make other improvements to the aging interchange. Alviti said DOT’s engineers advised him that, so far, the estimates for the cost of the boulevard approach appear to be about the same as replacing the bridges.

The idea, which DOT officials said could expand or contract as the planning process unfolds, would provide enough road room for traffic while doing it in a way that addresses concerns that city officials, transit advocates and neighborhood groups have raised.

“This is not where the old DOT would take you,” Alviti said. “This is where the new DOT wants to take transportation in this state.”

At a public meeting to discuss the plan Wednesday night, Mayor Jorge O. Elorza called this is a chance to remold the artery and revitalize its neighborhoods at the same time. Well over a hundred people attended the meeting.

"Now is the opportunity to be creative and innovative," he said.

City's Planning Director Bonnie Nickerson said the city was encouraged by DOT’s preliminary design.

"We think it's a great starting point," she said.

When it was built in the first burst of national highway construction in the 1950s, the 6-10 Connector was intended as a bypass for Olneyville, but over the last 30 years Alviti said traffic volumes have increased and the conditions of its bridges have deteriorated to where they must be replaced.

The advantage of burying Route 10 is that it would create level ground over the highway, eliminating the need for overpasses. The tunnel would accommodate existing traffic lanes plus two lanes for buses. The plan also includes a bike path on the west side of Route 10 that could connect with the Woonasquatucket Bike Path.

Elevated ramps and overpasses, with their tall support columns, are extremely expensive, Alviti said. The boulevard approach will eliminate the need for several of them, replacing overpasses with what will be cheaper roads on the new flat ground covering the entombed Route 10. That savings would pay for the boulevard.

The plan DOT unveiled Wednesday has the Route 10 enclosure going about a quarter mile, just past Broadway, but Alviti said it is designed so that it can be extended as far as the north end of Route 10, with its ramps to Route 95 north and south.

Besides bridges in the immediate area, the project also calls for conventional replacement of the overpasses that carry Plainfield Street and Hartford Avenue over Route 6. But DOT spokesman Charles St. Martin said DOT planners weren’t ruling out the possibility that a boulevard style design could extend to them as well.

Besides replacing the bridges, the state wants to add a jug-handle lane on the median to give northbound Route 10 drivers a direct way to get to Route 6 west.

You can’t get there from Route 10 now. Drivers must go through Olneyville, over Westminster or down Tobey Street in search of a Route 6 on-ramp. St. Martin said the agency estimates that a Route 10 north-Route 6 west ramp would draw about 4,750 trips a day off those local sidestreets.

The interchange of Route 6, which comes in from Johnston and a connection with Route 295 in the west, and Route 10, a major north-south way in and out of the city, is a major part of the state’s transportation infrastructure. Combined, the two routes handle more than a quarter-million car trips per working day.

Plans are to build the project so that it can handle two bus-only lanes on Route 10. That effort would be financed by other federal money, Alviti said. The plan calls for a small bus terminal to be built on the new median to provide access to Olneyville, the West End and Federal Hill.

Pabel Fernandez, a landscape architecture student at the University of Rhode Island and a resident of Olneyville, liked the drawings that DOT had released, which reminded him of somewhat similar projects undertaken in the city of Boston.

"Anything green in this area is an improvement," he said.

Journal Staff Writer Mark Reynolds contributed to this report.