The first aspects of construction on the new roundabout near Exit 16 will begin next week and continue in various forms until mid-October.
The contractor will begin by clearing the site and doing drainage work, said GMI Asphalt representative Randy Freeman at the 11th and final public hearing on the project Tuesday.
At the end of May, GMI Asphalt will step aside while several utility companies move their assets around the four-way intersection in preparation for the new design.
Then the contractor will return again at the beginning of August to begin the heavy construction, which at certain times will require a reduction to alternating one-lane traffic, Freeman said.
“Hopefully (we’ll) get out of here middle of October is the plan,” Freeman said.
City Engineer Ed Roberge said the city will use message boards to direct traffic patterns during the redesign of the intersection of Mountain Road, Shawmut Street and East Side Drive.
“We’re going to be moving traffic around quite a bit and quite often, so those message boards will kind of give you some guidance” to slow down and take note of the current lane configuration, he said, adding, “It’s not going to happen on an hourly basis, but it certainly will happen on a weekly basis.”
The utility lines were originally planned to be moved last year, but the crews were tied up working on the Main Street Project. Originally estimated to take about 12 weeks, the project is now set to take more than twice that time.
Roberge and City Manager Tom Aspell fielded questions about the project for 45 minutes from roughly 50 attendees in the cafeteria of Broken Ground School.
Several residents voiced concerns that landscaping would be planted and then left for them to maintain. Aspell asked whether it would be better to reduce the landscaping, noting that city staff wouldn’t regularly maintain it.
“I can cut back on this project, save all you taxpayers a whole lot of money, if we reduce these trees, eliminate the landscaping, if that’s what folks want,” he said. “I heard that two or three times here now.”
But ultimately there wasn’t much support for that idea. Roberge noted that the trees were chosen to be low-maintenance and that the East Concord Garden Club and other residents nearby signaled they would step in.
The roundabout was designed large enough that tractor-trailer trucks could navigate through, but also with the purpose to maintain the village feel with cobblestones and lighting similar to that in Penacook’s center.
Roberge said it’s designed for vehicles to travel 12 to 15 mph through it. The center will be planted with trees that intentionally obscure the line of sight through the roundabout to keep drivers focused on their left when entering the circle and their right while inside.
There’s no need to see straight through, Roberge said, and the trees will help drivers to realize they can’t drive straight ahead.
The gas station on the intersection will maintain two curb cuts, although the northernmost one will be exit-only and empty into the roundabout.
Roberge said there will be flaggers on the site when necessary to help direct traffic, including to get people in and out of side streets and the gas station.
He said the contractor will pay special attention to mitigating traffic during peak hours between 7 and 8 a.m. and 3 and 5 p.m.
“The rest of the day is manageable,” Roberge said. “I’m not going to say if there was one-lane alternating traffic it’s not going to back up, because it probably will. They’ve got a flagger team that will be working the intersection.”
In the end, the roundabout is supposed to calm traffic through the area and reduce the possibilities for conflict.
“There’s so many areas where something can go wrong,” he said. “The roundabout significantly reduces that from, say, 32 points of conflict in a standard intersection to eight.”
(Nick Reid can be reached at 369-3325, nreid@cmonitor.com or on Twitter at @NickBReid.)