MARLBOROUGH — State Department of Transportation officials celebrated the completion of a “micro-resurfacing” of a stretch of Route 12 Friday morning and took the opportunity to talk up the repaving technique that should save the department millions in road reconstruction costs.

The “micro-surfacing” pavement on 4½ miles of Route 12 in Swanzey, Troy and Marlborough costs far less than a full reconstruction of the roadway and has a smaller environmental impact, said Eric Thibodeau, DOT pavement management chief.

The same stretch of road was rebuilt in 2002 for $3.9 million, Thibodeau said.

Historically, the department would reconstruct a road every 25 years. Instead of waiting for the quarter century mark, the department returned to the stretch of Route 12 this summer to repave it with a mixture of asphalt, water and cement for $298,000.

The plan is to keep this “good” road in good condition and avoid any future reconstruction.

“As our dollars are stretched and our budgets are taxed we really have to look at pavement preservation as a way of keeping good roads good. So it frees up money to work on the fair to poor roads. … Keeping good roads good is cost effective. It's analogous to doing preventative maintenance to your car,” Thibodeau said. “These preservation projects emit less greenhouse gas and use less nature materials so we really have to look at it from that perspective as well.”

DOT Commissioner Chris Clement said once the Interstate 93 Concord/Bow reconstruction project is completed in 2016 or 2017, the department plans to focus on preventative maintenance and keeping track of current assets.

The state has $3.7 billion in road infrastructure, but is only reinvesting 1.5 percent of that each year, he said.

Using the micro-surfacing technique on good roads frees up resources for reconstruction needed on the 16,000 miles of poor roads in the state, he said.

DOT has used the technique on 10 projects since 2006. Micro-surfacing was invented in Germany in the 1960s, but has only been used in the United States since 1980.

Bill Boynton, DOT spokesman, said of the technique, “It's much cheaper. And yet ... people see what they think is a fairly good road” being repaved, “and what you are doing is trying to preserve the life of the road.

Alan Rawson, the department's head of materials and resource bureau, said “The big question is, 'Why are you out there resurfacing a good road?' It's that preservation aspect that people don't understand. … Our goal is perpetual repavement.”

Thibodeau added that if the department only focused on poor roads it would fall behind. “It's just a losing battle trying to fix worst roads first.”

Boynton said, “This is an important new direction that the New Hampshire DOT has been heading in as well as the DOTs across the country in order to better effectively use constrained budgets and to preserve the life of pavements.”

“Once the roads fail, now you have a very expensive project. So the key in our road management program is to try to keep our higher-volume roads in as good condition as possible so that they don't slip to that point of failure.”

mpierce@newstote.com