The Newfoundland and Labrador’s Department of Transportation and Works (DTW) is hoping to put an end to premature road surface rutting on the province’s roads and highways with a novel approach to selecting the best asphalt.
The DTW will tender a contract this month or next for the placement of four to six different asphalt types over a several kilometre stretch of a "high-volume highway," says Joe Dunford, assistant deputy minister, transportation, DTW.
"We’re seeing after three or four years rutting on some of our roads and issues with longevity of the asphalt. We’re trying to get closer to solving that problem."
Dunford says the idea of the test to be conducted over a few years is "to identify the most appropriate mix of asphalt to use that will give us the greatest life cycle."
Four to six asphalt mixes will be on trial. Each may be placed up to about a kilometre of highway.
Asphalt possibilities could include performance grade 58-28 with a three per cent void on one section and one per cent void on another section. Other highway sections might have performance grade 64-34 asphalts with one per cent and three per cent voids.
Voids, says Dunford, act "almost like a sponge" that provides asphalt "flex" and the ability of the pavement topping to absorb water.
Each section will be identified with signage so that drivers will be aware of the asphalt types as they wear over their life cycle, he says.
"We are doing this in a very public and transparent manner because the public is very engaged with our roads. This gives us an opportunity to show we’re listening to them."
Dunford says while the trial might not show any notable pavement deterioration after the first winter, but the following two or three winters "we’ll have a good idea of which one is performing better."
The assistant deputy minister says "it is critical" that the trial be awarded to one contractor to ensure consistent placement practices. "We want to minimize the variables."
Jim Organ, executive director, Heavy Civil Association of Newfoundland and Labrador (HCANL), says the asphalt test by DTW is new to the province.
"They have tested pavement before but I don’t think I have ever seen them put down several separate mixes in a row by one contractor for the specific purpose of seeing the characteristics of the different mixes," says Organ.
The HCANL represents contractors and suppliers building roads and other infrastructure.
Dunford says the test will probably be done on the Trans-Canada Highway near St. John’s.
"We want to use one of our highest volume routes simply because you’ll see the wear sooner and get results faster."
While the cost of the project has yet to be determined, Dunford says the DTW hopes to see a cost savings by using the most durable asphalt for future contracts.
"If we can find a way to use an asphalt that improves the life cycle of our roads from eight years to 10 years for resurfacing, obviously there will be savings associated with those extra two years."
But Dunford says the main reason for doing the project is public safety.
Organ points out that premature rutting can damage vehicles and also create unsafe driving conditions. A case in point is when ruts become stream beds during heavy rain that can cause vehicles to hydroplane.
Organ says the DTW has provided the HCANL with several mixes and has asked the association to include one of its own asphalt mixes as well in the trial.
The performance tests "will be based on a 58-20 mix of some sort," says Organ.
"There will definitely be one, if not several, polymer type mixes along with what mix we may or may not put forward."
Dunford says the paving contract should be completed in the 2017 construction season that typically runs June to October.