February 26, 2010

GRAHAM BROS.

A perfect paving job starts long before the hot mix arrives, a panel of experts told an Ontario Hot Mix Producers Association seminar recently.

FEATURE | Roadbuilding

Build better roads starting from bottom up

IAN HARVEY

correspondent

Apparently thicker is better — at least when it comes to paving roads — according to an MTO expert. The critical thing is good design, Chris Raymond, acting head of the Ministry of Transportation Ontario bituminous section recently told an industry audience.

“If you can’t afford a good design, I tell agencies and municipalities, you can’t afford to waste your money on a poor design — you’ll just be throwing your money away,”

A strong advocate of the MTO’s Superpave standard, Raymond also said lift is important and urged opting for more thickness to ensure better roads and longevity.

“Unfortunately, costs drive agencies to go for minimum thickness,” he said, “Pavement wears from the top but falls apart from the bottom.”

With limited dollars and a growing number of kilometres to pave, owners cut back but will pay for it in the long run because those installations will fail long before they should and start to pothole and crack.

“A higher lift, say going from 40 mm to 50 mm, isn’t a 25 per cent increase in cost because while you are using more asphalt cement and materials your equipment and labour costs are the same,” Sandy Brown, technical director of the Ontario Hot Mix Producers Association told a seminar during an association convention.

IAN HARVEY

The optimum lift depends on the type of traffic the road faces.

Brown said the optimum lift depends on the type of traffic the road faces and accordingly which aggregate has been specified. Thinner lifts stretch the asphalt and budget further, but add to later maintenance and rehabilitation costs.

“Most of the problems we find in forensic engineering analysis is that something simple was done wrong in the beginning of the process,” said Dale Decker, president of Dale S Decker LLC, a U.S. expert consultant who outlined five steps to better pavement.

In the end, it comes down to best practices, said Decker, whose recommended steps start with a design that addresses quality and function required of the road, specifications that clearly define the work, inspection to ensure proper construction according to the design, construction combing technology, workmanship and maintenance.

He said road designers must for consistently look to state-of-the-art design standards — not just what’s always been used before.

“Perpetual pavements, for example, have been used around the world for years and we’re just getting to use them in the U.S.”

Making sure the job is being done correctly is also critical.

“Who are the inspectors? Are they certified? We’re they working as a Wal-Mart greeter yesterday and working as a road inspector today?”

There’s a continuing shift by owners to an “end result contract” in which the contractor is given free reign to determine the construction of the road as long as it meets specifications.

But contractors must shoulder more responsibility and partner with owners to realize value engineering rather than take the old adversarial stance, he added.

He said the last step is the one which fails more often.

“Maintenance and rehabilitation is my major pet peeve,” he says. “We built one of the top 10 transportation systems in the world, but now three-quarters of our bridges are structurally unsound and our highways are in the same situation because we didn’t maintain the system.”

Vince Aurilo, manager of pavement engineering services at DBA Engineering, who also spoke on the specification and inspection process at the seminar, said partnerships between owner and contractors will be increasingly important.

Reducing variations from specification in aggregate mix, careful inspection and sampling, using the right equipment in the right way with trained, skilled workers is the surest way to meet the standards and get smooth, long-lasting pavement, he said.

“Stopping and starting the paver or bumping the screed because you are not using a shuttle buggy, for example, leads to bumps and affects the thickness. We’re going for smooth because smooth lasts longer.”

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