Roundabout solution

by Carroll McCormick

TRURO, N.S. — After some oversize load drivers found that they could not get through a nearly-finished roundabout just off the Trans-Canada’s Exit 12 between Truro and Amherst this June, a productive meeting with representatives from the Department of Transportation and Infrastructure Renewal (TIR) resulted in a simple solution.

“It is excellent that they came forward and that we could react. In this case, we were not made aware of these vehicles. We had the solution, we just had to know where to apply it,” says Keith Boddy, senior highway design engineer with TIR.

The roundabout, the province’s 32nd, is at the junction of the old Trunk 4 and a connector crossing the Trans-Canada. It was installed to slow Trunk 4 traffic to safer speeds and reduce the risk of high-speed collisions. The intersection is near the Double C Truck Stop, a favorite haunt for truckers, and a safe haven for drivers of oversize loads looking for a place to park.

The 60-meter inscribed circle diameter of this roundabout was designed to accommodate a 53-ft. trailer hauled by a tractor with a sleeper.

“We allow for it to be on asphalt all the time,” Boddy says.

While even longer trailers could go ’round and ’round the roundabout all day long, some drivers found that their super long trailers, like those hauling wind turbine blades, could not negotiate the exit that would let them reach the Double C.

While trucks operating with special permits are responsible for scoping out drivable routes, in this case, the Double C got involved, and elevated the problem beyond being just a one-off pain, to a design issue that had to be fixed. Following a meeting this June at the Double C with TIR representatives, TIR staffers went back to their computers and tweaked the exits.

With some truck configuration information in hand from the trucking representatives at that meeting, TIR quickly figured out what to do.

“I think we used a 110-ft. trailer (in the modeling software) as the maximum length usually going through there. They gave us a couple of configurations, and my co-workers built it into the modeling software,” Boddy says.

The solution was to add what is sometimes called grass stone on parts of the exits’ shoulders. These are honeycombed blocks with the strength to handle a lot of weight, but with holes through which grass can grow. It is standard to put grass stone in the center of roundabouts as an override surface for long trucks. Not many were needed, as the computer simulation showed just where the long trailers’ wheels would drop off the asphalt.

After examining how trucks passed through the roundabout, TIR crews applied the grass stone treatment to a number of locations, including two exits and three entrances.

Peter Ross, dimensional load manager for TDR Transport in Dartmouth, N.S., was skeptical that the improvements would do the trick, and sure enough, the rumor mill lurched into gear when, a few days later, an oversize load being delivered by Transport Bellemare International from the Ceres Terminal in Halifax to Ottawa was not allowed in the roundabout.

A quick call to Serge Turcotte, chief dispatch, oversize transport, Transport Bellemare International put the rumor out of its misery. On that day, contractors were diverting all traffic away from the roundabout because they were paving.

“When we arrived at the place, it was in construction,” Turcotte says. The asphalt was really fresh. Every car was routed through the Masstown Market. “For us it went very well.”
Turcotte also noted, “Our guy told us that the roundabout is small…(but) all roundabouts are complicated for us. You can take every roundabout from Halifax to Thunder Bay, and you will have difficulties. We used to pass through Mattawa, in Ontario, without difficulty. Then they built a roundabout and now we have difficulties.”

Truckers in Nova Scotia should not be shy about getting in touch with TIR when they spot issues of concern.

“The Department of Transportation and Infrastructure Renewal works closely with industry,” Boddy says. “We welcome the interaction, as a design group and as a department. For us to effectively communicate with (the trucking industry) before a design is very difficult. We are a small shop and can deal with these things quickly, because we do the work in-house. We can take a query, and within a day there are 10 sets of eyes on it, and have a solution out the door.”

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