N.B. tightens rules as mothers of killed teens arrange test proving winter tires' importance
Mar 06, 2010 by John Mahler Special to the Star, Wheels.ca
BRIMLEY, MICH.–On a crisp, cold day last week, Isabelle Hains, Ana Acevedo and Marcella Kelly stood on the hard-packed snow of the vast Continental Tire testing grounds here, near Sault Ste. Marie, Mich., and watched as a bright yellow school minibus came to a full ABS emergency stop in a lane of traffic cones.
In this photo, all seasons on front, winters on rear. The obstacle represents where the same bus outfitted with six winter tires on all four axles had stopped. Photo by John Mahler, February 24, 2010, Continental Tires Testing Facility, near Sault Ste. Marie, Michigan.
Without winter tires on the front axle, the bus can't stop in the same distance. In this photo, all seasons on front, winters on rear. Photo by John Mahler, February 24, 2010, Continental Tires Testing Facility, near Sault Ste. Marie, Michigan.
Continental's chief test driver, Baldemar Carmona, was putting the bus through its paces to show the women what was possible for a minibus properly equipped with winter tires.
Videos of individual minibus tire tests.
The three women lost sons in a crash between a school van and a transport truck in January 2008 outside Bathurst, N.B. Seven young men and one adult were killed.
This extraordinary tire test was to prove to the New Brunswick government's departments of education and transportation that if winter tires are fitted to a vehicle, they must be fitted to all wheel positions. And that winter tires on all four wheels work much better than a mixed tire set-up.
After the inquest into the crash that killed the young men, New Brunswick passed a law requiring winter tires on all school vehicles. However, it excluded multi-function activity vehicles, or MFAVs, the kind of buses that take children to after-school activities.
An MFAV is a yellow school minibus painted white and lacking the extendable stop sign. That the province's education department allowed winter tires on the rear and all-seasons on the front was a tragically wrong decision – and now, for the first time, there's proof.
As it happens, the day before the tests, the New Brunswick government announced it was changing the regulation to mandate winter tires all round on minibuses. Score a victory for the women (see accompanying story).
Meanwhile, Carmona and his crew had worked from 6 p.m. to 3 a.m. the night before the tire tests, doing endless reruns with the bus loaded with instruments to provide measurements down to centimetres. They tested every tire combination along with a set of control tires. The data were irrefutable: using winter tires at all positions was the safest practice by a huge margin.
"We have to have all this data," explained Jay Spears, Continental's technical manager. "No test is valid unless it is repeatable by another crew in another place. Any test must be scientifically valid."
Continental's chief test driver brought the bus, fitted with winter tires on all axles, to a halt in a quick 38.7 metres from a speed of 60 km/h on hard-packed snow. A Styrofoam barrier was placed across the lane at the spot the bus had stopped.
Then the tire configuration was changed to the New Brunswick mixed-tire set-up: premium quality all-seasons on the front, winters on the back. The minibus approached at exactly the same speed and the driver braked, but now the bus showed no chance of stopping. It hit the barrier with a thwack and the barrier exploded into pieces.
Marcella Kelly winced at the sound as the barrier cushions went flying.
It took the vehicle a substantial 11 metres more to come to a stop at 49.6 metres which, after using sophisticated instrument tracking and calculations, means a braking ability of just 71.6 per cent of the set-up with all winter tires.
Continental conducted two other tests. One, measuring cornering ability, proved eye-opening. The bus drove into a large sweeping corner at ever-increasing speed until it could no longer make the turn.
The winter tire combo produced a grip of 0.417 G (the G-force is the force pulling on you when you go around a corner).
The mixed tire set-up produced a mediocre 0.181 G, just 43.5 per cent of the winter tire's grip – barely better than a set of all-season tires on all axles, which produced a grip of 0.173 G.
The final test was the most dramatic, requiring the braking and turning abilities of the previous exercises. It simulated driving down a road, discovering a lane is blocked, and not having enough distance to stop – as if someone suddenly backed out of their driveway or a deer ran onto the road. The objective was to brake as hard as possible, then steer around the object.
Approaching at 65 km/h with four winter tires installed, the minibus made the turn.
A barrier simulating a stalled car at the turn was put up and the tires were changed to front all-seasons. The bus approached at the same speed and on braking, dramatically smashed into the "car," spreading Styrofoam everywhere.
It was obvious that despite a pronounced turning of the front all-season tires, the bus just could not respond and continued into a head-on collision.
Videos of individual minibus tire tests.