Governments to hasten move to self-steering axles

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TORONTO, Ont. – Why is the Ontario government in favour of self-steer axles?

In a recent speech to delegates of the annual Canadian Fleet Maintenance conference, Ron Madill, project leader, vehicle weights and dimension reforms, Ministry of Transportation Ontario, set out to build a context around the subject.

“We’re in the midst of a significant four phase vehicle weights and dimensions reform of which the third phase will be implemented middle of this year,” he said, noting there are two primary reasons the provincial governments are aiming to migrate commercial vehicles over to self-steer axles. Speaking for Ontario, Madill said some 4.3 billion dollars have been spent between all levels of government on roads in Ontario, and a recent audit report said that one third of all bridges, and half of pavements in the province will require repaving this year.

“Some heavy trucks cause $300 million/year in avoidable damage. It’s not the weight that is a concern per se, but that certain configurations are causing excessive and avoidable damage, and the main culprits are multi-axle vehicles with liftable axles for manoevering corners,” said Madill.

The second reason he cited deals with highway safety.

“While Ontario has some of the safest highways in North America there are still 17,000 heavy duty vehicle accidents annually, one third of which involve tractor trailers. In analyzing the data, we found certain tractor-trailers having a disproportionately high rate of accidents (# of accidents per million km of travel). The primary culprits were multi-axle semi trailers, the same group we’re concerned about for infrastructure damage,” he said.

The primary belief why they’re involved relates to stability, controllability, and the space they occupy during various high and low speed manoeuvers, Madill added.

“The way we’re addressing these issues is through vehicle weights and dimensions reform, for example by identifying alternatives to the ones we view as problems. The alternatives must have dynamic performance characteristics, be productive (We have no intention of general reductions in types of weights but in getting it properly distributed), and must be infrastructure-friendly (in general this means replacing liftable axles with self-steering), with load equalizing on all the axles,” he said.

These vehicles will be identified as “Safe Productive Infrastructure Friendly” (SPIF) vehicles, Madill said.

“There are three basic types of SPIF tractor trailers – those equipped with fixed axles, single, tandem or tridem. There are three-, four- and six axle self-steer versions, A, B, and C train double-trailers. All self-steering axles must load equalize, with whatever weight is on the fixed axle group within 500 kg. Many wheel cuts are specified for these, ranging from a minimum 20-30 degrees required wheel cut,” he said.

The further the self-steer axle is mounted from the pivot point of the trailer (the centre of the fixed axle group) the more sharply it will have to turn. Self-steer axles may be equipped with single or dual tires. In all but one case there is no impact on the maximum weight of vehicle.

Self-steers may be liftable if the vehicle is empty or lightly loaded, but there are limits on the controls for raising or lowering the axle. They cannot be located in the cab of the tractor, (excepting vehicles that can carry rough forest products). There can be automatic controls self-contained on the trailer that automatically raise the self-steer when the vehicle is reversing. There will also be provisions for an emergency attachment to raise the self-steer axle and transfer the weight onto drive axles in emergency conditions, Madill said.

He expects a configuration migration of around 7,000 self-steer triaxle vehicles, 15,000 existing self steer quad trailers, 3,500 five-axle and around 1,000 six-axle versions.

“How are we going to cause the migration? We need to group the trailers into three as a good starting point. The first group involves light semi-trailers – one-, two- and three-axle. These must conform to SPIF standards by the end of this year. The next group involves dump semi-trailers-any of these built since 2003 have had to be built to SPIF standards or face immediate weight reductions. The third group involves heavy (non-dump) semis and doubles four-, five-, and six-axle semis and all doubles-any built from 2006 onwards have to be built to SPIF standards or face immediate weight reductions. Any vehicles on the road prior to the end of this year will be grandfathered for their reasonable weight,” he said. Madill expects that by 2025, 25-30,000 self-steer SPIF trailers will have been migrated over.

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