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Dimensional Deja Vu

Canadian carriers studying the proposed NAFTA standards for truck dimensions will find them strangely familiarAfter five years of talking, the three NAFTA partners have finally agreed on aspects of tr...

Canadian carriers studying the proposed NAFTA standards for truck dimensions will find them strangely familiar

After five years of talking, the three NAFTA partners have finally agreed on aspects of truck weight and dimension regulations. The agreement doesn’t look like much on the surface, and the maximum limits will be pretty familiar to Canadian truckers, but look deeper and you’ll find important goalposts for future changes to weight and dimension regulations in the three countries.

Canada, the U.S. and Mexico signed NAFTA in 1992 and, under the agreement, established committees to harmonize standards. The Lands Transportation Standards Committee Working Group 2 (LTSS 2) has been meeting since 1994. Progress has been painfully slow but the working group has finally settled on truck dimensions and some aspects of performance (how the truck behaves on the road). There is no agreement on acceptable axle or gross weights yet and the dimensions and performance standards “agreed to” are for discussion purposes only – they have no force in law.

Truck dimensions LTSS 2 put out for discussion are the same as those underlying Canadian regulations. These were developed in a 1988 agreement signed by all provinces and territories. These Canadian numbers are now to apply to almost the whole North American continent:

Maximum height of 4.15 metres (13’7″)

Maximum width of 2.6 metres (102.4″)

Maximum length of 23.0 metres (75’6″) for tractor-semitrailers and 25.0 metres (82′) for doubles

Maximum semitrailer length of 16.2 metres (53’2″)

Maximum box length, the length between the front of the first trailer in a double and the rear of the second trailer, of 20.0 metres (65’7″).

In addition to these heights, widths and lengths, LTSS 2 has agreed to several performance standards. For example, there should be no more than 5.6 metres (18’4″) offtracking when a tractor-semitrailer or other combination negotiates a 90-degree turn. (Offtracking is the distance between the furthest outside corner of the front of a vehicle as it makes a turn and the inside track of the last axle on the other side of the vehicle.)

Other accepted performance standards are:

A maximum front swingout – the distance the front corner of a trailer swings out into the opposing lane during a 90-degree turn;

A maximum rear swingout – the distance the rear corner of a trailer swings out in a turn;

A load transfer ratio – the weight transfers from tires on one side of an axle to another during a sharp steering maneuver at highway speeds; and

A maximum transient high-speed offtracking distance – the wiggle in a double when a driver makes a sharp lane change on the highway.

These performance characteristics are determined by a number of factors such as the allowed wheelbases, overhangs, kingpin setbacks, trailer connection types, suspensions, tires and so on.

No agreement could be reached on weights because the Americans are loath to put anything in writing that will hint at a change to current federal axle weight, gross weight and bridge formula limits. It’s too dangerous politically to broach this subject in the U.S. as the anti-truck lobbies see red when the possibility of larger or heavier trucks is mentioned. However, since Canada and Mexico allow considerably heavier trucks than the U.S., any agreement on weights is probably going to require the Americans to bend. This will not happen any time soon.

While the dimensions and performances standards agreed to don’t change regulations in any country, they will serve as goalposts for future changes. This is important as it means that over time there will be a gradual convergence in the existing patchwork of regulations.

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