Speed Governors

Trucks with which we share our highways are not all driving under the same safety control rules. Many fleets of trucks have their top speeds limited by simple on-board software (speed governor) that, if set, limits the top speed the truck can achieve. This simply enables the truck driver to hopefully stop or nearly stop in a reasonable distance if an emergency occurs.

(Some trucking industry stakeholders refer to this device as a speed limiter. RSA prefers the term speed governor to avoid the impression that speed limits are being changed.)

Unfortunately, the United States lags behind the rest of the technologically advanced world in this area. The European Union, Japan, Australia and the most populous Canadian provinces (Ontario and Quebec) all require speed governors to be set on heavy commercial vehicles at speeds varying from 55 mph in Japan to 65 mph in Canada. This common-sense requirement simply keeps these heavy vehicles, which need more distance to stop than the smaller vehicles with which they share the road, at a top speed that gives them a chance to stop or nearly stop, in the same distance as other vehicles. The use of the speed governors is profit enhancing as they save approximately 6 gallons of fuel per day per truck on average, limit the liability costs of the trucking companies since they are in fewer crashes (especially the kind in which they are at fault) and extend the life of equipment (brakes, tires, and engines all last longer). NOTE: All heavy commercial trucks manufactured since 1992 come equipped with electronic speed governors as standard equipment so there is no capital expense to do this.

Cruise Control

Did you know that heavy commercial trucks can actually have cruise control? As most will admit, use of cruise control causes the driver to be less-engaged and slower to react. Many of the safest fleets of tractor-trailers only allow cruise control to be used at slower speeds than the speed-governor setting (which any company with such a policy would voluntarily use) to adjust for this lost reaction time.

We strongly believe that the only type of cruise control that is safe to use on a heavy commercial vehicle is adaptive cruise control, with active braking. This type of cruise control sets both speed and the distance between the front of the truck and the vehicle it is following. Sensors cause the truck to slow down automatically if the vehicle it is following slows down, and active braking will actually stop the truck safely without any action from the driver.

The term “tractor-trailer” or "big-rig" used on this website
refers to all Class 8 trucks which is the heaviest class.

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