There has been confusion in industry on the setting of speed limiters fitted to or part of road train rated prime movers.

Queensland Transport specifies in the Transport Operations Road Use Management (Vehicle Standards and Safety Regulations 1999)
“For third edition ADR 65, the maximum road speed capability of a motor vehicle used in a road train is 100km/h.”

From the Queensland Road Rules
24A Speed limit for certain vehicles
(c) for a driver driving a road train—90 km/h;

The Queensland Transport Guideline for Multi-combination Vehicles states the following:
“4.2 Speed limits
4.2.1 Vehicles operating under this guideline must not exceed the lesser of the displayed speed limit or:
- for a road train that is not a B-triple or a prime mover/semitrailer combination towing one converter dolly, a speed of 90km/h; or
- for a B-double, a B-triple, or a prime mover/semitrailer combination towing one converter dolly, a speed of 100km/h.”

So it is clear that it is permissible to set the limiter at 100kph but the vehicle may only be driven at 90kph while part of a road train combination. These changes have been made to facilitate operation of prime movers in different combinations at different speed limits.

The onus is on the driver to obey the appropriate speed limit for the combination being driven.

For further information j.samson@cviaq.asn.au