MEASUREMENT ADJUSTMENTS

New arrangements for weighing heavy vehicles are to be introduced nationally from 1 July 2006. Known as a "measurement adjustment", the new arrangements allow for greater accuracy for measuring heavy vehicle mass by roadside enforcement officers.

Why the change?

It has been the practice of all Australian road agencies to apply a tolerance to all heavy vehicle mass weighings to account for variances in the weighing process. These tolerances were developed in the 1980s and are now outdated. Improvements in the accuracy of weighing devices allow more accurate weight measurements to be made in most circumstances.

The introduction of the measurement adjustments system is a national reform, which has been agreed by all States and Territories with a common start date of 1 July 2006.

The measurement adjustment process places an increased emphasis on compliance with the applicable mass limits. Improved compliance by heavy vehicles with mass limits has road safety benefits for all road users and helps protect road infrastructure.

The measurement adjustments relate to the roadside weighing process and have no impact on the applicable mass limits. In Western Australia, the measurement adjustment process will apply to all roadside weight checks by all enforcement officers across the State.

What do transport operators need to do?

Transport operators should continue to load to the legal mass limit of their vehicle. The measurement adjustments are not a tolerance.

Under the proposed Compliance and Enforcement chain of responsibility laws, all parties in the transport supply chain – the consignor, packer, loader, consignee as well as the driver and operator – must take positive steps to prevent a breach of the road transport mass, dimension and load restraint laws. These parties can be held liable for these offences.

Transport operators should encourage their supply chain partners to be aware of, and actively comply with, their obligation under road transport law.

Weighing site categories

Three categories of weighing sites have been defined to accommodate differences in weighing equipment and to account for the environmental factors (for example, gradient and slope) at weighing sites.

• Category 1 weighings are generally the best available sites, such as certified weighbridges or sites designed and constructed for accurate, reliable use with portable scales.
• Category 2 weighings are generally at well set out temporary roadside sites, such as enforcement sites using portable scales.
• Category 3 weighings are generally conducted under less favourable conditions than other sites. However, in the interests of certainty in weighing, there are limits on the circumstances where heavy vehicles can be weighed even at a Category 3 site.

Measurement adjustments

The measurement adjustment procedure relies on two concepts:

1. measured mass: the reading from the weighing equipment or portable scale; and
2. assessed mass: the measured mass minus the relevant measurement adjustment.

The relevant measurement adjustments for each axle and gross mass are given below.

The measurement adjustment is applied for each weighing step. A weighing step is any movement of the vehicle or combination needed to complete the weighing process for an axle, axle group(s) and/or vehicle gross.

The assessment of gross mass, or any summed mass, can therefore involve the application of multiple measurement adjustments.

Examples of how measurement adjustments will apply

Example 1

• Three (3) axle rigid vehicle
• Category 3 site
• Vehicle weighed in one movement, using six (6) portable scales

From the above calculations, it can be seen that there is one offence. The vehicle"s assessed mass on the gross exceeds the relevant legal limit.

Example 2

• Six (6) axle articulated vehicle
• Category 3 site
• Vehicle weighed in two movements, using six (6) portable scales

From the above calculations, it can be seen that there are three breaches as the assessed mass for the drive axle, tri axle and gross mass have all exceed the applicable limits. Note that two (2) measurement adjustments have been applied to the assessed mass on the gross.

Example 3

• B double
• Category 3 site
• Vehicle weighed in three movements, using six (6) portable scales

The above calculations show that there are four instances where the assessed mass for either the axle groups or the vehicle"s gross mass has exceeded the applicable mass limits. Note that three measurement adjustments have been applied to the assessed mass on the gross.

The new measurement adjustment system provides very clear boundaries to ensure heavy vehicle compliance with the applicable mass limits.

Thank you for your cooperation.

Mark Walker
Director Heavy Vehicle Operations
29 June 2006