Main Roads Heavy Vehicle Services would like to advise that a suite of new online Tow Coupling D-Rating Calculators are now available on the Permits and Orders page on our website, which replaces our previous single online fifth wheel coupling D-rating calculator.

The new online calculators are listed below, which provide options for both fifth wheel and pin-type / drawbar couplings across various combination types.

• D-Rating Calculator - Prime Mover Fifth Wheel

In accordance with AS 4968.1:2023 with options for assessing prime mover fifth wheel couplings connected in a single trailer combination or a road train combination.

• D-Rating Calculator - A-Trailer Fifth Wheel

In accordance with AS 4968.1:2023 with options for assessing fifth wheel couplings on an A-trailer in a B-double or B-triple combination.

• D-Rating Calculator - Dolly Fifth Wheel

In accordance with AS 4968.1:2023 with options for assessing fifth wheel couplings on a dolly with either a hinged drawbar or rigid drawbar.

• D-Rating Calculator - Dolly Drawbar Coupling

In accordance with AS 2213.1:2022 with options for assessing drawbar couplings on truck and dog trailer combinations or road train combinations.

We have developed these online calculators to assist transport operators in ensuring their tow couplings are adequately rated.

Ensuring vehicles and their components are adequately rated for your transport task is not only a legal obligation but is also part of your responsibility to ensure road safety.

For further information, please contact the Heavy Vehicle Services Helpdesk on 138 486 or email hvs@mainroads.wa.gov.au

Heavy Vehicle Services
22 April 2024

Please note: This HVS Update will be published for 1 month.