Main Roads Heavy Vehicle Services (HVS) advises the Single Trip OSOM Vehicle Standard Operating Conditions and the Movement of High Risk OSOM Vehicles Policy have been amended to exclude the length of additional block trucks for the purpose of Oversize Overmass Transport Management Plan (OSOM-TMP) requirements. 

This means an OSOM-TMP is only required if the primary towing vehicle and trailer(s) exceed 50 metres in length. Additional block trucks are not included in this length measurement.

However, permit applications must still include the length of any additional block trucks, unless the additional block trucks are optional. 

We have also made a minor amendment to the Single Trip OSOM Vehicle Standard Operating Conditions and the Class 1 RAV Oversize Period Permit Operating Conditions to include the Port Hedland Port Precinct into the night curfew concessions.  

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

Heavy Vehicle Services

1 May 2026

Note: This HVS Update will be published for 1 month.