Performance Based Standards (PBS) help determine whether non-standard heavy vehicles meet the safety performance requirements equivalent to standard vehicles.

Standards, in this situation, are set of performance measures (for example tail swing) used to evaluate a design.

The dimension requirements for a standard heavy vehicle are contained in the Vehicle Dimensions and Mass Rule 2016 (VDAM)

However, some heavy vehicle designs or combinations don’t meet the VDAM Rule’s standard vehicle criteria. In these instances, PBS are used to assess whether a non-standard vehicle will be safe to operate on the road.

The PBS provide a consistent, transparent process for ensuring that any new, non-standard heavy vehicles will fit safely on our roads, and whether those vehicles can be used on either general access or constrained routes.

New PBS were released in May 2019.

Proforma designs

Proforma designs are approved non-standard vehicle designs that meet the PBS. They are developed based on greatest identified need – so will be added to over time. Some new designs were published in May 2019, and there is a transition period for moving to the new proformas.  

Find out more about proforma designs