LST small print revealed

Colin Barnett
May 31, 2023


Having announced in early May that approval was about to be given for the regularised use of Longer Semi-Trailers (LSTs) on UK roads, with effect from 31 May, full details of the change have now been confirmed by the DfT. Any thoughts that there would simply be a 2.05m extension to existing length regulations were optimistic. LST’s have instead been added as a new type of STGO trailer by the new 2023 No. 52 Road Vehicles (Authorisation of Special Types) (General) Order 2023.

An LST is defined as being longer than 12.0m from kingpin to rear, up to a maximum of 14.05m. Unlike existing trailer dimensions, measured from the front of the bulkhead and any projections to the rear, the maximum 15.65m length of an LST is measured from the front of the loading area, ie inside the trailer, to the rear. This allows for the carriage of an additional four UK pallets per deck. The trailer must still comply with the current 2.4m swing radius ahead of the kingpin, and the overall combination length of 18.55m cannot be exceeded.

Maximum GCW remains at 44 tonnes on six axles, with one of the trailer axles needing to be steered. If the GCW exceeds 38 tonnes, an on-board weighing system must be fitted.

Operationally, there are a few hoops to jump through. Any route intended to be used, including any likely diversionary routes, must have a prior route plan and risk assessment, given to drivers. Ths Secretary of State must be notified of the prospective use of LSTs, via the O-licencing system

Other guidance includes enhanced driver training and scheduling, and specific LST training for any other staff included in their operation, including loading. Any operators participating in the LST trial can continue under those permits before joining the new regime after a transitional period up to 30 November 2023, after which time, existing permits will be revoked.

For leading manufacturer of high volume trailers, Don-Bur, Richard Owens, technical support specialist and marketing manager, said: “We are delighted that Longer Semi-Trailers can finally be run without trial VSOs on UK roads. The additional 15% increase in cube will suit a wide variety of operators and our double deck versions will take up to 60 UK pallets. The positive impact on efficiency and subsequent reduction in fuel and CO2 will be felt across the industry for those with light to medium weight freights.”

The full official guidance document for the new STGO Amendment can be seen online at .

About the Author


Colin Barnett

Colin Barnett has been involved in the road transport industry since becoming an apprentice truck mechanic in the early seventies. The end of 2022 will see him complete 25 years with Commercial Motor, with a secondment as editor of sister title Truck & Driver along the way. Today, as technical editor, he is witnessing at first hand the greatest changes in heavy goods vehicles since they replaced horses.

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