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DfT Announces LST (Longer Semi-Trailers) Consultation


Following the announcement yesterday from the DfT of a consultation period to discuss revising current legislation to include longer trailers, Don-Bur is delighted that the ongoing debate is moving forward.

With ever-increasing fuel costs, it is becoming more critical to increase operational efficiency. For some time now, additional cubic volume (in the form of double deck trailers or Draw-Bar combinations) has become a recognised way to significantly reduce trunking trip frequency and fuel/CO2 saving is the most direct and obvious benefit. A 44 pallet double deck (52 max) will eliminate 2 trips out of every 5 to transport the same amount of load, and will also offer the opportunity to reduce fleetholding, together with all associated costs. The proposal to increase trailer length by 2.05m will generate room for an additional 4 UK pallets (6 Euro Pallets) or 8 UK Pallets (12 Euro Pallets) on longer double decks.

Having built the 16m long “Donny Rear Steer” trailer in May 1999, Don-Bur is no stranger to longer trailer design. It was established early on that steering would be an issue that would need attention; resulting in the development and production of the SCM (Steering Correction Mechanism) which was fitted to the Donny Rear Steer trailer. The SCM is a 1-3 axle true self-tracking system, which follows the turning circle more accurately than a normal self-tracker and allows a 16m trailer to fit easily within the current 5.3-12.5m regulations. Despite comments made in the DfT announcement that suitable steering systems will not be available for another 18 months, we could argue that adequate technology is already in place.

More recently, Don-Bur has been developing and building 15.750m trailers (in anticipation of the proposal) with positive rear steer axles for major operators who will be trialling them, pending clarification of the proposals. One such design has an aerodynamic Teardrop™ roof, offering both additional cube and improved mpg.

As always, new legislation comes at a price. Contained within the proposal is a limit of 4.57m overall height for longer trailer trials and whilst this does not eliminate the use of double decking, it does restrict the number of operators who would truly benefit from longer double decks. At 4.88m (16’), with low floor height, a double deck currently provides comfortable head height on both decks; providing both ease of loading and ample aperture for a wide range of stillages. A 4.57m height limit would restrict double deck aperture heights to a maximum of circa 1.8m each. For many, this is clearly not feasible.

In conclusion, a 13% cube increase afforded by a 2.05m extension to trailer length is, on first glance, a welcome revision; however many operators trunking low density loads are already benefitting from a 70% increase in capacity generated by double decking. With the proposed restrictions on longer double deck heights, the majority of operators would suffer rather than benefit. Some operators carrying heavier loads and running at 44T gross may be able to benefit from additional load space, but not without the expense of lower tare weight tractor/trailer design.

Having been invited to contribute to the consultation, Don-Bur will actively support the concept of longer vehicles, provided that the clear benefits afforded by double decking and other existing technologies are not compromised. They will offer advice to all operators considering a move toward longer trailers and welcome the opportunity to continue development in this area.

Published: Thu 31 Mar 2011

Updated: Thu 11 Apr 2024

Author: Richard Owens

Published by: Don-Bur

Don-Bur (Bodies & Trailers) Ltd

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