Is Bigger Really Better? The Debate Around Longer Semitrailers

The haulage industry is always changing. It sounds obvious, but it’s true – new technology and environmental and regulatory pressures create strong incentives to innovate. But the sector is so important to the UK economy that all change must be carefully managed. Which means something as simple as longer semitrailers (LSTs) can become a controversial issue. In this article, we’ll run through some of the pros and cons, to help you make an informed decision for your company.

What are Longer Trailers?

Longer semitrailers are exactly what the name suggest: semitrailers slightly longer than the UK average. Generally 2.05m or longer, LSTs can reach as long as 15.65m in length, adding up to a total vehicle length of as much as 18.55m.

What are the Rules Governing Them?

Changes in the haulage industry are strongly dependent on government regulation, and LSTs are no exception. Accordingly, they’re limited to the same gross vehicle weight (GVW) as regular trailers: 44t. They must also include some form of self-steering or command steering to be able to navigate roundabouts.


Since 2012, 2.6 million road trips have been made using LSTs. In 2017, the government extended this trial for a further five years. The independent organisation Risk Solutions produces annual reports for the Department for Transport (DfT), providing data for ongoing trials.

The Argument Against

While longer trailers have proved popular within the haulage industry, many have voiced concerns about their potential impact. Chief among these have been worries about danger and road damage.

The pressure group Campaign for Better Transport has highlighted worries over the lack of local authority involvement in trials. Minor roads maintained by local authorities, the campaign notes, make up 97% of the total UK road network. And in 2017 reports suggested that LSTs made 38% of their journeys off motorways. Still, the campaign notes, ‘the majority of local authorities’ who manage minor roads ‘are unaware of the trial.’

Further, the campaign notes that LSTs have only been fully loaded for 37% of their journeys, and existing size HGVs are already seven times more likely than cars to be involved in collisions.

Freight on Rail also argues that reported findings are based on ‘flawed data and incorrect assumptions’, with manager Philippa Edmunds arguing that longer trailers are ‘actually more dangerous than standard HGVs’, due to their ‘7ft tail swing and extended blind spot.’

The Arguments in Favour

On the other hand, haulage industry representatives have been broadly supportive, and much of the reported data seems to back them. Crucially, proponents note that companies and government both have strong incentives to maintain high safety standards. This is supported by the fact that the weight limit for longer trailers is the same as for existing trailers.

In fact, LSTs may actually outperform existing trailers in some areas. Studies show that use of LSTs allows the same amount of freight to be delivered with 7% fewer journeys. Moreover, they are less likely to run empty: where 29% of regular trailers on the roads are unladen, only 18% of LSTs are. In addition, 10 million miles of HGV journeys were saved by the use of LSTs in 2016 alone, and an analysis of the report data reveals that only 2% of LST journeys were on minor roads managed by local authorities – 36% were on A-roads.

There are clearly good arguments on both sides of the debate, then. But one thing remains clear: companies working in the haulage industry should keep a close eye on ongoing LST trials, and be ready to adapt their practices in future.

Norman Dulwich is a Correspondent for Haulage Exchange, the leading online trade network for the road transport industry. Connecting professionals across the UK and Europe through their website, Haulage Exchange provides a valuable service for the haulage industry, matching delivery work with available vehicles. It is now the fastest growing Freight Exchange in the UK.

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