Longer semi-trailers in Britain sparks safety concerns

Per deck, longer semi-trailers can carry four more standard UK pallets than standard semi-trailers.

New government laws allowing Longer Semi-Trailers (LSTs) on Britain roads has sparked debate as to whether the decision is safe or necessary.

There are currently 3,000 of these longer semi-trailers on the road but they are expected to increase with the new legislation, which comes into effect at the end of May.

The Department for Transport (DfT), which has been trialling the trucks since 2011, has stated they are safe and will ultimately help businesses become more productive and drastically reduce carbon dioxide emissions.

LSTs are a type of Heavy Goods Vehicle (HGV) trailer up to 2.05 metres longer than the current standard semi-trailers on UK roads – 15.65 metres instead of 13.6 metres. These are not the road trains permitted in some other countries or the 25.25 metres designs in use in some EU countries.

The total weight of the LST, the goods and the prime mover, according to DfT, must still be within the UK domestic weight limit of 44 tonnes. They must pass the turning circle test applied to the existing 13.6 metre trailers, for which the LSTs require a steered rear axle.

Fully loaded LSTs can move the same volume of goods using fewer journeys than current trailers, for little change in fuel use per mile, while reducing overall emissions, congestion, and collision risk.

LSTs complement other approaches to freight carbon reduction, such as modal shift, increasing engine efficiency, and the use of electric vehicles, but LSTs can be implemented without the need for further significant technological and infrastructure development.

Road safety advocates, however, have voiced concern that the 18.55m-long trailers  could pose a danger to cyclists and pedestrians because of their increased tail swing.

Tail swing is the movement of the rear of a truck as it turns and can increase its area, depending on the length of the trailer and the weight of the load.

According to the DfT, the new trailer rule is set to result in £1.4 billion of economic benefits and take one standard-size trailer off the road for every 12 trips. It estimates the vehicles will save 70,000 tonnes of carbon dioxide from being released into the atmosphere over 11 years.

Furthermore, the trial demonstrated that, with appropriate operational management, LSTs can be operated safely and deliver up to a 13 to 14 per cent reduction in real world emissions, with an average saving of 8.0 to 9.0 per cent across the whole trial. The trial also carried out route modelling and specialist analysis of the impact of LSTs on vulnerable road user groups.

Following demonstration of consistent trial safety and emissions performance, DfT has introduced regulations to permit LSTs to be used widely across Britain.

The Campaign for Better Transport, however, has argued that the new size will pose a safety risk and possibly damage current infrastructure. It maintains that the government should be focusing its efforts on increasing train transport as opposed to larger trucks.

According to the European Rail Freight Forward coalition, every freight train emits 80 to 100 per cent less CO2, than a freight truck and replaces 50 trucks at a time.

Interestingly, many of these concerns echo what Australia has worked through over the years with the evolution and rollout of its Performance-Based Standards (PBS) high productivity scheme.

In Australia, the uptake of PBS vehicles continues to rise. In particular, A-double and B-triple road train combinations have grown in popularity in New South Wales and Victoria.

Earlier this year it was also reported by the National Heavy Vehicle Regulator (NHVR) that there had been more A-doubles approved for the high productivity scheme than truck and dog combinations.

In some instances, the A-double in Australia (with a length limit of up to 36.5m) is overtaking the 19m B-double.

NHVR Chief Engineer, Les Bruzsa, said at the beginning of 2023 that Tasmania, Victoria and New South Wales were looking at the length limit in light of A-double combinations for Level 2 which are longer than 30m.

“If an operator needs to optimise a vehicle for a freight task and if it’s a little bit longer than 30 metres, but it still meets PBS Level 2 performance requirements, then the jurisdiction will investigate potential options for access,” he said.

“This could be a game-changer for A-doubles because using 45’ trailers under the 30m overall length limit can be difficult. But if the length is around 30-32 metres it’s just a small enough addition to enable an operator to utilise existing 45’ long trailers.”

In January 2023 there were more than 4,7000 transport operators running PBS vehicles in Australia.

Ultimately, there are tangible gains from growing the national PBS fleet which include reducing heavy vehicle exposure on roads, reducing fuel usage, cutting emissions – even minimising the environmental impact on roads and transport-related infrastructure.

Guidance on the full implementation of LSTs in Britain can be found here.

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