The government should make the use of longer semi-trailers (LSTs) a permanent fixture on the UK’s roads following the successful outcome of its trial, according to the FTA.

The DfT funded study demonstrates that use of these vehicles continues to have a significant impact on the reduction of carbon emissions and road congestion across the UK.

They have also been found to be safe for both the driver and other road users.

Explained Phil Lloyd, head of engineering & vehicle standards policy at the FTA: “Failure to make LSTs permanent is holding back an opportunity to significantly reduce carbon emissions. After all, the benefits LSTs provide to both the environment and the economy have been made evident in the government’s study.

"The UK’s roads are congested and carbon emissions from road transport remain too high.

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"With LSTs are able to carry more goods per journey than traditional HGVs, they present an efficient and environmentally-prudent method of freight transportation.

"The quantity of freight that needs to be moved is relatively fixed – if we can move the same amount with fewer journeys, the better for the environment, the economy and other road users.”

The DfT has been running a trial of the operation of LSTs on roads for the past seven years. Over this period, use of LSTs resulted in 365,000 fewer journeys taking place.

This reduction in mileage has led to the saving of 37,000 tonnes of CO2e and 187 tonnes of NOx. Additionally, LSTs had 55% fewer collisions compared to the HGV average.

"At a time when the road transport sector needs to reduce its environmental impact while businesses are also seeking to improve efficiencies, LSTs present a perfect, well evidenced, solution," Lloyd added. "We hope government seizes this opportunity and makes their use permanent as soon as possible."