Saturday 30 May 2020

Jost highlights longer semi-trailer trial success

Richard Flackett, sales manager at Jost Axle Systems, looks at the progress of the government’s longer semi-trailer (LST) trial and the benefits offered for operators

As the Department for Transport (DfT) trial of longer semi-trailers (LSTs) continues, the latest independent report, issued in March 2020, analyses the data collected so far.

As the LST fleet continues to grow, so the volume of data recording journeys undertaken and any incidents occurring is providing a clearer picture on the benefits of these vehicles.

Eight years into the 15-year trial of LSTs on the UK road network, and the data collected so far continues to support the wider introduction of these vehicles.

Operators that have signed up to the trial have to provide specialist training for drivers and detailed journey data, as well as information on any incident on the public road.

Each year, the data is analysed to assess the impact LSTs can have on road freight journeys and compares their performance to standard articulated trailers. To the end of 2018, over 4.7 million journeys had been completed by a fleet of 2,194 LSTs, amounting to a total distance of 587 million kilometres.

The increased size of LSTs, as well as their initial investment cost, mean that hauliers want to maximise their use and minimise the risk of damage to the trailers.

Apart from the driver training courses, operators are also carefully planning the routes for these vehicles to make them as efficient as possible. LSTs are predominantly being used for journeys between distribution centres, supplier depots and larger retail sites that are close to major trunk roads.

Due to the extended length of the LSTs, and the desire to optimise their efficiency, the report shows that these trailers used 7.5 per cent fewer journeys to deliver the same amount of freight as conventional trailers.

Since the axle load limits are the same, this translates to an equivalent saving in road damage, fuel consumption and CO2 emissions. At the same time, fewer vehicles on the road will help to ease congestion as well.

Since the LSTs represent a considerable investment for the operators, it is in their best interest to use them in the most efficient way. This accounts for the 19-20 per cent of distance travelled while empty, compared to 29-30 per cent for conventional articulated trailers.

One of the initial concerns raised over the use of LSTs was the increased swing of the rear of the trailer when turning, due to the larger overhang beyond the rear axle.

To counteract this concern, almost all of the LSTs have been equipped with one or more of the axles having a steering component that is controlled either mechanically or electronically. This enables the LSTs to follow the tractor unit more closely and also reduces tyre wear when turning sharply.

Jost UK has been working with many of the operators and trailer manufacturers involved in the trial to ensure the LSTs meet the legislative requirements and provide a safe driving experience.

The Tridec TD mechanical steering system can be used on one or two axles, providing better manoeuvrability, especially when negotiating roundabouts.

The Tridec solution is a command (or positive) steer system which is linked directly to the fifth-wheel via a mechanical rod. This provides greater control when on the road and increased control during reversing as, unlike self-steer systems, which are locked when in reverse, command steers remain active.

The LST trial, initially set to run for ten years, has been extended until 2027. The recent increase in the fleet of trailers will help to increase the volume of data being collected and reinforce the benefits that are being achieved for operators.

Of course, they will not be appropriate for everyone; the smaller, urban deliveries are much better suited to rigid or shorter articulated vehicles. However, for an industry that is looking to reduce emissions and be more cost-effective, the LST certainly has a place for longer, inter-depot routes.

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