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  • Writer's pictureSafer Highways

Longer heavier vehicles: policy statement

The Department for Transport (DfT) commissioned consultants WSP, Apollo Vehicle Safety and Risk Solutions to undertake a feasibility study of whether a national trial of Longer Heavier Vehicles (LHVs) could be conducted, and if so, how would such a trial be designed. For the study, LHVs up to 25.25m and 50 or 60 tonnes (Gross Vehicle Weight) were considered.

The LHV trial feasibility study final report was published on 22 August 2022. It provides a summary of findings related to the possibility of running a LHV trial in Great Britain.

The approach taken for the study was to begin from what was known from the previous UK study conducted in 2008 by the Transport Research Laboratory (TRL)[footnote 1] on the potential use of LHVs and updating that knowledge in the light of the experience gained in trials across the world, especially in Europe, and developments in vehicle technology.

LHVs are now used in many countries both within and outside Europe. The study found that exact estimates vary, but all countries using the vehicles report substantial gains in efficiency, translating to reductions in traffic, emissions, casualties and costs. However, like the TRL 2008 study, this study has identified risks associated with their use but also a range of methods used in different places to mitigate those risks. From this, a framework has been developed within which DfT can explore a range of approaches that could be taken to such a trial. These approaches are based on different mechanisms to managing the primary sources of risk to infrastructure (especially bridges and vehicle restraint systems), other road users and mode shift.

Five potential policy options have been defined to highlight the various approaches to a trial. DfT can select one of these options or could tailor one of the options to their own specification.

Options 1 to 4 all assume that LHVs would not be permitted on all roads and that approved routes would be done on a route by route basis derived from operator demand.

  • Option 0: Do nothing

  • Option 1: Route-based risk control

  • Option 2: Vehicle-based risk control

  • Option 3: Rules-based risk control

  • Option 4: Hybrid of option 2 and option 3

The resources and costs to create the system were another important factor behind the proposal that all options are based on route-by-route approval, to avoid the costs of examining routes for which there may be no demand.

The study found that demand for using LHVs has varied considerably in different countries. In those that have permitted their use for many decades, they take a major proportion of all freight, for example around three-quarters of tonne miles in Sweden. In those without this long culture of use, the demand has been lower, for example, around 1.5% of HGVs in the Netherlands are authorised for LHV use after around 20 years of trialling and in Spain around 0.4%.

The sectors where demand is seen are quite diverse but forestry, automotive, fast moving consumer goods, shipping containers and palletised goods, particularly on longer hauls are all regularly reported. Countries that have permitted or trialled LHVshave generally reported that the implementation has been an overall success, although details of policies are also often improved over time. For example, in Australia it has been estimated that over 20 years their performance based standard scheme has saved between $8 billion and $20 billion and 5.9 million tonnes of diesel.

In general, the findings on performance, operator take-up conditions and safety outcomes are broadly consistent with those of the GB longer semi-trailer trial, but with increased gains because of the larger capacities and a wider range of risks and policies needed to control those risks. Evidence from the study suggests that demand in GBwould be likely to start modestly and grow over time.

The report concludes that, if a ‘do something’ option is selected, a preparation and testing stage should commence immediately to maintain momentum with existing stakeholders, identify additional stakeholders to develop specific use cases (vehicle combinations and routes) and to complete essential work items to address the knowledge gaps, before moving to a subsequent commercial trial stage or concluding that an LHV trial is not feasible.

The essential work items involve answering the following questions.

  • Is there sufficient GB demand to justify a trial?

  • What emissions effects are expected?

  • Can highway structures sustain the vertical loads imposed?

  • What risks of modal shift exist?

  • Will LHVs pose increased risk to highway structures from collisions?

  • How much of the road network can be safely accessed by LHVs?

  • How can the proposed approval processes be resourced?

  • What needs to be done to ensure drivers are competent with LHVs?

  • The ability to accommodate LHVs at parking facilities?

  • What are the casualty risks and appropriate mitigations in standards and approvals?

Next Steps

It is clear that there are risks to implementing LHVs and that it can take considerable effort to make implementation a success, including time and cost. Therefore the recommendation in the report that more work needs to be done to prepare for any road trials of LHVs on GB roads is being taken forward and the department will be commissioning WSP, Apollo Vehicle Safety and Risk Solutions to undertake that work.

This work will include looking more closely into the two key areas that can undermine the benefits of LHVs, which are:

  • the availability of sufficient bridges that can take the loading to make enough routes economically viable

  • the risk of a substantial mode shift from lower carbon forms of transport undermining the environmental benefits

A decision on whether to conduct road trials will be made after this work has concluded.

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