Longer semi-trailer trial: 2021 annual report findings summary
Published 17 May 2023
© Crown copyright 2023
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This publication is available at https://www.gov.uk/government/publications/longer-semi-trailer-trial-evaluation-annual-report-2021/longer-semi-trailer-trial-2021-annual-report-findings-summary
This summarises some main findings from the 11-year longer semi trailer trial. It also summarises some estimated impacts of their introduction into general use outside of trial conditions, which is presented in the impact assessment.
Trial findings
Utilisation and kilometres (km) saved
| Utilisation and km saved (2021) | Utilisation and km saved (2012 to 2021) |
|---|---|
| 78 to 86 million | Vehicle km saved by LST operations. Lower – upper estimates (upper includes empty return legs that would also be saved) |
Journeys saved
| Journeys saved (2021) | Utilisation and km saved (2012 to 2021) |
|---|---|
| 621 to 688,000 | Journeys by 13.6 metre trailers saved by using LSTs based on 125 km average journey. Upper estimate (including some return legs) is used in the saving and emissions figures that follow |
| 1 in 12 (8.2%) | Average saving across all operators – 1 in ‘n’ journeys |
Emissions saved by LSTs
Estimates compared with the emissions from delivering an equivalent quantity of cargo on standard trailers:
- savings of carbon monoxide (CO)
- particulate matter (PM) (exhaust)
- volatile organic compounds (VOC)
Are also calculated.
| Emissions (tonnes) | Estimates compared with the emissions from delivering an equivalent quantity of cargo on standard trailers |
|---|---|
| 70,000 | CO2(e) (1) tonnes of CO2(e). Carbon dioxide equivalent or CO2(e) is a term for describing different greenhouse gases in a common unit. For any quantity and type of greenhouse gas, CO2(e) signifies the amount of CO2 with an equivalent global warming impact |
| 97 | NOx tonnes of NOx of which 6.2% saved within 200 m of designated areas – 2017 modelling estimates – NOx savings are lower than projected in the annual report 2019 as EURO VI engine impact is now being modelled |
Collisions and casualties
Collisions or casualties where LST involved on public highways or public access areas – 2012 to 2021 – which resulted in an injury.
| Collisions ratio | Casualties ratio |
|---|---|
| 0.39 | 0.32 |
Collision and casualty rate ratio is calculated by LST vs all GB artic. HGVs.
The casualty ratio represents the likelihood of a LST being involved in a collision compared to all GB artics (i.e. a ratio of 1 would mean LSTs and GB artics have the same likelihood of a collision, and a value less than one would indicate LSTs lead to comparatively fewer collisions).
On a per kilometre basis, nationally, we estimate LSTs have been involved in around 61% fewer personal injury collisions than GB articulated HGV average.
This is against a background collision rate for GB articulated HGVs that has been falling for several years.
Estimated impacts of introducing LSTs into general use
This table demonstrates the impact and totals over the appraisal period (PV) – 20 years appraisal period, to the nearest £ million.
| Costs | Best estimate (£m) | High (£m) | Low (£m) |
|---|---|---|---|
| Trailer replacement | 196 | 157 | 236 |
| Taxation revenue | 195 | 195 | 195 |
| Regulation costs | 135 | 108 | 162 |
| Initial assessment | 9 | 7 | 11 |
| Viability assessment | 24 | 19 | 29 |
| Total | 560 | 487 | 633 |
| Benefits | Best estimate (£m) | High (£m) | Low (£m) |
|---|---|---|---|
| Fuel saving | 349 | 380 | 318 |
| Labour saving | 289 | 347 | 278 |
| Congestion | 614 | 654 | 488 |
| Air quality and greenhouse gases | 227 | 227 | 227 |
| Infrastructure | 133 | 133 | 133 |
| Noise | 61 | 61 | 61 |
| Tyre saving | 13 | 15 | 12 |
| Repairs and maintenance saving | 41 | 49 | 39 |
| Vehicle excercise duty and road user licensing saving | 10 | 12 | 9 |
| Total | 1, 737 | 1,879 | 1,566 |
| Net present value | 1,177 | 1,392 | 933 |
Notes: These values estimate impacts across society, and are taken directly from the published impact assessment, where a full explanation on their calculation has been included. These impacts are made up of direct and indirect components, which may affect different economic agents (i.e. businesses, individuals and public bodies).
Attribution of these impacts between economy and other impacts can depend on the interpretation of direct and indirect impacts and can vary between the impact of enabling the uptake, and the operating, of longer vehicles.
Such as, considering the gross total benefits of £1,737 million and excluding those that are non-tangible and purely to society (£288 million) this could present maximum total benefits to businesses and government of £1,449 million.
These values are expressed in 2019 prices and discounted to their present value using the green book discount rate.
CO2(e) reduction
The total emissions saved over the 20-year appraisal period is 1,200,000 tonnes.
Note: These values estimate the total CO2(e) emissions reduced, and are taken directly from the published impact assessment, where a full explanation on their calculation has been included.