Light trailer compliance report
Published 1 March 2023
Applies to England, Scotland and Wales
© Crown copyright 2023
This publication is licensed under the terms of the Open Government Licence v3.0 except where otherwise stated. To view this licence, visit nationalarchives.gov.uk/doc/open-government-licence/version/3 or write to the Information Policy Team, The National Archives, Kew, London TW9 4DU, or email: psi@nationalarchives.gov.uk.
Where we have identified any third party copyright information you will need to obtain permission from the copyright holders concerned.
This publication is available at https://www.gov.uk/government/publications/light-trailer-compliance-report/light-trailer-compliance-report
Executive summary
Between 2019 and 2021 the DVSA checked 3,813 non-testable trailers, of which 730 were caravans. However, due to reporting constraints during the pandemic, there is less data than anticipated relating to some areas, as identified below.
The checks show a disparity between the compliance of trailers and caravans. Of 3,083 trailers (non-caravan) that were checked, 50% were non-compliant, and 41% were issued with an immediate prohibition (that is, defects so dangerous that repairs are required before further use of the trailer). Of the 730 caravans that were checked, 12% had a prohibitable defect, 7% being issued with an immediate prohibition.
The most common defects for non-caravans related to lamps (36% of all non-caravan defects were for lamps), running gear (which includes tyres, 21%), and brakes (20%). For caravans, the most common defect was also lamps (57%), followed by chassis (which includes breakaway cables, 22%), and running gear (which includes tyres, 11%).
Only 537 of the 3,083 (non-caravan) trailers checked recorded the trailer type. The data available shows that construction trailers had the highest prohibition rates (52%), compared to agriculture (32%), livestock (28%) and vehicle transporter (28%). However, analysts have advised that this data should be considered indicative rather than comprehensive due to the sample size.
Introduction
The Advanced Analytics Division (AAD) has been commissioned by the Driver and Vehicle Standards Agency (DVSA) to analyse the roadworthiness of a random sample of the non-testable trailers on British roads. These roadworthiness checks were performed on randomly selected trailers and caravans by DVSA examiners at sites across England, Scotland, and Wales.
This paper presents the results of these checks to inform the DVSA, DfT policy colleagues and the All-Party Parliamentary Group on Trailer and Towing Safety.
The roadside inspection survey of non-testable trailers started in 2019 and aimed to test 1,300 trailers (up to 3.5 tonnes maximum weight) and 700 touring caravans over a year. Checks were planned to be spread over the year to account for seasonal effects – for example, caravans are more commonly used in the summer months. Unfortunately, the restrictions imposed in response to the Covid-19 pandemic meant that the caravan checks were impossible for certain periods, but the trailer checks were continued. As a result, the survey period was extended, and the final checks were completed in the summer of 2021.
Trailers and caravans were not targeted for checks, they were chosen randomly. Data was recorded in 2 places; main check details were recorded in the electronic Mobile Compliance System (MCS) and additional details were recorded manually on paper forms that were returned separately. Whilst data from the MCS was available for all checks, due to Covid-19 restrictions forms were not completed for all trailer checks. Of the forms that were received, only 77% could be matched to the corresponding checks in the MCS. This means that results based on data from the forms are less robust than those based solely on MCS data.
In total 3,813 non-testable trailers were checked, of which 730 were caravans. The DVSA guidance on roadworthiness enforcement action is available here: Roadworthiness enforcement action.
DVSA enforcement examiners have powers to prohibit unroadworthy vehicles and trailers which have serious defects under Section 69 of the Road Traffic Act 1988
Prohibition action can be:
- immediate – for defects considered dangerous
- delayed – for serious defects which are not considered immediately dangerous
Drivers can also be advised of less serious defects by an inspection notice.
Please note, due to rounding, percentages given in this report may not sum to 100%.
Trailers up to 3.5 tonnes maximum weight
Trailer defect rates
3,083 trailers (not including caravans) were inspected in the Roadside Inspection Survey. 1,546 of these were found to have no defect and 7 were issued with an Inspection Notice. 1,530 (50%) were found to have a prohibitable defect, either immediate or delayed, with a 95% confidence interval of 47.9%-51.4%.
Figure 1. Severity of trailer defects
| Prohibitions (trailers) | Percentage |
|---|---|
| Delayed prohibition | 9% |
| Immediate prohibition | 41% |
| Inspection notice | 0.23% |
| No defect | 50% |
Proportions of prohibitable defects, by category
The charts below show the defect type of all prohibitions issued to trailers (not including caravans).
If any given trailer had multiple defects, they are all counted in these graphs individually to give an overview of the defects that occurred most frequently. Of the 3,083 trailers that were encountered (not including caravans), 4,031 prohibitable defects were found.1,366 of the prohibitions that were issued for lamp defects were immediate and 95 were delayed.
Of all prohibitions issued, 36% were for lamps and 21% were for running gear.
Figure 2. Defect categories of prohibitions
| Defect category | Percentage |
|---|---|
| Lamps | 36% |
| Running gear | 21% |
| Brakes | 20% |
| Chassis | 10% |
| Bodywork | 6% |
| Suspension | 4% |
| Security of body | 2% |
| Uncategorised defects | 0.55% |
| Electrical | 0.05% |
| Engine | 0.05% |
| Seat belts | 0.02% |
In this chart, running gear includes all tyre defects and chassis includes breakaway cables and towing attachments.
Figure 3. Frequency of defects, by category
| Defect category | Delayed prohibition | Immediate prohibition |
|---|---|---|
| Lamps | 95 | 1366 |
| Running gear | 105 | 753 |
| Brakes | 143 | 671 |
| Chassis | 359 | 41 |
| Bodywork | 205 | 26 |
| Suspension | 131 | 48 |
| Security of body | 0 | 61 |
| Uncategorised defects | 7 | 15 |
| Electrical | 0 | 2 |
| Engine | 1 | 1 |
| Seat belts | 1 | 0 |
Frequency of defects in each category
Within each defect category there is a defect type. The graphs below show the frequency with which each defect type occurred in each of the six categories with the most defects. Of the 1,461 prohibitable lamp defects, 806 were in relation to direction indicators and 537 were in relation to ‘lamps, reflectors and electrical equipment’.
Figure 4. Lamps
| Labels | Total prohibition |
|---|---|
| Direction of indicators | 806 |
| Lamps, reflectors and electrical equipment | 537 |
| Rear position lamps | 109 |
| All lamps | 7 |
| Front position lamps | 2 |
Figure 5. Running gear
| Labels | Total prohibition |
|---|---|
| Condition of tyres | 722 |
| Road wheels and hubs | 88 |
| Axles and stub axles and wheel bearings | 48 |
Figure 6. Brakes figure
| Labels | Total prohibition |
|---|---|
| Service brake operation and performance | 463 |
| Mechanical components | 164 |
| Parking brake operation and performance | 123 |
| Controls | 37 |
| Complete braking system | 8 |
| Brake and adjustment indicators travel s | 6 |
| Additional braking devices and retarders & exhaust brakes | 5 |
| Brake pipes and hoses | 4 |
| Brake systems and components | 4 |
Figure 7. Chassis
| Labels | Total prohibition |
|---|---|
| Coupling on trailer | 359 |
| Chassis and attachments | 26 |
| Trailer coupling | 15 |
Figure 8. Bodywork
| Labels | Total prohibition |
|---|---|
| Registration plates and VIN details | 200 |
| Body panelling | 19 |
| Wings and wheel arches | 12 |
Figure 9. Suspension
| Labels | Total prohibition |
|---|---|
| Anchor and shackle pins | 123 |
| Shock absorbers | 15 |
| General | 14 |
| Springs | 14 |
| Spring brackets | 12 |
| Bonded units | 1 |
Type of use
The usage of the trailers (private/commercial) was recorded on the manual forms. As such, usage information is only available for a proportion of trailers.
537 of the 615 forms matched to MCS data were for trailers. 80% of these were commercial and 20% were private.
Figure 10. Type of use of trailers
| Type of use | Percentage |
|---|---|
| Commercial | 80% |
| Private | 20% |
Defect rate by type of use
60% of commercial trailers had no defect, while this figure was 46% for private trailers. 29% of commercial trailers were issued an immediate prohibition and 10% were issued a Delayed prohibition. For private trailers, 39% were issued an immediate prohibition and 15% were issued a delayed prohibition.
Figure 11. Frequency of defects by type of use
| Types of defect | Commercial | Private |
|---|---|---|
| No defect | 60% | 40% |
| Immediate prohibition | 29% | 39% |
| Delayed prohibition | 10% | 15% |
Trailer type
Of the 615 trailers for which a form was received, construction trailers had the highest prohibition rate, with 52% receiving a prohibition. Flat trailers had a high prohibition rate, but due to small numbers of flat trailers being checked, this result could be spurious.
Figure 12. Prohibition rate by trailer type
| Trailer type | Prohibition rate |
|---|---|
| Construction | 52.0% |
| General purpose | 49.3% |
| Other | 40.4% |
| Agriculture | 32.0% |
| Vehicle transporter | 28.3% |
| Livestock | 28.1% |
| Flat | 55.6% |
Caravans
Caravan defect rates
730 caravans were inspected in the Roadside Inspection Survey. 635 of these were found to have no defect and 10 were issued with an inspection notice. 85 (12%) were found to have a prohibitable defect, with a 95% confidence interval of 9.3%-14.0%.
Figure 13. Severity of caravan defects
| Prohibitions | Percentage |
|---|---|
| No defect | 87% |
| Immediate prohibition | 7% |
| Delayed prohibition | 4% |
| Inspection notice | 1% |
Proportions of prohibitable defects, by category
The charts below show the defect type of all prohibitions issued to caravans.
If any given caravan had multiple defects, they are all counted in these graphs individually to give an overview of the defects that occurred most frequently. Of all prohibitions issued for lamp defects, 83 were immediate and 3 were delayed.
Of all prohibitions issued for caravans, 57% were for lamps and 21.9% were for chassis.
Figure 14. Defect categories of prohibitions
| Defect category | Percentage |
|---|---|
| Lamps | 57% |
| Chassis | 22% |
| Running gear | 11% |
| Bodywork | 8% |
| Brakes | 2% |
| Suspension | 0.7% |
In this chart, running gear includes all tyre defects and chassis includes breakaway cables and towing attachments.
Figure 15. Frequency of defect occurrences
| Defect category | Delayed prohibition | Immediate prohibition |
|---|---|---|
| Lamps | 3 | 83 |
| Chassis | 33 | 0 |
| Running gear | 3 | 13 |
| Bodywork | 10 | 2 |
| Brakes | 1 | 2 |
| Suspension | 1 | 0 |
Type of use
The usage of the caravans (private/commercial) was recorded on the manual forms. As such, usage information is only available for a proportion of trailers.
78 of the 615 manual forms that were matched to the MCS data were caravans. 92% of these were Private and 8% were commercial.
Figure 4.3. Type of use (caravans)
| Type of use | Prohibition of caravans |
|---|---|
| Commercial | 8% |
| Private | 92% |
Data Quality
The analysis has been quality assured by analysts within AAD and is considered fit for purpose.
However, there are some issues that need to be considered:
- the number of non-testable trailers in the country is unknown. Similarly, accurate estimates of distance travelled by non-testable trailers are not available. This means the representativeness of the sample is not known
- the number of trailer checks recorded on the MCS that could be matched to manual returns was limited, partly due to the change in methodology because of the Covid-19 pandemic. As a consequence, any results based on manual returns should be considered indicative rather than comprehensive