Guide 19. How to Calculate Vehicle Safety Inspection Frequencies

Maintaining the safety and roadworthiness of vehicles is a cornerstone of compliance for any operator holding an Operator’s Licence in the UK. One of the most crucial elements in achieving this is ensuring that vehicles are inspected at appropriate intervals. But how do you determine how frequently these inspections should take place?

In this post, we’ll break down the key factors that influence inspection intervals and show you how to calculate a schedule that keeps you both compliant and safe.

Why Safety Inspections Matter

Regular safety inspections (also known as Preventive Maintenance Inspections or PMIs) are essential for identifying wear and tear, mechanical issues, and any other problems that could lead to vehicle failure. They form part of your commitment to the DVSA’s Guide to Maintaining Roadworthiness and can directly affect your OCRS score and risk of enforcement action.

Factors That Affect Inspection Frequency

The frequency of inspections is not a one-size-fits-all calculation. Instead, it’s based on several key variables:

1. Vehicle Mileage

Vehicles that cover high annual mileage will typically experience more wear and tear. The more miles a vehicle covers between inspections, the higher the risk that faults could develop unnoticed.

Rule of thumb:

• High mileage (e.g., >100,000 miles per year): PMI every 4-6 weeks

• Medium mileage (e.g., 50,000–100,000 miles per year): PMI every 6-8 weeks

• Low mileage (e.g., <50,000 miles per year): PMI every 8-12 weeks

2. Age of the Vehicle

Older vehicles generally require more frequent inspections due to increased likelihood of component degradation and age-related faults.

Recommendations:

• New vehicles (<2 years old): May be inspected every 10–12 weeks, if supported by low mileage and good condition

• Middle-aged (2–5 years): 6–8 weeks

• Older vehicles (5+ years): 4–6 weeks, especially if used intensively

3. Type of Work / Use

Vehicles engaged in heavy-duty or stop-start work (e.g. refuse collection, urban delivery) endure more strain and require closer monitoring.

Examples:

• Construction or off-road use: Inspection every 4 weeks or less

• Urban delivery with frequent stops: Every 6 weeks

• Long-haul motorway use: 8–12 weeks may be acceptable, based on vehicle condition

4. Operator Risk Profile

The DVSA may expect higher standards from operators with previous compliance issues, new licences, or adverse OCRS scores.

5. Manufacturer Recommendations

Vehicle manufacturers may provide guidance on inspection frequencies for different operating conditions. While not mandatory, these should be considered as part of your risk assessment.

6. Trailer Use

Don’t forget trailers – they must be included in your inspection programme, and the same principles apply.

Calculating Your Inspection Interval

Here’s a step-by-step guide:

Step 1: Assess annual mileage

Estimate how many miles each vehicle will cover annually. Divide this figure by 52 to get a weekly mileage.

Step 2: Estimate wear rate

Use your knowledge of the vehicle’s age and application to determine if wear is low, medium, or high.

Step 3: Consult the DVSA inspection frequency guide

Refer to the DVSA’s Guide to Maintaining Roadworthiness. It includes example frequencies for different scenarios and vehicle types.

Step 4: Set an initial inspection interval

Choose a starting point (e.g., every 6 weeks), then adjust based on performance and history. Keep a risk-based approach in mind.

Step 5: Monitor and review

Use maintenance records and defect reporting to monitor how well your chosen interval is working. If defects are frequently found, consider reducing the interval.

Minimum Inspection Frequency (DVSA Guidance)

The DVSA suggests the maximum inspection interval should not exceed 13 weeks. However, many operators choose much more frequent checks due to the nature of their operations. Regular safety inspections are in addition to daily walkaround checks.

Example Scenarios

• New 44-tonne tractor unit used for long-haul:

  • Low wear, high mileage: 6-week interval

• 7.5-tonne rigid in local delivery work:

  • High wear, stop/start use: 4-week interval

• 10-year-old tipper working on construction sites:

  • Very high wear: 3–4-week interval

Recording and Evidence

Always document your PMI schedule in your maintenance planner and ensure all inspections are logged, with reports retained for at least 15 months. This helps demonstrate your commitment to compliance during audits or DVSA investigations.

Final Thoughts

Calculating the correct frequency for vehicle safety inspections isn’t about ticking boxes—it’s about ensuring your vehicles stay roadworthy, your drivers are safe, and your business remains compliant. Use a risk-based, evidence-led approach, and be prepared to adapt your schedule as vehicles age, workloads change, or DVSA guidance evolves.

Keeping inspection intervals under review is good practice—and a key step in running a compliant and professional operation.