Tachograph analysis is how an operator proves it manages drivers’ hours rather than just hoping nobody breaks them. You download the data, run it through analysis software, read what the software flags, and then deal with every infringement through a documented process. Get that loop right and a DVSA audit is a non-event. Get it wrong and the data becomes the evidence against you at a public inquiry.
I have managed fleets where the tachograph data was sitting in a drawer, undownloaded, for months. When DVSA asked for it, we could not produce it. That single failure tells a Traffic Commissioner more about an operator than any amount of polished policy. Below is how tachograph analysis actually works, what the law requires, and how to run an infringement process that stands up to scrutiny.
Why tachograph analysis matters more than the rules themselves
Most operators know the headline drivers’ hours limits. A daily driving limit of 9 hours, extendable to 10 hours twice a week. A 45 minute break after 4.5 hours of driving. A weekly limit of 56 hours and 90 hours across any two consecutive weeks. Daily and weekly rest requirements on top of that.
Knowing the rules is not the point. Demonstrating that you check whether drivers follow them is the point. The tachograph records what the driver actually did. Analysis is the act of comparing that reality against the law and acting on the gaps. When a Traffic Commissioner asks “how do you manage drivers’ hours,” the honest answer is “I download the data on schedule, I analyse it, I record the infringements, and I deal with the drivers.” That is what tachograph analysis is. It is your evidence, not a box-tick.
Download frequency and the law
Two separate legal duties apply. The first is downloading the data on time. The second is keeping it. Under retained EU Regulation 165/2014 you must download the driver card and the vehicle unit at set maximum intervals. Miss those intervals and you commit an offence regardless of whether the underlying driving was clean.
The driver card stores roughly 28 days of activity before it starts overwriting the oldest data, which is why the 28 day download rule exists. The vehicle unit holds far more, but you must still pull it at least every 90 days. Many busy multi-drop operators download more often than the legal minimum precisely because high activity fills the card faster.
| Item | Maximum download interval | Minimum retention |
|---|---|---|
| Driver card | At least every 28 days | At least 12 months |
| Vehicle unit (VU) | At least every 90 days | At least 12 months |
| Analysed reports and infringement records | n/a | At least 12 months (keep longer in practice) |
| Driver records carried at the roadside | n/a | Current day plus previous 28 days |
The 12 month retention point catches operators out. You keep the raw driver and vehicle data, the analysed output, and the infringement paperwork for at least a year, and you must be able to hand it to DVSA on request. A driver, separately, must be able to produce a full record of activity for the current day and the previous 28 days at a roadside check. Those are two different obligations and both have to be met.
How analysis software works and what it flags
Analysis packages such as Tachomaster, TruTac and Smartanalysis do the same core job. You import the digital download files, the software reads the activity blocks (drive, other work, availability, rest), and it measures them against the drivers’ hours and tachograph regulations. It then produces a report listing every breach, the driver responsible, the date and the severity.
Good software does more than count hours. It cross-checks the vehicle unit against the driver card so you can spot a vehicle that moved without a card inserted. It reconciles odometer readings to expose distance the driver cannot account for. It tracks the calendar so you know which cards and units are overdue for download before you breach the interval. Treat the software as a tool that surfaces problems. It does not manage them for you. The judgement, the driver conversations and the corrective action are still yours.
The main infringement categories
Almost everything the software flags falls into one of these groups. Knowing the category tells you how serious it is and how to investigate.
- Driving time. Exceeding the 4.5 hour limit before a break, the daily 9 or 10 hour limit, the 56 hour week or the 90 hour fortnight.
- Breaks. No break, a break that is too short, or a split break that does not meet the 15 then 30 minute pattern.
- Daily and weekly rest. Insufficient daily rest, a reduced weekly rest taken when it was not permitted, or a missing compensation period.
- Missing mileage and unaccounted time. The odometer shows distance travelled with no driver card recording it, or there is a gap in the activity timeline.
- Mode and manual entries. The driver left the tachograph on the wrong mode, failed to record other work, or made manual entries that do not reconcile with the rest of the day.
The first three are about driving too long or resting too little. The last two are about the record itself being incomplete, and they are the ones DVSA examiners scrutinise hardest because they can hide deliberate falsification.
Investigating missing mileage and unaccounted time
Missing mileage is the gap between the distance the vehicle physically travelled and the distance recorded against a driver card. If a vehicle’s odometer moved 40 miles but no card was inserted for that movement, the software flags missing mileage. It almost always has an innocent explanation, but you have to find it and record it.
Common causes I have investigated over the years include a fitter or yard shunter moving the vehicle without a card, a driver pulling onto a weighbridge or moving to fuel without inserting their card, a card fault, or a genuine forgotten insertion. The serious version is a driver deliberately driving on rest by removing the card to hide the activity. Your job is to establish which it was.
A workable investigation runs like this:
- Pull the vehicle unit data around the gap and identify the exact start and end odometer readings.
- Check who was rostered to that vehicle and ask them directly what happened.
- Cross-reference fuel receipts, weighbridge tickets, gate records or telematics for the period.
- Record the explanation in writing, attach the evidence, and have the driver sign it.
- If there is no innocent explanation, treat it as a potential falsification and escalate.
Unaccounted time is the same principle applied to the clock rather than the odometer. A gap where the card shows nothing has to be explained as rest, other work recorded elsewhere, or a missed manual entry.
Manual entries and the ‘other work’ rules
When a driver inserts the card at the start of a shift, the tachograph asks them to manually enter what they did since the card was last removed. This is where other work, availability and rest before driving get captured. Drivers get this wrong constantly, and wrong manual entries produce phantom infringements that waste your time and real ones that hide.
The legal position is that all working time has to be accounted for. Other work (loading, paperwork, a second job) must be recorded, not left as a gap. Drivers must hold a full record of activity for the current day and the previous 28 days, covering driving, other work, periods of availability, breaks, rest, and annual or sick leave. DVSA actively enforces complete records for that whole window, not just the days the driver was driving. Train drivers to make accurate manual entries every time and most of your “infringements” disappear, because they were never breaches, just bad data entry.
Running an infringement process
Flagging an infringement is the easy part. What a Traffic Commissioner wants to see is the process that follows it. An infringement with no recorded action is worse than no detection at all, because it proves you knew and did nothing.
A defensible process has these stages:
- Report. Produce the infringement report from the analysis software, ideally on a regular weekly cycle so nothing ages.
- Driver sign-off. Put each infringement in front of the driver, capture their explanation, and have them sign to confirm they have seen it.
- Categorise and respond. A one-off two minute break overrun is a verbal word. A repeated pattern is a formal warning. Decide proportionately and record the decision.
- Escalation. Build a clear ladder: verbal, written warning, retraining, disciplinary. Apply it consistently across all drivers.
- Retraining. Where the cause is knowledge or habit, deliver and document targeted training, then check the next download to confirm it worked.
The thread running through all of it is documentation. Every infringement, explanation, signature and action recorded and retained.
Worked example: a 4.5 hour driving overrun
The software flags driver J. Patel for driving 4 hours 58 minutes without a break, an overrun of 28 minutes on the 4.5 hour limit. You print the report. At sign-off the driver explains he was caught in a motorway closure with nowhere to stop and took his break the moment he cleared it. You check the vehicle unit and the location data, which confirm stationary traffic at that time. You record this as a genuine but explained infringement, note the mitigating circumstance, have the driver sign, and take no disciplinary action. If the same driver overran three times in a month with no such reason, the same flag would instead trigger a written warning and a refresher on break planning. Same infringement, different response, both fully recorded. That contrast is exactly what good management looks like.
Records, retention and what good looks like at audit
At a DVSA audit or a public inquiry, the examiner is testing one thing: do you have a working system. Strong operators can put their hand on the last 12 months of raw downloads, the analysed reports, the infringement log with driver signatures, evidence of escalation and retraining, and a download schedule that has never been breached. They can show that missing mileage was investigated, not ignored, and that manual entry errors were corrected through training.
Weak operators have gaps in the downloads, infringements with no recorded action, no driver sign-off, and no answer when asked who checks the data. The data is identical in both cases. The difference is entirely in the analysis and the process wrapped around it. For the wider picture of how this sits alongside your other duties, see our guide to drivers’ hours and tachograph rules and run through the operator licence compliance checklist to confirm nothing else is slipping.
Frequently asked questions
How often must I download tachograph data?
The driver card must be downloaded at least every 28 days and the vehicle unit at least every 90 days under retained Regulation 165/2014. Busy operations often download more frequently because the driver card overwrites older data once it fills.
How long must tachograph records be kept?
Operators must keep the raw driver and vehicle data, the analysed reports and the infringement records for at least 12 months and produce them to DVSA on request. Separately, a driver must be able to show activity for the current day and the previous 28 days at the roadside.
What is missing mileage on a tachograph?
Missing mileage is distance the vehicle physically travelled, shown by the odometer, with no driver card recording who was driving. It usually has an innocent cause such as a yard move or a forgotten card insertion, but every instance must be investigated, explained in writing and retained as evidence.
What are the most common drivers’ hours infringements?
The most frequent are break failures (no break or one that is too short after 4.5 hours), daily driving overruns, insufficient daily or weekly rest, missing mileage, and mode or manual entry errors where the driver did not record other work correctly.
Do I have to make drivers sign their infringements?
There is no single statutory wording, but driver sign-off is expected good practice and is what DVSA and Traffic Commissioners look for. It proves the driver was made aware, captures their explanation, and shows you ran a managed process rather than simply detecting breaches.
How ETM helps with tachograph analysis and drivers’ hours
Running tachograph analysis properly takes time, software and someone who knows what a flag actually means. Many operators do not have that capacity in house, and a missed download or an unmanaged infringement log is exactly what undermines an otherwise good fleet at audit. External Transport Manager connects you with verified transport managers and compliance specialists who handle tachograph downloads, analysis and infringement management as part of their service, so the data is read, the gaps are investigated and the paperwork is ready if DVSA ever asks. If you want that managed properly, start a support request and we will match you with someone who does it every day.