Open, read and convert .DDD files.

What is a .DDD file?

A tachograph is the device in a lorry or bus cab that records driving time, breaks and rest, other work and periods of availability (waiting time you know about in advance, such as waiting while the vehicle is loaded or travelling with it on a ferry), and the vehicle's speed and distance. Each driver also has a driver card: a personal smart card they put in the tachograph while they work. A .DDD file is the download from either the driver card or the tachograph itself, known as the vehicle unit (VU).

Each download is saved as a single file. Some download tools give the same kind of file a different extension, such as .v1b, .c1b or .tgd, and Tachoparser reads those too. Your .DDD files are made by whatever you use to download your cards and tachographs: a card reader, a download key or a remote-download service. If you don't have them, ask whoever does your downloads.

Older vehicles with an analogue tachograph record on paper charts, not .DDD files.

Sources: GOV.UK: tachograph rules

How to open and read a .DDD file

You can't open a .DDD file like a document or a spreadsheet. It is a coded (binary) file in a format set out in tachograph law, so you need tachograph analysis software (sometimes called a DDD viewer or reader) to read it. Opening it in Excel, Word or Notepad won't show you anything you can read. You can't run a .DDD file either: it is data, not a program, so there is nothing to install.

The data is downloaded together with a digital signature, so anyone checking the file can tell whether it has been altered since it was downloaded. Keep the original file safe, even after you've read it.

The simplest way to read one is to run your .DDD files through Tachoparser. Upload them above: before you pay, we show you how many driver-weeks of data they hold and the exact price (from £5). We then turn them into an Excel workbook that sets out the infringements, speeding and driving without a driver card (from vehicle unit files) for each driver and vehicle.

Sources: Regulation 2016/799 Annex IC, definitions · Annex IC 3.18 (downloading)

What's inside a .DDD file?

Inside a .DDD file is a detailed record of who drove which vehicle, when and for how long. What else it holds depends on where it came from: a driver card or a vehicle unit.

Because these files name drivers and show where and when they worked, they are personal data under UK GDPR. A vehicle unit file includes every driver of that vehicle, and a driver card file includes every vehicle that driver used. A vehicle unit download made with your company card (the card, issued by DVLA in your company's name, that acts as the key for downloading the vehicle unit) only includes driver data (who drove, their activities and places) for periods that no other company has locked.

Sources: Annex IC 4.5 (card memory) · Annex IC 3.12 (vehicle unit memory) · Annex IC section 2 (company mode) · GOV.UK: tachograph rules · GOV.UK: responsibilities of vehicle operators · UK GDPR, Article 4

How much data is in one .DDD file?

There is no set length: one .DDD file can hold weeks or many months of data. The law sets how much a driver card or vehicle unit must be able to store and how often it must be downloaded, not how long a file should be.

Driver card files: 28 days is an average, not a fixed length

By law a driver card must have room for at least 28 days of an "average" driver's activity, where an average day has 93 changes of activity. That is a memory size, not a number of days: GOV.UK notes that a card used for busier days may hold less than 28 days of data. It works the other way too. The card only stores days on which it was used, and quieter days take up less room, so a card can cover more than 28 calendar days. The law also only sets a minimum memory size, so some cards hold more.

Each download repeats what is still on the card

Downloading copies the data and never deletes it. So every new download of a card includes all the older days still stored on it, back to the oldest day not yet overwritten. That means a card file can reach back weeks before the period you were asked about, and can include time the driver spent working for a previous employer.

Vehicle unit files: from a single day to a year or more

A vehicle unit must be able to hold at least 365 days of data, covering every driver who used the vehicle. When its memory is full, the oldest data is overwritten. A vehicle unit file can cover anything from a single day to everything stored, depending on the dates chosen when it was downloaded.

How often files must be downloaded and kept

In Great Britain, operators must download each driver card at least every 28 days and each vehicle unit at least every 90 days, and in any case as often as necessary so that no data is lost: a busy driver's card can fill up in less than 28 days. Operators must be able to produce the records to enforcement officers for 12 months. If you use your tachograph data as your working time records, the Road Transport (Working Time) Regulations 2005 require you to keep those records for at least two years.

One vehicle unit file can hold months of data for several drivers, and a card file can reach back to before a driver worked for you. To keep the report, and the price, to the dates you need, set the report period under "About your fleet" in the upload section: we then only report on, and charge for, those dates. The free quote shows how many driver-weeks your files contain before you pay.

Sources: GOV.UK: responsibilities of vehicle operators · Annex IC 4.5 (card memory) · Annex IC 3.12 (vehicle unit memory) · Regulation 2016/799 Annex IC, definitions · Regulation 165/2014, Article 33 · Road Transport (Working Time) Regulations 2005, regulation 11

Been asked to send tachograph data to the DVSA?

Send the original .DDD files, but check what's in them first: you are handing over everything each file contains, not just the dates or the driver you were asked about. Don't try to edit or cut the files down: they are digitally signed, so any change shows. Send them exactly as they were downloaded.

What DVSA asks for, and why

DVSA can legally require you to hand over tachograph records and downloaded data. If an examiner sends you a written notice, it says where to send them and must give you at least 10 days. Not handing over tachograph records when an enforcement officer asks is an offence with a level 5 fine: the highest band on the standard scale of fines, with no upper limit in England and Wales.

When the law talks about "downloaded data", it means these files: downloading is defined as copying the data together with its digital signature. A report or spreadsheet made from the files is not the same thing, so if you're asked for your digital data, send the .DDD files themselves.

A request can also list other records. In one published Traffic Commissioner decision, DVSA's letters asked for "documents, data, records, and reports". Send everything the request lists. (Traffic Commissioners license and regulate the operators of lorries, buses and coaches.)

What your files will show

• Every driver in a vehicle unit file, by name and card number, not only the driver being checked.
• Every change between driving, other work, availability and rest: the record that drivers' hours rules are checked against.
• Driving without a driver card (from vehicle unit files): times the vehicle was driven with no card inserted.
• Over-speeding events recorded by the vehicle unit (the most serious one on each of the last 10 days they happened, and the 5 most serious in the past year).
• Older days still stored on a driver card, which may fall outside the period you were asked about.

These files are personal data about your drivers. Send them only to the officer who asked for them, in the way they asked.

See what you're sending before you send it

Upload the same files here first. Before you pay, the free quote shows how many driver-weeks of data they hold. For £1 per driver-week (minimum £5), Tachoparser then gives you an Excel report of the infringements, speeding and driving without a driver card (from vehicle unit files) in them, so you know what the files show before anyone else looks at them. Then send the original .DDD files as requested, not our report, unless you are asked for a report as well.

Tachoparser is an independent service run by Fleet Transport Consultants Ltd. It is not affiliated with or endorsed by DVSA. This page is general information, not legal advice: always follow the wording of the request you received.

Sources: Regulation 165/2014, Article 33 · Transport Act 1968, section 99ZA · GOV.UK: enforcement and penalties · Sentencing Act 2020, section 122 (standard scale) · LASPO Act 2012, section 85 · Regulation 2016/799 Annex IC, definitions · Traffic Commissioner decision: Nirwan Ltd (2022) · GOV.UK: Traffic Commissioners · Annex IC 3.12 (vehicle unit memory)

Check your .DDD files