|This article needs additional citations for verification. (December 2013)|
The digital tachograph succeeded the analogue tachograph as a result of European Union regulation 1360/2002 that made digital tachographs mandatory for all relevant vehicles manufactured after August 1, 2005. Digital tachographs would be required as of May 1, 2006 for all new vehicles for which EWG regulation VO(EWG)3820/85 applies, as is published in the official newsletter of the European Union L102 from April 11, 2006.
Technical Development Team
The European Root Certification Authority (ERCA) for the EU's Digital Tachograph has been designed, implemented and is currently operated by the European Commission's Joint Research Centre (JRC) at Ispra, Italy. The technical lead for the project in its first incarnation was James Bishop, while Fotios Basagiannis was the architect and lead developer. Roberto Sgnaolin worked on the project as support developer and system administrator.
Digital tachograph system
A digital tachograph system consists of a sender unit mounted to the vehicle gearbox, the tachograph head and a digital driver card. The sender unit produces electronic pulses as the gearbox output shaft turns. These pulses are interpreted as speed data by the head.
The sender unit and head are electronically paired and the pulses from the sender to the head are encrypted, therefore deterring tampering by intercepting or replicating the pulse signal in the intermediate wiring.
As well as automatically receiving speed data, the tachograph records the driver's activity selected from a choice of modes. The 'drive mode' is activated automatically when the vehicle is in motion, and digital tachograph heads usually default to the 'other work' mode upon coming to rest. The 'rest' and 'availability' modes can be manually selected by the driver whilst stationary.
Drivers are legally required to accurately record their activities, retain the records and produce them on demand to transport authorities who are charged with enforcing regulations governing drivers' working hours. Regulation (EC) 561/2006 of the European Parliament and of the Council  defines drivers hours.
Digital tachograph head models
Siemens / Continental VDO DTCO 1381
Stoneridge Electronics SE5000
Efkon Efas 3 / Intellic Efas 4
Digital card types
Driver cards are used by drivers to record driving information.
Company cards are used by operators to retrieve data regarding their employees from the tachograph head. It also allows a company to lock information so that it cannot be subsequently by obtained by another operator.
Control cards are used by law enforcement agencies to retrieve data from the tachograph head. A control card overrides any company locks put in place by operators.
Workshop cards are used by authorised tachograph technicians to fit and calibrate tachographs.
The activity information is stored in the tachograph head’s internal memory and simultaneously onto the flash memory chip contained within the digital driver card whilst it is inserted into the head.
Speed information is also stored, but only on the tachograph head’s internal memory. Speed data is stored in at least 1-hertz intervals, depending on the model of tachograph head.
When either memory bank is full, the oldest data is automatically overwritten with the current data. Design specifications prevent data being altered or deleted, therefore ensuring the integrity of the data for subsequent analysis and presentation in a court case.
Data can be locked in the tachograph head by using a company card. This ensures that the data cannot be retrieved by another company should the vehicle subsequently change ownership, or in the case or lease or hire vehicles that are used by many companies during their life. All data can still be retrieved by use of a control card.
Data is stored as a .ddd file that can be imported into tachograph analysis software.
Advantages over the previous analogue system
The digital data stored by the tachograph system can be analysed by computer and infringements automatically identified.
Digital data is encrypted and cannot be altered or deleted by the driver once stored on the card or in the head.
Information is more explicitly defined in digital form and is less likely to be misinterpreted. When an analogue chart is visually analysed, a margin of error is present, dependant on the quality of the recording and the skill level of the analyst.
Disadvantages compared to the previous analogue system
Without a digital card reader, computer and analysis software, the data can be more difficult to interpret as it is not visually represented as the analogue chart is, and requires mathematical calculations to decipher the information from its presented format. Some Renault branded tachograph heads can produce printed information in a graphical format, similar in appearance to the activity trace on an analogue tachograph chart.
There is no facility to record the start and end locations for each day. Only the country is permitted, except in Spain where the region may also be specified. This causes difficulties for law enforcement agencies in identifying some infringements.
As the information is not handwritten as an analogue chart is, it can be more difficult to identify instances where a driver has used a digital card that belongs to another driver. With the analogue system, law enforcement agencies can be assisted by identifying differing handwriting styles when examining a number of charts purporting to be completed by the same driver.
- http://dtc.jrc.it/erca_of_doc/JRC53429_ERCA_CP_v2_1.pdf European Root Policy
- Regulation (EC) No 561/2006 of the European Parliament and of the Council of March 15, 2006 on the harmonisation of certain social legislation relating to road transport and amending Council Regulations (EEC) No 3821/85 and (EC) No 2135/98 and repealing Council Regulation (EEC) No 3820/85