Unaccounted mileage...  Missing mileage...

Unaccounted mileage... Missing mileage...

Tuesday 1st February 2022


Marc Caplin, Aquarius IT's Compliance Advisor, discusses how unaccounted mileage differs from missing mileage, and why in either instance, it's the operator's responsibility to ensure that all data is downloaded.

When it comes to vehicle data downloaded from a digital tachograph, there are some keys things that operators need to actively monitor. These include vehicle over-speeds, unaccounted vehicle movements (where the vehicle has been driven with no driver card used), and missing mileage.

In the days of analogue, missing mileage had to be investigated by an operator manually leafing through reams of paper charts, carefully comparing start and end odometer readings. The introduction of digital tachographs in 2006, thankfully, changed all that and, with the aid of the appropriate software, the process of analysing a vehicle's missing mileage became a lot easier.

But let's pause for a moment, because although developments in technology may have converted scruffily scribbled odo readings written on old paper charts into a stream of 1s and 0s, there are a few things that an operator needs to consider when dealing with missing mileage.

Firstly, what do we mean by "missing mileage"?
In the "good old days", if there was a difference between the end odo reading of one chart with the start odo reading of the next one along, chances are the vehicle had been moved without a chart in. Nowadays, when we refer to "missing mileage", the details of which are usually presented by an operator's tachograph analysis software, the situation is not always so clear-cut. When dealing with digital tachographs, there is a clear distinction to be made between mileage that is unaccounted for through vehicle usage and data that is actually missing from your tachograph analysis system.

Unaccounted mileage
Let's examine each scenario in turn, starting with the more conventional mileage that has been accumulated through vehicle usage. We should more correctly term this type of data as "unaccounted mileage".

  • 1. Perhaps the vehicle has been moved for a short distance around an operator's yard or other private premises. These short periods of unaccounted mileage of perhaps one or two kms can be easily cross-referenced as they will usually be accompanied by similarly short periods of unaccounted vehicle movement which have been recorded on the tachograph memory. In addition to the vehicle's odometer readings, the tachograph will record the amount of time that the vehicle has been driven with no card inserted which will marry up with any unaccounted mileage. We are very often asked what an acceptable single instance of unaccounted mileage is deemed to be in this scenario and the answer can vary depending on who you ask. As a rule of thumb, anything more than 5km should be investigated but some operators will err on the side of caution and investigate anything over 3km. Many operators will assume that anything less than this must be yard shunting or other similar activity but sometimes assumptions can carry an element of risk!

"As a rule of thumb, anything more than 5km should be investigated but some operators will err on the side of caution and investigate anything over 3km"

  • 2. Alternatively, unaccounted mileage may be recorded due to a vehicle being driven without a driver card quite legitimately for up to 15 days if a driver is awaiting a replacement card due to their original being lost or stolen or has developed a malfunction. In this scenario, the guidance is very clear - the driver should generate a vehicle printout at the start of their duty period and one at the end, both of which should carry the driver's personal details on the back. These should then be treated like any other tachograph record and carried with the driver for 28 days and handed in to the operator accordingly. This unaccounted mileage, of which there would be a considerable amount, can then be viewed within your tachograph analysis software and, in most cases, can be supplemented with explanatory notes and copies of any relevant printouts.
  • 3. A third cause of unaccounted mileage may be caused by workshop activity; a vehicle may have been moved by a mechanic as part of routine maintenance. In our experience, some mechanics and fitters use driver cards and some do not. These types of occurrences can be easily accounted for using maintenance records with notes added to your analysis system.
  • 4. Lastly, and let's face it the real reason enforcement authorities ask operators to analyse this information in the first place, unaccounted mileage can be caused by drivers using their cards "creatively". It is a source of constant amazement to us that, despite all the technology fitted to modern vehicles, some drivers still seem to think they can disappear into thin air simply by removing their driver card. Despite operators' best efforts, nestling in the bowels of their analysis software there will often be an instance of a driver pulling the card out in an effort to get back to base when they have run out of time, or to generally swerve some sort of infringement. This sort of activity is actually quite easy to detect as it will not only create a variance in odometer readings, it will also generate a clear instance of unaccounted vehicle movement expressed as a period of time. Some systems, such as our own ClockWatcher Elite, will display this information graphically making it easier for operators to investigate; others will produce this data in the form of unaccounted mileage and unaccounted vehicle movement reports which can then be cross-referenced. Either way, the data is there - it is down to the operator to check, if found, debrief these types occurrences appropriately.

So, there are some instances where unaccounted mileage might occur - let's look at mileage information that is actually missing.

Missing Mileage
I could, at this stage, disappear down a technical rabbit hole and go into great detail about which part of the vehicle file is used to calculate unaccounted mileage (don't worry, I won't) but in short, unaccounted mileage is calculated by lining up successive vehicle files and looking at insertion and ejection records therein.

In addition to the more conventional reasons, we have looked at above, sometimes vehicle data can actually be missing from an operator's analysis software. It is not uncommon in cases where a missing vehicle record which spans a number of weeks for unaccounted mileage records to be several thousand kms. This is because an analysis system is trying to compare the last ejection record contained within a vehicle file with the insertion record of next one along which may have arrived several months later. Vehicle data can go missing for several reasons.

The most basic reason is that data has not been downloaded in time; perhaps the operator has left it too long between downloads and the configuration of their chosen download device does not look back far enough in time. This is not something we routinely come across as most operators we speak to will download their vehicles monthly in line with current advice from Traffic Commissioners. In any event, most download devices will have a full download facility which will look back across a longer period which should fill in any gaps.

Data gaps are not confined to manual download methods, however; sometimes operators that use remote download technology may also experience disruption to their data from time to time. Although they save huge amounts of time and manpower, automated systems should not be taken for granted. Operators should run unaccounted mileage reports regularly to detect conventional instances of unaccounted mileage, but also to detect any technical issues which, if found, should be reported to their download provider.

Very occasionally, unaccounted kms can also be generated due an error within the data itself. For example, if your analysis system receives a vehicle file which does not contain the relevant parts of the record needed to compare odometer readings the system may produce an unexpected unaccounted mileage result. As these anomalies can often originate from within the tachograph, it would usually involve more in-depth investigation to determine the cause.

In our experience as analysis providers, one of the first things we check for when presented with one of these "gaps" in data is the status of the vehicle's Company Card lock. Issues surrounding Company Cards are probably worthy of their own article but, in brief, if a vehicle has been temporarily locked in to the incorrect Company Card for a period and is then locked back in using the correct one, there will be a gap in the data that can only be accessed by carrying out a download using the "wrong" card. A legitimate example of this could be:

• Vehicle is locked in by the original operator using CARD A.

• At a later point, the vehicle is hired out to another operator who uses CARD B.

• The vehicle is returned to the original operator who locks it back in again using CARD A.

The operator will not be able to access the period locked in under CARD B, creating a gap in data that can sometimes be represented by tens of thousands of unaccounted kms.

This can also happen inadvertently, especially in larger operations with multiple sites; a vehicle may be sent to the nearest depot for download but, as the organisation's Company Cards might be registered to individual operating centre with different Company Card numbers, all that happens on arrival at a different operating centre is that previous data is locked out. Some analysis systems will allow examination of the Company Card lock status which can be useful in this scenario.

What is clear is that, regardless of the cause of an operator's unaccounted mileage, there is the expectation that operators should be scrutinising this information and clamping down on areas such as unaccounted vehicle usage and drivers removing cards when they shouldn't. It is also worth bearing in mind the above scenarios where data is actually missing as it's an operator's responsibility to ensure that all data is downloaded, so the relevant steps should be taken to resolve any technical issues.