Driving Style calculations explained

Acceleration and Braking

The Quartix system monitors the speed of your vehicles every second, and the acceleration and braking indexes are calculated from the number of times per hour that the speed changes by more than a given amount between one second and the next.

These are then weighted according to how severe they are, and averaged over a driving hour to calculate the acceleration index and the braking index.
The speedometer (above image) shows the 10 levels of acceleration and braking, each level has a weighting based on its severity. For example, if the speed increase by 6 mph in a second, that is a level 3 acceleration. If the speed decreases by 9 mph that is a level 3 braking and so on.

Calculating Acceleration and Braking Indexes

The acceleration index is the sum of all the acceleration incidents, each multiplied by their severity and finally divided by the driving time in hours. A driver with modest acceleration will show an acceleration index of about 1 to 20 per hour, and for drivers using harsh acceleration on a regular basis their index will be 50 or more.

The braking index is worked out in a similar way, except that the levels of speed change are slightly different as are the severity weightings.

Example: If your vehicle is driven for 2 hours, and during that time you have 20 level 1 accelerations (severity 0.2) and 15 level 2 accelerations (severity 0.5) then your acceleration index will be (20x0.2+15x0.5)/2=5.75. This would be a relatively low index, showing a modest acceleration.

Driving Style Score

Your driving style score is the overall score out 100 for a give period, typically a day, a week or month. Our systems will add up all of the weighted acceleration and braking events with their severities, calculate the total driving time and work out the acceleration and braking indexes. The average of these will then be subtracted from 100 to give you your driving style score. 

For example, if you have a driver with an acceleration index of 10 and a braking index of 6, the average for this driver would be 8. This drivers driving score would be 100-8 equally a score of 92.

Distribution of daily driving style scores

The graph below shows an analysis of 830,000 trips pulled from our trips database for a range of customers, giving scores for 64,000 'driver days'.

As referred to in the above section on accelerating and braking indexes the driving style scores are based on a 'per hour' calculation. Calculating it in this way means that no drivers are penalised for driving more or less than any other driver.

Our systems calculates the driver score each day based on the amount of driving for that day or shift. We apply colours to the scores as shown in the graph above. If the score is >80 it will be green which represents the best 30% of drivers. If the score is between 50 and 80 it will show in amber, this represents the middle 50% of daily scores. 50 or below is red, which represents the worst 20%.

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