### Acceleration and Braking

*SatSafe* is powered by Quartix, the market leading teematics technology which is currently used by some of the UK’s leading insurers including The AA, Swinton Insurance, The Co-Op, Hastings, Sheila’s Wheels and Sabre Insurance.

The tracking device monitors the speed of the vehicle every 32/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.

### 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 a driver using harsh acceleration regularly the 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 a vehicle is driven for 2 hours, and during that time there are 20 level 1 accelerations (severity 0.2) and 15 level 2 accelerations (severity 0.5) then the acceleration index is (20×0.2+15×0.5)/2 =5.75 This is a relatively low index, showing modest acceleration.

### Driving Style Score

The Driving Style Score is the overall score out of 100 for a given period, typically a day, a week or a month. The system will add up all 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 the score. So if a driver has an acceleration index of 10 and a braking index of 6, the average is 8. The Driving Style Score is 100-8, i.e. 92/100.

### Distribution of Daily Driving Style Scores

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

The calculation of the acceleration and braking indexes and hence, the driving style score, are based on a ‘per hour’ calculation. Calculating the average per hour means that no drivers are penalised for driving more or less than any other driver.

The system calculates the Daily Driving Style Score for each day, based on the amount of driving for that day or shift (excluding any parts of trips before the start or after the end of the day/shift). We apply colours to the Daily Driving Style scores as shown on the plot below. If the score is >80 it is green, and this represents the best 30% of drivers. If the score is between 50 and 80 it is shown as amber, and this represents the middle 50% of daily scores. 50 or below is red, and that’s the worst 20%.

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