The Track24 DriveSafe Score is a way of taking all the sensor data from each vehicle in a given calendar month, and combining them into a single score that gives a measure of the overall performance of a driver. Based on the score, we then classify the drivers into three groups to further indicate in a qualitative and approximate way which drivers may need coaching or further investigation, or else which drivers are thought to be driving sufficiently safely.
CAUTION: The Track24 DriveSafe score is an indicative and approximate measure of safety only. It should form part of a variety of driver safety measures including adherence to national standards and regulations, seatbelt usage for both driver and passengers, driver safety training, driver coaching, vehicle maintenance, and driver fatigue avoidance. We also encourage actions to reward drivers for sustained good driving rather than exclusively intervening for poor driving.
The DriveSafe Score
The DriveSafe Score is intended to be a simple, explainable, reproducible measure of driver safety and is defined in the following way:
DriveSafe Score = (Number of Harsh Braking x Harsh Braking Weight +
Number of Harsh Acceleration x Harsh Acceleration Weight +
Number of Harsh Cornering x Harsh Cornering Weight +
Total Time Speeding/10s x Overspeeding Weight)/
Total Weight/(Total Distance/100km)
In words, this equation says that the DriveSafe Score is a weighted sum of the total number of Harsh Braking, Acceleration and Cornering, plus the total time speeding (in intervals of ten seconds), all divided by the total distance driven (by each vehicle or driver) in distance intervals of 100 km.
Example 1: A Driver A who speeds for 80 seconds and drives 200 km in one month would receive a DriveSafe Score of one (assuming all weights set to the default value of one).
Example 2: Driver B who speeds for 160 seconds and drives 400 km will also receive a DriveSafe Score of one.
Example 3: Driver C who harsh brakes sixteen times and drives 200 km will receive a DriveSafe Score of two.
The higher the DriveSafe Score, then the higher the rate of exposure to risk, as measured by the speed and acceleration.
CAUTION: These three examples illustrate how the DriveSafe Score is a ‘rate’, normalised by distance driven, which helps to make comparisons between different drivers who may drive very different total distances. This also means that while Driver A and Driver B both receive the same DriveSafe Score, Driver B is actually exposed to a greater quantity risk than the first driver. This means that the total distance driven is also an important parameter when considering the total risk exposure of a driver.
Adjusting DriveSafe Score Parameters
DriveSafe has three different types of parameters to adjust.
- The weights (default value of one).
- The minimum distance driven in order to be classified (default value of 80 km).
- The classification thresholds (described below).
In the absence of any other reasons, we recommend setting the default value of the weights in the DriveSafe score to one. Changes in the weights change the relative importance of the different contributors to the DriveSafe score and will affect its final value.
Example 4: The overspeeding weight is adjusted from a value of one to a value of 1.6 in keeping with company policies to tolerate less speeding than previously. All other weights are reduced to 0.8. Driver A in Example 1 above now has an increased DriveSafe Score of 1.6 while Driver C’s score is now 0.8.
The minimum distance driven to be classified sets the distance scale below which a driver will not be classified, with a default value of 80 km in each reporting period. This is to ensure that a sufficient amount of data is collected in order to make a fair assessment of the driver.
Example 5: Driver D drives 1 km in one month and during that journey overspeeds for 10s. Their DriveSafe score is 100. Because they have driven less than 80km, then they are not classified using the Red-Amber-Green.
CAUTION: For unclassified drivers, we recommend looking at other metrics, such as the Maximum Speed, the total time speeding (not the total time speeding per 100km), or the total number of harsh braking events (not total number per 100km). In future versions of DriveSafe we will look to improve the handling of these ‘low mileage’ drivers.
The classification thresholds control how the DriveSafe Score is converted into a ‘Red-Amber-Green’ classification. The default DriveSafe thresholds are:
- DriveSafe threshold for Green is 1.
- DriveSafe threshold for Amber is 4.
- All other classified drivers with DriveSafe Score greater than ‘threshold for Amber’ are shown as Red.
The thresholds can be adjusted according your the safety and coaching needs.
Example 6: Drivers E, F and G have DriveSafe Scores of 0.5, 1.5, and 4.5 respectively, and have all driven more than 200 km in a month. They are classified as Green, Amber and Red respectively.
CAUTION: The DriveSafe Classifications are intended to give an indication of which drivers have the highest rate (per 100km) of risk exposure. Drivers of all classifications should be carefully evaluated.
It is important to note that the 'Green' Classification does not require the driver to attain a DriveSafe score of zero. We do not recommend setting threshold for green close or exactly to zero in order to allow for a margin of error in the data, or to allow for occasional instances when the driver takes defensive actions and so has a legitimate reason for, for instance, Harsh Braking.
Changes to these parameters will only affect the current calendar month’s classifications and do not act retrospectively to previous months. Our intention here is to avoid ‘moving the goalposts’ and so that company priorities for the future can be clearly communicated to drivers for subsequent safety campaigns, or if it is desired to gradually ‘ratchet down’ the classification thresholds.
Changes to these parameters will be logged in the Settings pages.
DriveSafe device specific parameters
The overall intent and future direction of our DriveSafe Score is to give a consistent picture, regardless of the device type that is being used (Rhino, Jackal, Lynx, Dongle or Smartphone).
In the case of the Rhino, and the Dongle, there are currently a couple of approximations that we need to make for the total time overspeeding calculations.
Specifically, the total time speeding for the Rhino and Dongle must be approximated as the number of overspeeding alerts times a duration. This duration can be approximated as being the reporting period of the device (for long distance speeding). It could also be set to a value of 10 seconds to implement 1 unit of overspeeding per overspeeding message.
In the case of the Jackal and Lynx, the device sends the overspeeding start and end times, and so no approximation is necessary.
This approximation for should be borne in mind when evaluating the DriveScore results.
We plan to improve the Dongle and Rhino in the future, in order to remove this approximation.