Distance from home
From Wiki
Distance from home is a measure built into MAST which is based on a calculation of the distance in kilometres between a crash location and the home address of each person involved. MAST aggregates all the results of this calculation, and expresses them as averages for all individuals included, summarised by dimensions as required.
MAST has calculated distance from home for both drivers and casualties.
Viewing Distance from home values
In any Vehicles or Casualties report, simply change the measure to Average Distance From Home.
Interpreting Distance from home values
Absolute average distance from home values are often not very meaningful in themselves, especially over large sample sizes. The value of this measure lies principally in identifying and examining cases which differ significantly from relevant norms.
It is also important to understand that distance from home is likely to vary considerably between crashes on different classes of road. It will also differ between modes of transport, taking into consideration vehicle types and casualty class.
The following table contains the overall national average distance from home values for all casualties by vehicle type, casualty class, road class and road environment, in cases where all relevant data is known. These values can be considered as a fair indication of typical values, and comparable figures for more restricted aspects of road risk are often best interpreted by considering by what percentage they vary from these norms.
| Road Class | M | A and B | Other | All | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Casualty type | Urban | Rural | Overall | Urban | Rural | Overall | Urban | Rural | Overall | Overall |
| Motorcycle User | 32.6 | 49.9 | 46.8 | 9.7 | 26.1 | 16.0 | 5.4 | 11.2 | 6.9 | 13.4 |
| Car User | 37.2 | 61.3 | 58.1 | 11.1 | 25.9 | 18.6 | 7.3 | 12.9 | 9.2 | 18.3 |
| Bus User | 67.7 | 139.1 | 133.8 | 7.6 | 25.2 | 10.3 | 5.7 | 13.2 | 6.6 | 10.9 |
| Goods Vehicle User | 53.9 | 76.6 | 74.4 | 22.1 | 44.2 | 36.5 | 13.8 | 23.4 | 18.1 | 37.8 |
| Pedal Cyclist | 4.0 | 7.2 | 5.6 | 5.2 | 11.7 | 6.4 | 2.9 | 8.7 | 3.8 | 5.1 |
| Pedestrian | 16.6 | 48.0 | 39.2 | 7.4 | 16.2 | 8.7 | 6.0 | 11.6 | 6.7 | 7.6 |
| Overall | 38.0 | 63.1 | 59.8 | 10.1 | 26.3 | 17.3 | 6.5 | 12.8 | 8.2 | 16.3 |
It may also be worthwhile to capture similar norm values for specific localities, so that different road risks can be assessed relative to local norms. This is particularly important in areas which are unusually densely or sparsely populated.
Calculation algorithm
The method of calculation for each individual is as follows:
- MAST checks if a valid postcode was recorded for the individual in STATS19, and if so looks up the NSGR of the centre point of that postcode
- MAST checks if the NSGR supplied for the crash location in STATS19 falls within the National Grid
- If both these NSGR references are valid, the distance between these two points is calculated using Pythagoras' theorem; these results are then aggregated in the measure to calculate an average
- If either or both NSGR references are suspect or missing, then that individual is entirely excluded from calculation of the average
