This month another batch of road casualty data was published by the Department for Transport. Grouped by Police Force Area, it comprises the most recent twelve months figures for each area up to January 2015. I have extracted the following graph, comparing the area surrounding Bristol (the Avon and Somerset Police Force Area) with Gloucestershire (because we are neighbours) and with eight other (mostly urban) areas where the largest cities can be found. Have a look first and see what sense you can make of it and what questions it raises.
The per capita columns, in red, warn us that London had the worst odds for anyone wanting to avoid injury in 2014 while the green columns suggest they also have the best odds for avoiding death.
Gloucestershire stands out as having by far the worst record for road deaths per one thousand people and being one of only three areas (along with Avon and Somerset and Nottinghamshire) where fatalities are disproportionately high when set against figures for all casualties. The contrast between Gloucestershire and London (The Metropolitan and The City of London Police Force Areas together) is striking. In Gloucestershire fatalities make up a much bigger share of the road carnage than is the case in London.
Beyond these simple generalisations there are only questions and guesses. I think I would be going to Gloucester and to Bristol (and Nottingham) and asking to see data on every fatality for that 12 months and asking what design suggestions emerge from the forensic evidence. Are any related to road layouts? To speed? To surfaces, signage or sight-lines? If carelessness is involved could the road or its immediate environment have reduced the danger of someone being careless another occasion?
I have one other thought arising form this graph and that is that however unreliable the data for injuries are, we can probably treat data on fatalities as highly reliable. We know that a lot of casualties go unrecorded, even when injuries are sustained but deaths are different. Areas that have what appear to be relatively (rather than absolutely) high on fatality rates might simply be under-reporting slight (and even serious) casualties.
Mostly, I wonder if anyone knows of research that analyses the lessons learned from road fatalities or the effectiveness of actions that have been taken as a result?