Because there are significant annual variations, we've averaged the red line over rolling five year periods. These are "trailing periods". So take, for example, the 1980 point. It shows that the average fatal rate for '76-'80 (inclusive) was 4% less than the average fatal rate for '75-'79 (inclusive).

The black line is a standard regression analysis to reveal the underlying trend.

The underlying changes are clearly revealed. There's an ongoing trend whereby the fatal accident rate change is fairly steady, and in very much the wrong direction.

Firstly from the third graph, we have reason to believe that the black trend lines in the other two graphs might be reasonable. The real change in trend in red line in the third graph is extremely worrying.

Remembering that the third graph is averaged over 5 years, we can see that the new trend emerged in about 1992 or 1993. The real figure for 1992 is included in the plotted points for 1992, 1993, 1994, 1995 and 1996.

We then should consider what changed in about 1992 or 1993 that could possibly have reversed the previous road safety trends. Speed cameras were first introduced to UK roads in 1992. It's quite possible that the growth of speed cameras (and the attitudes and policies which support them.) are solely responsible for the trend reversals. We obviously haven't proved a causal link, but it's becoming increasingly difficult to imagine any other explanation.

Conclusions and concerns

There are clearly some very unwelcome trends in the accident statistics. For drivers, riders and passengers, it's actually getting more dangerous out there, for pedestrians, it's getting safer (always assuming that that the fall in pedestrian accidents isn't due to them using motorised transport, or being scared off the roads by garbage speed kills publicity.
 

What are the changes causing the road safety trends?

Speed kills changes

Speed cameras
mobile speed traps
loss of traffic police
HGV speed limiters
Traffic calming
 

Now, all these things are supposed to be improving safety. Where the hell is the benefit? The net effect of these changes must be negative, since we know we have improvements in vehicles and roads which have always given us good trends in the past.

Other changes

Ongoing improvements in vehicle safety
Ongoing improvements in road design

We'll be making all this information available, including links to official references sources for the figures, all the graphs and the even the spreadsheet we've worked things out on. It'll take a few days to get this information on-line.

In the meantime, drive carefully and have a great new year.

Paul Smith. 3rd January 2003.