Monday, 27 February 2012

What if the HSE ran the DfT? part II

In the previous article I looked at the hierarchy of risk control and the sorts of things the HSE might expect to be considered when attempting to reduce risks for cyclists.

In this section we are going to get rather cold hearted I'm afraid. If we are to continue imagining how the HSE might approach the topic of road safety then we must familiarise ourselves with one of the basic characteristics of their method, 'reasonably practicable'.

We would like to prevent all road deaths however it would not be practicable to do so. You would either
  • Have to ban all motorised transport.
  • Spend an incredibly huge amount of money to prevent as many as possible.
The plain fact of the matter is that society doesn't value a life high enough to justify the amount of spending that would be required. When we say value, we mean just that, cold hard cash, a few years ago the HSE did some research and found that we're willing to spend just over £1m to prevent a fatality. Add in the other costs such as emergency services and loss of output and the figure we arrive at is £1,778,000 per non-motorway fatality. The cost of serious injuries is £208,000 and the cost of slight injuries is £22,000. These figures are known as the Value of Prevention of Fatality/Accident. It's a tricky concept, the HSE describes it as...
VPF is often misunderstood to mean that a value is being placed on a life. This is not the case. It is simply another way of saying what people are prepared to pay to secure a certain averaged risk reduction. A VPF of £1,000,000 corresponds to a reduction in risk of one in a hundred thousand being worth about £10 to an average individual. VPF therefore, is not to be confused with the value society, or the courts, might put on the life of a real person or the compensation appropriate to its loss
This spreadsheet kindly tells us how many cyclists are injured. Multiply it all together and the figure we arrive at is £1,067,746,000 quite a large number. I'm willing to agree that approximating a true VPA/VPF figure is very difficult, so if we strip out the guesstimated part for a minute leaving only the actual costs of cycling accidents we get the figure £292,849,372. Of course government doesn't bear all the costs of an accident but eventually 45% of everything flows through the government's coffers, which would be £131m of our £292m. So depending on which figures you choose it would be considered reasonably practicable to spend between £131m and £1.067bn on cycling infrastructure.

Alternatively the HSE might say an amount proportional to the quantity of cycling should be spent, this article says £13.4bn was spent on roads and we know that cyclists account for 1% of distance travelled which means spending should be £134m (remarkably similar to the figure of £131m above). However, the government is trying to encourage cycling so we might expect them to spend a disproportionately high amount on cycling. Rather than distance though we could use a time spent travelling equivalence, in the previous article I used 12mph average speed for bicycles and 30mph for cars, both guesstimates, but it bumps the spending requirement up to £335m, kind of in the ballpark of the £292m mentioned earlier.

Even the HSE might blanche at spending £1bn per year on cycle infrastructure but a lower bound of £130m up to £300m seems reasonable, or indeed, reasonably practicable.When you consider that an accident is money down the drain year after year, but infrastructure spending keeps giving back, year after year and that what is good for cyclist will also be good for pedestrians to an extent, then the figures look even better.


  1. For speed guestimates, the DfT supply average distances driven and ridden per person across the population of GB in 2010.

    Car drivers: 3415.7 miles in 140.5 hours, so 24.3 mph.
    Cyclists: 42.4 miles in 5.4 hours, so 7.9 mph.
    (Distances from DfT NTS0305, time from NTS0310.)

    So the ratio of hours driving divided by hours cycling is 3.08, which is close to your value of 2.5.

  2. Very interesting pair of posts, thanks!