Steve Kidd 002454726 Geo0sk TRAN2050 Transport Tutorial

Activities carry risk, and our behaviour ideally should reflect the cost effectiveness of those risks. As humans though, we may

• Not estimate the risk accurately (e.g. Drive the car to Spain instead of the aeroplane)
• When risk is remote, discount it (Drive to the newspaper shop)
• When risk is prominent, over estimate it (Buy a gas mask)
• Discount risks to others (Install Bull Bars on Four by fours)
• Take risks!

In most natural human activities, natural selection has endowed us with a remarkable facility to instinctively avoid danger (although remote risk leads to our habit of 'sufficing', e.g. living on flood plains and under volcanoes).

The travel culture of the last 170 years has introduced elements of risk which are completely foreign to the human psyche. Despite overwhelming factual evidence, we not only participate in, but are actively, constantly and successfully encouraged to take, risks which might be considered prohibitive in other activities.

We still speak in terms of 'accidents' in transport, which in itself diminishes the comprehension of risk. Words stop short of describing how dangerous travel is, and for now we can only describe motorised travel as 'incomprehensibly' dangerous.

Before we describe risk numerically it is important to understand the nature of safety in travel. Two risks exist

• Risk to the user (hitting a tree in a car head on would be dangerous for the driver and passengers of the car) i.e. Internal
• Risks to the non user (being the tree is inherently non hazardous until the car enters the equation) i.e. external

Likewise walking in itself is a comparatively risk free activity, the ostensible benefits of which far outweigh the danger, but pedestrians are statistically more at risk than car users only because of the car users.

In any assessment of transport risk it is vital to bear this in mind. Unfortunately it is all too often ignored, and where there may be an overwhelming perception of victim in, for instance, a child being crippled for life by a land mine, the same child who runs in front of a car is often regarded as a litigant for the drivers insurance company.

We will consider, for the sake of simplicity,

9 modes of transport (TWMV = Motorbike)

Assume a serious injury to cost £100,000

Assume a slight injury to cost £10,000

Assume the ratio of Fatal:Serious:Slight injuries to be 1:10:100

Therefore each death indicates a cost of £3,000,000

Though not precise, these generalisations are close enough to illustrate well

Time is largely an internal cost and so we will use a distance coefficient to assess risk

When Cost per Kilometer (pence) = C

Fatalities per 1 x 10⁹ km = F

and each fatality costs 3 x 10⁸ p

Again for the sake of simplicity this is a general, but indicative assessment. Where two or more modes are involved in an injury it is assumed that the costs are entirely the cost of the less vulnerable user. E.G. if a HGV runs over a pedestrian the costs to the pedestrian are caused by the HGV. Although blame may be apportioned to either party, it is obvious that the very existence of the wagon does the damage.

Modes of travel were placed in a group of 'vulnerability'.

1. Pedestrians
2. Cyclists
3. TWMV
4. Enclosed Motor vehicles

It was taken that when two modes were involved in an 'accident' that the higher numbered mode 'took the blame' for risk. We can see from Appendix table 3 that some casualties are sustained by less vulnerable users in 'accidents' with more vulnerable users. These have been discounted for

The risk burden was calculated by regarding involvement with other groups, i.e.

half casualties with same group

+ All casualties with less vulnerable user groups

Divided by casualties involving group

All subtracted from unity (casualties involving group)

The 'risk to other users' was calculated by

casualties with more vulnerable users

+ half casualties with own group

Divided by casualties involving group