ABSTRACT
The Role of Safety Targets The whole concept of risk and safety analysis is predicated on the notion that there is some level of risk exposure that is acceptable. I do not intend to contradict this. However, there are difficulties with having a fixed line in the sand that mandates that one side is safe and the other side is not. This is very difficult to justify and control. Consider for a moment the concept of road traffic speed limits. Irrespective of what they actually are in your country and the units of speed used, what is the purpose of them, what is the implication of driving above them? Are speed limits the marker between safe and unsafe driving speeds? That certainly appears to be a correct interpretation. But as we have seen in the previous chapter, having a universal speed limit for road users has not equalised the accident rates for each user type. If you do believe that speed is a/the major contributor to road traffic accidents, it might be prudent to have different speed limits for each road user type, with three wheeled motor vehicles having the lowest limit. Indeed this sort of thing is already happening with large heavy trucks – the larger and heavier the truck is, the lower the speed limit is. This is not necessarily declared on the roads and highways, but on the rear of the vehicle in question. These limits and other ‘safety targets’ are fixed points along the scale of risk by which people can assess performance. In a few examples there are legislative implications for exceeding a safety target, but may be better described as safety limits – as in the fines that are administered for (being caught) speeding. So it is essential to realise that safety targets are not safety limits. Targets may be exceeded, but there are implications for doing so - extra regulation, additional impact reduction measures, limits on the operational capability. In the UK, it is not uncommon for pedal cyclists to be cautioned and fined for travelling too fast. When using motorised two-wheeled vehicles on the roads in the UK, it is mandatory to wear a crash-helmet, this is not the case for un-powered cycles, even though on down-hill sections, near equivalent speeds can be reached – so I’m told of course! Setting a Safety Target There are several ways of setting safety targets, and for each safety case the scale used and the specific points of good and bad need to be defined. These fundamentals are absolutely essential.
