There was a programme last night on BBC 5 about railway safety. It was "Built by disaster", in the Megastructures series. The thesis, illustrated by the accidents at Eschede, Gare de Lyon and between Perth and Dundee, was that railway safety had improved as a result of detailed investigation of railway accidents.

That is hardly news, and certainly unarguable. It was put rather better and less emotively in L.T.C. Rolt's book, "Red for Danger", first published in 1955 and still in print.

There were however a number of points about the programme which were debateable.

The first part reviewed the Eschede disaster. A broken wheel on one of the leading vehicles damaged a set of points: because of this, the front bogie of one carriage followed one line and the rear bogie followed another. Travelling broadside on, the carriage demolished a road bridge and the rest of the train piled up into it. An Alstom speaker highlighted the safety features of the new AGV train, and it was said that these design improvements made the AGV significantly safer than the ICE, the train involved at Eschede. No doubt true. But if the same thing happened to an AGV - if it hit 300 tonnes of bridge at 200 km/h - no amount of crumple zones, planned deformation and finite element analysis would save the passengers.

The second point is that of responsibility in reporting. Any reporter discussing railway safety risks influencing people to use roads - and these are dramatically less safe. Last night's programme did not make this point. There was an interesting symmetry a few years ago. In Great Britain, 3740 people were killed on the roads. The 5-year average number of fatalities among rail passengers was 3.74 - one-thousandth of that.

This leads to a third point. Any railway accident is thoroughly and comprehensively investigated and examined by experts - both within and independent of the rail industry. The results are published: lessons are learnt and effectively are imposed on railway companies. If the same thing was done for road accidents, we would live on a safer planet. This kind of investigation has been done for railway accidents since the 1840s, so all of the low-hanging fruit has long since been picked: the same is emphatically not true of road accidents.

Finally, what is safety worth? Would people pay for safer travel?

Safety is pretty low on most peoples shopping lists - if it wasn't, they'd never travel by car. Safety is a low priority even when choosing a car - partly because it's a given, partly because "It won't happen to me", and partly because there are more interesting things to look for.

John Adams' book, "Risk and Freedom", is very instructive here - read it.

After one rail accident in the 1980s was investigated and a long and expensive list of recommendations published, one prominent railway manager commented that, "There was no point in having a railway system so safe that no-one could afford to use it".

Railways are exceptionally safe. The transport system as a whole is significantly less safe, because of the lack of attention to road safety. If we wish to improve transport safety, that is where we need to focus. Programmes like this do not contribute to that end.