The central tenet of their article is that any potential economic benefit of higher speed limits is likely to be outweighed by the adverse effects on health.
To try and get a handle on the adverse health effects, they postulate (and work hard to exaggerate) these:
- Greater casualties on the road. They quote a US study which showed a 16.6% increase in deaths when speed limits were increased. They postulate that this could be due to both greater traffic and greater collision risk.
- Greater emissions
- (Potentially) greater obesity as more people take to the cars, rather than walk.
Surely the point of speed limits and travel is not to minimise road casualties. If that were true, this study suggests that only men between the ages of 25-44 should drive as they are the safest in terms of casualties per 100,000. Actually, an even better way to minimise traffic casualties is to shoot babies at birth in the delivery suite - that would reduce road casualties by 100% in due course.
And surely no sensible person is going to really think that increased speed limits would have an impact on obesity! Where is the evidence?.
Of course, they acknowledge that there may be some benefits. The only one they mention of course is widely positioned as "economic benefits." The two particular areas of economic benefit that they note are freight transport (the benefits to which they dismiss contemptuously saying that HGVs would continue to have a 60 mph speed limit); and small vehicles transport - where they do not see any impact on journey times (as most small vehicle transport happens during the busiest times, they claim, when there will not be an impact from higher speed llimits).
Doctors who - after 6 and more years of training - cannot master public health, cannot be expected to understand the basic tenets of economics. MM would like to point out that economic benefits of higher speed limits accrue to consumers as well as producers. These include leisure travellers, sunday drivers and everybody else. Economic benefits are the sum of consumer and producer surpluses (not just the latter as these authors seem to believe).
And even the benefits to producers cannot be quantified by theoretical argument. It is an empirical question. That these proposals have resulted in such voluminous coverage, and as they would have the impacts on casualties that the authors believe show that we may expect higher speed limits to alter behavoiur and travel times. And therefore the economic benefits are likely to be substantial - and need to be shown empirically.
That is the central point that is missed by these authors. That you need empirical evidence both for the benefits as well as the costs. You cannot conclude an argument purely by juxtaposing an estimate of one of the costs (casualties) with a flimsy theoretical dismissal of the benefits, coupled with shroud waving over obesity.
Only if they have such evidence can they write "In the light of this evidence, it is difficult to see the proposal to raise the speed limit as anything other than a populist gimmick . . ." Without it, this is just a rhetorical device.
And once these benefits have been shown, the choice should not be left to some paternalist, confused public health doctors; but voters.
Lastly, I cannot rest without pointing out that "extending coach and bus lanes on motorways during busy periods or subsidising rail fares" are not really alternatives. They require more money. They are alternatives in the same way that Buckingham Palace is an alternative to a terraced house in Tottenham. Clearly the former is a place where Militant Manager would be comfortable; but it is only the latter that she can afford.
Overall, I cannot see how the BMJ can take itself seriously when it publishes such drivel.
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