3 comments on “Drive Slower

  1. The relationship between speed and deaths is a very non-linear curve.

    You are of course entirely right but based on your 1000+ number and the reference to the freakonomics article I am guessing everyone is mostly advocating the reduction in speed to 55. However if we want to find the sweet spot for saved lives the greatest reduction comes when dropping down to the 40-45 mph area. So if going from 55 to 45 saves 1000, going from 55-45 saves many thousands. Once you get down to 40 mph with the current safety features in the cars, death becomes a much more remote event in any crash. So anyone advocating for a reduction in speed based on lives saved cannot simply stop at 55. It really doesn’t make much sense to go to 55 when 10 or 15 mph more gets you a massively more significant increase in lives saved.

    However I doubt anyone would seriously consider dropping the speed limit on rural interstates to 45 or 40 (40 is the minimum now, not the maximum).

  2. The safety features in the best cars currently being sold, or the ones in the cars currently on the road? I suspect there are enough low-safety cars being driven that reducing the speed limit below 40 would save lives.

    Anyone who thinks that if a regulation saves lives, that’s sufficient reason to enact the regulation, ought to support reducing the speed limit to at least 40. I prefer to evaluate regulations by criteria more like “maximise economic efficiency”, which probably implies a more modest reduction in speed limits.

  3. You need the quantify the cost in lives of reduced economic productivity when you lower the speed limit. I think a usual figure is $1M per life. So if reducing the speed limit reduces productivity by $1B, you’ll end up breaking even. If more, you’ll end up losing more lives than you gain.

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