OK, now this is another weird bit from the bbc.
http://news.bbc.co.uk/1/hi/health/7266687.stmFirst, how can this "health boost" be unexpected? Since the effect is at the moment purely speculative, it is predicted by a model. That's pretty much the definition of "expected" to me... What would be unexpected is if the model were violated, which will of course be nigh-impossible to evaluate.
But even so, the benefit is a total of 1888 years of life amongst 7M residents since 2003. Uhhh... Crunching this down we get a spectacular benefit of 0.59
hours of life per person, per year of living in the city. Since living in a city in the first place has undoubtedly a much greater negative effect, this is straining at gnats.
The other reasons for the traffic tax are probably reasonable (I support one for nyc for many reasons), but supposing that I were to spend 30 years commuting in London, I think trading off 0.59h*30=about-half-a-day of my life to save about £2000*30*($2/£1) = $120K... you'd be insane not to do it.
I wish that we could come up with consensus measures for "happiness" (which would account for unjust-feeling adversities such as cancer and depression but not some ridiculous mean effect). The traffic tax would certainly help with happiness (hopefully), at least in the big picture. And if it didn't, we could scrap it. Then we wouldn't have to bullshit ourselves about living an expected 16 extra hours.
It reminds me of this, also British; there would be American examples but we don't give even an illusory damn about our wellbeing:
http://www.stat.columbia.edu/~cook/movabletype/archives/2005/12/the_ministry_of.html