Economic Transport

This tweet came to me via my local bicycle lobby group:

'Every bicycle km ridden saves society 25 cents in the dollar, every car km driven costs society 60 cents in the dollar' Jan Gehl

So the author is an architect, with experience developing public spaces. His emphasis is for a more compact people friendly environments. A resident of Copenhagen, who advocates the bicycle front and center in urban planning. But where do these figure come from?
 
Well I've heard some good statistics that may give this claim weight. Such as:

• The cost of 1 km of highway can build 200km of bike path
• Cyclists halve their risk of coronary heart disease
• The average american spends more on car transportation than they do on food.

But when the above areas of the economy (Health and Transportation), account for only about 12% of GDP, these numbers start looking shaky.

So much of the benefits of a truly cycle friendly city verge on the intangible. How much would people pay for clean air, or a more sedate, human centric public thoroughfares. I know the city's personality would change, but would economic prosperity?

Property values are at premium prices along bike paths, crikey! This is not a saving, its more like a cost!

The numbers just don't add up! Help!