"By 2017, the City of Portland will have experienced a net positive return on investment in its bicycle infrastructure of $500 million in healthcare savings and $200 million fuel savings."
Gotschi, Thomas. Costs and benefits of bicycling investments in Portland, Oregon. Journal of Physical Activity and Health, 2011,8 (Suppl 1), S49-S58.
via oregon metro regional active transportation plan, aug. 2013 draft, pg.19.