Discussions about density, transit, biking, and pedestrians generally center on two issues: the implications for low-income people and environmental impact. Lest we forget the enormous public health implications of these policies, The Economist has some encouraging figures ($):
London’s authorities calculate that if every Londoner switched to walking for trips under 2km, and to cycling for trips of 2-8km, the share who got enough exercise to remain healthy simply by getting around would rise from 25% to 60%. That would amount to 61,500 years of healthy life gained each year.
Obviously, most Londoners are going to have more short trips than most Seattle residents since stuff is simply closer together. And since walking and bicycling are often unsafe in Seattle, collisions with cars while using these modes would probably claw back some of the health gains. But a directed policy of densification and ped/bike safety would have large, positive economic and quality-of-life implications.
In a companion article, the magazine shares a less London-specific finding ($):
Even a little exercise has a huge health effect, whether or not people shed their extra pounds. Research presented on August 30th at a cardiology conference in London suggests that walking fast for 25 minutes a day can buy three to seven years of extra life. A bigger study by a team at Cambridge University tracked 300,000 Europeans over 12 years, and found that a brisk daily 20-minute walk, or the equivalent, cut the annual death rate for people of normal weight by a quarter, and for the obese by 16%. Getting everyone sedentary to do this would save twice as many lives as ending obesity, says Ulf Ekelund, the lead researcher.
Many readers here probably recognize about 20 minutes of brisk walking inherent in their use of transit. I wouldn’t go so far as to say that transit agencies should deliberately increase the amount of walking their customers do — encouraging ridership through practical usability trumps enforced exercise — but sometimes the time penalty of using transit can be a feature, not a bug.