Also discussed here: Cars and Robust Cities Are Fundamentally Incompatible(Chris McCahill and Norman Garrick, The Atlantic Cities, Feb 12, 2013)
And here: How too much parking hurt cities(Norman Garrick and Chris McCahill, Better Cities and Towns, Feb. 12, 2013)
Today we review a study that compares a number of mid-sized cities and the impact that the amount of parking space available has on the economic and by inference, the environment, by its effect on the number of people who chose to commute by car. The study also looked at the effect of cities that increase or reduce the parking available. The results indicate that the percent of people who drive increased by 10% if the parking increased by 2,500 sq. meters per 1000 people. Downtown space – as much as 20-30 % of the urban area- that could have been used for people to live and walk to work is used for parking cars. Cities with abundant parking space encourage more people to drive than use public transit- the option of choice for low income population. Cities than have reduced the amount of parking have seen significant economic improvements for downtown businesses as well as less traffic and less pollution. If demand pricing (for parking rates as we have seen in San Francisco or for peak road use as we have seen in Stockholm) is added along with reduced parking space, it would seem to further encourage the shift from driving to transit and walking.
Key Quotes:
“on average each increase of 10 percentage points in the portion of commuters traveling by automobile is associated with an increase of more than 2500 m2 of parking per 1000 people and a decrease of 1700 people/km2”
“cities with higher rates of driving have fewer people – a difference of more than 4,000 people per square mile for each 10 percent change in automobile use….this has to do with the amount of land used to move and store all those cars”
“the amount of land used for parking is a key indicator of how seriously automobile infrastructure has impacted an urban environment”
“In cities with higher rates of automobile use ..about twice as much land is committed to parking for each resident and employee…Driving increased for people commuting in and out of the city by more than 30 percent. But even for shorter trips within each city, driving increased by as much as 45 percent”
“The combined effects of improved convenience for drivers, a degraded walking environment, service cuts to public transit and the physical separation of residential and commercial areas were forcing city-dwellers into cars. “