A great place to park a tree

Philadelphia's ample expanses of blacktop
offer a greening opportunity

Philadelphia Inquirer
Wednesday, June 9, 2010

By Thomas Hylton

Parks and Recreation Commissioner Michael DiBerardinis has said he wants 300,000 more trees planted in Philadelphia by 2015, increasing the city’s canopy from 15 percent to 30 percent over the next two decades.

Here’s a good place to start:  parking lots.

Surface parking lots cover an enormous amount of land in urban areas, from 18 percent in New York City to more than 80 percent in downtown Los Angeles.  Philadelphia and its suburbs have thousands of asphalted acres dedicated solely to cars.

Because we must provide parking for cars at every possible destination, we’ve created far more parking spaces than we have cars.  That means most parking stalls are empty most of the time – an enormous waste of space.

Parking lots are not only land consumptive, they’re ugly, and they’re bad for the environment.  Among other drawbacks, their black expanses of asphalt absorb the sun’s rays in the summer, making hot cities even hotter.  The storm water runoff they generate is so harmful and costly to manage that the city will start taxing it in July, based on impervious surface area.

But parking lots can be transformed into green spaces through the creative use of trees.  Simple geometry  makes this possible:  The footprint of even a humungous tree seldom exceeds five square feet, but its trunk can rise up five stories and unfurl a canopy the breadth of a house.  If necessary, shade trees can be distributed throughout a parking lot without sacrificing a single parking space.  (More about this later.)

Even a cash-strapped city like Philadelphia can get started simply by adopting an ordinance to require shade trees in all new and expanded parking lots.  In 2003, my town of Pottstown adopted a new ordinance for parking lots requiring one tree for every two parking spaces, evenly distributed throughout the lot.  Seven years later, it’s showing some tangible results.

Earlier this month, the Montgomery County Community College held a dedication ceremony in for a new parking lot at its West Campus in Pottstown – an unusual observance even in our car-crazed society. What was so special?  Trees.

The parking lot is a brownfield reclamation project, and it has green features like LED lighting and bioswales to absorb storm water runoff, but its most prominent feature is the shade trees – 130 of them, in a lot with spaces for 202 cars.  Thirty years from now, the college’s daily assembly of hardtops will be softened by a blanket of green.

When our ordinance was first passed, it was greeted with considerable skepticism and derision.  We were accused of trying to create a forest where it doesn’t belong.  But trees belong wherever people live and work.  Fortunately, we got a big boost almost immediately from the Montgomery County Housing Authority, which built an exemplary parking lot in a prominent downtown Pottstown location.
 
When a new McDonald’s Restaurant was proposed, the owner wanted more parking and fewer trees than our ordinance called for.  But we compromised on a plan that placed the restaurant – distinctively designed -- close to the street with the parking to the side and rear, with one tree for every three parking spaces.

Often, the major objection is a loss of parking spaces.  That was the case with the recent expansion of our hospital’s parking lot.  But when cars face each other in a double row – a typical configuration – there is an open space where the front car fenders come together.  That corner can accommodate a five-foot-square pit for a tree without intruding on the area where people enter and exit their cars.  Using that design, our hospital was able to add 22 trees without sacrificing any parking spaces.

Of course, there is no more hostile environment for a tree than a parking lot.  Most tree species won’t get close to their natural size in one, but we’ve had great luck with London plane trees.   People complain about their falling seed balls and peeling bark (neither of which harm cars or people), but planes grow big and strong – and like the Timex watch, they can take a licking and keep on ticking.

Everybody loves parks, and trees are a way to create a park-like environment throughout our urban areas.  While the suburbs boast horizontal green spaces, urban areas can enjoy vertical ones with the generous use of trees.
 
Goethe exhorted us to encourage the beautiful, because the useful encourages itself.  Trees in parking lots help us do both.