I’ve been playing a game this summer when driving to this or that shopping mall.  Park int he shade.  Inevitably, the one or two parking spaces with any trees at the edge have been taken, so I park the car near the edge, in the vain hopes that my errand will take long enough for the sun to actually  move in the sky, cooling my headlights briefly before I have to get back in  the roasting car for the trip home.

Visiting downtown, where there is damned little foliage between concrete and glass buildings on concrete sidewalks and streets, I make a point of walking on the south side of streets, even if my meeting is on the north.  That side is shaded by the buildings along the sidewalk, and is ten degrees cooler there.  I’ll sometimes get the glare from a glass building shining upon my sidewalk, but it carries no heat.

Biking in the summer can be a chore.  Not just from the traffic and the act of peddling up and down hills, but from the sun’s heat and glare on the open road.  The shortest route between 2 places, an arterial built for traffic with multiple lanes of fast traffic, is usually full of fast traffic and bereft of shade.  Trees near the roadway are only collision hazards for cars leaving the road and visibility impediments to important directional and informational signs.  A road with a clear zone is a pleasant thing to drive in traffic, but kinda excruciating to drive on a bike.

GreenMap
Forest and Plain Land Use (2006 MRLC)

Shade is valuable to biker and a walker in a way that it is not to traffic.  Shade represents poor light conditions for traffic, including Bus Transit.  A beautifully hypnotic condition is the strobe effect of a fast moving car through dappled shade, which produces a rapidly flashing effect on the windshield.  Highway engineers the world over see trees too close to the roadway as a hazard, and work to maintain a “clear zone” of nothing but sun-swept lawn around their roadways.  Great for traffic, terrible for walkers and bikers.  Rail transit moves the same no matter what the shade is from trees, The leaves of deciduous trees do make the rails slippery and can stall trains on hills every fall without constant clearing of the tracks by beleaguered operations staff.  

At the beginning and end of every traffic trip is a parking space, a 9×18 foot paved rectangle of black asphalt or rarely gravel.  Shade switches from a hazard for the traffic journey to an asset for the parking station.  The reason there isn;’t a lot of shade on most parking lots is that builders are in the forest-clearing business, not the forest-growing business.  The only reason a developer would put trees, and not parking lots, in their parking lot, is if they were getting some kind of stormwater, noise, or other credit for them.  You see many more trees in parking lots in Florida.  Water is more precious there.

sac_pkglot_solar-shade_vs_trees_2

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