Friday, August 27, 2010

Parking Lots -- Too Big and Too Little

The planned Tavistock development is slated for the upper area of this photograph, to the left of Apopka-Vineland Road and north of the Cascades Publix shopping plaza.  The photo captures a typical day when the half of the parking lot closest to Apopka-Vineland Road (and furthest from the Publix) sits as empty asphalt.  In contrast, St. Luke's Methodist Church, across the street, relies on grassy areas for overflow parking.   

Tavistock is requesting a waiver to remove several hundred parking spaces required under the Orange County Code at a planned development at the southwest corner of Apopka-Vineland and Conroy-Windermere Roads.  Tavistock is justifying the request on the basis that calculations for required parking spaces are based on single use, whereas Tavistock is planning multiple uses that will experience peak hours at different times. 

For example, Tavistock's planned fitness center will generate the most parking in the early morning and evening whereas the bank and office building will generate the most parking during business hours.    Even during the noon hour, when fitness center use increases, total parking generation will not exceed 1,000 spaces, according to a shared parking analysis by the planning firm Glatting Jackson. 

These business should share parking spaces.  To save unnecessary construction costs, every proposed mixed use development should conduct, and the County Code should recognize, a shared parking analysis. 

The County's voluminous parking requirements are based on annual peak demand--for example, the Sunday before Christmas for retail development--which leaves huge expanses of half-empty asphalt 90% of the time.  Our off-street parking requirements are generally too large and denigrate the built environment. 
Typical half-empty parking lot in front of strip shopping center on Hiawassee Road.

Winter Park K-Mart Plaza.  Typical parking patterns with huge expanses of empty asphalt. 

Developers pay for all the extra, unused asphalt, which drives up rent, which increases the cost of goods and services to consumers.  We pay this hidden parking fee everyday.  If the County grants Tavistock the waiver it seeks, it will avoid the cost of building a structured parking garage, which could cost about $10,000 per parking space.  Such a garage would drive up rents and consumer costs. 

I am the first to concede notable instances when we can't find enough parking.  I often find a packed parking lot at The Fountains on Sand Lake Road on Friday and Saturday evenings, when its myriad restaurants (all the same land use) are doing the most business at the same time.  Winter Park Village, on 17-92, historically had insufficient parking at peak shopping and eating times. 

In most instances, however, when we say we can't find parking, we can't find convenient parking within a few hundred feet of our destination. 

ITE Parking Generation Calculations--Voodoo Mathematics

Most local governments base parking requirements on mathematical formulas published by the Institute for Transportation Engineers ("ITE").  For example, a fast food restaurant with a drive-through window must have 9.95 parking spaces per thousand square feet.  Consequently, most suburban 3,000 square foot McDonalds and other fast food restaurants nationwide will have 30 parking spaces--regardless of the availability of transit, walkability from adjacent neighborhoods, or actual experience.  

Donald Shoup, a University of California at Los Angeles professor of land planning, analyzed the ITE requirements and found them statistically indefensible.   ITE bases many of its parking demand graphs on a miniscule number of studies of limited observations in auto dependent environments lacking transit. 

Shoup sharply criticizes the parking requirements for drive-through fast food restaurants.  ITE reports average parking generation of 9.95 spaces per thousand feet.  Shoup argues this precision gives a false sense of mathematical certainty.  A closer look at the ITE graph below (from the 1987 edition of ITE's Parking Generation) shows that the 9.95 average per 1,000 square feet bears no relationship to the wide range of parking demand.  Square footage is a poor basis on which to calculate parking demand.  

ITE plotted peak parking demand on the vertical axis and restaurant square footage on the horizontal axis.  The plotted squares measure the various observations.  The diagonal line marks the average and serves as the basis for the precise 9.95/1,000 square feet ITE parking generation calculation.  Local governments adopt ITE's calculations for maximum, peak demand as minimum Code requirements.  However, the diagonal line bears virtually no relationship to the scattered observations. 

The chart above plots the basis for a regression equation. (Don't let the mathematical term scare you--read on.)  A regression equation measures predictability on a scale of 0 to 1--from zero predictability to complete predictability.  If parking demand truly and absolutely related to square footage, the plotted squares would all fall on the average line and the regression calculation (R squared) would be 1.  If restaurant square footage was a significant, but not exclusive factor in parking demand, the plotted squares would fall near the diagonal line.  However, in the chart above, the plotted squares fall haphazardly all over the chart. 

One of the largest restaurants, at over 5,500 square feet (on the right side of the graph) generated only about 20 full parking spaces at peak hour.  A restaurant more than half as small, 2,500 square feet, generated about 35 full parking spaces, tying for fourth highest on the chart.  The regression calculation on this chart (R squared) stands at an abysmal 0.038--very close to zero.  The line drawn by ITE is statistically indefensible.  In later editions of its Parking Generation book, ITE removed the R squared calculation. 

Our everyday experience confirms that square footage does not necessarily mean more parking usage. Despite voluminous passer-by traffic, most parking spaces at the Burger King at Kirkman and Colonial are empty at dinner time. A parking lot at a much smaller restaurant, the McDonalds on 17-92 in Maitland, is often packed at the same time.   

Several years ago, when Professor Shoup asked ITE to publish his article articulating these deficiencies in its Journal, ITE refused.  I would have preferred to see ITE acknowledge deficiencies and start a dialogue within the transportation engineering community about how to improve the methodology.  I would like to see ITE publish recommendations for shared parking, parking for areas served by transit, transit oriented development, and walkable communities. 

Corporate Demand for Parking Spaces

Developers contend the corporations they want to lure are driving large numbers of parking spaces.  CVS requests 75-80 parking spaces for each store location.  At the Tavistock community meeting last week,  attended by several dozen people, I asked how many people had ever seen 80 people in a CVS.  Not one hand raised. 

Walgreen's at C.R. 535 and Tilden Road in the City of Winter Garden.  Typical pattern--fifteen parking stalls used and more than forty empty.  The store would have more than sixty empty stalls if this were a CVS with the usual 75-80 parking spaces.   

However, even CVS will depart from its prototype.  The CVS in Baldwin Park has a limited number of on-street parking spaces in front and a shared parking lot in the rear, in the middle of block, hidden from street view.

Baldwin Park CVS.  Limited, shared on-street parking in front and a shared parking lot in the rear.

Many corporations have not grasped that half-empty parking lots make their investments appear economically unhealthy.  In the Pine Hills, this contributes to the perception of downward spiraling businesses. 

Strip shopping center at Pine Hills Road and Silver Star. 

In contrast to CVS, Home Depot conducted a study of its stores and, based on the findings, lowered its parking requirement from over 900 spaces to around 540 spaces per store.  Lower development costs can enable Home Depot to gain a price advantage over its closest rival, Lowes. 

Orange County staff has grasped the over-abundance of parking and no longer permits developers to pave more than 10% over the minimum requirement.  The current code hinders shared parking by requiring Affidavits.  As the planning staff works on a Unified Land Development Code, it should incorporate provisions encouraging shared parking, including payment into a fund for shared parking lots, and loosen the virtual prohibition on on-street parking. 

UPDATE 8/29: At last week's community meeting, I incorrectly identified Professor Shoup as from the University of California at Berkley.  He is at UCLA.