‘Parking Availability Bias’

Driving home from the Yale event last night (which was packed, and filled with all kinds of interesting traffic types, ranging from Norman Garrick to Anne Lutz Fernandez), as I was listening to various renditions of La Boheme on Doug Fox’s wonderful program (Mr. Fox, I didn’t catch the details on that second act), which I discovered for the first time, a warm presence amidst the eerie fog-tinged, arc-lighted Stygian gloom of I-95, I was thinking back to Donald Shoup’s reply to a question I had posed to him, which itself was related to Brian Pijanowski’s study of parking-lot sprawl in Indiana. Despite a huge and quantifiable overabundance of parking in the county he studied, he was interested to note that people still complained “there wasn’t enough parking.”

I asked Shoup, who of course from the groves of academe has helped ignite a quiet but fomenting revolution in parking policy, to what extent this question of perception in the parking equation had been studied or quantified — keeping in mind that perception is a crucial, if often under-appreciated part of the traffic/planning nexus (e.g., commute times, etc.). One part of Shoup’s answer stuck with me: He talked of studying a parking garage in West Hollywood. On the bottom floors, there were cars, and in the empty spaces, plenty of oil stains to indicate past users. On the upper floors, he noted, it looked as if the spaces had never been graced by a single car. And yet the word from drivers was that there was ‘nowhere to park.’ But the problem, Shoup noted, is that drivers’ perception parking supply is informed by the parking spaces they can actually see. Call it “parking availability bias” (ode to Tversky and Kahneman). And the spaces that are most easily seen, of course, are curb spaces, hence the importance of rational market pricing policies to ensure turnover and vacancy. A few empty spaces (15%) can go a long way.

This perception is a powerful force and leads cities into all kinds of policies that turn out to be misguided and rife with unintended consequences; take the “free holiday parking” approach. Towns hoping to lure shoppers downtown, away from the big boxes, offer up free parking. But beware the power of incentives: Given that many of the best parking spaces in front of local businesses are often occupied (it happens right here in Brooklyn) by the store keepers themselves, the free parking bonanza ends up actually enticing local employees (who would have parked elsewhere or not driven) to grab some free real estate for the day — leaving would-be shoppers with the perception (all-too-real in this case) that there’s ‘nowhere to park.’ Here’s how it went down in Providence.

This is a case where ITS may prove quite useful: Let the algorithms, not fallible human perception, guide the driver to the (properly priced) parking. In the meantime planners and politicians should take parking complaints with a healthy dose of salt.

This entry was posted on Wednesday, January 20th, 2010 at 9:00 am and is filed under Parking, Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

20 Responses to “‘Parking Availability Bias’”

  1. Brent Says:

    I’ll admit to being confused and frustrated in many parking garages by the apparent lack of space. Much of it is just getting to know the garage, but unless I visit a place regularly, that’s not much of an option. In recent years, however, I’ve seen an increase in useful displays to find parking. A couple of malls (here in Los Angeles) have entry billboards showing remaining spaces on each floor — higher floors typically have more — while another has put up a green/red light system above each space (look for green). These systems probably go far towards countering the bias you mention, and certainly reduce my frustration.

  2. Rick Steele Says:

    The Baltimore Washington International airport has a fantastic approach to this problem. Each parking spot in their garage is metered and when you approach the garage it tell you how many spots are available and signs guide you right to open spaces. The perception of “no parking” is completely avoided by broadcasting the EXACT number of spots and direction to each spot. It is a terrific customer experience. See

    Great talk night Tom!

  3. Josh R Says:

    My method for finding parking at a mall or big box store.

    1. Go to the section of the lot that’s furthest from the door, if in a parking garage, go to the top.

    2. Park in one of the many empty spaces.

    People get into this strange “hunter” mode when looking to park and it colors their perception. Of course it’s going to seem like there’s “no parking spaces” if you’re hell bent on finding a spot as close as possible to the door, and you spend 10 minutes circling to find one. If your objective is just to find somewhere to leave the damn car so you can get on with your day, then there are tons of spaces available.

  4. Jan Says:

    Brent: “A couple of malls (here in Los Angeles) have entry billboards showing remaining spaces on each floor”

    Here in the Netherlands, it is not uncommon to find signs all across cities that indicate the parking garages with the most free spaces. In my own city of Breda, a system is currently being installed that even guides drivers who just exited the highway to the roads that lead to the garages with most spaces. The system should be up and running in february or march. I am very curious about how good it will work, considering the current situation where everybody keeps queueing in front of the garage that is closest to the city center…

  5. Rob B. Says:

    I live in a New York suburb with about 12,000 people, and not-so-great downtown. There is much talk about building a garage in the middle of downtown to be used as a “last resort” reservoir for those that cannot find a curb space.

    Opponents of the garage have documented lots of open curb spaces during regular business hours, and think the garage will be an eyesore and a huge waste of money.

    Are there cheap systems that can alert drivers to open spaces along curbs?

  6. Ian Turner Says:

    In the UK, most city centers have signs indicating the number of spaces available at nearby garages. This not only avoids cruising for spaces, it also avoids the “Parking Availability Bias” you suggest.

  7. MU Says:

    I’m sure a lot of this is that the available spaces are not visible. But I also know many people who will circle for 5 minutes to avoid a 2 minute walk from the top floor or more distant lot. I think it is a psychological result of the driving experience. Once you can step out your door and into the car, you expect the same experience at the destination. And the expectation of “having to walk” becomes perceived as more of a burden that the extra time hunting for a close spot. Laziness breeds laziness.

  8. Dave Says:

    In Portland, we apparently have some of the lowest downtown parking costs in the country, and the result is that often all the parking is literally full, and you have to drive to the roof of the parking garages to find open spaces, or park 5 minutes walk from where you want to be. I think a certain amount of making parking less available to people (by reducing quantity and increasing price) is actually beneficial to those who really need to be driving, since it will help to keep the “I *could* ride the bus or my bike, but driving is so convenient” people out of the downtown parking.

    It’s been interesting to watch as we have replaced curbside parking spots here and there all over the city with bike parking corrals (20-25 bikes in 2 car-parking spots, by the way, and that’s low-density bike parking), and in most places, those bike parking corrals are often at 75% capacity or more (at least, from my own anecdotal experience). It just furthers the idea of “if you make it convenient, they will come” – whatever the means of getting there.

  9. RSR Says:

    I recently parked in a downtown garage in Philly. It was a design where the route wound up through the floors on one series of ramps and back down a different series of ramps. All the spaces on the inbound up ramps closest to the elevators were densely occupied, with some cars stopped and waiting for a soon-to-open-up spot.

    Meanwhile, I noticed that the outbound, downward ramps were virtually empty. We went up one more floor, through a pass to the downward side and back down to prime real estate right next to an elevator.

    Without prior knowledge or some thought to look at the exit side of the system, you wouldn’t really have any information about the availability of ‘prime’ parking in the garage, even though there was an abundance of it.

  10. Juan de la Cocina Says:

    5 minutes? Waaaah!

  11. Tony Zbaraschuk Says:

    The other thing to keep in mind is that in many parking garages (particularly older ones) it may take several minutes to maneuver the car up the ramps and into the (hypothetical) upper-level slot. Easier just to move on in search of another spot.

  12. Paul Johnson Says:

    The bike corrals are high density bike parking. It’s just not feasible to park more than two bicycles in a 4’x6′ area and still have room to lock and unlock the bike, as well as enter or exit the rack without damaging your bike or someone else’s, which is why after many studies, Portland designed it’s own cheap, effective, “staple” rack and lines them up in such a manner to encourage people to park parallel to the rack. Those MUNI racks you see in most places (but are starting to get phased out in favor of the cheaper, more effective staple racks) are just plain garbage all around. You can either park the direction they were designed to park in and risk potentially severe damage, or park parallel to the rack and reduce the rack’s capacity by 8-12.

  13. Dave Says:

    Juan de la Cocina: I’m not saying a 5 minute walk is a bad thing, I’m simply saying that if parking is convenient and cheap, it fills up quickly.

  14. David Moulton Says:

    I’d be curious to know what ITS is.


  15. cereal Says:

    You must know that this “psychological” phenomenon is not a general human one – but rather only an American one.

    In the UK and Europe, this simply does not apply. For some reason, Europeans and Brits are not the whiney, entitled, lazy fools that Americans evidently are – they are willing to “walk” from their cars to stores, they are willing to drive up to the second (or third, fourth, etc.) level of a parking garage to find a spot, and so on.

    It surely helps that parking garages here indicate the number of available spaces – and that there are frequently signs at major traffic points indicating how many spaces are available at which parking garages in the center city area, pointing you towards them as well, so you avoid futile hunting in a full garage.

    Perhaps Europeans and Brits are just used to this extra information or used to dealing with more crowded city centers, more used to relying on centralized planning for their parking and many other things.

    Or perhaps Americans are just a race of lazy idiots, and even providing additional parking information will do nothing to disabuse them of the bred-in notion that they deserve a parking spot directly in front of the Hamburger Gulper outlet they want to visit, and that if there is no such spot then there is “no parking” and more, more more and bigger spaces must be built for them immediately.

  16. paul Says:

    In my small town, where people also complain endlessly about the lack of parking the local parking garage doesn’t even post prices visible from the street, much less availability.

  17. Vin Says:

    I do exactly what Josh R. does. It never ceases to amaze me that people insist on spending ten minutes looking for ‘the best’ parking space, as opposed to going to where there is likely to be available spaces and walking for five minutes. I do the same with curbside parking, including where I normally park near my apartment in Brooklyn.

  18. D Reese Says:

    In reference to cereal, I know plenty of Brits that complain about having to park blocks from their desired destinations. More so, I know several that enter a garage and leave when they too become frustrated with phantom available spaces.

    I personally would rather park in a garage than on a surface street. I try to go to the uppermost stories where I am almost guaranteed a space and I leave my car there opposed to driving to my next destination. I remember during my senior year (’07-’08) at Penn State the Borough of State College, PA was in the process of implementing a system of VMS signs throughout the downtown alerting motorists of where garages were and how many spaces were available. When I returned for a visit last spring I was happy to see it installed and working beautifully.

    I compare this to the situation in the city near where I grew up, Wilkes-Barre, PA. The city has plenty of parking spaces but only a few garages are utilized to their fullest potential. I’ve unknowingly entered one garage on an occasion only to go through the whole facility without finding one space. A “full” sign would have been too nice of the city to put in front of the entrance. In addition, I wasn’t the only sucker to enter the garage. All in all it took me over an hour and a half to make it to the top and back out, utterly ridiculous.

    As a transportation planner I believe more American cities should implement systems that our friends in the UK and Europe have been spoiled with for years now. Also, we wouldn’t have this problem if transit in this country was better and more abundant.

  19. Maharet Says:

    David @ 14,

    ITS stands for Intelligent Traffic System (or Signals, depending on the usage).

  20. dave2 Says:

    What is not specified is if there is a distinction between private and public parking. My town has, overall, an oversupply of parking. But much of it is private and the stores and offices that built all that parking did so because of local ordinances that specifically dictate the number of parking spaces a particular building and use must have. It is built into local law. Opening private parking to the general public raises some liability and burdens of expense questions.

    On the other hand, I know of a few retail business that are well aware of this perception problem, and when they build a store they build many more parking spaces than they require. This is done so that when people drive up there always appears to be plenty of parking. That is, “close to the store” is always a relative thing. A space far away can seem close if the lot itself extends out some seemingly infinite distance.

    And a good bit of transportation research in the U.S. was funded by automobile manufacturers. That means that if the problem is congestion, the question being asked might be how do we move more cars more efficiently, not how do we get people to drive less. That bias eventually filters it’s way down to local ordinances and we end up with things like huge parking lots.

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