
Where to park your car, according to math - dnetesn
https://phys.org/news/2019-09-car-math.html
======
technothrasher
I've never been called 'meek' before! But then I think I'm looking at the
problem differently. I don't consider the walking time wasted, I don't mind
the walk. I want to get the car parked as quickly as possible, not spend the
least amount of time between entering the lot and getting to my destination.
In fact, I will often park further away even when I can directly see that
close up spots are free.

~~~
amelius
Walking can be nice, but in an indoor parking garage not so much, with all
those exhaust fumes and cars driving by without a clear sidewalk.

~~~
technothrasher
Ah, yes, well for most indoor parking garages my usual strategy is to
immediately head for the top (or bottom) floor. Almost nobody parks there
unless they have to, so there's often lots of open spaces and much less
traffic. If there aren't and good spots on the last level, then there likely
aren't any good spaces anywhere in the garage anyway.

------
OliverJones
OK, I admit it. I use the meek strategy. Why? because I believe the parking
spots that minimize walking from car to destination should be left empty for
people who need them more than I do.

On the rare occasion where I need to minimize walking (because I have
something heavy to carry, for example) I park to minimize walking even if I
have to waste some time and fuel doing it. In that case it helps me when other
people use my default strategy.

Optimization-theory work like this paper has a fundamental flaw: it assumes
the actor is a classic "econ" \-- the ideal person (defined by classical
economics) working to optimize purely personal utility. In fact, many people
work to optimize community utility.

Studying that community-optimization model is harder. But it is probably
worthwhile. Such large-scale systems as autonomous vehicles will require
community optimization to succeed.

It's time to reread Kahneman and Tversky, and Richard Thaler.

~~~
esotericn
Right.

I actively want the exercise. I take the stairs at work rather than the
elevator when practical for the same reason.

I don't think it's fair to categorise being a decent person as "meek". If more
people did that, we'd have a far lower need for things like disabled and
family spaces because people would fill inwards.

~~~
OliverJones
Agreed, entirely.

But the social-science and system-science issues get confused by using
ethically charged words like "decent." Modeling "decent" gets confusing
without ways of measuring it. (I'll spare us a long digression on how slippery
it can be to understand ethical / moral reasoning.)

Do I leave parking spots for other people because I'm a "decent" person? I
like to think so -- I like to think I put others' needs ahead of my own when I
can -- but that's my business. From a systems point of view I do it to help
control parking lot congestion.

If I were a business owner and didn't leave convenient parking spots for
others, I'd be deliberately adding to congestion near my business. That's a
cost. What's the benefit?

Example: Van Jacobson's slow-start / exponential-backoff algorithm to help
prevent TCP endpoints from saturating routers. It's certainly possible to
explain this to a roomful of undergrads as a "be nice" requirement on web
servers and other sources of large TCP streams. But it's more productive to
model it as part of a large-scale system to control congestion.

------
pgt
Sounds like the Secretary Problem, which involves optimal stopping theory:
[https://en.wikipedia.org/wiki/Secretary_problem](https://en.wikipedia.org/wiki/Secretary_problem)

The naive answer is 1/e (where e is the base of the natural logarithm). If you
have N applications, reject ~N/e applications and choose the first applicant
who is better than every previous applicant.

~~~
jameshart
It’s similar but not quite the same. In the parking problem you don’t know how
many free spaces there are to begin with, and the ‘quality’ metric of each
space is just a linear function of its location. In the idealized problem
presented, each space as you go along the line is strictly better than every
previous space - you just don’t know whether it is the last one.

The analogous secretary problem would be to be presented with a sequence of
increasingly suitable candidates, but never knowing whether each candidate is
the last one.

------
rbg246
In multi-level car parks I believe people overestimate vertical distance and
underestimate horizontal.

In the carpark I park in, I often just speed down to the level where there
first begins to be car spaces and I can often get much closer to the stairs
which lead back up to the exit on the ground floor.

Extra vertical distance is only 4-5m but saved horizontal distance can be 50m.

~~~
CPLX
> Extra vertical distance is only 4-5m but saved horizontal distance can be
> 50m.

Indeed, for the walking component. However having to drive up and then back
down additional levels has time and hassle costs too.

~~~
rbg246
This is true, the car park has a ramp system that is all in one corner of the
car park but I guess most places make you drive to the other side to go up one

------
ape4
Other factors: getting a bit of exercise, wanting to be away from the busiest
areas to avoid your car being dinged.

~~~
dazc
I always try and park away from the busiest areas for the same reasons but,
purely from observation, it's obvious most people don't since the area closest
to the store entrance is almost always utilised the most.

I do often wonder why people are so lazy or so busy that saving on walking an
extra few yards is so important to them?

~~~
VBprogrammer
When our baby was younger we tended to park as far away from anyone else as
possible to give us room to put her back in the car. It's amazing how often we
come back to find someone parked right next to us.

~~~
mszcz
I've noticed this as well. If I park in the middle of the parking lot with no
cars anywhere near me, very often I come back to find another car parked right
next to mine.

My theory as to why this happens is that a parked car is a clearer indicator
of how to park properly. If I try to park properly using the painted lines
(which are often not very visible and go out of sight when you start entering
your parking spot) I might miss the mark. However, a parked car that's more
visible is a better indicator of whether I've parked correctly.

~~~
systemtest
One of the reasons I back into parking spots. Back in, watch your mirrors,
line up the lines using your mirrors or backup camera and continue going back.
You will park perfectly in the middle every time.

~~~
bluGill
For safety you should always park so you drive out of your parking spot. If
you back out you risk that you don't see some kid walking right behind your
car. Particularly if when you live a couple trucks/vans have parked next to
you so there is no way to see if there is anything else coming and you have to
guess.

~~~
systemtest
Correct! And if we are listing reasons for backing up: Because you have to
pass the parking spot before you back in, you can see if the spot is clear of
debris, shopping carts and children.

------
zaind
From the paper:

"However, if there a few meek drivers while the majority follow the prudent or
optimistic strategy, then the meek strategy is not bad because meek drivers
will park a distance λ from the target."

I am a 'meek' driver for this very reason. My assumption is that the majority
of other drivers are either 'optimistic' or 'prudent,' and as such the parking
cost of the meek strategy is much lower. Would be very interesting to test
this in the real world!

~~~
croon
There are a few parking lots at my workplace, and I park at one fairly close,
at a time where the last spots usually fill up.

I haven't kept a tally, but there have been multiple times (after a few
earlier experiences on the other end of the spectrum) where I've gotten the
last spot on the far end of the lot, only to see the few cars ahead of me
drive around and eventually end up going off to another lot.

In my case I'm the meek driver on a micro/lot level, but a prudent/optimistic
one on a macro/workplace level. But in my anecdata it's probably saved me more
time than any other behavior I could employ.

------
bovermyer
Of all the metrics in my life, optimizing for minimum car-to-store time is not
important or even a consideration for me.

Unless it's pouring rain, I'll usually park near the back of the lot and take
my time walking to the store. Even if it's raining, I won't usually opt for
the spots closest to the store. I don't know _why_ that latter behavior
exists, but it's what I do.

------
ismail
I thought I had read this before. Here is the link to the original blog post
from the institute that did the research.

[https://www.santafe.edu/news-center/news/where-how-park-
your...](https://www.santafe.edu/news-center/news/where-how-park-your-car-
according-math)

~~~
donpott
I had the same feeling. If memory serves, the problem of optimal stopping is
discussed (using a parking lot as an example) in the book "Algorithms to live
by"

[http://algorithmstoliveby.com/](http://algorithmstoliveby.com/)

------
an_ko
I'd like to see a version of this that optimises for this problem more
globally. Other people exist!

e.g. Park further away if you can handle it (arrived on time, and are in good
health, and have little luggage). Then people who are struggling (arrived
late, with kids, in poor health, with lots of luggage) have a higher chance to
find a space closer to the entrance. This might invisibly make someone have a
less shitty day, and reduce my own risk of running into an angry person later.
It's more impactful to optimise for that, rather than save seconds of walking.

Any ideas for how to math this?

------
andrew-v
I am wondering how did the "meek" strategy look like in detail.

Because, if you try to occupy the very first spot available, then of course it
makes very little sense. But I believe that a "human meek" would instead skip
the whole line of unoccupied spaces and take the last spot in such a line.
This "unoccupied line" does not even have to begin with the first parking
space, but for example with the third. Though you need to assume that the line
of empty spots is in driver's line of sight.

------
TimMurnaghan
This model assumes hiigh availability of spaces - and that's not what I see
very often outside the wide open spaces of America. A better model would
include time to find a free parking space. Searching and queuing time can
quickly dominate under high utilization. Taking the first available space is
very far from "meek" when you have to struggle to get it.

------
mattlondon
Hmm - do non-mathematicians "optimise" their parking? I really doubt it.

I feel like the people trying to park right near the door/entrance to the
shops are not "optimising" the time they're there - I feel like they're
probably just being lazy and "optimising" for the smallest amount of energy
exertion possible (consciously or not). After all, why walk when you have a
car? They don't seem to mind spending time following people walking back to
their cars, or just looping around and around, or trying to squeeze into
spaces that are too small when it is clearly obvious that you can just pull
straight into a space another 20-30m away without any waiting or tight
squeezes, then spend 15-30 seconds more walking. They're wasting a lot more
time trying to get close so it _can 't_ be time they are optimising for
otherwise people wouldn't do it.

(some people of course can't walk distance but then there are disabled spaces,
parent + child spaces etc)

~~~
lostmsu
There is not much difference between conscious and "non-conscious" optimizing.

------
deaps
This is great. Fortunately, at my work, if I just drive past the _main_
entrance, and enter the parking lot nearest our entry door, I can start my
journey through the lot at the closest point. This obviously eliminates the
need for guessing or betting or settling early.

I admit that at certain times I do enter from the furthest entrance...and I
always drive past the first spot, and bet on that second one. Quite often
there is a better spot as I'm walking in, but sometimes there's not. So when
faced with the opportunity, I follow the prudent strategy.

Now at an unfamiliar location (walmart, movie theater, whatever), I always try
to find a spot that butts up against a curb (preferably on one side AND the
back of the spot as well) to lessen exposure of my vehicle to other motorists
(doors, bumpers) as much as possible.

~~~
jameshart
This actually suggests that there are interesting psychological implications
to parking lot circulation design. If you design a lot so that people can
explore it in an order that matches a monotonous decrease in the ‘value
function’ they place on each space location, you reduce driver stress because
they can take the simple strategy of parking in the first available space and
know they could not possibly have done better by following a different
strategy (ah - except for waiting by the entrance and holding up traffic til
someone leaves, of course).

This assumes you can identify a common value function everyone (or most
people) places on each space of course.

Making people follow the value function in increasing order - as in the
example, where each space you pass is closer to the entrance and so ‘better’ -
seems to force this strategy choice.

This suggests all kinds of analogies in user experience and organizational and
game design problems...

------
bradfa
I park to optimize my exit from the parking lot. Pull-through spots to avoid
reversing, avoiding needing to perform left turns, things like that. If I'm at
the food store I'll also try to be near a cart return area, if possible.

------
amingilani
Curve-ball: the mall I visit most often has separate entrance and exits. The
best spot equidistant from both. I've spent way too much time on this problem
in my head.

~~~
looperhacks
Isn't the best spot closer to the exit, considering you probably have to carry
stuff/push a cart there?

~~~
amingilani
That usually doesn't matter because—when I do grocery—the mall has the option
to have an attendant carry it for you for free.

With that in mind, I usually opt to carry the grocery out myself because I
prefer it. But rationally, the cost disappears because of the option.

------
cmurf
Meanwhile in another study, "meek" parkers found to have lower blood pressure
from all this "excessive" walking.

------
cryptozeus
I usually try to be prudent driver but its hard to tell when to stop looking
for empty spots as you get closer to the exit.

~~~
djmips
I'm the optimistic driver and the childish enjoyment of finding that spot near
the front when the whole parking lot is full is worth the back tracking when
it fails. In reality the meek approach isn't really terrible in the grand
scheme and you get more exercise.

------
alecmg
I go by hypermiler advice, optimize distance traveled by car.

Choose spot closest to entry-exit path of car park. Park closer to exit, and
so that you don't need to reverse out, minimize inefficient slow/idle movement
with cold engine.

And any additional walking is a bonus as mentioned by several people here.

------
lvturner
I may be meek, but I always get a parking spot!

------
alex_young
Or just park in a modern garage that tells you where the empty spots are and
how many of them are each direction.

