# Door opener at grocery store **URL:** \ **Category:** Factual Questions\ **Created:** [July 14, 2005, 5:40pm UTC](https://boards.straightdope.com/t/door-opener-at-grocery-store/312539 "2005-07-14T17:40:14Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![pkbites](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pkbites/32/204_2.png) [@pkbites](https://boards.straightdope.com/u/pkbites)\ **Post date:** [July 14, 2005, 5:40pm UTC](https://boards.straightdope.com/t/door-opener-at-grocery-store/312539/1 "2005-07-14T17:40:14Z")
At one time all the grocery stores all had doors that would open automatically when you stepped upon a black rubber mat that lay about 4-5 feet in front of the door. They worked great. As you walked the doors swung open. there was some kind of trip switch under that black mat. Today every door at any store is opened by a sensor using X-band radar. When the radar gun senses movement, the door opens. What bugs the bejebbers out of me is, it seems none of those things is aimed right. Perhaps I walk faster than the average bear, but I’m always right on top of the stupid door before it opens. I always have to change my stride or I’ll end up bumping into the door! :mad: What exactly is the benefit of using this type of system or the black mat method? I would think the old method (which worked better) would be far, far cheaper than a device that has to generate a radar signal. Why did everyone go to this system, and why can’t they make it open the door about 3 seconds sooner? ---
**Author:** ![Padeye](https://avatars.discourse-cdn.com/v4/letter/p/a9a28c/32.png) [@Padeye](https://boards.straightdope.com/u/Padeye)\ **Post date:** [July 14, 2005, 5:44pm UTC](https://boards.straightdope.com/t/door-opener-at-grocery-store/312539/2 "2005-07-14T17:44:35Z")
What makes you think a motion sensor, likely ultrasonic and certainly not radar, would be cheaper than a mechanical pressure sensor that has to be durable enough for people to walk on? Ultrasonic sensors are cheap and don’t have the drawback of blocking the door when you have to work on one as with a pressure mat. ---
**Author:** ![yoyodyne](https://avatars.discourse-cdn.com/v4/letter/y/a9a28c/32.png) [@yoyodyne](https://boards.straightdope.com/u/yoyodyne)\ **Post date:** [July 14, 2005, 5:44pm UTC](https://boards.straightdope.com/t/door-opener-at-grocery-store/312539/3 "2005-07-14T17:44:51Z")
They always open for me just fine. Maybe it’s my tinfoil hat. ---
**Author:** ![Cagey\_Drifter](https://avatars.discourse-cdn.com/v4/letter/c/b2d939/32.png) [@Cagey\_Drifter](https://boards.straightdope.com/u/Cagey_Drifter)\ **Post date:** [July 14, 2005, 5:46pm UTC](https://boards.straightdope.com/t/door-opener-at-grocery-store/312539/4 "2005-07-14T17:46:19Z")
if anything, i find that they are too sensitive and open even if i have no intention of walking through the door-- which bothers me because i feel like it’s a waste of energy. ---
**Author:** ![pkbites](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pkbites/32/204_2.png) [@pkbites](https://boards.straightdope.com/u/pkbites)\ **Post date:** [July 14, 2005, 6:10pm UTC](https://boards.straightdope.com/t/door-opener-at-grocery-store/312539/5 "2005-07-14T18:10:24Z")
> [@Padeye](#): > > What makes you think a motion sensor, likely ultrasonic and certainly not radar, would be cheaper than a mechanical pressure sensor that has to be durable enough for people to walk on? Ultrasonic sensors are cheap and don’t have the drawback of blocking the door when you have to work on one as with a pressure mat. I can tell you for a fact that many of them operate on X band radar. I’m usually right on top on them before they start to open. It’s not so bad if it’s a regular door that I can just push open. But those that open horizontally are a pain to wait for. I don’t want to come to a stop waiting for a door. One of the reasons it’s automatic is to be a convenience. I suppose a person with shorter legs walks at a slower gait than myself and doesn’t notice. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [July 14, 2005, 6:36pm UTC](https://boards.straightdope.com/t/door-opener-at-grocery-store/312539/6 "2005-07-14T18:36:53Z")
Totally off-topic, but does anyone remember the _SNL_ video (it wasn’t a life skit but a prerecorded short subject that took place outside the studio) where Rich Hall, playing a grocery clerk, is ordered by his obnoxious boss (Jim Belushi) to clean the store, during which he discovers that the “black pad” materal doesn’t just open the front door but any door you’re standing in front of. He then proceeds to embark on a clever, _Alfred Hitchcock Presents_-type vengence upon his boss using said pad. I think it was probably the funniest thing I ever saw on _SNL_. Stranger ---
**Author:** ![bouv](https://avatars.discourse-cdn.com/v4/letter/b/bc8723/32.png) [@bouv](https://boards.straightdope.com/u/bouv)\ **Post date:** [July 14, 2005, 6:52pm UTC](https://boards.straightdope.com/t/door-opener-at-grocery-store/312539/7 "2005-07-14T18:52:19Z")
I hate the black pad. 1. It’s ugly. 2. I don’t like the way it feels when I walk on it 3. I always had to wait for them as well. Myabe you walk in that perfect speed between too fast for radar doors, but good enough for black mat, but I have to wait for them regardless of the type of auto door they are, with some exceptions (the outaside door to my Price Chopper is good…but the inner door is bad.) ---
**Author:** ![Scarlett67](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/scarlett67/32/7387_2.png) [@Scarlett67](https://boards.straightdope.com/u/Scarlett67)\ **Post date:** [July 14, 2005, 7:06pm UTC](https://boards.straightdope.com/t/door-opener-at-grocery-store/312539/8 "2005-07-14T19:06:04Z")
> [@Stranger On A Train](#): > > Totally off-topic, but does anyone remember the _SNL_ video (it wasn’t a life skit but a prerecorded short subject that took place outside the studio) where Rich Hall, playing a grocery clerk, is ordered by his obnoxious boss (Jim Belushi) to clean the store, during which he discovers that the “black pad” materal doesn’t just open the front door but any door you’re standing in front of. He then proceeds to embark on a clever, _Alfred Hitchcock Presents_-type vengence upon his boss using said pad. First thing I thought of when I saw the thread title. It’s gotta be in SNL’s top ten best pieces. ---
**Author:** ![Nanoda](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Nanoda](https://boards.straightdope.com/u/Nanoda)\ **Post date:** [July 14, 2005, 7:19pm UTC](https://boards.straightdope.com/t/door-opener-at-grocery-store/312539/9 "2005-07-14T19:19:10Z")
How tall are you? In a very unscientific survey conducted by myself, it seemed that being 6’5" was what caused my problem with the doors. Or I just walk faster than everyone else. ---
**Author:** ![Balthisar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/balthisar/32/2825_2.png) [@Balthisar](https://boards.straightdope.com/u/Balthisar)\ **Post date:** [July 14, 2005, 7:42pm UTC](https://boards.straightdope.com/t/door-opener-at-grocery-store/312539/10 "2005-07-14T19:42:56Z")
> [@pkbites](#): > > What bugs the bejebbers out of me is, it seems none of those things is aimed right. I invariably have the same problem. I just run into the things and express a huffy attitude. When leaving the store, the the racket of the cart hitting the door makes quite a bit of noise. Now I’m sure someone will caution me that I’ll be responsible if I break the thing. Be assured that they’re strong, and I’ve yet to break one. The crappy aiming is an artifact of being either a quick walker or being tall. Heck, one of the first things I have to do when I enter a grocery store with a cart is grab a plastic bag from the produce aisle, and tie the cart’s bottom rack (you know, the thing for big dog food bags or cases of beer?) to the bottom of the cart so that I don’t make a racket in the store. If I don’t do this, then with the carts as most stores, I kick the bottom rack with every step I take, which makes a loud noise at the kick and at the return. Being tall and having big feet sucks. ---
**Author:** ![Hampshire](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hampshire/32/4887_2.png) [@Hampshire](https://boards.straightdope.com/u/Hampshire)\ **Post date:** [July 14, 2005, 7:45pm UTC](https://boards.straightdope.com/t/door-opener-at-grocery-store/312539/11 "2005-07-14T19:45:11Z")
> [@Scarlett67](#): > > First thing I thought of when I saw the thread title. It’s gotta be in SNL’s top ten best pieces. My favorite part being right after he lifts the mat to clean under it and the lady carrying two bags of groceries walks directly into the closed door 😛 ---
**Author:** ![Antonius\_Block](https://avatars.discourse-cdn.com/v4/letter/a/51bf81/32.png) [@Antonius\_Block](https://boards.straightdope.com/u/Antonius_Block)\ **Post date:** [July 14, 2005, 9:39pm UTC](https://boards.straightdope.com/t/door-opener-at-grocery-store/312539/12 "2005-07-14T21:39:42Z")
> [@Stranger On A Train](#): > > Totally off-topic, but does anyone remember the _SNL_ video (it wasn’t a life skit but a prerecorded short subject that took place outside the studio) where Rich Hall, playing a grocery clerk, is ordered by his obnoxious boss (Jim Belushi) to clean the store, during which he discovers that the “black pad” materal doesn’t just open the front door but any door you’re standing in front of. He then proceeds to embark on a clever, _Alfred Hitchcock Presents_-type vengence upon his boss using said pad. > > I think it was probably the funniest thing I ever saw on _SNL_. > > Stranger I never saw that, but I’m laughing at the possibilities just from your description! ---
**Author:** ![Hampshire](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hampshire/32/4887_2.png) [@Hampshire](https://boards.straightdope.com/u/Hampshire)\ **Post date:** [July 14, 2005, 9:47pm UTC](https://boards.straightdope.com/t/door-opener-at-grocery-store/312539/13 "2005-07-14T21:47:52Z")
> [@Antonius Block](#): > > I never saw that, but I’m laughing at the possibilities just from your description! I think he cuts some of the black pad and glues it to the bottom of a pair of shoes and proceeds to make doors open around the city. He then mails the shoes anonamously to his boss. You see his boss not being able to keep his car door shut while driving, can’t keep his briefcase from popping open, and ultimately walks into an empty elevator shaft when the door opens for him. ---
**Author:** ![Snowboarder\_Bo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/snowboarder_bo/32/229_2.png) [@Snowboarder\_Bo](https://boards.straightdope.com/u/Snowboarder_Bo)\ **Post date:** [July 15, 2005, 6:04am UTC](https://boards.straightdope.com/t/door-opener-at-grocery-store/312539/14 "2005-07-15T06:04:23Z")
I love that film! I thought it aired on **Not Necessarily The News** , tho. ---
**Author:** ![Antonius\_Block](https://avatars.discourse-cdn.com/v4/letter/a/51bf81/32.png) [@Antonius\_Block](https://boards.straightdope.com/u/Antonius_Block)\ **Post date:** [July 15, 2005, 6:36am UTC](https://boards.straightdope.com/t/door-opener-at-grocery-store/312539/15 "2005-07-15T06:36:56Z")
> [@Hampshire](#): > > I think he cuts some of the black pad and glues it to the bottom of a pair of shoes and proceeds to make doors open around the city. > He then mails the shoes anonamously to his boss. You see his boss not being able to keep his car door shut while driving, can’t keep his briefcase from popping open, and ultimately walks into an empty elevator shaft when the door opens for him. You know, they should just play that on a continuous loop when SNL is broadcast, rather than most of the more-recently-written garbage. Clever ideas, and Jim Belushi dies at the end? I’d buy _that_ for a dollar! ---
**Author:** ![Tuckerfan](https://avatars.discourse-cdn.com/v4/letter/t/eada6e/32.png) [@Tuckerfan](https://boards.straightdope.com/u/Tuckerfan)\ **Post date:** [July 15, 2005, 7:09am UTC](https://boards.straightdope.com/t/door-opener-at-grocery-store/312539/16 "2005-07-15T07:09:25Z")
My dad ran a business for years installing automatic doors in places like grocery stores, etc., and I pretty much spent my summers working for him, so I know a thing or two about the doors. Many of them _do_ use X-band radar, but they also have ultrasonic models, it depends upon the manufacturer as to which one they use. The range of the units is adjustable by the installers as well as the delay from when the person enters the beam to when the door opens and how long it stays open. Like crosswalk lights, the installers try to set the units based on the kind of traffic they expect, so hospital doors have a different setting than grocery stores. Horton (one of the companies my dad sold doors for), is **very** conscious of having the doors properly adjusted. They got hit with a number of lawsuits over the years, and their doors have more safety features than any others (I’ve noticed this by comparing them to other doors, not from any company literature). Generally, on the doorframe, near the emitter, there’s a sticker for the installer which will have a phone number on it. Couldn’t hurt to give them a call and explain the situation to them, it might simply be that the store’s maintence man has tampered with the door and played with the settings. ---
**Author:** ![Scarlett67](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/scarlett67/32/7387_2.png) [@Scarlett67](https://boards.straightdope.com/u/Scarlett67)\ **Post date:** [July 15, 2005, 12:16pm UTC](https://boards.straightdope.com/t/door-opener-at-grocery-store/312539/17 "2005-07-15T12:16:05Z")
> [@Hampshire](#): > > I think he cuts some of the black pad and glues it to the bottom of a pair of shoes and proceeds to make doors open around the city. > He then mails the shoes anonamously to his boss. You see his boss not being able to keep his car door shut while driving, can’t keep his briefcase from popping open, and ultimately walks into an empty elevator shaft when the door opens for him. I remember it like this: He puts the black pad on the bottom of his shoes and walks around opening doors: car doors, a mailbox (all the mail falls out), and the lid of a coffin are the ones that come to mind. Then he drops off the shoes at the boss’s door. We see the boss take them into his apartment and then comes out wearing his snazzy new shoes. He tries to close his apartment door but can’t and finally just leaves it open. He indeed can’t keep his briefcase closed and angrily throws it down the hall. Then he goes down the shaft. Right up there with “The Brad Hall Show” for best sketches, in my book. ---
**Author:** ![Canadjun](https://avatars.discourse-cdn.com/v4/letter/c/76d3ee/32.png) [@Canadjun](https://boards.straightdope.com/u/Canadjun)\ **Post date:** [July 15, 2005, 1:08pm UTC](https://boards.straightdope.com/t/door-opener-at-grocery-store/312539/18 "2005-07-15T13:08:00Z")
I very occasionally run into ones (literally and metaphorically 🙂 ) that are aimed too high, so they don’t notice me in my electric scooter. Then again, my scooter has lots of power, so if that happens the door just gets shoved open **hard**. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [July 15, 2005, 1:48pm UTC](https://boards.straightdope.com/t/door-opener-at-grocery-store/312539/19 "2005-07-15T13:48:04Z")
> [@pkbites](#): > > I would think the old method (which worked better) would be far, far cheaper than a device that has to generate a radar signal. I would think the mechanical switch is more expensive. The door-mat switch gets stepped on millions of times, sometimes by heavy boots, high heels, clutches and heavily loaded carts/dollies. They get immersed with salt water and baked by direct sunlight. It’s not trivial to make a switch that can survive all that for many years. ---
**Author:** ![Mollie\_Magill](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mollie_magill/32/20882_2.png) [@Mollie\_Magill](https://boards.straightdope.com/u/Mollie_Magill)\ **Post date:** [July 15, 2005, 8:32pm UTC](https://boards.straightdope.com/t/door-opener-at-grocery-store/312539/20 "2005-07-15T20:32:27Z")
> [@bouv](#): > > Myabe you walk in that perfect speed between too fast for radar doors, but good enough for black mat, but I have to wait for them regardless of the type of auto door they are, with some exceptions (the outaside door to my Price Chopper is good…but the inner door is bad.) Why am I picturing stores with **bouv** shaped holes where the doors once were. [Next page](https://boards.straightdope.com/t/door-opener-at-grocery-store/312539.md?page=2)