What makes this such a localised phenomenon? Locking shopping cart wheels just aren't a thing here in the Netherlands (or neighbouring countries). It used to be that most required a €1 coin inserted to unlock its link tethering it to the next car in the row, but then covid happened and a lot of shops simply disabled those locks and concluded that the system worked better without — probably driven in part by an increasing number of people who don't carry any cash.
Losing a cart is expensive, but it doesn't seem to happen at the scale that would make a full blown locking wheel solution cost effective.
Homelessness in the US. They steal carts to carry their stuff around, or to collect trash aluminum cans to earn money, etc. In certain areas, it's pretty common and probably crosses the cost:benefit line for stores.
Larger stores in Sweden also use the coin system, even though as in the Netherlands it feels like use is declining in favor of just unlocked carts.
My favorite part of the system in larger stores is that to handle people not carrying cash (Sweden is pretty long-gone in this regard), you can usually go inside the store to get a free plastic token that fits the reader.
That always made me chuckle, since the entire point of the system is that you're supposed to be incentivized to return the cart to get your money back, so by replacing your money with a free plastic token that they hand out from a basket, they did .. something to the overall system design.
Still fun as an example of how the customer's overall experience is more important than the point of an entire security system, I think.
> Larger stores in Sweden also use the coin system, even though as in the Netherlands it feels like use is declining in favor of just unlocked carts.
The coins are so that people put them back in their designated storage area, not to prevent theft. A significant fraction of the population are lazy asshole who tend to leave carts next to where their car was parked instead of walking the 10-20 meters it take to return them.
> That always made me chuckle, since the entire point of the system is that you're supposed to be incentivized to return the cart to get your money back
I always kinda doubted that part, or at least its effectiveness. Iirc a 50 eurocent coin will unlock most trolleys, which is pretty cheap for a whole ass trolley.
And sure enough, there's a lot of elderly people that just have a shopping trolley in their yard or something. This morning I found one randomly in our bike shed.
It's not an incentive to "not steal the trolley", it's an incentive to put it back in its place for people who were already not planning on stealing one.
This way the store and the customers don't have to deal with trolleys strewn around everywhere and blocking parking spaces, among other advantages.
I think when they removed the coins during Covid they just noticed that most people were already well-behaved enough to return the carts to their places, so the incentive is just not needed anymore. Actually in Belgium, Colruyt had never had coins for their carts and it just works.
In the United States, carts are free. There is a stereotype that homeless people have shopping carts in which they keep their things.
There's no particular need to change this, because one person can only use so many shopping carts. If you maintain the price at "free", demand saturates and people stop stealing carts.
It's common for people to return carts to a designated area, and it's also not rare for people to just leave the carts somewhere convenient for them. Store employees periodically go around and move the carts back to the place where you expect to pick them up.
Costco is an interesting hybrid case. They make it easy to return the carts "correctly" by providing little depots scattered throughout their enormous parking lot. Realistically, the parking lot is so large that very few people would be willing to return a cart to the front of the store, where you get the cart from if you're going shopping.
However, people also aren't going to pick up carts from those depots deep within the parking lot and wheel them over to the store. So Costco employees still have to make rounds of the parking lot and move carts that have been left there to their correct location at the front of the store. But for Costco, you're supposed to leave the cart in the parking lot, but only in certain locations.
This brought back a memory of living in Byron Bay Australia in 1999 - there was a person who’s full time job was driving around town with a trailer, collecting shopping trolleys and returning them to the Woolworths supermarket.
I’d never seen that in the uk - but maybe that town was the sweet spot in size where it was small enough that you could actually get home with a trolley (and it was nice and flat), and maybe the number of visitors passing through meant rules got broken more - though the trolleys were more in the suburban areas than just where the hostels were.
There used to be a supermarket that had these near my student housing complex in Utrecht (the Netherlands). Only place I ever encountered them. This was 20 years ago tho.
It was completely counterproductive, too. The edge of the zone was about 50% of the way home. Out of spite, we'd push the cart up to the edge, and leave it stranded there, carrying everything the last 200m ourselves.
Not proud of that in retrospect; it goes to show that you can't stop assholes with technology.
When I was a kid we didn't have this coin thing in supermarkets in France, and the problem wasn't people stealing carts (which they could do for for €1 anyway) but many people were leaving them at random places in the parking lot, basically near where they were parked. That made driving in the parking around the carts a big mess.
It's most common in places with lots of elderly or homeless, both groups find these carts very useful and will simply take them, homeless to keep, elderly to abandon near their home once they have transported their groceries.
It's more also common in places where people walk, since it can be hard to bring groceries home on public transport.
So yes, very localized.
The shop near me doesn't have locking wheels (they used to, but stopped), instead they have a guy in a pickup that drives around occasionally, searching for carts.
I understand about homeless people but elderly? Don't they have personnal shopping trolley? Like those with 3 wheels to be able to go climb curbs and small stairs? Regular carts are only used inside or by people who need to bring their stuff to their car and a pain in the ass to operate in the streets as they don't climb curbs easily.
Locally all supermarkets actually have locks at the entrace so that people can lock their shopping trolleys next to the cashiers.
> Regular carts are only used inside or by people who need to bring their stuff to their car and a pain in the ass to operate in the streets as they don't climb curbs easily.
Curbs have onramps. Pretty much every corner and every driveway provides a ramp where wheeled vehicles can easily get on to the sidewalk. You will never have any difficulty pushing a shopping cart onto a sidewalk.
The Kroger by my house as these (or ones that look very similar). I generally avoid that store for many reasons, but I’m tempted to go there just to try this out. This is a few years old now; I wonder if they changed the tones.
Not sure if the original site owner will ever see this, but the hit counter they use (counter12 [dot] com) is flagged by Malwarebytes for phishing (and seems to have a history of popping fake virus links? [0])
I despise these wheels. About 15 years ago, my wife and I went to Target and first went to lunch at the far end of the parking lot. After lunch we headed into the store, grabbed a cart, now loaded with our newborn in his car seat, and our two year old sitting in the cart. A quick shopping trip later, we headed back to the car. When crossing the Target parking lot, the wheels locked up, in the middle of the road. Cart wouldn’t budge. Traffic all over the place, and now I have to pull both my children out, along with the shopping, and carry them all to my car. Pissed is an understatement. After my wife and kids were secured back in the car, I retuned to Target, complaining to the manager. A shrug was the best I received. Why did they need to put the wire in the middle of the road???
I hope someone attaches Bluetooth speakers to their shoes and locks every cart in target, so they have to remove the system.
No. That won't work. It needs the electromagnetic / rf field. It can work if your phone is nearby becaause of the " parasitic EMF from your phone's speaker to "transmit" a similar code by playing a crafted audio file" according to the article and the DEFCON talk
> I hope someone attaches Bluetooth speakers to their shoes and locks every cart in target, so they have to remove the system.
Friends did this college in like 2005. Cambridge area, Shaws Market I think. I imagine the hardware setup was a bit different. All the details are hazy but I recall their lock transmission signal had a huge range and locked all carts in a wide area.
Based on what's still around, likely the one (now rebranded a Star Market, same holding company) in Porter Square, right by Porter Square station.
Based on what I recall, I believe there was one on the southeastern end of Green Street, a bit between Central and Kendall Square, barely northwest of MIT's primary campus area on the corner Massachusetts Ave and Vassar Street. That location has apparently closed in recent years.
Around that year, or maybe even earlier, I remember reading an article about how to DIY one of those devices with a PIC microcontroller and wreck havoc on the store. It might have been something very similar to this:
As other people have pointed out "audio range" is generally 20Hz-20kHz. Your phone (and other audio equipment) is therefore built to be able to transmit those frequencies. The way a speaker creates sound is by passing electricity through a wire, creating a magnetic field, and pushing against a permanent magnet. Either the magnet or the wire is attached to a membrane that will then get pushed out. Doing this between 20-20k times a second and you make sound. However when charged particles (like the electrons in a wire) accelerate they create radio waves, so the magnetic coil in the speaker will also create a small amount of radio waves in the same frequency as the sound it is producing. This is what's called parasitic EMF, and in this case it turns out that this small amount of radio signal is enough to interact with the radio in the wheels.
> Since 7.8 kHz is in the audio range, you can use the parasitic EMF from your phone's speaker to "transmit" a similar code by playing a crafted audio file
The range of human hearing is about 20 to 20000 Hz. As a by-product of producing physical vibrations at those frequencies (i.e. producing sound) via an electromagnetic coil, a speaker will produce an EMF with the same frequencies.
I believe this is referring to the human ear's frequency range, so 20Hz-20kHz, which is a range that phone speakers can produce pressure waves at. I didn't watch the talk either, but I'm assuming that one of the following cases is true:
1. The phone's speaker generates a small amount of EM intereference at the audio frequency it's playing at
2. The sound waves hitting the locking electronics cause them to vibrate at that frequency and pick up random noise from the environment as a signal.
Either way, by using a frequency between 20Hz and 20kHz, everyone has some kind of "transmitter" that can generate mostly arbitrary waveforms.
It's not really because it's "in audio range" but rather "in a range which your phone speaker can transmit" which "happens" to be in audio/hearing range we can mostly hear for obvious reasons.
Has several definitions, usually 20 Hz — 20 kHz: https://en.m.wikipedia.org/wiki/Audio_frequency, but sometimes may refer to the range of specific codec (telephony might have something like 300—3400 Hz for example, so not this case). TFA means it as “I have a peripherial readily available”.
I suppose now I can admit that we did this in college in 2003 (with RF, not audio), and had great fun seeing a grocery store descend into utter pandemonium, until the power electronics overheated and burned the signal carrier to whose chest the circuit had been taped, who started yelping in the store and drawing a lot of suspicion to himself.
You can also take a wrench with you, to quickly remove the locking wheel from your cart. Maybe replace it with a non-locking wheel from another cart.
Shouldn't be difficult to find carts left near or beyond the edge of the parking lot.
I find the locking wheels annoying, because they're so often defective and make it a noisy struggle to get your cart through the store. But years ago I also had a neighbor in my apartment complex who would walk home with a cart every week, and would just leave (a dozen of) them there... she couldn't be bothered to push the empty carts back to the store, not even once. I'd think a $1 deposit/return system for carts would work better, and give the homeless in the area some gainful employment.
Huh, years ago ago living overseas my sharehouse all did that. But we'd take the trolley straight back to the supermarket because we weren't totally degenerate.
Losing a cart is expensive, but it doesn't seem to happen at the scale that would make a full blown locking wheel solution cost effective.
My favorite part of the system in larger stores is that to handle people not carrying cash (Sweden is pretty long-gone in this regard), you can usually go inside the store to get a free plastic token that fits the reader.
That always made me chuckle, since the entire point of the system is that you're supposed to be incentivized to return the cart to get your money back, so by replacing your money with a free plastic token that they hand out from a basket, they did .. something to the overall system design.
Still fun as an example of how the customer's overall experience is more important than the point of an entire security system, I think.
The coins are so that people put them back in their designated storage area, not to prevent theft. A significant fraction of the population are lazy asshole who tend to leave carts next to where their car was parked instead of walking the 10-20 meters it take to return them.
I always kinda doubted that part, or at least its effectiveness. Iirc a 50 eurocent coin will unlock most trolleys, which is pretty cheap for a whole ass trolley.
And sure enough, there's a lot of elderly people that just have a shopping trolley in their yard or something. This morning I found one randomly in our bike shed.
It's not an incentive to "not steal the trolley", it's an incentive to put it back in its place for people who were already not planning on stealing one.
This way the store and the customers don't have to deal with trolleys strewn around everywhere and blocking parking spaces, among other advantages.
I think when they removed the coins during Covid they just noticed that most people were already well-behaved enough to return the carts to their places, so the incentive is just not needed anymore. Actually in Belgium, Colruyt had never had coins for their carts and it just works.
There's no particular need to change this, because one person can only use so many shopping carts. If you maintain the price at "free", demand saturates and people stop stealing carts.
It's common for people to return carts to a designated area, and it's also not rare for people to just leave the carts somewhere convenient for them. Store employees periodically go around and move the carts back to the place where you expect to pick them up.
Costco is an interesting hybrid case. They make it easy to return the carts "correctly" by providing little depots scattered throughout their enormous parking lot. Realistically, the parking lot is so large that very few people would be willing to return a cart to the front of the store, where you get the cart from if you're going shopping.
However, people also aren't going to pick up carts from those depots deep within the parking lot and wheel them over to the store. So Costco employees still have to make rounds of the parking lot and move carts that have been left there to their correct location at the front of the store. But for Costco, you're supposed to leave the cart in the parking lot, but only in certain locations.
I’d never seen that in the uk - but maybe that town was the sweet spot in size where it was small enough that you could actually get home with a trolley (and it was nice and flat), and maybe the number of visitors passing through meant rules got broken more - though the trolleys were more in the suburban areas than just where the hostels were.
It was completely counterproductive, too. The edge of the zone was about 50% of the way home. Out of spite, we'd push the cart up to the edge, and leave it stranded there, carrying everything the last 200m ourselves.
Not proud of that in retrospect; it goes to show that you can't stop assholes with technology.
It's more also common in places where people walk, since it can be hard to bring groceries home on public transport.
So yes, very localized.
The shop near me doesn't have locking wheels (they used to, but stopped), instead they have a guy in a pickup that drives around occasionally, searching for carts.
Locally all supermarkets actually have locks at the entrace so that people can lock their shopping trolleys next to the cashiers.
Curbs have onramps. Pretty much every corner and every driveway provides a ramp where wheeled vehicles can easily get on to the sidewalk. You will never have any difficulty pushing a shopping cart onto a sidewalk.
https://sdotblog.seattle.gov/wp-content/uploads/sites/10/202...
Reminds me of the LoLRa project from cnlohr that transmits LoRa without a radio transceiver.
[0]: https://www.reddit.com/r/neocities/comments/1i7di1c/help_fak...
I hope someone attaches Bluetooth speakers to their shoes and locks every cart in target, so they have to remove the system.
https://hackaday.com/2016/03/04/social-engineering-your-way-...
Edit: looks like an Ardunio can do this with PWM too
Friends did this college in like 2005. Cambridge area, Shaws Market I think. I imagine the hardware setup was a bit different. All the details are hazy but I recall their lock transmission signal had a huge range and locked all carts in a wide area.
Based on what I recall, I believe there was one on the southeastern end of Green Street, a bit between Central and Kendall Square, barely northwest of MIT's primary campus area on the corner Massachusetts Ave and Vassar Street. That location has apparently closed in recent years.
https://www.instructables.com/EMP-shopping-cart-locker/
It might been the same text that somebody copy/pasted there, sounds vaguely familiar.
> Since 7.8 kHz is in the audio range
What is "the audio range" in the context of radio frequencies?
The range of human hearing is about 20 to 20000 Hz. As a by-product of producing physical vibrations at those frequencies (i.e. producing sound) via an electromagnetic coil, a speaker will produce an EMF with the same frequencies.
1. The phone's speaker generates a small amount of EM intereference at the audio frequency it's playing at 2. The sound waves hitting the locking electronics cause them to vibrate at that frequency and pick up random noise from the environment as a signal.
Either way, by using a frequency between 20Hz and 20kHz, everyone has some kind of "transmitter" that can generate mostly arbitrary waveforms.
Shouldn't be difficult to find carts left near or beyond the edge of the parking lot.
I find the locking wheels annoying, because they're so often defective and make it a noisy struggle to get your cart through the store. But years ago I also had a neighbor in my apartment complex who would walk home with a cart every week, and would just leave (a dozen of) them there... she couldn't be bothered to push the empty carts back to the store, not even once. I'd think a $1 deposit/return system for carts would work better, and give the homeless in the area some gainful employment.