Every shopping cart is equipped with some sort of alarm (along the lines of a car's 'you left your lights on' alarm.) Every aisle in the supermarket has one shelf (at cart level) with some sort of 'contact' strip running the length of it. The Cart alarm is wired so that it will stay off as long as there are two hands on the cart handlebar or the cart is in contact with the aisle contact strips.

The idea is to give a friendly reminder to people about shopping cart etiquette, namely the rule about not leaving your cart in the middle of the aisle while you are searching the shelves.

No hands in the middle of the aisle = instant alarm; One Hand in the middle of the aisle = you have a 10 -15 second grace period before the alarm sounds. If cart is outside of the store in the parking lot, no alarm. The shopping cart corral is also fitted with the contact strip to keep things quiet over there too.

Advanced model can include proximity sensors to determine when other carts are around that should be let to pass.
-- blahginger, Sep 20 2000

Brilliant. I would suggest an especially loud and embarrasing alarm if a cart loiters in the exit for more than ten seconds.
-- Scott_D, Sep 20 2000


What about people with only one arm?
-- amadeus, Sep 20 2000


Also, when the alarm goes off, a team of security men rush to the scene, confiscate all of the items out of the trolley, and force the miscreant to go round again from the start.
-- DrBob, Sep 26 2000


I often push with one hand and then (Note: this only works with UK-style shopping carts with free steering rear wheels, not the US-style ones with fixed rear wheels) violently push the handle of the shopping cart sideways. The cart spins through 360° and I catch the handle again. Works best with a partially-loaded cart as a certain amount of rotational momentum makes the cart spin more predictably.
-- hippo, Sep 26 2000


The trolleys that I use seem to do that without the need for any assistance from me.
-- DrBob, Sep 28 2000


Four independently perverse wheels...

Because the steering is so bad on the carts, I often walk in front of it and drag it behind me by a hand in the wire/plastic at the front. It's moving in the correct orientation, but the motive power is applied at the front, instead of the back.
-- StarChaser, Sep 28 2000


You kids got the carts that won't go past the parking lot? (wheel locks up at perimeter to prevent theft)
-- thumbwax, Sep 29 2000


Yup. I thought those were a cool idea when I lived in California (up until June) - then, I get back to Blighty and we've got them here too.
-- hippo, Sep 29 2000


Wild. I've never seen those...<I do all my shopping at one of two stores, though, and their carts are so ragged out that no self-respecting homeless would want one...>
-- StarChaser, Sep 30 2000


Mostly the same 3000 miles away. Vons in some beach cities have the antitheft feature. Gelsons and Mayfair Markets have the cleanest carts. The unbelievably polite staff at these stores will take you right to what you're looking for. Every other store, Hahaha.
-- thumbwax, Sep 30 2000


I am a designer in the US and am working on a shopping trolley design right now, I find the best way to steer a trolley is when they have fixed back wheels, this way you can lean into it and it turns for you, marvelous! or you could just drag it behind you with a large belt or dressing gown tie around your waist, watch for corners tho.
-- blanchard, Nov 14 2003



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