Ever wonder what those yellow lines in the parking lot of your favorite grocery store are there for? And ever wonder why your shopping cart has that funny looking wheel or two? If the answer is yes, you are either a curious person, a nerd, or just plain weird. The system is basically similar to an electric fence someone would use to keep their dog in the yard. The difference is that instead of getting shocked, the wheel locks up. One of the more popular methods is a GS2 system.
How does it know when to lock up? The store has to bury a wire in the parking lot (see picture below that goes around the entire lot to set up a perimeter and back to the store. The store then has to replace at least one wheel on shopping carts with special wheels that have a battery and a transmitter along with a locking mechanism. The store then sends a special signal (from my understanding it’s magnetic) and when the wheel gets close to or passes the buried wire, it locks up until a store employee with a hand held transmitter can unlock it.
In areas where people take shopping carts off (most likely poor areas with lots of apartments) this is a great idea. The problem is that sometimes the store’s execution is head scratching. Case in point a Kroger near the Galleria area in Houston. Everytime I go there, I see a dozen or so carts that are stuck right in front of the store and angry customers who have to carry their groceries or drive up to the cart. So the photo of the day (cell phone camera) is the shopping cart graveyard: