Electric shopping carts are common in large grocery stores. Essential for users with mobility impairments, they are also helpful for pregnant women, elderly shoppers, and other who have trouble walking long distances.
A few months ago, my grandfather overturned such a cart in a parking lot and broke his hip. Interested in what might have caused the accident, I examined a similar cart at my local store.
While the cart appeared stable, red-and-white signs affixed to the inside and outside of the basket read, in large letters, “IN-STORE USE ONLY.” Two others warned, “INTENDED FOR USE INDOORS ON LEVEL SURFACES ONLY!” and “DO NOT TAKE THIS CART OUTSIDE THE STORE.” An instruction manual I found online had similar statements in several places.
Here is the problem: A customer who uses the cart while shopping will surely want to use it when taking groceries to the car. My grandfather lived independently and drove himself to the store, but rheumatoid arthritis made walking difficult. Using an electric cart made it possible for him to do his own shopping. While he most likely saw the warning, he may have dismissed it as a statement written to merely to discourage lawsuits. (This is speculation–he could not converse following the accident and died a few weeks later–but it is consistent with his personality.)
Clearly the manufacturer had anticipated that people would use the carts outside and thought this behavior might be hazardous. But did the store share this concern? Since the cashier loaded the bags into his cart following the purchase, it appears that, despite the warning, the store expected him to drive the cart to the parking lot.
The signs and repeated warning statements in the manual suggest a mismatch between the design of the product and the expected behavior of users. So how should the problem be addressed?
- If the carts are truly not stable outdoors, stores should not allow them to be driven into the parking lot. Instead, employees should carry out groceries for all customers who use a motorized cart.
- Offering the service is not enough; some customers, not wanting to be a bother, will refuse assistance if asked. Instead, when the cashier begins checking out a customer with an electric cart, she should immediately summon a worker to load the groceries into a push cart and take the groceries to the customer’s vehicle.
- Manufacturers should assume that customers will take electric carts outdoors and design them accordingly. Motorized scooters intended for outdoor use are widely available.
- If they have not already done so, shopping cart manufacturers should implement similar stability features. As human factors engineers have said for years, a warning is no substitute for good design.
- Good warnings tend to have a “why” that informs the user about the hazard when that hazard is not immediately obvious. If you though the reason to keep the cart indoors was because you might be hit by a car, your decision to take the cart outdoors could be different than if you knew the cart were unstable.
Kim Wolfinbarger is the recruitment coordinator and an adjunct instructor for the School of Industrial Engineering, University of Oklahoma. Her research interests include usability, product design, industrial ergonomics and design for special populations.