Dangerous condition at Walmart Part 2

This is part 2 of a series on my attempts to get Walmart to fix a dangerous situation in its stores.

The dangerous situation has two elements. First, the floor is slippery.

It's not so bad if you are walking around. Shoe soles seem to stick just fine. But skateboard wheels slide sideways easily. To make things worse, it's misleading. The floor is made of concrete. A kid might think it's the same material as the sidewalk, and feel confident of his skills. But it is very different and surprising. My daughter says her accident never would have happened on the sidewalk or pavement.

To see just how different it is, I measured the coefficient of static friction of a skateboard on various surfaces. I used a hand scale to measure the greatest sideways force I could put on the skateboard without slipping, and then divided by the weight of the skateboard:

Here are the results:

The friction in an aisle is about half what a kid would expect from prior skateboarding experiences.

In my next post I'll describe what Walmart has done to prevent injuries and why it is inadequate.