For the Olympics, signs such as these were erected in most stations. It was nice to see the use of kilometres for distances (rather than just miles) but a a grievance which I hold is the measurement of walking distances exclusively in miles per hour.
At minimum, for the sake of consistency, the speeds should have been given in km/h as well – or even better, only in km/h.
Personally, I find it impossible to gauge walking/cycling speeds in mph. It's a lot easier to use metres per second, which is easily convertible to km/h - a lot more accurate too!
I guess it's just the country we live in.