This has been the law in Alberta for a couple of years and people still can't figure it out. It only appies to the adjacent lane but people on a double divide highway will slow down in all lanes in both directions. More accidents waiting to happen because of stupid drivers.
Instead of 60 km max, I don't know why it wasn't written that the speed around any emergency vehicle/worker/ situation should be 'no more than '1/2 of posted speed' on any road in question. Max speed then would only be 55 km.