As far as I'm aware it's only for military purposes, though I guess it would be handy to know where they in case of emergency - you'd just have to fins a way to get rid of those pesky cars.
Handy, yes. Allowed, no. It's forbidden to mark the location of such strips and you can be prosecuted for doing so (no kidding!). Although in the age of Google Earth anybody can now scout for them from the safety of their home. Unless they are
blanked out like military installations in the Netherlands, which would make them even easier to spot. Just look for the blanked-out strips of road.
Ciao,
Dg800