Big orange arrow road signs

Does anyone know what the big orange arrows mean that you can see on motorway signs? I heard they are something to do with provding direction to the armed services but does anyone actually know?

Also, what are those little signs showing tanks with arrows pointing up and down, with numbers like 50, 80, 90, etc printed on them? I think they are orange as well!

IIRC, the big orange signs on the autobahn show directions to an alternate route.

The little yellow sings with tanks on them, are placed at bridges (even small ones you wouldn't recognise) and show the allowed weight in tons.

Road signs

Orange arrows indicate a recommended route: PDF StVO page 78

Thanks for that!

That alternative route thing is a little confusing because once you are off the motorway where are you supposed to go then? I don't think I have noticed other big orange arrows on the "B" roads, or am I just incredibly unobservant?

Also, this alternative route is an alternative to where?!?!

It's an alternative way via another autobahn.
A deviation that would lead you away from the autobahn is marked with blue signs saying "U 22" for example.

As you can see it here

To nowhere in particular!

Or to be more exact, it's for long-distance traffic to find it's way around congested areas. You see it used most when there are exhibitions or festivals on, that create extreme localised congestion eg. CeBit in Hannover, Oktoberfest in Munich etc.

They're becoming more and more redundant with the proliferation of electronic roadside and overhead information systems.