|Military vehicles road-sign spotted in Celle, Germany|
In fact the sign refers to the NATO designated Military Load Classification (MLC or Militärische Lastenklasse) for wheeled and caterpillar-tracked vehicles that it is safe for a bridge or road to carry.
Here we have a top classification of 150 for wheeled vehicles - so basically no restriction - and an MLC of 50 for tracked vehicles, which means a maximum of 45.4 tonnes. The Leopard 1 has a weight of 42.2 tonnes so that would have been allowed.
These road-signs are gradually being phased out since Germany's re-unification and the consequent withdrawal of NATO troops after the Cold War. Similar signs can still be seen in other areas where NATO forces were deployed, such as in Kosovo, but thankfully they are increasingly not needed any more in Europe.
This sign is a relic of the British Army Base Celle Station and RAF Celle airfield. Trenchard Barracks, on the northern edge of Celle town centre on Hohe Wende, had been a British base since the end of the war until it began closing down in August 2012. Here is a British Forces News item from 26.06.11 about the closure: