A catenary switch at Ohligs Bf, seen on 13 September 2003. This is what is
called the frog on normal (railway) switches. The drive located above moves
four tongues which form the "rail" for the pantograph. As the pantographs move
indipendently, it is not possible to let the other one running on the outer
"rail" (visible near the edge) guide the one passing the frog (as it is done
with the wheels at railways).
<p>
Digital photo by
<a href="http://www-users.rwth-aachen.de/christoph.schmitz2/index.html">Christoph
Schmitz</a>