Hi,
I did this last winter which ran two trains at once:
http://www.eurobricks.com/forum/index.php?showtopic=87600entry1773620
with lego switches it is
is possible to have trains come backwards the wrong way
through switches, so a special arrangement will lead the train
train through all sections.
It is essentially two connected loopbacks, but then using
Two extra switches to connect the loops...
With a crossing a simpler arrangement can be made
made, if you can construct crossing that is..