Left vs Right hand side driving (Was Australian trolleybuses??? )

[Chris Brownbill <cbrnbill@enternet.com.au>]

Dave McL wrote:

> There is also a nice modern trolleybus system in Tehran in Iran, opened
> in 1992. Again I don't know what side of the road Iran drives on.
> 

The best reference for which side of the road countries drive on is the Thomas
Cook International Timetable.  There are some fascinating anomolies - why for
example do Mauritania and Venezuela drive on the Left when neighbouring
countries are on the right?  (PS I realise that Guyana also drives on the Left).

This leads to a question - what happens at international borders where the rules
change from one side to the other?  Is there a flyover?  Maybe traffic lights
control a 'Change sides now' intersection?

What about a trivia question -  Which is the only country which drives on BOTH
sides of the road (in different provinces)?

I know is a bit off topic - but its interesting anyway.