On 20 Dez., 09:57, "Graham Harrison"
wrote:

And, I am aware of the new double deck trams in Hong Kong.

Alexandria also has some double-deck trams. I beleive they are of
Chinese make.


In the past, double deck trams were more common. Paris and Berlin both
had them and no doubt several other cities besides.

I am not sure about the details, but I believe that one factor that
was different in the UK was legislation concerning trailers. I am not
sure whether they were banend outright, or it was something else.
Anyway, although some British trams did have trailers, they were
extremely rare. Where the Germans for example used trailers to grow
capacity, British operators built upwards.

Of course one disadvantage of trailers was that they needed to be
shunted at the at end of trip, and so loop tracks had to be provided.
Many operators worked around this by building turning loops in which
no shunting was required but the entire tram went around on a cicle of
track to face the other direction. The provison of these prepared the
way for the next development which was that of the uni-directional
tram, having a cab at only one end and doors on only one side. They
were less flexible in service as they needed loops but from the
maintenance perspective there was less hardware to be maintained. The
absence of doors on the off side also meant that more seats could be
provided. From there they went to articulated trams which again was a
step backwards in terms of flexibility (compared to trailers) but had
advanatges in terms of passenger flow and better utilisation of space
etc. Also the concept was scalable so longer and longer trams could be
made just by adding intermediate segments.