In article , David Bradley
writes
High speeds are not likely to be a problem along the Uxbridge Road (the
proposed mean speed for the tramway is 13 M.P.H.!).

Is this mean speed while running, mean speed calculated start-to-stop,
or mean speed from end point to end point? There's a huge difference
between these.

For example, consider a route 10km long with 29 intermediate stops (that
is, a stop every 333m), assume that the dwell time at stops is 30
seconds, and that trams can accelerate and brake at 2m/s^2. I'll use
5m/s (11.2mph) for ease of calculation:

* End-to-end speed of 5m/s means end-to-end time of 2000 seconds (just
under 35 minutes).
* 870 seconds is spent stopped, so that's 1130 seconds of running time,
or just under 38 seconds between stops. That's a start-to-stop speed of
8.85m/s (19.9mph).
* This requires accelerating to 10m/s (22.5mph), running at that speed
for 28 seconds, then decelerating again.

So the end-to-end speed is only half the service speed.

There is
no experience whatsoever of 40 metre trams in UK streets, so we have no
knowledge of how they will fare even with their fixed path.

There is experience with coupled pairs in Manchester and even Blackpool.
We also have hundreds of years of experience of rail transport which
shows us that all the vehicles follow the same fixed path, whether the
combination is 5 or 500m long.

--
Clive D.W. Feather | Home:
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