In article ,
Tony Bryer wrote:
In article , Tom
Anderson wrote:
Then they're travelling too close together. Unless the traffic's
flowing at 40 mph, at which speed 2 seconds is almost enough.

Your arithmetic is wrong

Irrelevant (and arguable).

When using _your_ figure of 120 pax per minute per lane - which is
somewhat optimistic and assumes ideal conditions - you still get a
answer which says that a 3 lane motorway has the same capacity as
the central line.

It may be interesting to compare the projected cost of crossrail
with the projected cost of a 4 or 5 lane motorway over the same
route.

They would probably have equilvilent capacity according to your
figures; I'm assuming that crossrail capacity will be half as much
again as the central because it has longer trains, but that's a
somewhat back-of-the-envelope calculation.

--
Mike Bristow - really a very good driver