On Wed, 18 Jul 2012 12:58:05 +0100, "Mortimer" wrote:

"Recliner" wrote in message
.. .
On Tue, 17 Jul 2012 23:56:08 -0700 (PDT), e27002
wrote:



IMHO, not a good program. It was simplistic tothose with some
knowledge of the subject. It was misleading to those without. The
graphics were not bad.

What was misleading about it? Other than that it mentioned TfL and
Crossrail
projects in the same breath rather than making it clear that Crossrail
is
not part of TfL or "the London Underground system".

The City & South London was the first subway line? Whatever happened
to the Met? Apparently steam motive pwer was considered! (On a tube
line). Greathead was the first to tunnel with a shield! What was
Marc Brunel utilizing (OK, not so refined, but still the same
principle).

The program was simplistic and lacked detail, even for "normals".

Yes, it was simplistic and lacked detail, being intended for the US
market, although it apparently still required a longer attention span
than you could muster. It made quite clear the difference between the
Met's cut and cover tunnels (complete with horse-drawn carriages
driving on the right) and the pioneering deep tube tunnels used by the
C&SLR. It separately explained that multiple-unit electric trains (as
pioneered in NYC) had better traction than steam loco-hauled trains,
though it didn't mention the intermediate option of electric locos, as
used initially by the C&SLR.

Wasn't the better traction caused by the multiple driving wheels distributed
along the train rather than the use of electricity as opposed to steam?
Wouldn't an electric loco (with the same number of driving wheels as a steam
loco) have the same traction problems? Wouldn't a diesel multiple unit (or a
"steam multiple unit", if such things existed) be as good as an EMU?

Yes, exactly. They were explaining why distributed traction is better,
though they wrongly implied that every axle is driven (it is in some
modern stock, but in older units, typically only between one third and
two thirds of the axles are driven). I'm not aware of any DMUs with
all axles driven, but it would be possible.

Of course an electric loco would still provide better traction than a
steam loco, as all of its weight would be carried by driven axles,
which is not the case with larger steam locos (ie, anything larger
than a small 0-6-0T).

Locos have another problem which the programme didn't mention, which
is their high axle loading, with particularly high unsprung weight if
the motors are axle-mounted. This caused serious problems for the CLR
when it opened in 1900, as the vibration from the heavy early
(US-built) locos disturbed the occupants of the buildings above. The
trains had to be hurriedly converted from loco-hauled to multiple
units, which was completed by mid 1903 (imagine how much longer such a
change would take today).

This was before the New York Subway's first underground line opened in
1904, so perhaps the programme could be criticised for wrongly
crediting the NY Subway with pioneering underground EMUS, when the CLR
actually beat them to it by more than a year. Of course, EMUs had been
used above ground before then: the Liverpool Overhead Railway had used
EMUs, including into its underground terminus from 1893, so perhaps it
deserves the credit. Either way, this US-made programme could be
credited with giving more credit for this particular innovation to the
New York Subway than it actually deserves.