Neil Williams wrote:
On Tue, 24 Jan 2012 09:57:21 -0800 (PST), wrote:
SL-2/3 the situation will improve, but the SL-4 still have manual
traps.
What do you mean by "traps" here?
Say your railcar is designed to berth at stations with two different
platform heights: high platform, or floor-height boarding, and standard
platform height. In North America, the standard platform height is
8 inches above top-of-rail. There can be a high step up, then two or
three more steps to get up to floor height.
When berthing at a high-level platform, a trap door is lowered,
covering the steps in the vestibule.
What would you call it?
Chicago South Shore and South Bend uses traps because it has trackage
rights on Illinois Central suburban tracks to reach the Chicago Loop.
IC suburban stations were generally high level, back to the 1870's.
On its own tracks, CSS&SB passenger trains are mixed with freight,
so there are standard platforms.
Why 8 inches? Because it is still assumed that a brakeman or switchman
or carman is hanging off the side of the train, sigh. This hasn't been
railroad operating practice in decades except when cars are actually
being switched, something that just won't happen too often near
passenger stations.
Generally, high-level platforms were designed so that a standard
boxcar could clear. IC has two branches with high-level platforms, both
of which used to have freight customers.
Someone told me that there are merely three oversize freight car types in
North America that won't clear an 8 inch platform, and that 15 inches
might make a practical platform standard. It would sure speed up boarding.