Han Monsees:
This certainly is a problem in doubledecker trains. It is not possible
to have more doors than the ones above the bogies at the end of the
carriages (it takes way [too] much space to make doors + stairs in the
middle; it would cancel out the gain of having a doubledecker). ...
Paris does in fact have some double-decker RER trains with an additional
set of doors in mid-car. I have here a La Vie du Rail special from 1999
about the then new RER Line E (also called Eole), and here's a free
translation of one section of it:
# Rolling stock specifically adapted to the operator's demands
# ------------------------------------------------------------
#
# But with the MI2N rolling stock, ALSTOM (leader of an industrial
# group formed with ANF-Bombardier) has broken a sigificant barrier
# in favor of client satisfaction. The builder has learned to develop
# and product a specific stock conforming 100% to the requirements of
# the two customers ordering the MI2N trains. The RATP, confronted
# by operational constraints related to station dwell times, had in
# fact made it a non-negotiable requirement to install three large
# doors per car. The objective was to speed loading and unloading,
# and thus the dwell times of the trains in the stations. 14 trainsets
# are currently being successfully used on RER line A. The SNCF, for
# its part, faced with the increasing growth of the daily migrations
# in the Ile-de-France, had to find rolling stock with the greatest
# possible capacity while assuring improved comfort.
#
# The bet was won. A double MI2N set offers the capacity to load or
# unload 1,100 people in 50 seconds, thanks to the three doors per
# car, each providing an opening 2 m wide. And it can carry close to
# 3,000 riders. Such performance, never achieved by other stock,
# makes Eole a unique product in the world, a reference point on the
# battlements of Mass Transit. In peak hours, MI2N trains can provide
# the capacity to transport 90,000 passengers per hour in each direction.
# Such levels of traffic permit the operator to more effectively
# amortize the infrastructure cost.
--
Mark Brader, Toronto | "We don't use clubs; they weren't invented here.
| We use rocks." -- David Keldsen