Clive Feather and I (Mark Brader) wrote:

and used to be a 13bis).

First I've heard of it, if so.

Look for maps of the 1960s and 1970s. The western branch of the old 13
was 13bis (though unlike 3bis or 7bis trains ran all the way from the
southern terminus, rather than just on the branch).

Ah, interesting. Okay, I have one book from that period: "Notre Metro"
by Jean Robert (1967 edition). The color map at the back of the book,
specifically dated December 1 of that year, shows both branches as
Line 13, the same as today. But on flipping through the book, I see
that the track diagram of the system does show Line 13bis as Clive
describes. As far as I can see, all other maps show both branches as
Line 13 (or Line B, depending on the time period depicted), and so does
the text as well as the table of opening dates.

However, while checking this out, I found references to two *other*
"bis" lines.

The original 1898 plan for Line 8 had it running from Opera to Porte
d'Auteuil, with the western part following what is now Line 10. This
was modified in 1910 to a plan with two branches, one as just described
and the other following the line's present route to Balard. But the
line as actually first opened in 1913 followed the original plan,
running to Porte d'Auteuil only. The second branch was not built
until 1937. But the line never operated with two branches, because
by the time the branch was built, it was part of a project to reroute
and extend two other lines, and Line 10 took over the Porte d'Auteuil
branch the same day that Line 8 first ran to Balard.

Anyway, in the section where this is discussed, Robert repeatedly
refers to the new Balard section of Line 8 as Line 8bis. Presumably
this was a working name for the branch during construction.

The other "bis" line was Line 5bis. According to both Robert and
Tricoire, this was the name originally used for the new section of
Line 5 when it was extended in 1942 from Gare du Nord to Eglise de
Pantin. Note that this was never a separate service, not even a
branch, but a simple extension of an existing line, but it was given
a "bis" number anyway. The extension did involve relocating the
line's Gare du Nord station, which was originally on a terminal loop.
--
Mark Brader "How can we believe that?"
Toronto "Because this time it's true!"
-- Lynn & Jay: YES, PRIME MINISTER

My text in this article is in the public domain.