Wednesday 27 July 2022

London 1 - Paris 13 (Part 3)

 When Is A Tangent Not A Tangent

We all remember our Geometry lessons at school (don't we?) and are therefore well aware that a Tangent is a line which just touches a circle at right angles to the radius. With that piece of useful information firmly ensconced in the grey matter, we might be able to unravel the problem of real trains at the Noisy-le-Roi tram stop!
One of the many maps of Paris' tram T13 shows all its connections with other rail services and an extension which will undoubtedly appear in due course.
Next stop north from Noisy-le-Roi is the snappily named Saint-Nom-la-Breteche-Foret-de-Marly, only slightly abbreviated on the station name board!
There we meet Transilien Line L. Transilien is an SNCF "brand" for trains serving the Ile-de-France area, i.e. Greater Greater Paris.
Cleverly, Paris is marked with a P; surrounded by Greater Paris (very faintly shown as A, B and C); then come the much larger Ile de France districts. Our tram T13 runs from near Versailles to St Germain-en-Laye, relatively close to the Greater Paris boundary.

Line L, like all these suburban non-RER lines is a bit of a hotchpotch of branches, usually emanating from one of the the Paris terminus stations; in the case of L that is Gare Saint Lazare.

A diagrammatic plan of the rail lines shows one of the branches of L terminating at St Nom etc. (map below, upper left).
And here is a train arriving at St Nom.
The station building and tram stop are adjacent.
Transilien L would appear to be popular with park and ride commuters!
Another branch runs to Versailles (same map), a line which fbb has ridden AND blogged about (search for Variety in Visiting Versailles). The third L sets off in the opposite direction and joins RER line A to the north west of the city.

Diagrams are OK, but fbb likes to fit transport into the geography, so was delighted to come across a geographical map of Transilien and RER routes.

And look! There is the northern branch of the L (coloured lilac) ...
... and the two southern branches.
But look again at what happens at St Nom.
There is a shortish bit of line L called the Tangentielle

It would appear that "Tangentielle" is/was a brand name for services re-opening the Grande Ceinture line which ran all the way round Paris,

Tramway T11 (partially open but planned to expand) was originally branded as Tangentielle Nord ...
... and there are big plans for Tangentielle Est serving Aeroport Charles de Gaulle ...
...and Marne-la-Vallee Chessy (as in EuroDisney).
This line, if it happens (surely when it happens), will be mostly a re-operning of a local service on the Grande Ceinture. None of these lines are anything like a "Tangent" - surely "Orbitale" would be mathematically better?

Another label which crops up on-line, associated with the Tangentielle L and tram T13 is Grande Ceinture Ouest.

That little nomenclature discovery finally unlocks the truth of the railway that became tram T13.

La Grande Ceinture Ouest (GCO) était un service de voyageurs exploité sur la ligne de la grande ceinture de Paris de 2004 à 2019, en tant que partie intégrante de la ligne L du Transilien.

Intégralement située dans le département devs Yvelines, la GCO reliait la gare de Saint-Germain-en-Laye-Grande-Ceinture à la gare de Noisy-le-Roi. Elle est mise en service le 12 décembre 2004, marquant le retour du trafic de passagers sur la ligne après 68 années de fermeture.

Le succès de cette courte ligne, ne reliant aucun pôle d'importance, et isolée du reste du réseau, est toutefois mitigé, celle-ci connaissant un trafic anecdotique. La ligne est néanmoins utilisée comme une vitrine pour la SNCF, qui y teste diverses innovations dans les trains et dans les gares.

Dans le cadre du projet de ligne tangentielle ouest, il est décidé de transformer la ligne en tram-train et de la prolonger à ses deux extrémités. Elle laisse sa place à la ligne T13 Express du tramway d'Île-de-France, qui est mise en service le 6 juillet 2022.

Creating this line mainly as a test bed for future S N C F developments was far from cheap. Notable (and expensive!) work involved the rebuilding of a former lattice girder viaduct across the Val St Leger near the northern terminus of Saint-Germain-en-Laye Grande Ceinture.
Yep. A big job!
Here is the whole thing c/o Google Earth.
There is even a footpath all the way across, from south ...
... to north.
There doesn't appear to be a footpath over the original viaduct but fbb is not sure!

Tomorrow, we will complete our virtual survey of the tram route but meanwhile, a question.

Would British Rail, Railtrack, Notwork Rail, Great British Railways (or whatever it is called next) even consider reopening and electrifying the line between Northampton and Bedford, then, fifteen years later, converting it to tram train and extending north to Market Harborough and east to Sandy?

As folk are wont to say ...


How Much?
That deLuxe Bachmann class 47, in its weird Rail Operations Group livery, is not cheap.
Only £370!! BEYOND OUCH!

On-line Error!
It's not a SECAND - it's a SECANT.
Never believe anything you read on line without some validation! 

fbb had never heard of a  "secanD" but had heard of a "secanT" but had no idea what it was!

 Next T13 blog : Thursday 28th  July 

1 comment:

  1. Andrew Kleissner27 July 2022 at 09:21

    I believe that, in US rail terminology, a tangent is simply a (?fairly lengthy) section of straight track.