TGV Atlantique - 10 vs 8 cars

[BahrainLad]

I'v always been intrigued as to why a TGV Atlantique set is formed of 2 power cars and 10 trailer cars, rather than the typical 8 you see on a TGV Sud Est, Reseau, Thalys, Duplex etc etc

I assumed it was something to do with the traffic patterns on the LGV Atlantique when it originally opened - such a short length of LGV compared to the overall route length to (for example) Bordeaux meant that a TGV was probably replacing a loco-hauled service, rather than expanding additional frequencies and so needed 10 cars to reflect the replaced capacity. Or something like that. Would be curious to know if there was another reason.

 

[MarcVD]

The TGV Atlantique line is essentially flat, does not have the 3,5% slopes of the Paris Lyon line when going through the Morvan hills. In addition, traction technology switched from serial motors to synchronous (think BB22500 to BB26000). So the traction capacity increased quite a lot, even with only 4 powered bogies instead of 6. That made an increase in length of the sets technically possible. And initial plans did not foresee an interconnection between the two lines, so incompatible rolling stock was not an issue. It took them less than a year to regret this decision...

 

[SHD]

Indeed the main reason for having 10-car TGV Atlantique trainsets has to do with traffic patterns on the Western (formerly from Montparnasse : Brittany, Nantes) and Southwestern (formerly from Austerlitz : Tours, Bordeaux, Toulouse) lines.

- heavy leisure traffic esp. on weekends, during school holidays, and in summer

- longer journey times than the core 1980s market of the LGV Sud Est

In addition, the LGV Atlantique has an easier profile than the LGV Sud Est (max. gradient 25‰)

So what was needed? Capacity.
What were the possibilities?

- longer trains
- double decker trains

In 1988, the easiest solution was 10-car trainsets. Yet, it was necessary to upgrade many platforms on the western & Southwestern lines. Note that the two additional coaches are standard class (logical isn’t it?)

Atlantique trainsets, the first TGVs designed for 300 km/h operation, are noticeably more powerful than Sud-Est TGVs (8.8 MW vs 6.4)