Letter to the editor

Sir - I would like to add some further information and make some corrections to the article Haut-Bugey revival will speed TGVs (RG 8.05 p489).

Administrative and financial delays mean completion has been put back to mid-2008. This autumn the Bourg - Brion section will close to traffic for two years for rebuilding. Local DMU services could restart in late 2007, ahead of the rest of the line where the most difficult point will be the building of a new chord in Bellegarde with a curved island platform for the TGVs.

A 1 km deviation at Bourg will eliminate two level crossings and extend the current 140 km/h line speed to Ceyzeriat, as well as reducing noise in residential areas. A 5 km section suitable for 140 km/h will be on a relatively flat and straight section between Nurieux and Brion, but double-tracking has been dropped and the passing loops will be retained.

The time saved by the new line will be 25min, rather than 20 min, allowing a 2h55/2h57 Paris - Genève schedule for TGVs calling only at Bellegarde, or 2h50/2h53 non-stop. Between Paris and Mâcon the use of TGV Duplex or Réseau trainsets instead of PSE will save 2min. By around 2012 when renovation of the Paris - Lyon route has been completed, an extra 3 to 4min could be saved, as the current timetable allows for overnight possessions which impose 120 km/h speed limits where work is currently underway.

The Haut-Bugey line will be fed by one 2 x 25 kV substation in Cize-Bolozon. Because of the 2·5% gradient from Bellegarde station it was planned to electrify the first 8 km to Châtillon de Michaille at 1·5 kV in order to put the changeover point in a more suitable location, but after careful examination this was changed to 25 kV all the way to Bellegarde, even if the changeover will be a little more difficult. This saves the cost of a 1·5 kV substation, makes better use of the powerful Cize substation, particularly where the current demand is high, and will bring significant maintenance savings and reduced energy losses.

This also paves the way for the conversion of the Bellegarde - Genève line to 25 kV, which SBB and RFF are discussing along with the CEVA project for a new line between Genève and Annemasse. Conversion of 15 km of line on each side of the border at La Plaine would be a relatively simple operation, as the loading gauge is already sufficient, and manual block of this line is to be changed in the next five to seven years to an automatic block insulated against AC interference. If adopted, this will greatly simplify the electrical map of the Genève area, replacing 1·5 kV DC, 25 kV 50Hz and 15 kV 162/3Hz with two AC systems which meet in a similar way to other electrical junctions between the French and Swiss networks. This would simplify commuter operations in Genève, and allow the use of the same rolling stock as in Basel. Four DC substations could be removed, at the expense of a single new AC one.

On the French side, the Savoy area AC electrification which branches off at Longeray 4 km from Bellegarde could be connected to the Haut-Bugey electrification, avoiding changeovers 4 km apart and the Haut-Bugey AC section being isolated in a DC network. The financial case is not obvious, and reinsulation of the catenary is a costly procedure, so adoption cannot yet be taken for granted. But there is strong interest from all parties, and ideally it would be completed in 2012, the date set for the new Genève - Annemasse line to open.

Christophe Keseljevic
Manager of Benchmarking &Technology Developments,
Réseau Ferré de France