It suffered a gradual decline, until in 2006 it had a new lease of life as its renovation was chosen as the most cost-effective way to shorten the journey time from Paris to Geneva.

The upgraded line was inaugurated on 2 December 2010 featuring 25 kV AC electrification, replacement of 18 level-crossings with bridges, avalanche protection and daylighting a tunnel.

[4] This project, deemed insufficiently lucrative by the major companies was given life thanks to a law passed in 1865 allowing lines 'of local interest' to be financed by departments and municipalities.

The outcome was a requirement to share stations with existing ones on the network and to use standard gauge track to ensure interoperability.

After 1878, the Freycinet Plan called for standard gauge 'local interest lines'[4] be integrated into the national network prior to nationalisation.

During the second world war, the line had strategic importance, as there was a lot of resistance activity in the Ain and on the Jura plateau.

On 2 May 2003 another accident occurred in the Mornay tunnel when a diesel railcar caught fire 300m from the Bolozon portal.

Geneva and the surrounding areas have long sought to reduce the rail journey time to Paris.

Having considered 220 km of possible routes, the final report, delivered in September 1990, recommended an HSL starting from the Macon-Amberieu line below Polliat and entering Geneva either from the North or the South with a junction to the la Praille goods yard and a spur to Archamps to connect to the Longeray – Annemasse – Evian line.

The crossing of existing rails at Nurieux and Chatillon-en-Michaille would have allowed construction to take place in phases.

Options that could be combined with this project were upgrading the Pont-de-Veyle - Polliat section to 200 km/h, and electrification of the Sathonay-Bourg line, with construction of two new stations, Bourg-north and Nurieux.

However, this option was considered to be far too expensive at 2.3 billion euros, mostly due to the extensive engineering works needed, and the project went no further.

A freight route in the Albarine gorge between Ambérieu and Culoz, using two long tunnels to straighten and shorten the line would have brought an 8-minute gain, but this was abandoned by the ministry of transport.

The heavy environmental footprint, and the exorbitant cost of this option (1.3 billion euros) led to it too being abandoned on 18 September 1988.

The project has upgraded existing tracks to enable higher speeds by both TGV and regular trains.

The reopened line has reduced journey times between Paris and Geneva due to both a shorter distance and higher speeds.

The improved line now allows TGV trains to shorten their route to Geneva by 47 kilometres, reducing the Paris–Geneva journey time by about twenty minutes to just over three hours.

A special effort has been made for environmental protection, particularly at the lakes of Nantua and Sylans, and to utilise rail noise screening.

[13] Finally, commercial service began on 12 December 2010[14] The Haut-Bugey line links Bourg-en-Bresse to Bellegarde-sur-Valserine.

Leaving Bourg-en-Bresse station, in the town centre, the line heads South through residential areas.

The hilly nature of the terrain required the line to take a steep and sinuous course, crossing and recrossing the route départementale several times.

The Racouse tunnel takes the line through the second ridge of the Revermont, then the Cize-Bolozon viaduct crosses the river Ain to Bolozon station.

Then comes a long climb up the slopes of Mont Berthiand culminating in the Mornay tunnel after which the line runs flat and straight to Nurieux-Volognat station.

A short climb through le Neyrolles along the Sylans lake to the village of Charix, then plunges down the valley of the river Semine to Bellegarde.

The rest of the line is limited to 90 km/h except between les Neyrolles and St Germain de Joux which can be taken at 100 km/h.

Nurieux-Volognat, is close to the town of Oyonnax which sits at the heart of an industrial cluster specialising in plastics technology.

The 141Rs so prevalent on the SNCF network, saw no service on the Haut-Bugey line as their axle weight was too heavy for the rails, although they did exceptionally run up to Nantua on trains unloading rubble from the Cret d'Eau tunnel.

They could be found coupled to X2800 (a powerful 825 hp railcar designed to haul several carriages and operate on steep gradients).

The TER service between Brion and Bellegarde is only provided by buses; no regional trains runs on this section any more.

[30] However the journey times are expected to fall when the Geneva - la Plaine and Bourg - Macon sections are upgraded.