Almost all French trains will run to changed times from this Sunday – the biggest overnight revolution in railway timetables ever attempted.
Chaos, even "catastrophe", is confidently forecast by passengers' groups when 12,000 out of 14,000 trains change their familiar daily departure times from next week. Protest petitions are circulating and demonstrations are planned.
The state railway company, the SNCF, admits that its "big bang" is likely to "produce a few false notes". Trains may have no drivers. Drivers may have no trains. Passengers may turn up too late or find that their usual train to work or school no longer stops at their station.
In the longer run, however, the Société Nationale des Chemins de Fer Français insists its new pattern of services will be more frequent, more reliable and easier for passengers to remember.
Three reasons are given by the SNCF for recasting 85 per cent of one of the most comprehensive main line and suburban railway timetables in the world. Firstly, a new section of high speed railway opens on Sunday between Dijon and Mulhouse in eastern France. Secondly, a €13bn (£11bn), seven-year programme of overdue modernisation of older lines will improve some services and disrupt others up to 2015.
Thirdly, the SNCF has decided to catch up with the idea of "regular interval" departures: something introduced on Swiss and German, and even British, railways from the 1950s. At present, long distance trains, and even many suburban ones, run to a haphazard timetable which varies from day to day.
From Sunday, a proportion of French lines will move to a pattern of fixed interval departures. High speed trains from Paris to Lyon, for instance, will leave at 27 minutes and 57 minutes past the hour , except for those which leave at 23 minutes past the hour).
Passenger groups claim, however, that the SNCF has used its timetabling "big bang" to hide bad news. Some services, such as overnight trains from Paris to Bordeaux and direct trains from Bordeaux to Marseille, via Toulouse, have vanished altogether. In rural areas, local services have been reduced or trains no longer call at all the stops.
Willy Colin, founder of the protest group "Collective of train passengers of the 11 December", accuses the state-owned SNCF of trying to reduce costs before EU rules force competition in French rail passenger services over the next few years.
"Why is all this being done in such a hurry?" he asks. "In Switzerland, regular interval services were recast over ten years. By changing so many of the times at once, we are heading for catastrophe."
Ghislain de Rugy, head of the SNCF project, insists that new timetables are passenger-friendly. "Over the years, train times have piled up like sediment in river to the point of becoming incomprehensible," he said.
"Regular intervals will make things easier to understand. They also make it possible to run more trains on the same tracks."
Sunday's big bang is just the beginning. French timetables will be recast to increase fixed interval services in each of the following three Decembers.
SNCF in figures
16 per cent Proportion of French rail services which will operate at fixed intervals under the new timetable – double the number in the old schedule.
15,000 Number of trains the new timetable will affect, which amounts to around 85 per cent of French rail services.
€10m Estimated price of the advertising and information campaign needed to alert the public to the timetable changes.