Itinéraire Bis

The cunning bison doesn't follow the crowds! The Itinéraires Bis, simply translating as "alternative routes" is a network of secondary routes designed to take long distance traffic away from congested roads.

The scheme was born following the very hot summer of 1975, where on 2 August the N10 route (a 800km trunk road from Paris towards the Spanish border) was badly congested. At 11am, the authorities reported over 600km of the route was suffering with traffic jams. The heat, coupled with a number of accidents, led to 145 deaths that day.

The consequence was (naturally) a need to do something to avoid a future repeat. The PALOMAR Plan - standing for Paris, Lyon, Marseille - was established to promote a network consisting of 3,500 km of alternative routes that motorists could take to help shed some of the load onto other roads.

To promote the network would be Bison Futé, the Cunning Bison. Free maps would be provided to provide details of traffic hotspots, alternative routes, information points and useful ameneties. This tradition lasted until 2003, by which time the motorway network was developed enough to disperse traffic on its own. As for the Bison itself, it lives on as a traffic advisory website.

 

From 1984, many of these alternative routes have been permanently signposted as part of PALOMAR. Such routes consist of alternative motorways, trunk routes and better quality secondary routes (often de-trunked roads).

Originally signposted using green signage with a yellow square featuring the word Bis, their design was updated in 1998 (although many older signs still exist) to make them more easily recognisable - a yellow-on-black icon situated on a yellow panel:

 

Signage at the start of a Bis route	End of Bis route signage

When roads are congested, the authorites will activate PALOMAR locally, whereby variable message signs warn of problems further down the motorway and request that traffic diverts via the Bis. The police may also hinder access to the motorway by closing off access points, requesting these motorists use the same alternative route.

Bis route to Limoges signposted on the D956 in Loir-et-Cher, as part of an alternative to the A20 south of Orléans. This example is in the older design.

As such routes are permanently signposted, they can make for a leisurely drive through the French countryside - even if the motorway is also quiet. Great if you're not too pushed for time!

 

Itinéraires de Substitution

On a much more local level, these are strategic diversion routes that are shorter deviations from the motorway.

Marked with a number prefixed with the letter "S", they typically bring you back to the intended route one or two junctions further down. They are similar to what the UK signposts with shape icons.

Signage at the start of a Bis route	End of Bis route signage

Signpost just outside Blois indicating substitution routes S3 and S8 in the event of problems on the A10.

 Picture credits
   D86 signage  is taken from an original by Chris Zwolle and used under this Creative Commons license