Questions / Answers > Bad weather

Aren't you able to forecast the severity of episodes of bad weather ?

In partnership with Météo France, ASF has acquired cutting-edge systems to have real-time access to detailed Météo France weather forecasts and to be informed about weather conditions in the motorway network (lien page asf/exploit/sécurité). But it is impossible to predict precisely the intensity of weather events at a local level. Practically speaking, modern technology can predict that there will be snow in a region, but cannot specify the exact time at which it will fall or differences in intensity from one town to another.

When people are stranded by bad weather, why do you leave them to fend for themselves ?

Only emergency assistance teams coordinated by the Prefecture are authorized to provide help to individuals. But ASF staff assist them and facilitate their work, by welcoming and informing people at toll plazas, offering emergency food and hot drinks, and if needed directing drivers toward shelters. Commercial facilities in service areas also remain open to serve as places of refuge.

Why do you have to shut the motorway in the event of strong snowstorms ?

We know that one accident in five takes place in bad weather. Heavy vehicles, in particular, become hard to control on even a thin layer of snow or ice, and they are liable to block the motorway very rapidly by skidding in the exits and ending up perpendicular to the road. Traffic is then paralyzed over long distances and it becomes difficult for emergency rescue teams to act effectively. These chains of events happen all too frequently, leading us to implement a policy of notifying the Préfecture as soon as bad weather conditions are announced, since the latter is the only authority able to shut down the motorway. The aim is to act fast and shut down early enough to avoid the motorway becoming completely blocked and to allow snow removal. As a first step before deciding to close down, heavy vehicles can be grouped into convoys or parked in stabilized areas (either in service areas or on the side of the road), so that traffic is limited to light vehicles. These provisions are included in snowstorm contingency plans.

Why don't you spread more salt to speed up snow removal ?

Salt is far from being a miracle product. Because its melting power is actually fairly low, you have to spread 500g (one pound) of salt per square meter (11 sq. feet) to melt only 3 cm (2 inches) of snow. Salt is also not recommended in some cases, because it can lower the temperature of the snow and the road, and lead to widespread icing. When there is a lot of snow on the road, the only effective method for removing it remains mechanical scraping using snowploughs.

Why don't you shut down the motorway as soon as the first snowflake falls ?

A first snowflake doesn't necessarily mean that a snowstorm will follow. In the face of moderate snowfalls, it is possible for traffic to remain relatively fluid. For this reason, an observation period is needed to be sure the right decisions are being made, which means assessing the situation area by area and implementing the most suitable measures.

Why don't you use more snowploughs ?

The number of snowploughs deployed by ASF in snowstorms has been calculated to allow a satisfactory response to heavy snowfall. These machines then work in continuous shifts on both sides of the motorway. However, in exceptional circumstances with very heavy and intense snowfall, it is sometimes not possible, even with a large number of snowploughs, to keep the road clear of snow during the entire duration of the storm. In addition, when traffic is paralyzed and a large number of vehicles block the road, snowploughs can no longer reach the affected areas, so their number becomes irrelevant.

How much time do you need to shut down the motorway ?

The Préfet must first assess the impact that the closure will have on the secondary roads network and on organizational logistics in nearby départements, for example in terms of accommodation resources, prior to notifying ASF of his decision. From that moment, ASF needs one hour (during which cars and lorries continue to enter) to set up, well ahead of the exit, the signage and displays for closing and, if appropriate, to take the necessary measures for parking heavy vehicles.

Why don't you clear all the lanes ?

As long as snow is falling, the priority is to clear a limited number of lanes (one or two instead of the two or three that are open under normal conditions), because concentrating snow removal equipment on a smaller number of lanes makes it possible to keep the motorway open longer. Keeping traffic on a limited number of lanes also helps the motorway remain clear of snow in the event of moderate snowfall. In three-lane motorways, we begin by scraping the right and middle lanes. As long as traffic allows it, the snowploughs try to clear the right-hand lane as a first priority, so that the vehicles with the least mobility (heavy vehicles in particular) remain in their designated lane. But our efforts to keep the motorway usable as long as possible can be ruined by the dangerous behaviour of impatient drivers who try to pass, use the lanes that have not been cleared of snow and then find themselves blocked or perpendicular to the road, thus preventing other vehicles from coming through.

When you know that you are going to close down the motorway and that it is already blocked, why do you let vehicles enter the trap ?

The flow of vehicles varies according to the hour, day and direction. On weekdays, the A7 has 70,000 vehicles daily. That is why we cannot wait for the decision to shut down, which can only be taken by the Préfet. We have to take appropriate early-warning measures. This begins with displays on the signs located before the entrances to the motorway, recommending that users not enter the motorway, and explanations to the same effect given by toll agents and on Radio Trafic (FM 107.7). There are, however, two problems: those drivers that have already entered the motorway prior to the beginning of the snowstorm or while the snowfall was still very moderate; and the regrettably large number of people who ignore the recommendations given during the pre-alert phase and further complicate the situation, or even block the motorway completely if they lose control of their vehicle.

Why are we badly informed ?

ASF is aware of how much of a challenge providing real-time information can be, and has taken steps to improve communication in its various media, by:- Adding more electronic displays in strategic places where they can be useful to drivers;- Broadcasting more precise and detailed information, as much as our sources allow, on our motorway radio Radio Trafic FM 107.7 and from our Autoroutel information call centre. Further, ASF has decided to a proactively inform its customers as soon as a reliable bad weather alert. This precautionary principle leads us to inform our customers on a preventive basis, using all available live media, such as Autoroutel, asf.fr, Radio Trafic FM, national and regional radio et television stations, as well as press agencies.

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Questions / Answers > Bad weather