Staffer’s Notebook: Trees and road safety


I am currently in France visiting family for a little over two weeks. Since my job is also my hobby I took the opportunity of travelling without young children to turn this holiday into an urban planning field trip. Europe is far ahead of North America when it comes to managing population density, resource conservation and the perils of pollution. It’s not a criticism as much as an observation: they addressed those concerns as they emerged, they just emerged earlier than they did in North America..

Yesterday, we travelled from Rouen (in Normandy) to the Ardèche region, a forested mountainous area near the Rhône and within a crow’s flight of the French Alpes’ foothills. It’s in the south-eastern quadrant of the Hexagon.

Instagram: @hey.vero_

We travelled most of the way on France’s privatized toll highway system and finished the trip with a short stint on the “Nationale 7” , the historic tree-lined trunk road stretching from Paris to the Italian border. Used by thousands on their way to the Mediterranean, it is known in popular culture as “Route des vacances” (Holiday route) and — more tragically — “Route de la mort” (Death Route). It is comparable in history and popular culture to America’s Route 66. If Route 66 had been built by the Romans.

We drove down the old Nationale 7 along the Rhône River towards the mountains of Ardèche.

Later that evening, we were discussing road safety and how a series of French policies in the 80’s and 90’s had seen a steady decrease in road casualties from 18,000 a year down to 4,000 with an increasing population. My uncle said in passing that it was hard to parse out which policy had had what impact “between alcohol, speed, seatbelts and trees…”

Trees?

My mother said “Oh, these trees killed a lot of people!”

As it turns out, the iconic borders of trees have a storied past. Seen by some as a road safety hazard, they are also part of France’s cultural heritage to be saved and protected:

Avec la vitesse, la conduite en état d’ivresse, les incivilités, les arbres d’alignement en bord de routes sont aujourd’hui considérés comme un danger à éliminer. Et pourtant… Depuis des siècles, nos paysages sont structurés par les alignements qui bordent routes, fossés, canaux et rivières. Les arbres de bord de route, et en particulier les alignements, constituent un patrimoine reconnu, protégé par la loi dans certains pays.

http://www.patrimoine-environnement.fr/les-alignements-darbres-en-danger-partout-en-france/

Believed to be an answer to medieval deforestation and a solution to shipbuilding needs , the trees, called “arbres d’alignement” for the way they delineate the roadway, were mandated by Henri III in 1552.

Roadway tree planting intensified at the beginning of the 19th Century as a mean of reducing the dust caused by vehicular traffic. By 1895, 3 million trees lined 35,000 km of national roads and even more could be found alongside secondary roads and channels.

In the 1940’s the border trees — until then considered a source of shade and cultural identity — became the scapegoat for the death toll brought on by the rise of the automobile. Calls for their systematic removal met cries for their preservation. Accused of causing 10% of roadway deaths, border trees were not even given the grace of mentioning the state or behavior of the drivers before being killed.

Caught in the crosshair of a campaign to reduce road fatalities, border trees received the support of President George Pompidou in 1970 when he wrote an exasperated letter to his Minister of the Interior upon learning of a policy to remove border trees in spite of his express wishes that they be preserved (my translation):

Trees have no other defenders than myself it seems, and even this doesn’t seem to matter. France does not only exist to allow the French to drive around it at will. Regardless of their importance, road safety problems shouldn’t result in the disfiguration of France’s landscape.

Decreasing traffic accidents will only result from educating drivers and establishing simple rules adapted to the configuration of the road instead of the current complexity sought in signalisation as if it was a hobby. It will also result from more stringent rules in matters of drunk driving (…)

In other words, blaming the trees is a little rich when you were soaked as a Christmas cake behind the wheel. (My uncle told me that blood alcohol levels used to be an extenuating circumstance in vehicular manslaughter trials. We laughed but it wasn’t funny).

Ordinances calling for the systematic removal of roadside trees multiplied in the 80’s and 90’s until 2006 when studies of road safety revealed that border trees — or as one urban designer once told me “anything vertical close to the curb” — had a traffic calming effect. Studies of road safety statistics in communes where trees has been completely removed also emerged showing the questionable impact of designing roads to be wide, straight, and devoid of obstacles (spoiler: it makes people drive faster, has an hypnotic effect and contributes to an increase in accidents.)

In 2010, a village near Norfolk, England experimented with the traffic calming effect of the ironically called “French style avenue”. Borders of trees were shown to reduce the average speed upon entering the village by 3-5km/h for a fraction of the cost of buying and maintaining traffic cameras.

England is generally considered to be 30 years ahead of France in matters of traffic safety and yet, despite these positive results, the remaining French border trees have been singled out as part of a wide-ranging safety audit of French departmental roads.

If you are as interested in the confluence of road safety, traffic calming, environmental preservation, urban design and urban heritage as I am, go and read this 66-page document (with pictures) on road infrastructure and natural landscape from the European Landscape Convention : http://patrimoine-environnement.fr/wp-content/uploads/2015/03/CEP-CDPATEP-2009-15-TreeAvenues_fr.pdf

In the meantime, here is Charles Trenet singing the praises of Nationale 7:

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