A whiff of pure air: what measures can reduce traffic in cities?
By on 6 mars 2017
The high pollution levels that hit Europe in January brought home the importance of promoting less polluting modes of transport and redesigning traffic flows to reduce congestion. Some cities have tackled the problem by implementing traffic-regulating schemes. Cities have a major part to play but asthe mayors of 20 European cities reminded the COP21 audience in Paris, measures also have to be taken at the European level, for example by tightening up the overly lax European standards on NOx emissions.
Urban charging schemes
Urban charges are paid when entering a specific zone which is usually the city centre area. Like motorway tolls, a charge is made, usually only during office hours, to access the zone. This charge must be sufficiently high to discourage people from using their own cars in the area. So far, this scheme has been set up in 3 European cities : London, Stockholm and Milan. To be successful, this urban access charge needs to be combined with an increase in the availability of alternative modes of transport, such as public transport and soft mobility.
In Milan, the urban charge allows access to a specific area, Area C, which is the historic centre of the city, “Cerchia dei Bastioni”. The municipality decided to adopt this scheme in 2012, after having successfully tested for four years the “ecopass”, a charge on the most polluting vehicles entering the area. According to a 2007 study  involving 32 European cities, Milan ranks third in terms of concentration of fine particles (PM10). This explains why, unlike London’s congestion charge whose primary aim is to reduce traffic, the objective in this case is to tackle air pollution. The City of Milan also has one of the best public transport systems in Italy, including the largest underground network in terms of number of lines and stations.
Combining low-traffic zones and stickers
Implementation of the 2008 and 2013 European directives addressing air pollution has led in several countries to the introduction of stickers or labels classifying vehicles, from the least to the most polluting. These stickers are based on European emission standards. However, they are not an exact copy of them and vary from one country to another. These stickers are usually accompanied by the introduction of low-traffic zones that cities are encouraged to create together with any restrictions they see fit to implement. This means that stickers can be used to determine which vehicles may or may not enter the city. This dual system exists in a number of countries.
In Germany, the “Umweltplaketten” scheme was introduced in 2007. This sticker system establishes four categories of vehicles, from the most to the least polluting : no sticker, red sticker, yellow sticker and green sticker. The first low-traffic or environmental zones, called “Umweltzonen”, were introduced on 1st January 2008. As at 1st January 2017, Germany had 54 environmental zones, including 53 only accessible to the cleanest vehicles, those with a green sticker. As the first German city to introduce this system and following the example set by Paris and Oslo, Stuttgart has decided to go one step further : the State of Baden-Wurttemberg has recently decided that as of 2018, all vehicles not meeting the EURO 6 standard would be banned from entering the city, which means that most diesel vehicles will be excluded.
France introduced a similar sticker scheme on 1st January 2016 which establishes six categories of vehicles from the least to the most polluting. The stickers are called Crit’Air, or air quality certificates. First presented as a voluntary scheme, some cities like Grenoble in November 2016 and Paris since 15th January 2017 have made them compulsory before defining low-traffic zones : the city of Paris is now a low-traffic zone from which the most polluting vehicles are banned on weekdays from 8 am to 8 pm.
Other countries like Austria and Denmark have a similar sticker scheme.
Purer air, improved mobility
These initiatives are not mutually exclusive : Milan’s Area C for example is both a low-traffic (Zona a traffico limitato) and an urban charging area. To be a success in the long term, it is essential that these measures are part of an integrated policy covering transport management and other policy areas like urban development and housing. They must also be accompanied by an improvement in the availability of alternative transport, such as a better public transport network or the promotion of soft mobility and car-sharing.
Pending stricter European and national regulations, local authorities are not remaining idle : many have set up sustainable urban mobility plans (SUMPs) which make moving around an easier and more pleasant experience for their citizens.
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 Berrini M., Bono L., Report 2007 Urban ecosystem Europe : An integrated assessment on the sustainability of 32 European cities, 2007
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