When Paris banned 50% of cars from its roadways earlier this week, media agencies all around the world took notice. A lot of attention was put on French residents who were pissed off about the ban, and stated they wouldn't respect it. Indeed, about 4,000 tickets were issued on Monday to people who were driving but had a license plate ending with the wrong number. At a fee of €22 each, that's about €88,000 or $121,000 in fines.
Aside from thousands of drivers not respecting the ban, there's actually no clear proof that such bans have a positive long-term effect on air pollution, and there's concern the effect may even be negative.
Confused? Here's the deal: "Long-running licence plate schemes operate in many cities, including Athens, Beijing and Mexico City. Some ban cars every second day, others once a week. But drivers inevitably circumvent restrictions by buying cheap, inefficient cars with opposing number plates according to Lucy Sadler, who runs the Low Emission Zones in Europe website. This means some schemes have had an adverse effect on air quality."
The positive move taken in Paris, in my opinion, is that the ban excluded electric cars, hybrids, and people who carpooled (3 or more people to a car). So, rather than being encouraged to buy more cars of lower quality, such a policy would encourage people to buy electric cars and hybrids. But the concern mentioned above still seems valid. So far, studies on such bans have reportedly come to mixed conclusions.
Is there a better solution? It seems there are a couple of solutions that have been shown to work better: low emission zones (LEZs) and congestion charges. They go about the matter in different ways, so can actually offer better results when combined.
LEZs are areas of the city or roads in which vehicles that cross a certain polluting threshold are not allowed or are charged extra. Rather than encouraging people to buy two cheap and polluting vehicles as license plate bans can do, such zones encourage people to upgrade to more efficient vehicles, which improve air quality not just on days when pollution is so bad that a ban is implemented, but every day.
Congestion charges were a hot topic when I was studying transportation planning in graduate school 7-9 years ago. Basically, they add an extra charge to all or almost all vehicles in certain zones where traffic and pollution are deemed a big problem.
Both of these solutions are quite effective at reducing pollution. However, they also generate concerns regarding equity, since the wealthier have less trouble swallowing an extra transportation charge but the poor are either pushed off of roads (financially) or have even more of their limited budgets taken away by transportation costs. There are tradeoffs, and there are also ways around them, but to really dive into all of that would be the task of a research paper, not a blog post.
Coming back to license plate bans, let's note the obvious: they disrupt the normal activity of cities and and thus societies. As noted in The Guardian, "Short-term schemes also cause mass disruption and dissatisfaction.... 'The impact to society and to vehicle operators is horrendous. Suddenly, tomorrow, you're not allowed to move.'"
But I think that brings up a potential long-term benefit that many might be shy to even discuss. If the policy is so disruptive to people's driving habits, it might just get people thinking about whether or not they should be relying on a car at all. Even if it doesn't make them reflect on the matter, it could get them to simply say: "I can't deal with this disruptive policy, which can come with little warning and who knows how often? I'm going to switch to bicycling and public transit." The very unpleasant, disruptive nature of such policies may actually be effective at getting people out of their cars in the long term, which (from an environmental or air quality standpoint) is better than getting them to drive slightly more efficient cars.