“You need to slow down" has long been an existential exhortation. That it can also have literal real-world benefits is perhaps less well-known. That is why, when civic authorities in Paris announced that they were virtually putting the entire city under a 30kmph speed limit, questions were raised about the logic behind the decision. As it turns out, driving slower contributes both to safety of the roads and protecting the environment by lowering emissions. Here’s what you need to know.
How Is Paris Slowing Down To 30Kmph?
An announcement for a blanket curtailing of speed limits may appear dramatic, but reports say that about 60 per cent of the streets in the French capital already have the 30kmph speed limit. What the latest order does is to extend it to the entire city barring highways, peripheral ring roads and major boulevards, including the iconic Champs Elysees.
To violate the set limit can result in a fine and a docking of points on the driving licence. But these actions are not the first in the city aimed at how traffic moves. Reducing the public space taken up by cars is a stated objective of Paris mayor Anne Hidalgo and along with speed limits the city will also see a reduction of more than 40 per cent of the city’s road parking space, a widening of footpaths and increase in cycling lanes — all aimed at redefining how traffic is to move in the city.
“This measure is part of a coherent policy to transform public space. It’s a policy that favours so-called ‘soft’ mobility such as walking, cycling and public transport rather than the car, which we want to reserve for essential journeys," Paris deputy mayor David Belliard was quoted as telling a French news outlet.
And, the decision seems to have the backing of a majority of Parisiens, 59 per cent of whom told a survey that they supported the new speed limit. But people on the suburbs — who have to mostly rely on their cars to journey into the city — were not as enthused and more than 60 per cent of the respondents in the wider Ile-de-France region said they were against the speed limit.
How Will It Help?
From truckers to delivery professionals and taxi-drivers, those who spend substantial hours driving all said they were against the speed curbs. “It’s one of those tiny, slightly stupid measures, that means French people are sick of politics," a representative of car drivers’ group ’40 million d’automobilistes’ was quoted as telling another news outlet.
To many motorists, that lower speed limits can contribute to greater energy efficiency appears counter-intuitive. Questions have been raised over whether the rule wouldn’t lead to more emissions than actually limit air pollution. Driving slow will lead to traffic snarls and that, in turn, would lead to more emissions, they say.
But deputy mayor Belliard is said to have told a French affiliate of CNN that the rule is aimed at getting more people to ditch their cars in favour of walking, cycling or taking public transport. But he did maintain that it would also reduce air pollution. “A friendly clarification of what those who oppose lowering the speed limit are saying: NO, a speed limit of 30km/h doesn’t increase pollution… But actually improves safety for cyclists and pedestrians, reduces noise and makes the city calm," he wrote on Twitter.
What Do Experts Say?
Various studies and reports suggest that there are several factors that come into play as regards the link between speed limits and air pollution. A report by the European Environment Agency (EEA) says that while having “lower speed limits on motorways is expected to cut both fuel consumption and pollutant emissions", the exact benefit “depends on a number of factors".
Among those are “technological effects such as the fall in energy consumed when decreasing speed, and non-technological factors such as vehicle fleet composition, driving patterns, frequency of speeding, congestion and traffic diversion due to the speed limit".
The debate among French motorists has been fuelled also by reports that seem to suggest that lowering speed limits have a contrary effect on air pollution. A study by Cerema, the French public agency working on urban planning and ecological and energy transition, has been cited to say that more CO2 emissions were generated when vehicles moved at a constant 30kmph instead of at 50kmph.
However, Belliard said the study was “not adapted to traffic in urban centres such as Paris because it was based on average speed". In fact, reports said that this study actually states that a lot of emissions are generated by the constant slowing down and acceleration, which typically happens more if a vehicle is moving at higher speeds. “With this measure we are limiting the effects of acceleration and deceleration," Belliard said.
Where Else Are Speed Limits Being Brought In?
In May this year, as part of the 6th UN Global Road Safety Week, the World Health Organisation urged that authorities everywhere should adopt the 30 kmph “on streets where pedestrians, cyclists and others who are most at risk mix with motorised traffic". To be sure, the core principle at work in WHO’s appeal is the need for making streets safer and saving lives, but it also noted that lower speeds on roads also helps by “increasing walking and cycling by making the environment safer and more inviting… [and]reducing air and noise pollution".
In a note published on the occasion, Etienne Krug, the Director of WHO’s Department of Social Determinants of Health, said that “30 km/h speed limits and zones in cities such as Graz, London, New York, and Toronto have yielded reductions — often significant — in road traffic crashes, injuries and deaths". He added further that “evidence shows that 30 km/h streets not only save lives, but also facilitate walking and cycling and a move towards zero-carbon mobility".
Reports say that close to 200 towns in France have applied 30kmph speed limits with more set to embrace the rule. The Netherlands and Spain, too, have such curbs in many of their towns.
While noting that “decreasing car passenger speed limits in motorways could lead to substantial benefits", EEA says that “speed limitations of 80–90 km/h on motorways when entering cities and on city ring roads could significantly reduce both fuel consumption and pollutants emitted" but, on the other hand, “energy and emissions benefits from more stringent speed limits on local roads (e.g. from 50 to 30 km/h) are less clear".
It states, hence, that the “the key argument for lower speeds on local roads is therefore the desirability of a safer and more tranquil local environment, rather than environmental considerations". But a 2009 paper by researchers at Virginia Tech that was cited in a report in The Guardian notes that “traffic calming measures… can result in significantly higher fuel consumption and emission rates when drivers accelerate aggressively" although it also agrees that such measures “reduce vehicle speeds on neighbourhood streets and may contribute to enhanced road safety".
The study says that “by eliminating sharp acceleration manoeuvres significant energy and emission savings can be achieved. Consequently, significant improvements in air quality and energy consumption may be achievable through driver education".
Which would explain why WHO is stressing that the 30kmph speed limit should be pursued by “building or modifying roads with features that calm traffic, installing in-vehicle technologies such as intelligent speed assistance, and raising awareness among the public of the danger of speeding".
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