Anyone from Kent who has driven through London recently and remembers driving through the capital even just a few years ago will be delighted with today's experience.

It is altogether less frantic - and let's be frank, less scary - than it used to be.

This is partly due to Covid - with fewer office workers in their buildings, there is less traffic on the roads.

But it is primarily due to the blanket 20mph speed limit imposed since March 1 on all central London roads managed by Transport for London.

TfL is responsible for the so-called Red Routes - the key routes around the centre such as the Albert Embankment, Lambeth Palace Road, Lambeth Bridge, Millbank, Victoria Embankment, Upper and Lower Thames Streets, Tower Hill, Westminster Bridge Road, Waterloo Bridge and more.

They amount to about only 5% of the total number of roads but they are the routes which non-Londoners are most likely to travel along.

Before the new regulations came in, critics scoffed that they wished they could travel as fast as 20mph on London's congested streets, and it is true there is still plenty of queuing at peak times, but what the regulation has accomplished is doing away with the fierce acceleration as soon as a break in traffic appears, with motorists trying to imitate Lewis Hamilton leaving the grid at Silverstone.

TfL said it was introducing the 20 limit for safety reasons, pointing to evidence from Bristol, where a 20mph zone was imposed across the city centre in 2014.

A subsequent study by the University of the West of England found the number of fatal road accidents in Bristol had reduced by an average of 4.5 a year, while injuries had fallen by an average of 170 a year.

As well as the obvious gain in the avoidance of accidents, the university estimated the economic gain to the city was more than £15m a year.

Similar schemes in Edinburgh and Portsmouth were also found to reduce casualties by up to 15%, but the good news is not universal.

A staged roll-out of 20mph zones across Manchester was halted in 2017 after it was discovered traffic speeds and casualties had fallen only marginally and by less in the 20mph zones than they had in other parts of the city.

Similarly a study by consultants Atkins for the Department of Transport, reporting in November 2018, looked at a dozen 20mph schemes across the country and found that in only one (Brighton) was there a statistically significant fall in road accident casualties.

The difference may be dependent on the type of road placed in a 20mph zone. Most authorities are implementing 20mph restrictions only in quiet residential areas where average speeds and casualties are already low. Perhaps they are most effective when placed on main routes.

There are also other valid reasons why 20mph zones might be considered.

Kent County Council currently has plans to introduce four new 20mph zones across Kent - two town-wide schemes in Tonbridge and Faversham, and two centre-wide schemes in Tunbridge Wells and Margate.

But the justification is not specifically casualty reduction as KCC is using a Government "active travel grant". The argument is that if the public perceive the town centres to be safer, they are more likely to walk or cycle, and so help improve the nation's health and tackle obesity.

The Faversham scheme will extend to the north of London Road, between Link Road and Love Lane.

The changes will include 20mph road markings and signs as well as signed 20mph ‘gateways’ at the entries to the zone with a differently coloured road surface but there will be no other traffic-calming measures such as speed bumps. The Tonbridge scheme will extend north from the A21 between Upper Haysbrook Road in the west and the A26 in the east.

Again, initially, there will be only road markings, signage and gateways to denote the 20mph zone but KCC warned: "We will be monitoring the effectiveness of the scheme and there may be a need for further measures to ensure that the road design encourages motorists to keep to the 20mph limit."

In both Tunbridge Wells and Margate there are already a number of existing 20mph roads in the zone and they will be added to.

Tunbridge Wells will now include Camden Road, Calverley Road, High Street, Monson Road, Mount Pleasant Road, Mount Ephraim Road and Vale Road, among others.

While Margate will include Bilton Square, Broad Street, Eaton Hill, Fort Hill, Fort Road and Grosvenor Place, among others.

All four traffic schemes have been pushed through under an "experimental traffic order", meaning that they will start on September 18 and run for 18 months, after which KCC will make a new order to keep them, alter them or just allow them to lapse.

Although the evidence that more walking and cycling does improve public health is well documented, there are some who oppose 20mph zones on the grounds they increase pollution and so have a detrimental effect on health.

This is based on the recognition that most cars achieve their greatest fuel efficiency at around 55mph. Driving either faster or slower results in fewer miles per gallon.

However, whether this translates directly to more pollution is less clear.

A study by Imperial College London found that petrol cars produce more more nitrogen oxide pollution at 20mph than at 30mph, while diesel cars produce less. While for PM10 particulates - very small particles of dust or smoke that can be absorbed by the lungs - both diesel and petrol cars produce fewer particulates at 20mph than 30mph for engine sizes under 2,000cc but both diesel and petrol cars produced more pollution at 20mph than at 30mph for engines bigger than 2,000cc.

So the answer is not clear cut.

There is also the cost of the wasted time drivers will spend reaching their destination at a slower speed. A five-mile journey at 20mph takes 15 minutes, at 30mph, only 10 minutes.

But while drivers may object, the clamour from residents for more 20mph zones continues unabated.

In Maidstone, there have been petitions organised by both the Green Party and Labour requesting a 20mph zone in Fant, while the Lib Dems are pushing for one in the Buckland Hill area, which KCC is currently consulting on.

KCC's senior major capital programme project manager, Russell Boorman, told the last meeting of the Maidstone Joint Transportation Board he would like to implement a 20mph zone in Maidstone town centre.

The idea being that if the streets were safer, pedestrian footfall would increase and enhance the economic wellbeing of the town's shops and restaurants which are struggling in the wake of Covid 19.

Cllr Robert Eves (Con) said: "I’m a big believer in 20mph zones in strategic places. Putting them everywhere doesn’t work and doesn’t work as a deterrent."

"Although very rarely would they actually be policed, they do feed into a driver's moral compass and you do find that more people drive slower in these 20 zones.

"Nothing is perfect, but I think residents would much rather see this than a load of sleeping policemen or other traffic-calming measures that do nothing other than to stack up traffic, with no-one slowing down between the humps.

"I’d support 20mph zones being rolled out across the borough, even if just as a trial, as I think it would have a positive benefit to areas where slower speeds are really needed."

Cllr Jonathan Purle (Con) had similar views. He said: "We need to cut speed, whether it's residential streets being used as rat-runs or some of the routes used by large numbers of school children.

"So 20mph zones in certain places are a start, but we need proper enforcement, whether it’s a 20mph limit or a 30mph limit."

Cllr Purle addded: "If somebody hits a child while travelling at 20mph, they'll most probably escape with minor injuries.

"At 30mph, the risk of serious injury is much higher and there's a 20% chance of the child dying.

“In my patch, we’re getting a 20mph-limit on Buckland Hill soon which is going to help safety now the schools are returning but we’ve still got places like Bower Mount Road, Grace Avenue or Palmar Road where people seriously speed-through with disregard for residents and their safety.

"So 20mph would be good, but it would help if the existing speed-limit was enforced as well."

The Maidstone Green Party has warmly welcomed proposals for a 20mph zone in the Buckland Road area but says it is not enough.

Donna Greenan, Bridge Ward campaigner, said: “This scheme is very welcome and I hope that KCC agree to implement it.

"We have campaigned vigorously for 20mph limits for many years and it is good to see them being increasingly implemented. The rest of Maidstone’s residential area now need to follow suit.”

Maidstone borough Councillor Paul Harper (Lab) said: "It has been shown that 20 mph zones make the streets safer.

"Labour has long been campaigning to have all residential neighbourhoods, both in the town and villages made 20mph zones."

Cllr Harper said: "In Maidstone the town is perfect for 20mph zones, Fant is largely self-contained bound by the river Medway and Tonbridge Road, and is also ideal, while areas near schools such as Oakwood Road, Queens Road and Buckland Hill should also be candidates."

Lib Dem County Councillors Rob Bird and Dan Daley declared themselves "strong advocates" for 20mph speed restrictions, arguing 20 should be the default speed limit for all residential areas within Maidstone.

Cllr Daley said: “Increasing numbers of residents are demanding 20mph limits in their neighbourhoods and we are keen to bring viable schemes forward where we can.

"With the Government now encouraging people to walk or cycle to work or to school wherever possible, it is important to make our roads as safe possible for these users.

"Because of the way the regulations work, it is better to go for a 20mph zone covering as big an area as possible, rather than apply for separate limits in individual streets."

Cllr Daley said: “We have recently commissioned a new 20 mph limit in the Hildenborough Crescent area of Allington. This will benefit schoolchildren and elderly and disabled residents.

"We are keen to bring in other schemes as quickly as possible.”

Cllr Bird said: “The Buckland Hill area is particularly dangerous and there have been several instances of children and adults being knocked down by cars.

"Crossing the road outside the Barracks Station and at the intersection with Buckland Road is very hazardous.

"Unfortunately, there is no way we can instal formal pedestrian crossings in these two locations which meet safety guidelines, so reducing the speed limit is the most effective means of improving road safety.

'We are hopeful of a new 20mph limit soon'

He said: "Earlier this year, we conducted an informal survey throughout the Buckland Hill area; some 90% of respondents were in favour of a 20 mph limit in the area. We are hopeful the new 20 mph zone will be implemented in next few months.”

For more information on 20mph zones, click here.

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