There has been a boom in new bike lanes,
as cities around the world try to reduce our reliance on cars
to tackle the climate crisis, improve air quality
and promote active travel.
But towards the end of 2021
a number of headlines blaming cycle lanes
that increased congestion in London started appearing.
All the articles quote a claim
made by the team behind this document.
Which says the installation of cycle lanes introduced in London
has a negative impact on congestion.
Giving the explanation that the use of roads is all about supply and demand.
That if demand goes up but the road space is being shared with other forms of transport
there's less tarmac for cars to be on.
But here's the problem:
while the supply and demand argument sounds very plausible,
that's actually not how traffic works
The ‘less space = more traffic’ theory
known as level of service was once the established rule of traffic engineering,
but it has long been discredited.
To show how traffic really works
We need to look at a different supply and demand concept
called induced demand.
Which simply means the more you increase the supply of something,
in this instance roads,
the more people use it.
The West Way, as it's called, is the longest elevated road in Britain
and is designed to lift the dense commuter traffic out of west London's residential streets.
This flyover section of the A40
was built to relieve congestion in west London.
But when it was opened in the 1970s,
vehicle numbers shot up as people people rushed to use it
and traffic also rose on the parallel main roads around it,
which it was meant to help alleviate,
completely defeating the purpose.
This is because when you expand a road, travelling by car becomes quicker
and easier in the short term.
And this makes travelling by car more attractive
and so more people are more likely to use their cars than usual.
More car trips = more cars on the road
and all that extra space quickly disappears.
Now there is a limit to all of this.
If you make a 10-lane motorway into 100 lanes,
you could travel without seeing another car for miles,
But we're not talking about a mathematical principal, we're talking about human behaviour,
which is often influenced by a whole host of different factors.
Something which the level of service argument
cannot account for.
So what impact does the introduction of new bike lanes have?
Well the induced demand effect also works in reverse,
which means when you reduce road capacity,
by introducing new bike lanes for instance,
again there is an immediate impact, but this time car travel becomes slower
and more congested in the short term.
This then discourages road use and as a result congestion will largely go back to similar levels
as it was before and in some cases go down.
It's called traffic evaporation.
There are lots of case studies in the UK and across the world which support this.
In Hackney, east London,
17% of residents have had some roads in their neighbourhoods closed to motor vehicles
and those neighbourhoods have seen a 40% reduction in traffic as a result.
In Paris roadway restrictions have contributed to a 5% drop in car trips since 2010.
While the city has also seen a 54% increase in bike use, from September 2018 to 2019.
Of course some people will need to continue making the same journeys when road space is taken away,
even if it takes them longer.
But many drivers will change how they travel, because they don't want to sit in traffic.
Traffic is no more than people making decisions,
about where, when and how they travel
from one place to another.
This means that taking road space away from cars, in favour of bikes
in many cases can reduce congestion,
because you're making car travel less attractive while enticing people to travel
by bike, public transport or walking.
Across the UK people make on average five short car trips every week
and between 32% and 41% of people said they could just as easily
walk, cycle or take the bus for these trips.
In London TfL have calculated that over a million trips currently made by car
in the capital each day, are potentially cycle-able
and since more cycling infrastructure has been made available,
more and more people are choosing to use it,
with a 200% increase in cycling in London alone since the beginning of the pandemic.
On closer inspection,
the global study that declares London the most congested city in the world,
conveniently makes no mention
of cities in Asia or Africa.
And as far as blaming bike lanes for congestion, the analyst that was interviewed for the story
claims his quotes were misrepresented.
All the evidence points to bike lanes having a positive impact
on congestion, pollution and our health.
But don't be surprised if you see headlines like these popping up again,
as more cities push for a carbon-neutral future.