How to solve traffic jams Jonas Eliasson
hi I’m here to talk about congestion
namely road congestion road congestion
is a pervasive phenomena the existing
basically all of the cities all around
the world which is a little bit
surprising when you think about it I
mean think about how different cities
are actually I mean you have the typical
European cities with a dense urban core
good public transportation mostly not a
lot of Road capacity but then on the
other hand you have the American cities
it’s moving by itself okay
anyway the Americans say this lots of
roads dispersed to the large areas
almost no public transportation and then
you have the emerging world cities with
a mixed variety of vehicles mixed
land-use patterns also rather dispersed
but often with a very dense urban core
and traffic plan is all around the world
has tried lots of different measures
densities or dispersed stages lots of
roads or lots of public transport or
lots of bike lanes or more information
or lots of different things but nothing
seems to work but all of these attempts
have one thing in common they’re
basically attempts at figuring out what
people should do instead the rush-hour
car driving they’re essentially two
point attempts at planning what other
people should do planning their life for
them now planning complex social system
is a very hard thing to do and let me
tell you a story back in 1999 when the
Berlin Wall fell an urban planner in
London got a phone call from a colleague
in Moscow saying basic him hi this is
Vladimir I’d like to know who’s in
charge of London’s bread supply and the
urban plan was what do you mean who’s in
charge children’s I mean no one is in
charge oh but surely someone must be in
charge I mean it’s a very complicated
system someone must control all of this
no no no one is in charge I mean it
basically our haven’t through the fault
of it I mean it basically organizes
itself it organizes itself
that’s an example of a complex social
system which has the ability of
self-organizing and this is a very deep
insight when you try to solve really
complex social problems the right thing
to do is most of the time to create
incentives you don’t plan the details
and people will fight you figure out how
what to do how to adapt to this new
framework and let’s now look at this how
do we can we can use this insight to
combat road congestion
this is map of stock of my hometown now
Stockholm is a medium-sized city roughly
2 million people but Giacomo’s has lots
of water and lots of water means lots of
bridges narrow bridges old bridges which
means lots of road congestion these red
dots show the most congested parts which
other bridges that lead into the inner
city and then come what someone came up
with the idea that apart from good
public transport or import the support
from spending money on roads let’s try
to charge drivers one or two euros at
these bottlenecks now one or two use
that isn’t really a lot of money I mean
compared to parking charges andronica
cetera so you would probably expect that
car drivers wouldn’t really react to
this fairly small charge you would be
wrong
1 or 2 euros was enough to make 20
percent of course disappear from rush
hours now 20 percent well that’s a
fairly huge figure you might think but
you still get 80 percent left of the
problem right because you still have 80
percent of traffic now that’s also wrong
because traffic happens to be a
nonlinear phenomenon meaning that once
you reach above a certain capacity
threshold then congestion starts to
increase really real rapidly but
fortunately it also works the other way
around if you can reduce traffic even
somewhat then congestion will go down
much faster than you might think
now congestion charges were introduced
in Stockholm in the Dom On January 3rd
2006 and the first picture here is the
picture of Stockholm one of the typical
streets January 2nd the first day with
the congestion charges looked like this
this is what happens when you take away
20% of the cars from the streets you
really reduce congestion quite
substantially but well as I said I mean
car drivers adapt right so after a while
they would all come back because they
sort of get gotten used to the charges
wrong again it’s now six and a half
years ago since the congestion charge
bring to doose’s calm and we basically
have the same low traffic levels still
but
see there’s an interesting gap here in
the time series in 2007 well the thing
is that the congestion charges they were
introduced first as a trial so they were
introduced in January and then abolished
again in a at the end of July followed
by a referendum and then they were
reintroduced again in 2007 which of
course was the wonderful scientific
opportunity I mean this was really it
was a really fun experiment to start
with and we actually got to do it twice
and person I’d like to do this every
once a year or so but they wouldn’t let
me do that so but it was fun anyway
so we followed we followed up what
happened this is the last day with the
congestion charges July 31st and you see
the same street but now it’s summer in
summer in Stockholm is a very nice and
light time of the year and the first day
went without the congestion charges look
like this all the cars were back again
and you even have to admire the car
drivers they adapt to extremely quickly
the first day they all came back and
this effect and this effect hang on
so 2007 figures look like this now these
traffic figures are really exciting and
a little bit surprising and very useful
to know but I would say that the most
surprising slide here I’m going to show
today is not this one it’s this one this
shows public support for congestion
pricing in Stockholm and you see that
when congestion pricing were introduced
in well beginning of spring 2006 people
were fiercely against it seventy percent
of the population who didn’t want this
but what happened when the congestion
charge was there it’s not what you would
expect that people hated it more and
more no on the contrary they changed up
to a point where we now have seventy
percent support for keeping the charges
meaning that I mean let me repeat that
seventy percent of the population in
Stockholm want to keep the price for
something that used to be free okay so
why can’t that be why is that well think
about it this way
who changed I mean the 20% of the car
drivers that disappeared surely they
must be discontent in a way and where
did they go if we cannot just understand
this then maybe we can figure out how
people can be so happy with this well so
we did this huge interview survey with
lots of travel service and try to figure
out who changed and where did they go
and turned out that they don’t know
for some reason the car drivers are they
are confident they actually drive the
same way that they used to do and why is
that it’s because the travel patterns
are much less stable than you might
think each day people make new decisions
and people change and the world changes
around them and each day all of these
decisions are sort of nudged ever so
slightly away from rush hour car driving
in a way that people don’t even notice
they’re not even aware of this
themselves
and the other question that who changed
their mind who changed their opinion and
why so we did another interview servant
tried to figure out why people change
their mind and who would put type of
group change their mind and after
analyzing the answers it turned out that
more than half of them believe that they
haven’t changed their minds they are
actually confident that they have they
have like congestion pricing all along
which means that we are now in a
position where we have reduced traffic
across this tall cordon with 20% and
reduced congestion by enormous numbers
and people aren’t even aware that they
have changed and if they honestly
believe that they have liked this all
along this is the power of nudges when
trying to solve complex social problem
and when you do that
you shouldn’t try to tell people how to
adapt
you should just nudge them in the right
direction and if you do it right people
will actually embrace the change and if
you do it right people will actually
even like it thank you
you