
Why driverless cars may mean jams tomorrow - dishwishy
https://www.economist.com/news/finance-and-economics/21735019-they-will-spare-world-neither-traffic-congestion-nor-infrastructure-expense-why
======
softgrow
Driverless cars will bring safer roads in terms of exposure measures like
deaths/injuries per 1 Million/km. They will also lower the monetary cost of
transporting a person per km due to reduction in fleet size and optimised
driving and resource allocation. This will benefit nations and economies in
providing more economic growth, employment etc by moving more people and goods
over the same road network and a smaller fleet.

However they won't solve the fundamental problem of roads being a scarce
resource that lack a price signal so the demand is infinite. If you set the
price too low you get congestion. If hamburgers were free, everyone would want
one and a queue will develop, so instead of paying money you pay with time.
It's just the same as "free" parking where you pay time instead of money.
Obligatory mention of Donald Shoup and "The High Price of Free Parking".

~~~
ams6110
That's not exactly what "free" means in an economic context, but probably
doesn't alter your point.

Something is "free" if, at a price of zero, there is enough supply to meet
demand.

~~~
dmichulke
Interesting definition.

It follows that nothing is universally free, it can only be free within
spatial (and probably temporal) constraints. The usual candidates (water, air)
are certainly not free everywhere.

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Animats
No, the way it will work is that roads will have "surge pricing". You'll bid
on road space before you leave, and don't get to leave until there's road
space for you.

US airport landing slots work like that now. Commercial flights don't take off
for congested destinations until they've booked a landing slot. This
eliminated circling the destination waiting for a landing slot.

~~~
fragsworth
Or you could leave whenever you like, and there's an automated toll on every
road that adjusts based on time of day and/or current traffic.

~~~
yorwba
That only works to prevent congestion if some people decide not to drive on a
road when the toll is too high. In that case, why drive there in the first
place if your AI car can tell you in advance how much it will cost.

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alanfranzoni
This article seems to offer a somewhat limited vision. Personal, driverless
cars may mean as many jams as today. What about "ride-sharing" driverless
systems, where many people share the same car/minivan in an automated fashion,
reducing the number of vehicles on the road and the need for parking? That
would make, IMHO, the best compromise between mass transit (effective, but
inflexible to people needs) and personal transit (ineffective, but flexible).

~~~
skgoa
You mean sharing a ride like say a big, long vehicle with lots of seats that
visits a number of stops on a route? Yeah, that would be a great idea. We
could improve this even further by giving the ride-share vehicle it's own
lane, then turn both the wheels and the road surface into metal to reduce
friction. BRB, going to the patent office...

Not to be too snarky, but as a non-american it has been amazing to watch the
internet debate on the future applications of automated cars these last few
years. Slowly but surely people are starting to figure out that public
transport is a good thing.

~~~
nkoren
No, not like that. Trains work well for arterial routes that need to carry
large volumes of people along predictable corridors at predictable times of
day -- eg., for commuting. And yes America certainly needs to get better at
investing in them.

But trains _don 't_ work at all well for serving smaller volumes of people
moving in stochastic patterns at arbitrary times of day. Neither do buses.
Cars serve this need very well -- they also generate massive negative
externalities in the process, but they _do_ serve this need.

Why should we care about "people moving in stochastic patterns at arbitrary
times of day"? Transport planners call this "incidental travel," implying that
it isn't really significant. But this is because transport planners don't have
a good means of addressing it. In fact, incidental travel actually the
majority of trips that people take: going shopping, visiting friends, going to
the doctor's, eating out, etc. The balance is about 60/40 for incidental
travel / commuting.

People own cars to serve this need, because nothing else will (unless you're
in a mega-city that can afford to run high-frequency mass transport 24/7).
Then, since car ownership is a sunk cost, people use their cars for commuting
as well, where they're _really_ sub-optimal.

Travel demand is an incredibly heterogeneous problem, which can only be
addressed with a hierarchy of modes. That includes mass transport at fixed
schedules, individual transport that is on-demand, and intermediate collective
transport modes that currently doesn't really exist. Autonomous vehicles with
4-8 person capacities and demand-responsive routing would solve a broad class
of transport problems that conventional public transport cannot -- and could
do so without many of the negative externalities of private cars.

I've written much more on the subject, if you're interested:
[http://archive.podcar.org/blogs/nathan-
koren/article/news/th...](http://archive.podcar.org/blogs/nathan-
koren/article/news/the-case-for-grt-ii-a-hierarchy-of-modes/)

~~~
skgoa
I don't disagree. In fact I work on software for cars, so my career depends on
personal transport staying relevant. However, that doesn't adress the question
of whether automated cars will increase or decrease traffic.

The original claim was that automated cars will reduce traffic by being more
efficient (somehow) and people sharing them for trips. I pointed out that we
have the sharing aspect of the issue largely figured out already. The point I
did not make, but implied, is that automating cars, buses, trains, boats and
aeroplanes will not by itself have much impact on traffic. Instead only a
significant shift to more shared (instead of individual) use of these
transport modes would. I feel that the image of the trafficless automated
transport utopia that is so often conjured on HN, reddit etc. is a massive red
herring. Because the benefits people claim stem from automation actually stem
from public transport.

Whether the shift to shared transport will happen or not and if it happens how
big the shift will be, are completely open questions as far as I can see. I
believe that, trips for commuting have lots of scope for being bundled into
shared/public transport. Meanwhile the bulk of other trips will continue to be
made largely with personal transport. (And I make no claim as to whether those
vehicle are owned by the end user or by a fleet operator, that's an entirely
different debate.) Not coincidentally, this is exactly what happens in many
big european cities that have both good public transport and the road
infrastructure to allow for lots of cars to travel at the same time. Many
people over here commute daily by public transport, bycicle, rideshare etc.,
but they also have at least one car for those other trips.

~~~
nkoren
Okay, so we definitely agree that automation-driven traffic-less utopia is a
red herring! Certainly if personal vehicles are replaced 1:1 by automated
personal vehicles, congestion will, on average, get worse. Even if they're
replaced by automated taxis -- eliminating the need for parking -- this will
lead to at least a ~30% increase in vehicles actively on the road due to empty
vehicle movements. And that's before you factor in induced demand, which would
be significant.

Where I think we disagree is here:

> we have the sharing aspect of the issue largely figured out already.

No, we really haven't. With non-automated vehicles, sharing only works in
situations where you can amortise the cost of a driver. This requires
maintaining an average occupancy of > 25 people, which in turn limits you to
fixed routes at fixed schedules. Hence, bad for serving incidental demand.
Automated vehicles open up the possibility of having a range of smaller
vehicles that are demand-responsive yet shared. This would bridge the gap
between current private and public transport options, serving a substantial
travel regime where current technologies are inefficient.

~~~
skgoa
I agree, shared automated small shuttle buses that travel on ad-hoc
generated/adapted routes are probably going to be a thing. BTW thanks for this
thought-provocing discussion.

~~~
nkoren
Likewise! :-)

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moneytide1
Driverless is great for quicker reaction times, but they cannot anticipate
larger-scale situations. Perhaps if all cars were autonomous and connected it
could work, but that will not happen for a very long time.

When I see a heavy truck merge a mile ahead on the interstate, I will go ahead
and get in the left lane. Heavy trucks cannot accelerate like a passenger car.
If I can detect the age of the driver in front of me, I can anticipate an
older person with slower response time and tendency to drive slow, so I
accommodate them.

In a traffic jam, I will leave 50'-100' buffer zone between me and bumper of
car in front. Unfortunately, some drivers will quickly pass me and take up
this zone, because people like the idea of "getting ahead". This only clogs
visibility and increases braking. There are certain situations where this is
not appropriate, because that buffer zone can mean other drivers getting
caught at red lights. There are some tight situations where it is ideal to
drive bumper-to-bumper. Interstate jams are ideal for the buffer.

If the light turns red and I can see it a mile away going 55mph, I will begin
my coast with minimal braking so as to conserve momentum. Most times I never
get below 30 and can always catch green lights this way. I feel even better if
people stay behind me while I do this, because I am essentially saving their
energy by setting our pace. Sometimes slower is faster.

I'd like to think that just a handful of mindful drivers in a jam can improve
traffic flow.

~~~
catbird
I don't see any reason why an autonomous car couldn't be trained to move to
the left lane before an on ramp, or classify neighboring cars by their
observed behaviors (slow reaction time, etc).

Also, I would argue that maintaining a buffer zone in heavy traffic, though it
may feel like you are breaking less/going faster, is not actually helpful. The
flow rate of a section of highway (cars/hour) is the product of speed (miles
per hour) and density (cars/mile). Leaving a space in front of you lowers the
density, decreasing overall throughput. Ideally with self driving cars we
could have them going at high speeds very close together (or even mechanically
coupled like a train).

~~~
moneytide1
Yes, the train example would be the optimal way to use autonomy. The idea of
the buffer is rooted more in energy efficiency, rather than increasing flow
rate. But I understand that time may be more valuable than energy in this
situation, since we are talking about the throughput of economic components
(worker and resource transport).

The idea is that if the buffer were used more frequently, then the average
speed could increase. Multiplied by a lower density number, it could
potentially be a higher flow rate. It requires more energy and time to move
from a complete stop than it does to increase speed while already moving. The
buffer could eliminate jams completely, if we define "jam" as standstill
traffic.

Merging would be smoother because there wouldn't be stop and go. Think of all
the thousands of people in a 5 mile jam stretch that slow to a halt and wave
their hand while the other person takes time to look at them and make sure
they really do have clearance. Every time that happens, dozens of cars behind
must also come to a complete halt. With the buffer, speeds may temporarily
slow but never halt when introducing new vehicles into the line. If the buffer
was a standard implemented in drivers ed, then all drivers would have a
protocol for jams.

------
kthejoker2
Anyone who commutes in a large city quickly comes to recognize when there has
been either a major accident or a higher incident of minor accidents that day.
Potentially even hours before, but the ramifications are right there in front
of your bumper.

And conversely there are days when the stars seem to align and your commute is
unusually short and free of significant time going 0-5 mph. Sure you still
crawl, but by comparison it feels great.

Again, this is almost entirely an artifact of human-caused preventable road
accidents. I fail to see how, if you accept the premise that driverless cars
will dramatically reduce or outright eliminate accidents, traffic will not be
permanently improved.

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supreme_sublime
Kind of tangential to this article, but I can't believe that people are
willing to own a car that is impossible for them to control. While I don't
think it is necessary for self driving cars to lack the option for human
control, the prototypes I've seen lacked a steering wheel. Personally, I will
never buy a vehicle that I cannot control if there is an option not to. Of
course if the market becomes dominated by self driving cars without steering
wheels, I suppose I'll have no choice.

I also see a lot of talk (in other threads) about the eventual banning of
drivers in favor of a totally automated driving world. Can no one see the
potential problems with this? Even eliminating the potential for government
control, what kind of perverse incentives might arrive for companies? Taking
you on routes with more stores as a form of advertising is something I can
think of just off the top of my head.

Not to mention all of that kind of talk is very city-centric. Some people do
have legitimate need to go places that don't have roads, or at least mapped
roads. Rural places still exist, and it annoys me to see how no one seems to
think about these places when talking about driverless vehicles, or banning
drivers.

------
Theodores
Currently only a minority of people aged between 9 and 99 drive a car.
Although almost every baby boomer drives it is not so for other generations.
With driverless cars that you can just hop in 'taxi style' or own outright
then there are going to be a lot more people taking a lot more journeys.

However, the self driving car solves many other problems. For instance, in
some of our cities most of the traffic is people driving around looking for
some place to park. That is it, that is what they are doing rather than going
somewhere important.

At some stage the existing dumb cars we have parked on our streets now will
get sent off to the recycling facility, if, at the same time, more people are
getting glorified driverless cabs and not buying their own cars, then there
really can be a sizeable bit of highway real estate to recover. Hopefully
because the self driving cars go in convoy this extra road space can be for
people, e.g. on bicycles, and not for yet more automobile infrastructure.

Then there is the school run, no need for the journey there and back, plus the
ride sharing can get smarter to know who needs to be where and when, i.e. self
aware of all the meetings in town.

------
tomohawk
The odds are that self driving cars will stick to the posted speed limit, and
that those limits will not be raised. This will reduce the available capacity
of many interstate grade roads, as the posted speed is often unsafely low. On
the roads around here, the accepted and safe speed is often around 70mph, but
the posted speed is often 55mph.

[https://www.motorists.org/blog/speed-limits-slower-
safer/](https://www.motorists.org/blog/speed-limits-slower-safer/)

Additionally, self driving cars appear to have a higher accident rate per mile
driven (5x). This appears to be at least partly the result of the self driving
cars performing unorthodox maneuvers in some situations.

~~~
nimbix
This complete disregard for speed limits was a huge shock to me when I was
driving in Florida 2 weeks ago. In quite a few EU countries we stick to the
posted limits quite strictly. But in the US I was literally bullied into
driving way above the limit (75 in a 55 zone) and was still getting overtaken
on both sides - in one case even by a police car - and some people used
turning lanes to overtake on the right. In addition to this everyone was
slamming their brakes when they saw an empty police car parked by the side of
the road. Crazy.

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douglaswlance
Jams are caused by human drivers whose slow reaction time causes waves of
slowdowns that build up into complete stoppage.

We can get AI reaction time down to the speed of light since all vehicles can
communicate their speed, direction, and location simultaneously.

It is a totally new epoch of transportation and the old rules no longer apply.

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wannadub2
CrashFunction.com

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thisisit
This title is confusing. The actual title is more approachable - _Why
driverless cars may mean jams tomorrow_

Still I am confused by articles logic - Why would driveless car be any better
than the current ownership model? The logic presented is - _AIs that can pilot
cars more closely together will boost road capacity_. But using article's
logic on people movement - it might entice people who actually don't drive due
to various reason to actually buy a car. The increased number of cars might
lead to the said jam.

One of my controversial opinion is that going forward governments might be
tempted to label ride sharing companies as basic necessities, just like
internet, to try and improve transportation.

~~~
carlmr
I also don't follow that argument. IMHO accidents and bad swarm behavior
(people following too closely, switching lanes too often, accelerating and
braking too much) lead to traffic jams. If we can get that improved our roads
could take twice the cars.

~~~
gryzilepek
You don't get the point: if you create an empty space on the roads (whatever
solution you invent), people will start occupying it immediately, and you face
the same problem again.

~~~
carlmr
No reason to get offensive, I do get the point, I'm just saying the point
makes no sense. If we get to a fully automated future (that is without human
drivers interfering), we can get to twice the occupancy which is I think more
than the amount of children and seniors now driving cars that didn't before,
and still have less traffic.

It just runs counter to reality to think that every empty space you create is
occupied immediately. After all there are less congested cities and more
congested cities. Mostly because the less congested cities have a higher
road/road width/road quality to commuter ratio. That's why Seattle and SF have
huge issues. With the water and mountains it's impossible to get a good
infrastructure to population ratio. And no, cities with better traffic don't
start going on the road to occupy space just because it's there. There's
always a need for people to commute paired with inadequate infrastructure.

By utilising the infrastructure better, self-driving cars can basically
increase one side of the fraction. Higher number of drivers will probably
happen (seniors and children especially who couldn't drive before), but they
also usually I doubt it's even more than 20-30%, seniors won't start commuting
to jobs they don't have, children have more vacation, they're already only a
smaller part of the population.

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ImaCake
I'm not impressed with all the crap popping up in my browser when I load this
page. The economist used to be pretty good for focusing on the actual content.

~~~
progval
The site works nicely with an adblocker or with NoScript

