
Light Traffic - Schiphol
http://senseable.mit.edu/light-traffic/
======
maxander
So a system that requires _all_ vehicles on the road to have flawless sensor
and communications systems can achieve some improvement over current-day
technology (from the paper, approximately a "doubling of capacity" for
intersections with this implemented.)

This is a _profoundly uninteresting result,_ given the current-day technology
in question is "a dozen lights attached to a timer." Add devices that are
several orders of magnitude more expensive and _yeah_ you'll get something
better- that they only achieve a factor of two improvement (in theory!) reads
as a stunning failure of autonomous vehicle technology to pull their weight in
this regard. (Granted, more clever schemes might be produced that might get
better results from this scenario- it's hard to prove that they _can 't_ be
effective.)

Better idea- instead of having the world pay for sensor/communication systems
on _every car_ , have the same sensor packages installed _on the traffic
lights_ so that they can operate in a smarter fashion. Orders of magnitude
less expensive, and quite possibly as effective in reducing traffic backup.

~~~
jakecopp
What I don't understand is why every traffic light doesn't have cameras and
some image recognition/machine learning (whether local or remote) to improve
the timing - it would be such a cheap and easy fix compared to putting a
sensor in each car.

~~~
tedmiston
A sensor itself isn't expensive but moving, storing, and processing all of
that data to ultimately take action is.

Let alone concerns with people about being recorded in public, even if red
light cameras are permitted in some states today.

~~~
jakecopp
Even OpenCV running on a Raspberry Pi can pick out cars in a moving image - a
bad offline solution (with a sensible fallback) would be better than a timer.

On a large remote setup I think you are right though.

~~~
jakobegger
OpenCV on a Raspberry does not sound like something that is reliable and easy
to deploy.

It‘s a long way to go from something that you hack together in the living room
to something you can deploy on hundreds of traffic lights, that works in every
weather, that can easily be configured for different use cases, and that can
be serviced by the technicians.

~~~
halbritt
It can be:

[https://resin.io](https://resin.io)

A Raspberry Pi is a surprisingly useful and cost effective device when it
comes to IOT. Most industrially hardened devices of similar capacity cost a
bit north of an order of magnitude more.

There are really only a couple of things that would need to be addressed, a
good weather-tight case that allowed for heat dissipation, decent storage
(most microSD has a short lifespan), and a good 5v power supply.

In many cases, designing a system that is cheap, expendable, and expected to
fail is way less costly than the alternative.

~~~
TFortunato
Sone of what your saying is kind of making the point of the parent though.

Yes, you can make the software deployment go easier, and resin looks like an
interesting project from that front. But that really is only a small part of
the problen, and those hardware problems you described aren't trivial. The
testing you described to convincingly show that your device can handle the
environmental requirements isn't trivial. (And by environmental, I dont just
mean weather, but also things like available power quality, vibration, etc.)

These industrial devices aren't expensive just because the suppliers aren't
aware of RasPi, or are looking to gouge you. Its because they put in a lot of
work to qualify these devices for their intended conditions. The RasPi, hacked
up solution might actually be the WAY more expensive option over it's
lifetime, if I have to roll maintenance crews every couple of months to
replace SD cards or fix a flaky connector. And god forbid our code hangs in a
way that makes all of the lights at an intersection green. "Oh you have a way
to prevent that? Prove it." Designed to fail works fine for microservices
where I can spin up a new instance rapidly, but it isn't the best match for
industrial or infrastructure in most cases.

Apologies if I'm coming across overly snarky here. I genuinely love the
RaspPi, and its got a great niche for prototyping, hacking up one-off
projects, or even as the base for many types of connected projects. But I've
also worked on industrial and infrastructure types of systems, and more than
once I've seen someone say that they've got a cheaper solution to X, when
really they've got something that may look cheaper if your only looking at
upfront costs, but they are completely ignoring the lifetime costs of the
solution.

~~~
halbritt
No apologies necessary. I wasn't vehemently disagreeing with the parent so
much as saying that the cost-benefit analysis is worthwhile.

I do some IIoT stuff, so I have a little experience here. Many of the lower
cost PLCs and industrial edge devices have no better environmental
characteristics than a Raspberry Pi. They just happen to be more expensive by
comparison because they're competing in a market with _much_ more expensive
devices. In many cases, as you suggested, buying those devices is a false
economy.

My point is simply that they're not that bad, and like you said, one should
truly consider the lifecycle costs.

------
rcarmo
There's been a marked tendency to replace intersections with roundabouts and
shared spaces
([https://en.wikipedia.org/wiki/Shared_space](https://en.wikipedia.org/wiki/Shared_space))
in many places, including the outskirts of Lisbon (as well as a few legendary
mazes in Britain).

There was even a BBC report on the latter (which I can't find right now, as
usual, only a follow-up:
[http://www.bbc.com/news/uk-33303031](http://www.bbc.com/news/uk-33303031)).

Drawing a (admittedly inaccurate) parallel with shared spaces (which are
harder to navigate by sensory deprived humans than standard intersections),
I'd say roundabouts (which preserve crossings) would be a more sensible short-
term approach overall -- especially considering the remaining human drivers.

Full disclosure: I don't drive anymore. Gave it up decades ago because I
prefer to do something useful with my commute times, and resort to public
transportation or Uber whenever possible, which (ironically) allows me to
arrive earlier to meetings than most of my colleagues (who need to hunt down a
parking space).

~~~
tomxor
> Drawing a (admittedly inaccurate) parallel with shared spaces (which are
> harder to navigate by sensory deprived humans than standard intersections),
> I'd say roundabouts (which preserve crossings) would be a more sensible
> short-term approach overall -- especially considering the remaining human
> drivers.

I actually find roundabouts easier to navigate than large crossroads, I think
this is partly because they actually are objectively easier and safer to
navigate (one stream of traffic) and partly (but mostly) because they are
dominant in the UK.

But for the same reason (familiarity) I expect many in the US would find
roundabouts hard to navigate (and maybe unsafe as a result?), it's more about
what you are used to and what you had to learn as part of your driving test.

Are roundabouts part of driving tests in the US?

~~~
sndean
It wasn't part of my driving test in Virginia, at least when I took it. I'm
guessing if your state has a low number of roundabouts [0] then it's pretty
unlikely you'll be tested on it. I'd be interested to hear if Marylanders (#1
in roundabouts:intersections) have it on their test.

Personally, I freak out when I see a roundabout coming up, and slow down
dramatically. Or, I completely avoid them.

[0] [https://www.citylab.com/transportation/2016/03/america-
traff...](https://www.citylab.com/transportation/2016/03/america-traffic-
roundabouts-street-map/408598/)

~~~
rtpg
It's possible that even when slowing down the roundabout still ends up being
more efficient, since you don't have as much "stop/go" action going on

~~~
tomxor
This is generally how it works in the UK, except for newbies who tend to
always stop completely rather than try to time the merge where possible...
I've heard that this is actually taught in advanced driving in the UK (to
maintain flow when possible, time merges etc). Frankly there are some
roundabouts in cities at rush hour which are frightening for new drivers and
you just can't join unless you have good timing and can get up to speed
quickly (or get a lucky smooth merge).

------
w0de0
What about pedestrians? For me, a future in which vehicles have more control
of our public spaces is worse than the present, no matter the efficiency of
the arrangement. Many American cities are notorious for being designed for the
automobile, not the human. Let's not double down. More Ramblas!

~~~
seanmcdirmid
It is kind of funny because pedestrian crossings already kind of work like
this in China. The car will never ever stop for you, rather, it will adjust
its speed and swerve slightly to avoid a collision (if expected, if
unexpected, then its a totally different game). Likewise, the pedestrian is
expected to move in a consistent direction and adjust their speed to avoid
being in the way of a car. The result is that car traffic and pedestrian
traffic can keep moving at the same time even when orthogonal.

Of course, it often doesn't work, and it is only possible at all given the
slower vehicle speeds of a congested road network. Also, the flow of
pedestrians in China is rather more continuous than in America.

~~~
zten
Oddly, this is a cyclist behavior that is very widely admonished as being
pedestrian-hostile.

~~~
mindslight
"Widely" ? Maybe in altruism-display places like SoCal, where the expectation
for traffic interaction is to stop and have a ten minute meeting about how to
proceed so everyone can feel leave feeling superior.

In general it's just called _yielding_ , and that it happens in all four
dimensions is implicit. The difference in China is that the tolerances are
smaller.

~~~
vinay427
Can you elaborate on where this is coming from? I know you're exaggerating,
but in my limited experience I haven't noticed abnormally long yield times at
intersections in southern California.

~~~
mindslight
Try walking at a moving car in a parking lot, such that if both of you
maintain your velocity you will clearly pass behind the car after it has
passed. 9/10 times the driver will "helpfully" stop and "helpfully" wave you
on in front of them, delaying both of you.

------
mgbmtl
I feel like so many similar proposals tend to ignore how saturated our roads
are, how expensive the road infrastructure maintenance is, and how fast people
expect to drive (because of long commutes from endless suburbs).

We need to find innovative ways to implement forms of collective
transportation (rail or what not) in already dense areas. Rail/subways have
already proven how effective they are. Autonomous vehicles are necessary to
improve road safety, maybe they can help slightly reduce the amount space used
by roads, but they won't solve most of the problems we have today on our
unsustainable roads.

~~~
closeparen
Unsustainable compared to what? New York is clearly demonstrating that it’s
incapable of sustaining a subway, and it has just about the best conditions
possible for such a project. You think a place that can’t even manage roads
can swing a subway?

Is it sustainable to all move closer together? Not if the residents of
existing cities have anything to say about how those cities are governed. They
don’t want the extra population.

~~~
notatoad
unsustainable is an absolute, not a relative. A road network doesn't have to
be unsustainable relative to anything in order for it to be full to capacity
at and for there to be no room for any more roads, which is the situation New
York finds itself in. It is physically impossible for NYC to have sustained
substantial growth to their private vehicle infrastructure, hence
"unsustainable". If they want to grow their transportation network, they need
to do it via other modes.

And i reject your assertion that New York has the best possible conditions for
transportation infrastructure. A lack of space, a huge demand, and a corrupt
mixture of local government and unions don't make for an idea development
environment.

~~~
closeparen
Maintaining existing roads is certainly not beyond the economic capacity of
the United States. It just costs more than you're willing to pay. That's
valid, but the alternatives don't appear to be cheaper. New York also finds
maintaining its subways in working order, something that's certainly
physically possible, to cost more than it's willing to pay.

High density and high transportation demand are prerequisites for having a
public transit system at all. And what dense US city's government _isn 't_
corrupt or incompetent?

------
chiefofgxbxl
I think people are focused on maximizing the wrong metric. Traffic projects
like this tend to want to _maximize car throughput_ , when what we really need
is to _minimize travel distance /time_. Maybe then society would start looking
at the effects that cars have made to sprawl, and the self-reinforcement cycle
that emerges.

~~~
ImaCake
I honestly think the real toll is the mental concentration required and the
stress caused by driving a car. Self-driving cars automatically fix that
problem by removing the need for the passenger to concentrate on not killing
people. When I take the bus I don't worry so much about my commute time,
because I spend the ride relaxing and reading.

------
yeukhon
I thought this whole sensor thing a lot in the past, specifically as an
argument to criticize the state of our autonomous vehicle development. We must
be very careful handling electronic failures and sensor reliability.

I know someone will bring up "well, traditional car will fail and results in
fatal crash too, but technology can help us catch that and predict accidents
by looking at 360 degree!". True, but let's not let that promise blinds us.

Also, this senor-led, slot-based system won't work in areas like NYC midtown,
so not a one-size fits all solution (that's a given). If we exclude accidents
and roadworks, then traffic lights, narrow roads, increase of cars on the road
(due to ride-sharing and cars becoming more affordable), and double parking,
they all contribute to the majority of traffic jam.

Some futuristic fixes include flying cars, roads in mid-air, roads through
buildings, and more underpass might help but they don't scale when you keep
adding more cars.

We need to improve our mass transit. If you have ever played Skyline or
SimCity, you know that intersection sucks and mass transit is preferred over
roads. Too many school buses will slow down traffic. Multi-lane to single-lane
can jam the road. The NY subway system coverage is pretty good, but each train
runs on one lane and is a single point of failure. Kudos to those working in
transportation planning though...

------
paulsutter
This slot based system is hell for pedestrians and bicycles. Let’s put powered
vehicles underground and reserve the surface for humans.

“Without tunnels we’ll be in traffic hell forever” -Elon Musk

------
niftich
This is a cool video, but the paper itself [1] is pretty light. The substance
of the paper is basically (from the abstract):

 _" Despite simulation-based evidence of the potential benefits of SIs [Slot-
based Intersections], a comprehensive, analytical framework to compare their
relative performance with traffic lights is still lacking. Here, we develop
such a framework."_

A handful of other quotes from the body examine the rationale and context for
investigating this question.

They compare the results of a platooning-type control strategy with a fair
scheduling strategy, and the "usual", fixed-cycle strategy, and find that the
platooning one, deemed 'BATCH', scales towards the optimal throughput as the
number of vehicles increases. There's formulas and graphs to back this up.

This is good work, but the website is a marvellous example of marketing;
subtly promoting the higher implications of the work instead of the work
itself.

[1]
[http://senseable.mit.edu/papers/pdf/20160316_Tachet_etal_Rev...](http://senseable.mit.edu/papers/pdf/20160316_Tachet_etal_RevisitingStreet_PLOS.pdf)

------
IndrekR
This is a good video example of how manufacturing works in lean factories. By
reducing or avoiding inventories, fetching from temporary warehouses and
machining stops (traffic lights here) you can _often_ increase the production
rate significantly.

~~~
rcarmo
Look up "kiva warehouse robots". You'll spend an hour fascinated by modern
warehousing :)

~~~
IndrekR
Thanks! Kiva/Amazon is a great real-time optimization challenge. Digikey
logistics is a good example of how it is well done with non-machines:
[https://youtu.be/pYqzccJdgVY](https://youtu.be/pYqzccJdgVY)

------
Spivak
I think a short summary is that the researchers are looking at proposing a few
different schedulers for intersections with the aim of implementing them with
autonomous cars. The results exist in ideal conditions with little thought
given to real-world edge cases, what a transition might look like, how cars
would coordinate, or if a square intersection is even a good shape for this
kind of thing.

My lingering question after reading the paper is the enforcement mechanism.
Process scheduling because there's an omnipotent authority with total control
over all processes but whatever system is used needs to work with no central
control and if all the cars are programmed to be selfish.

------
natemurthy
This looks like an awesome project, and I hope this receives significant
attention from city planners. I imagine as cars become more connected, we'll
have better interfaces for integrating mobile traffic sensors with stationary
traffic sensors for optimal management of vehicle flow along congested
streets. But I do worry about the pace at which city planners adopt such
technology at a time when local government budgets are tight.

------
ramzyo
Cool idea. This seems like a big caveat though,

>> With today's traffic volumes, queues would vanish and travel delays would
be cut to almost zero.

I’m pretty sure it’s critical in traffic engineering to consider how the
design would hold up in the event of larger volume given greater efficiency.
There’s a single lane exit on the Mass Pike about 5 miles outside of Boston
that’s always backed up onto the highway. I’d always wondered why they hadn’t
added a lane, put a divider, or otherwise designed the exit differently. A few
years ago a former colleague met the engineer who did the traffic analysis for
that exit. Apparently adding capacity to achieve greater throughput would’ve
resulted in worse traffic at the exit. According to the models they developed,
the more constrained solution was actually optimal, although to the frustrated
driver (me!) it still seems poorly designed.

Granted, this is an example of increasing capacity rather than improving
efficiency. Regardless, I’d be interested to see how the MIT solution holds up
to increased traffic volume.

------
marten-de-vries
I'm curious if developments like this will mean future cars will not require
lights at all. After all, the same communication required for an intelligent
traffic intersection like this could just as well be used to exchange
breaking, lane changing and position information.

------
adrianmonk
These slots look way too small in the animation. Every slot needs a bit of a
safety buffer. Getting t-boned is more dangerous than getting rear-ended.

So it seems like they should be trying to amortize that cost by grouping cars
together, both horizontally (side by side) and vertically (front to back).

So in other words, have a cluster of, say, 5 or 10 cars that cross the
intersection together.

That can be done by adjusting the speed of cars well in advance of the
intersection to group them, so it's not necessary to come to a stop as with
stoplights.

------
ReverseCold
This all works okay if you can trust every car on the road, but what about XYZ
hacker broadcasting false information to slow everything down? Or more
nefarious, they could cause an accident.

------
ZenoArrow
What are the benefits of this proposal when compared to roundabouts?

~~~
tomxor
I live in the UK where roundabouts are almost everywhere. While they are
definitely more efficient than crossroads they still have some flow control
issues in some scenarios: each joining road effectively controls the flow of
the next joining road further along the roundabout through priority, this is
both a strength (automatic flow control) and a weakness (unbalanced flow of
joining roads): Imagine a simple roundabout in place of an crossroad with 4
joining roads, if only two joining roads next to each other are active and of
those two, the one to the right has an endless contiguous flow, then all
traffic on the road to the left is blocked - it's basically waiting for road
to the right to be blocked by someone coming onto the roundabout from the next
road along.

As a result we have traffic lights on roundabouts as well sometimes, which
prevents this unfairness but also takes them back closer to the efficiency of
a crossroad.

I think the best combinations would be autonomous + roundabouts, I think fast
crossroads are just dangerous (autonomous or not). Roundabouts force vehicles
to slow down due to the forced turn and negotiate one stream of traffic going
in one direction rather than two streams going in up to 4 directions at speed.
The potential injury from the later is so much higher it's a non-argument.

~~~
ZenoArrow
I also live in the UK, so I'm familiar with roundabouts for the same reasons
you are, but I'm glad you've given the explanation for those that are not.

In your example, "an crossroad with 4 joining roads, if only two joining roads
next to each other are active and of those two, the one to the right has an
endless contiguous flow, then all traffic on the road to the left is blocked",
this is a theoretical weakness, but in practice it rarely occurs. For
starters, the chances of zero traffic from the other two roads is small, and
"continuous" traffic is rarely busy to the level where cars from the road to
the left are blocked completely.

Furthermore, if such bottlenecks occur, they can be mitigated against by
diverting traffic, through the addition of changes to surrounding roads.

Roundabouts may not be something to be implemented without consideration to
the surrounding road infrastructure, but they seem like they would be decent
step forward for many busy intersections with traffic coming from multiple
directions.

------
zhoujianfu
What would people give the odds we achieve a world of autonomous flying drone
transport for local travel before a world of autonomous self-driving cars?

It seems right now like we’re really close with self-driving cars but
objectively flying ones would be a lot better:

Shorter distances to travel (point to point), easier to implement collision
avoidance, faster, no need for this crazy infrastructure we build/maintain of
roads, bridges, traffic lights, tunnels, snow plows, street cleaners, etc...

~~~
orasis
Drones are far too loud.

~~~
icebraining
Drones don't have to be quad/octocopters. I'd love to see a self-driving
electric paraplane.

------
sharpercoder
A few thoughts on this matter:

1\. Roundabouts are safer and better with human drivers but bad from a
usability standpoint. It's annoying to drive, slower, and makes people feel
nauseous when driving through many. When we have road usage of autonomous
vehicles surpassing 50%, I suggest to remove them.

2\. Two-Leveled intersections without left turns seem cost effective and
highly advantageous in cities. To lower the cost even further, it may be
possible to design them for vehicles only (much lower ceilings needed, so much
lower cost). Left turns can be achieved (especially in the US this is viable)
bu going right three times (going around the block). Two-leveled intersections
without left turns can reach 100% capacity in all lanes from all directions.

3\. Lane-specific traffic light already may increase efficiency on
intersections. Imagine a 2x2 intersection from both directions: the right
turns can be green (where cars turn right on the rightmost lane) while
through-traffic can use the left lane.

------
m3kw9
They should just keep it simple, convert large intersections to massive round
a-bouts.

------
purplejacket
For fucks sake, where are the pedestrians??

~~~
sharpercoder
On roads where you can drive 30+MPH (50 KMPH+), I would suggest removing any
possiblity for pedestrians to cross. Either make the road 20MPH (30KMPH) max
where all space is shared with pedestrians, bicycles and cars - or make much
better, safer & faster 50KMPH+ roads.

~~~
IshKebab
Is this satire? How do you walk anywhere otherwise?

~~~
ReverseCold
Maybe, but it's an interesting concept.

My city put bridges over a lot of the major roads for people to cross. A few
roads have a tunnels underneath as well.

~~~
greeneggs
I imagine you don't even have to put too many of them in, before any
pedestrians give up and drive---having tired of needing to climb and descend
four flights of stairs or, worse, walk an extra block along ramps, just to
cross the street.

------
Animats
The Stanford Cart people proposed something like that in the late 1960s/early
1970s. There may even have been a video.

------
JackFr
Curious to see how it would respond to to volumes higher than it can safely
handle. Revert to traffic light?

------
vs2
wont roundabouts solve the same problem today!?

------
opensourcenews
And the pedestrians go where?

