
MIT team’s school-bus algorithm could save $5M and 1M bus miles - frostmatthew
https://www.wsj.com/articles/how-do-you-fix-a-school-bus-problem-call-mit-1502456400
======
payne92
I worked with a startup years ago that did these kinds of optimizations (for
deliveries). The logistics & transportation market in the US is about a
TRILLION dollars -- small optimizations can make a HUGE impact.

The challenge for practical implementations is that there are lots and lots
and lots of optimization factors that are very hard to account for. Often, you
don't even know what they are until you try to automate the process.

For example: preferring small buses on side streets, as the article mentions.
Or, knowing about a major work project in an area (to avoid for the coming
year), or specific left turns that are tough for a bus. Also, highly optimized
schedules usually have (by definition) much less "slack" in the overall
system, and are less resilient to real world changes and variations.

My point: in my experience, there can often be a significant gap between
enthusiastic technologists (myself included) and real-world implementations.

~~~
trendia
Another example: a lot of rural areas have patches of gravel roads. It's not
obvious from Google maps where the roads go from paved to gravel (and they
sometimes do it in random sections).

Naively looking at a map, you'd think a roundabout route had potential to be
shorter, but not realize the road was gravel.

~~~
goodcanadian
In rural areas, school buses drive on gravel. Where I grew up, the buses were
speed limited by law, so the speed on gravel is often the same as on the
highway. Road surface might not matter as much as you think.

~~~
bluGill
In rural areas there are a lot of minimum maintenance roads. Legally they are
roads and you can drive on them all you want. However if you don't have 4
wheel drive you shouldn't drive on them, even with 4 wheel drive there are
times when you won't make it. A bus should never drive on these roads, and
google does not know which these roads are - as I've discovered when I had to
rescue someone who blindly followed google maps.

~~~
goodcanadian
Sure, I guess I was trying to comment specifically on gravel. You will need
accurate maps for this to work, but I think that is basically a given. A human
route planner will also need to have accurate maps.

~~~
vturner
A local human bus driver doesn't need the map, they know the route and the bad
road areas.

------
chrisbennet
Since this forum for founder/entrepreneur types, let me inject a bit of
caution from my own experience with dealing with government organizations:

If you save a _business_ organization money, they appreciate it.

If you save a _government_ organization money, the next year the "savings" is
likely to be deducted from their budget. They don't get to benefit from the
savings and thus their motivations aren't what you might expect if you are
used to dealing with businesses.

It makes sense but when I encountered this the first time it caught me by
surprise. I mean who wouldn't want to save money, right?

~~~
drej
> If you save a business organization money, they appreciate it.

Is that based on past experience?

~~~
chrisbennet
Yes, they appreciated it so much they'll paid me money. :-)

------
jmull
It will be interesting to see how it works out in real life.

As the article notes, they've tried this before and the algorithmically
generated route map didn't work well in real life. Assuming the algorithm was
good, the issue was probably that it didn't incorporate significant real-life
factors.

Perhaps they are getting more sophisticated though, by having the people who
have been doing this work by hand review the results and make adjustments (as
the article says, e.g., at first the algorithm allowed big busses on narrow
streets, which apparently doesn't work well).

Speaking of the people who have been doing the route maps manually... they
seem to have been doing an impressive job since the algorithm is expected to
be only 4% better.

------
towndrunk
Kind of off topic but... why is no one converting school buses to electric?
Seems like a perfect opportunity. Lots of space for batteries. High torque.
Short runs in the morning and afternoon. Think of how many diesel school
busses there are across just the USA every morning.

~~~
ztakeo
Not sure if by "converting" you mean retrofitting old buses or replacing
diesel buses with new electric buses. If it's the former definition, it's non-
trivial from a safety and engineering standpoint to integrate a high-voltage,
high-energy battery system into an old bus and expect to realize a decent ROI.
Those old clunkers are not designed with an electric powertrain nor efficiency
(i.e. they're heavy and have have drag coefficients) in mind. Furthermore,
safety is paramount in most bus operations, and a lot of thought needs to go
into mitigating thermal runaway or other catastrophic failure modes with
systems of that voltage (100s of V) and energy (300kWh+). Depending on the
existing bus system that the battery needs to be integrated into, this can be
challenging and sometimes infeasible.

I say all of this more to make the argument that rather than retrofit old
buses, in my opinion it makes more sense to outright replace them. Right now
Proterra is the largest domestic producer of pure electric buses. They compete
on most contracts with BYD in China, and New Flyer in Canada. Behind BYD and
the government, the electric bus market in China has absolutely exploded over
the last several years. Proterra is anticipating high growth in the U.S.
market as well and just launched a new factory in LA last month [2].

[1][https://www.proterra.com](https://www.proterra.com)
[2][https://www.forbes.com/sites/alanohnsman/2017/07/26/proterra...](https://www.forbes.com/sites/alanohnsman/2017/07/26/proterra-
opens-los-angeles-electric-bus-plant-targeting-west-coast-transit-sales/)

~~~
dsfyu404ed
Seriously?

While aerodynamic teardrops are most efficient that means nothing if the up
front cost is prohibitive.

Also, efficiency and a box that's strong enough to appease the "think of the
children" types are very much at odds with each other.

For a bus with low mile requirements some boxes to hold batteries and a big DC
motor where the engine goes would work fine.

The "scaled up golf cart" architecture works well if the route does not change
and is very cheap to implement.

~~~
ztakeo
The upfront cost is no longer prohibitive with all-electric buses realizing
savings in the form of reduced maintenance and fuel costs that exceed the
initial investment discrepancy [1-2].

On your second point, a bus doesn't necessarily have to have a heavy steel
frame for it to be safe. There are plenty of lighter weight (e.g.
composite/carbon fiber) solutions which don't sacrifice safety.

Sure, if the mileage requirements are low then there's definitely a cost-
effective retrofit solution. But if you're a company already building a full
electric bus and investing a lot of R&D into the pack design anyway, then you
could probably just sell battery solutions to school bus companies as another
revenue stream. I'd wager, though, that the larger addressable market is
customers looking for new electric buses for longer routes.

[1][http://www.columbia.edu/~ja3041/Electric%20Bus%20Analysis%20...](http://www.columbia.edu/~ja3041/Electric%20Bus%20Analysis%20for%20NYC%20Transit%20by%20J%20Aber%20Columbia%20University%20-%20May%202016.pdf)
[2][https://www.nrel.gov/docs/fy16osti/65274.pdf](https://www.nrel.gov/docs/fy16osti/65274.pdf)

------
yedpodtrzitko
Locked article. So I am just curious - is that a different algorithm than the
one with "no turning left" rule which saves money to UPS?

~~~
throwaway2016a
I was thinking that too. Surprisingly, if the image in the article is actually
accurate (it might not be, it's probably just a graphic designer's
illustration) then the route that was generated actually takes exclusively
left hand turns.

------
cropsieboss
Pickup and delivery optimizing algorithms have been optimizing stuff in
private businesses for years.

What do you think what kinds of algorithm makes schedules for trashbin
collection, newspaper delivery, sodapop machines etc.

If you aren't ondemand and there's multiple drivers there is someone who can
optimize it to (almost) optimality.

This is a pickup & delivery problem and the algorithms exist and work in
practice for decades.

~~~
jeddawson
Have you used any that are actually effective? Please share if so :)

I work within the trash collection industry and we've tried several different
optimization schemes that in general don't come close to optimal efficiency.
The marketing for a lot of the optimization companies would lead you to
believe that they're able to unlock a lot more efficiency than they actually
deliver. Our clients that have applied algorithms to optimize their routes
quickly reverted to human optimization since the algorithms fail to provide
any benefit and typically require tremendous effort to get started.

I would love to discover an algorithm that is able to consistently provide
actually optimized collection routes without hand holding!

------
mightytightywty
$120M budget to bus 30,000 children to school? Does that sound like a lot, or
is it just me? That's $4,000 per child per year. At 180 school days per year,
that's $22.22 per child per day!

At that rate, they could save many more millions by switching to Uber or some
other ride sharing service.

~~~
askvictor
This would create a crapton more traffic, if you could even satisfy the demand
in the first place.

------
Animats
If I'd made a really bad career decision, I would have spent years working on
this problem in a suburb of Cleveland. A startup I once worked for pivoted
from mainframe scientific time-sharing to school bus scheduling. Fortunately
I'd left by then.

------
theprof
Really cool (full disclosure - my advisor was Bertsimas's PhD advisor)! School
bus optimization is slightly different from UPS/DHL/last mile logistics
routing because you only solve the problem once or twice a semester and make
small changes as and when kids change schools etc. From a business point of
view there really aren't any off the shelf products that do this well plus its
tough selling to school districts. Ping me if this interests you.

------
vineet
I am glad that people are using algorithms to increase efficiency. But, this
seems to only save $5M out of a $120M budget - I was expecting and am hoping
for more.

I feel like it would be an awesome project to dissect a large public
institutions funding and to discuss ways that algorithms can help reduce costs
without reducing the quality of service and agility of the organization.

The site would not allow me to read the full article, so I might have missed
something.

~~~
dublinben
If you prepend "facebook.com/l.php?u=" to a wsj link, it will let you read the
full article. Like so:

[http://facebook.com/l.php?u=https://www.wsj.com/articles/how...](http://facebook.com/l.php?u=https://www.wsj.com/articles/how-
do-you-fix-a-school-bus-problem-call-mit-1502456400)

~~~
LeifCarrotson
WSJ: You cannot have your SEO marketing and social media virality cake and eat
it, too.

------
mck-
Given the scale of the problems they are tackling, I'm quite surprised how
little they are saving. $5m over $120m is only 4%. I would imagine
municipalities' manual route planners wouldn't be that great.

We have found with many real-world scenarios, that at a much smaller scale we
could save easily up to 40% in driving time and fuel costs. When we studied
cases of 20+ vehicles and ~1000 stops, sometimes the savings were up to 60%.

In one scenario we took 8 cars off the road form a fleet of 30. [1] That's 26%
compared to the article's 11.5%. Not to discount its results, dropping 75 bus
routes is incredible! Imagine dropping another 75 :)

Note that since this is an NP-complete problem, the larger the size of the
problem, the more constraints you add, the harder it is for any human route
planner to plan routes efficiently -- so the larger the potential efficiency
gains for an algorithm.

Disclaimer/plug: founder of Routific here.

[1] [https://routific.com/stories/spring-hope-food-
drive/](https://routific.com/stories/spring-hope-food-drive/)

~~~
cropsieboss
These are all just savings numbers for simplified problems, like vehicle
routing problem or simple pickup & delivery problem.

Points below properly define problem above:

* capacitated pickup and delivery with time windows (NP-hard)

* capacity of around 20-60

* every child has to stay maximum T minutes in the bus from the moment it is picked up

* each bus can work simultaneously on delivering to multiple schools (covered by standard p&d algorithms)

* additional routing/map constraints for roads/vehicle constraints - like minibus drivers being constrained to ares with different housing etc.

I'm pretty sure the third point is a tricky one, implementation and speed
wise, last one too. I'm skeptical that your API could solve the problem for
600 vehicles off-the-shelf. Not to mention that pickup&delivery slows things
down extremely compared to capacitated VRP. Each optimising step is a venture
into heavy graph theory. Or one can use easy heuristics and fail miserably by
exploring too little of constrained space.

I'm skeptical of these large savings. I've personally worked with some top
logistics people that did amazing things with pencils and rulers. Trumping
these methods gained savings of about 10-15%.

Not to mention the optimizing time. It is impossible (if algorithm is not
heavily optimized) to search through enough space for these heavily
constrained problems in short amount of time (couple of minutes) to get 60%
savings. I might be too critical, but I doubt that Common Lisp algorithm can
achieve those kinds of speeds.

What if a child was forgotten, how much will the replanning time impact the
real world workflow. All sorts of invisible issues.

------
rce123
How do they arrive at only 20,000 lb carbon emissions (presumably CO2), from
1M bus miles traveled? According to the EIA, 1 gallon of diesel produces
~22.4lbs of CO2. Even assuming ridiculously optimistic MPG ratings on the
buses, these numbers don't seem consistent with each other.

------
vit05
I think this is similar to what remix.com do, but just for Schoolar bus?

------
omot
Didn't read article, but bus routes are optimized for efficiency. They're
optimized for driver hours. This is what I read online... I'm not sure how
true this is.

------
qandrew
i can't access the WSJ journal... can someone link me the MIT profs involved
in this work?

------
mathattack
I'm surprised they're only pricing each mile at $5. The opportunity cost of
time on the bus would be a lot more than that too.

------
Sir_Cmpwn
Flagged, paywalls without a workaround are not permitted on HN.

[https://news.ycombinator.com/newsfaq.html](https://news.ycombinator.com/newsfaq.html)

~~~
m777z
There is a workaround posted elsewhere in the comments

[http://facebook.com/l.php?u=https://www.wsj.com/articles/how...](http://facebook.com/l.php?u=https://www.wsj.com/articles/how-
do-you-fix-a-school-bus-problem-call-mit-1502456400)

