The Bridges of Pittsburgh County … That Autonomous Cars can’t SLAM through !

Same as my post in Linkedin

Autonomous cars do bring out interesting nuances to the normal things that we take for granted and don’t think twice about !

Business Insider’s article “Here’s why self-driving cars can’t handle bridges” fits this category.

“Bridges are really hard,… and there are like 500 bridges in Pittsburgh.”

Of course, it is the infinite (or near infinite) context that we, humans can process and machines aren’t even close … But, one would think bridges would be easier – no distractions, well designed straight roads; of course with the current GPS accuracy, the car might think that it is in the water and start rolling out it’s fins !!

“You have a lot of infrastructure on the bridge above the level of the car that we as humans take into account, … But when you sense those things with a sensor that doesn’t have the domain knowledge that we do … you could imagine that the girders coming up from the side of the bridge and that kind of thing would be disturbing or possibly confusing.”

Pittsburgh does have bridges, lots of them … There is even a BBC documentary! Even how the city deals with the bridges is interesting.

In fact Pittsburgh is called “The City of Bridges”, even though some have different interpretations (we will come to that discussion in a minute)

While we are on the subject, I do have a couple of books for the Uber Car to read ! It can even order them through it’s robotic friend Alexa ! or drive to wherever fine books are sold, on it’s own time – Uber might not pay for the impromptu solo drive.

  1. Bob Regan’s Book is the first one to read
  2. Next is Pittsburgh’s Bridges (Images of America)
  3. The book Bridges… Pittsburgh at the Point… a Journey Through History gives interesting perspectives the riders would enjoy (of course, the ones with enquiring minds…)
  4. Finally, the hardcore bridge fans would be thrilled to hear from Pittsburgh’s Bridges: Architecture and Engineering

Now, to SLAM, it is the set of algorithms collectively called Simultaneous Localization And Mapping – a very interesting topic by itself.

In short, a SLAM system needs known points in addition to unknown points, to reason about & figure out it’s trajectory – bridges have less of known points it can rely on …

We can definitely employ Deep Learning ConvNets as well as traditional computer vision with a dash of contextualization is a good start … that is a topic for another time (sooner than later…). Probably an interesting opportunity for or

For those snappy Machine Learning experts, there is even a Pittsburgh Bridges Data Set at UCI, to start with ! Probably nowhere near the data needed to train modern Convolutional Nets, but one can augment the images with algorithms like Flip, Jitter, Random Crop and Scale et al.

If we think Pittsburgh is difficult, wait until Uber starts autonomous driving in Amsterdam ! While Pittsburgh has 446 bridges, many sources put Amsterdam with over 1000 bridges that cars can travel. There are many bicycle and pedestrian bridges in Amsterdam that an Uber car wouldn’t be interested in – except, of course, to pick up the tired pedestrians ;o). The which-city-has-max-number-of-bridges discussions can be followed here:



  • The bridges in Pittsburgh are not painted Yellow (as one might tend to think) but Aztec Gold !
  • And yep, it is Allegheny County ! But Pittsburgh rhymes better ;o)




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