“Confessions of a Recovering Engineer”

Charles L. Marohn, Jr.

Having quite liked the Strong Towns book and some of the YouTube channels based on it, I’ve had the sequel-of-sorts on my list for a while, and was finally able to get around to reading it. My overall review is “this is definitely an addendum to Strong Towns” – you can read it on its own, it goes to pretty solid lengths to reiterate material when it’s referencing it, but even with that it doesn’t particularly feel like it can stand on its own.

As a book, I think it’s fairly well-written; the use of a single street and a single incident as something to reference back to throughout is an effective device for centering the policy discussion.

Said policy discussion really comes down to two things. Firstly, that there should only be Roads and Streets — Roads being a thing focused on getting people from place to place quickly, and Streets being a place that people go to.1 The word/concept “stroad” comes up quite often in the book — a sort of painful middle ground, something trying to do both things and as a result doing both very poorly. Think of how you get to Best Buy, or Walmart, or any other big box store like that; clearly that’s meant to be a Road, because it’s a terrible place to walk around so it can’t be a Street… except it’s also pretty bad at driving on, because there’s people trying to turn onto or off of it, and probably a bunch of stoplights, and a general poor attempt at being a Road. Marohn makes a very good argument for abolishing these awkward things and forcing every piece of driving infrastructure to be either a Road or a Street, and then to be good at being what it is.

Which leads to the second point, and for this I’ll just use his own words:

T one safe, the street must communicate the real level of risk to the driver. In other words, the driver must feel discomfort driving in a manner that is unsafe. (40)

Or, more viscerally: when was the last time you went 45 on a narrow, technically-two-lane-but-for-the-people-parked, tree-lined, watch-out-for-the-kids-playing-basketball neighborhood street? Probably never, because doing 45 there feels deeply unsafe. You didn’t have to look for a speed limit sign to know that you should be going slowly; you can tell that the street does not want you going fast, and that if you try to go fast, you’re gonna have a bad time.

And that’s the design policy he advocates for. Our infrastructure is built around the idea of forgiving drivers for their mistakes… but once you account for human psychology, that means that drivers will make more mistakes, because they know they don’t have to pay as much attention.

And now, really, I’ve kinda spoiled the whole book. Those are the core arguments; everything else is filling in details or repeating points to drive them home. There’s a couple chapters at the end that felt like later additions, and in particular the one about his legal arguments with the state licensing board feels entirely out of place. The whole section on transport technologies is entirely too generous to Elon Musk, but then, at the time this was written, his reality distortion field hadn’t failed yet, so we were all a bit more forgiving.

One last pull-quote, though, to which I’ll add emphasis, because I thought it was a really great way to discuss some of the issues with policing in the US.

Police target areas they perceive as high crime. When they discover criminal activity, which they inevitably do given the approach, it reinforces the initial perception. There is no control group receiving equally aggressive policing to create comparable statistics. (195)

An excellent point about sampling bias, at the end of a chapter that’s a pretty good quick overview of everything wrong with the ‘routine traffic stop’ as a concept.

Overall, this is a pretty good read; go for the first one first, and if you’re still interested in more, give it a read.2

Interestingly, this concept can be broadened – I quite liked his discussion of how transit options like trains and planes are a form of road, whereas, say, a cruise ship is a street. Feels weird to say, but within this framework, it fits! ↩