Road design, safety and Vision Zero

[danbrotherston]

It's an understanding of fatalities as a parameter in the design, and if you set fatalities = 0, the design doesn't work. Instead, the approach should be that we have to engineer a solution to a problem (intersection, for example) - how now can we engineer it safely? I'm adding a stop light, what does that mean for safety? I'm adding a left-turn lane, what does that mean for safety?

My problem here is that there is generally no design that actually accomplishes fatalities of 0.  Why?  Because we, as a society, don't actually believe safety should be the only consideration.  Practicality matters.  And to have a design that really, truly, guarantees 0 fatalities (to something like the same level of confidence of a bridge collapsing due to load factors) would make our current transportation system (and by extension our quality of life, economy, etc.) grind to a halt.

So "zero fatalities" is great as a high level goal and guiding principle.  It's garbage if you want to treat it as an actual hard engineering constraint. [And, I'll note again that literally nowhere in the world that I know of, including Sweden, is anyone actually treating this as a hard engineering constraint].

This type of thinking already exists in engineering in terms of efficiency. Efficient traffic movement is a primary variable that they are designing for and constantly trying to improve. Safety is a secondary variable that they need to keep within an acceptable level.

I disagree with this premise that safety and efficiency are treated fundamentally differently.  Both are variables that are bring optimized and kept within acceptable levels.  Now, we can certainly argue that the trade offs being made now aren't the "best" ones.  And in that aspect, something like Vision Zero is great.  Bringing awareness to the trade offs and pointing out that maybe we're siding too often on efficiency and not safety.

First of all, there are no bridge designs, nor airplane designs that guarantee no failure.  What we do have is a process of checks and investigations in place to ensure when we do find a fault with the design, it is corrected.

This does not exist with road engineering.

Your belief such a system would make out transportation system "grind to a halt" is directly contradicted by Sweden, which implements such a system, yet has a fully functional, and in many ways, more functional transportation system than we have.

Claiming that either you "guarantee" zero deaths, or you refuse to make eliminating deaths part of the design process, is a false dichotomy.  People who design and test airplanes do so with the knowledge that there is no acceptable level of failure, but also know that they can and do make mistakes (and they did, recently, with the 787 MAX), yet are still able to design and build airplanes.

If we come back to practice, why is it that you, and people like our transportation commissioner oppose so vehemently, the system that Sweden has implemented. They have proven it is effective in reducing injuries and fatalities, without causing undue inconvenience to their transportation system, and yet here, we try to justify not implementing a similar safety program. Even when I give specific examples, you suggest it's "not always appropriate". So tired of seeing people killed, because people like our transportation commissioner don't consider safety a priority.