We should be grateful for this tweet. The public is mostly unaware that induced demand is a thing. Now Elon's helping us to spread the word!
A few links on induced demand in this thread
A few links on induced demand in this thread
There's a decent Wikipedia page for induced demand en.wikipedia.org/wiki/Induced_d… 
A corollary of induced demand is that, when you take road space away from cars, traffic does not necessarily increase - in fact it often 'disappears' - see this brilliant paper nacto.org/docs/usdg/disa…
(thread is paused because of family commitments, I'll be back with more links in a couple of hours...)
Links to a few key academic studies on induced demand:
- doi.org/10.1177%2F0881…
- aeaweb.org/articles?id=10…
- link.springer.com/article/10.100…
- doi.org/10.18757/ejtir…
- doi.org/10.1016/S1361-…
- bettertransport.org.uk/sites/default/…
- doi.org/10.1177%2F0881…
- aeaweb.org/articles?id=10…
- link.springer.com/article/10.100…
- doi.org/10.18757/ejtir…
- doi.org/10.1016/S1361-…
- bettertransport.org.uk/sites/default/…
Induced demand is a key element of the self-reinforcing process of car dependence: the more road infrastructure you provide, the more you incentivize car ownership & use, which fills up road capacity, leading to more road building/widening, and so on & so forth...
This self-reinforcing process of car dependence has been observed a long time ago, and it has been given many names. Engineers were aware of it already in the 1960s and called it the "magic circle" doi.org/10.1016/S0967-…
Other call it the "black hole of highway investment" urbandemographics.blogspot.com/2015/10/build-…
Anyway, the main point is: if induced demand is a thing, then providing more road infrastructure to deal with congestion is ultimately self-defeating. You will get congestion again, but at higher levels of traffic...
On the other hand, if your business model / life goal is to sell cars and build roads/tunnels (like Elon), then induced demand is both convenient & inconvenient
The induced demand phenomenon per se is convenient because building tunnels will help you sell cars, but...
The induced demand phenomenon per se is convenient because building tunnels will help you sell cars, but...
...*awareness* of induced demand phenomenon is of course inconvenient, because it may lead to try & stop the vicious circle.
So if you're selling cars, the best case scenario is one where induced demand actually exists, but awareness of it is not widespread
So if you're selling cars, the best case scenario is one where induced demand actually exists, but awareness of it is not widespread
So going back to Elon Musk's tweet what he's doing here is assuming that there is something like (latent) travel needs / demand which is *unaffected* by levels of infrastructure provision.
If that were the case, then you would expect to see "little traffic" in cities/areas with particularly generous (excessive) provision of road infrastructure. Traffic should be flowing freely in Los Angeles.
Now of course the alternative hypothesis is that *everywhere* there is latend demand/need for levels of car use that are as high as in LA (or higher). It's just that there is not enough roads to allow for it (hence congestion)
But even if that was the case, you probably don't want to build that much road space, so you're back to square one (ends)
PS: Brilliant piece on this by @carltonreid: "Musk is continuing a long tradition of motoring-besotted experts blithely ignoring the evidence of their eyes." forbes.com/sites/carltonr…
