for EJ_SA

Not for the stream, just for you (but if you happen to show it on the stream that's fine too; I just don't want this blog spammed as I use it for when I need to say something that wont fit on twitter.

Speaking of which.

I'm someone who is quite keen on urban planning and wanted to explain some of why Elon's tunnel plans are good and where the main challenge is.

The key here is the idea of reversible lanes. I can show that below.


normal highway

>>>lane>>>
>>>lane>>>
<<<lane<<<
<<<lane<<<

Lets assume the downtown core is to the left and the uptown suburbs to the right. Lets also change "lane" to the percent capacity that is being used.

This is what things might look like at 9am on a big highway

>>>033%>>>
>>>033%>>>
>>>033%>>>
<<<100%<<<
<<<100%<<<
<<<100%<<<

And this is what the same highway might look like at 5pm.

>>>100%>>>
>>>100%>>>
>>>100%>>>
<<<033%<<<
<<<033%<<<
<<<033%<<<

Without tunnels but with reversible lanes you can reach the same level of capacity just by doing this in the morning:

>>>100%>>>
<<<100%<<<
<<<100%<<<
<<<100%<<<

and this in the afternoon:

>>>100%>>>
>>>100%>>>
>>>100%>>>
<<<100%<<<

6 lanes becomes 4.
8 becomes 5.
16 becomes 9, and so on.

This works the same in tunnels as it does with reversible lanes; the difference is that we don't have space above ground to do this; but underground we do.

This leads me to the multiple entrances thing for a single tunnel; with that you can "zipper" in cars, which allows you to have them run closer together; this can be help with some kind of self-driving tech, or those guide grabbers that they showed in the video.


SO


The big "up" here is that you get the benefits of reversible lane highways with self driving cars by using this method; which increases capacity a ton.

the drawback is the cost of building the tunnel, and, especially, the connection from the tunnel to the outside. For example when building a subway line more money is spent on the stations than on the entire rest of it (the rails, electricity connection, tunnels, etc)

so if Elon can figure out how to do this on the cheap, he most certainly can be a world leader in this front, and, it will work amazingly.