By the way, the maximum rate of 60,000/hour in each direction for BART I quoted was from BART itself[1]. I should have provided a link. Primary sources are good

By the way, the maximum rate of 60,000/hour in each direction for BART I quoted was from BART itself[1]. I should have provided a link. Primary sources are good. Of course the sleds in an operating system would not be absolutely packed together. This was just a Fermi estimation to get some idea of the flow rate the parent comment was wondering about. Looks like max rates would vary from somewhat worse than trains to much better. The sleds would be automated so that when one wants to exit the others would give it enough space to do so without problems. Another Fermi estimation could be done to get an idea of how long the exit tunnel would need to be for a sled to stop given a range of deceleration rates. I think Musk is on the right track but that his biggest hurdles may be social and political in the USA. Maybe China or India will want to try it out (or the Swiss). [1] https://www.bart.gov/sites/default/files/docs/2016Factsheet_v12.pdf https://www.bart.gov/sites/default/files/docs/2016Factsheet_...