That's a very strange idea. XD<br><br>But it illustrates the common infrastructure problem - nobody uses a partial system, and it's extremely expensive to implement a full system from scratch.<br><br>A LOT of transportation ideas that sound good on paper suffer the same fate because of this.<br><br>It also goes some way to explaining why we have high speed rail in various places rather than say, maglev.<br><br>Sure, high speed rail effectively requires dedicated infrastructure...<br>But those dedicated high speed lines can still connect into the slower parts of a rail network - meaning, amongst other things you can run these trains straight into inner city stations that have existed for centuries without putting any new infrastructure in the cities themselves, which is the most expensive part. (also you can upgrade the city sections piecemeal alongside maintenance you'd have to be doing anyway.)<br><br>So many varied and interesting ideas, yet so few of them ever happen.