> However, there are shortcomings wiht traditional train systems, these new systems try to address. One big limitation for trains is, where to put the tracks. [

> However, there are shortcomings wiht traditional train systems, these new systems try to address. One big limitation for trains is, where to put the tracks. [...] The Boring companie tries to lower tunnel costs by making them less in diameter.Other systems try carts which run on or hang from stilts, reducing the space needed or allowing the train installations to go on top of existing roads. Which is one of the main points of the article: the limiting factor is not the type of propulsion, but how and where to put the tracks. Tunneling is expensive. Decreasing tunnel diameter just turns one knob of that system. Emergency access, switching and mergeing systems, and access to the tunnel itself use space and cost money. And if the idea is to just add tunnels to increase capacity, then that is probably more expense than building a proper train system with higher passenger density in the first place. Trains that hang from stilts still need the stilts to sit on the ground somewhere. Trains that sit atop of roads are limitied in their speed, by the traffic these roads where originally designed for. The curves might not be suitable to go around at high speeds. You can't also just increase speed - acceleration and deceleration forces as well as the forces acting on a whatever kind of pod on whatever kind of track are physical limitations that affect passenger safety and comfort. All these ideas improve on some small aspect of the system as a whole, but they do not solve the fundamental difficulties inherent in designing public transportation - they do the job, but not without the same real world problems that we have with traditional rail. Autonomous operation for increased frequency might make some sense, but then that's something that can probably be retro-fitted to existing systems, and has little to do with the propulsion system in use. ... and I know of at least one urban public transport system where the limiting factor for increased frequency is ( apart from the issue that six train lines share one bottleneck track ) the time the doors take to close safely... not something I would have had on my radar as being a problem.