>>1970747>What possible advantage could rail have under the ground beneath a city?It's cheaper to run a 8-10 car train than it is to run the equivalent of an 8-car tube train, which would be around six double-decker buses (just personnel cost alone is 1 tube driver's salary vs. 6 bus drivers' salaries).
Subways in the biggest cities run very frequently, every few minutes. The Victoria Line runs something around 36 trains per hour during rush hour which translates to 100 second intervals. Replace them all with double decker buses and you would have over 200 buses per hour in your proposed asphalt tunnel, that would be utter chaos. That would mean a bus at any given stop only has 18 seconds at a bus stop before the next bus would catch up. These are very lenient calculations btw as official figures state the New Routemaster buses only have a capacity of 87 whereas one Victoria Line tube train has a capacity of over 1100. If you want to do the same math but with individual cars, the maximum per-hour capacity of 1 lane of car traffic is about 12 Victoria Line cars. Remember that they run 8-car trains every 100 seconds.
Most of the busiest subway systems are older than the affordable/mass-produced automobile, and operating a deep level subway line with diesel buses is mass murder. Of course, electric buses exist now but they have been mass-produced for only a few years, and the oldest deep level tube lines date back to the 1890s.
