What a sad indictment of the situation that your wild fantasy system has 15m headways. 4 Trains Per Hour. That's borderline unusable. 10 TPH is what I'd consider tolerable. 18 TPH is what I expect from first class cities in developed countries.
To me 15m with a 1m variance is pretty usable. A typical trip on BART (it's intercity) is going to be 30-40 minutes, and in many parts of the system you have multiple train options, which also reduces the wait time.
To build some new train that works in SF, here's what you gotta do. https://en.wikipedia.org/wiki/Central_Subway Now that is about $1B-2B in building prices to go underground 1.7mi. Oh, that was built to replace a freeway that was torn down in 1989 after an earthquake. So we're just about to see the infrastructure replacement about 30 years later.
You can stop nearly any public transport project by using the state's EIR (IIRC the BART extension to the airport was slowed because of some endangered frogs).
Another issue is that many PT projects are pork-barrel. The route of the "high speed train from LA to SF" is a nice example of this; the train will not be high speed for the popular sources and destinations, because the central valley obtained concessions about the routing. It will probably never see ridership to justify its costs, and major contribution to that is that it can't bring people from downtown LA to downtown SF quickly. I dunno. does the shinkasen make a detour to rural agricultural areas? What about high speed trains in China? Do they go through second-tier cites?
My point is that while the US/SF is a first class city in a developed country, it lacks the political will to make great public transport, has trouble raising the funds to pay our very expensive building costs, and the alternatives are "just good enough" that the populace isn't super keen on large amounts of spending of PT without seeing some sort of benefit from it. Addressing all three of those and making change that makes the US a better place seems pretty implausible at this point.
It has enough space to continually and affordably reduce population density. I'm sure other countries make greater public transit investments because they do not have this convenience at their disposal.
American cities _did_ make large public transit networks in the past - L.A. once had the largest streetcar network in the world - the thing was that it subsidized cars and made preferential rules for cars to the point of bankrupting the alternatives and then ripped them up. Those streetcars also supported lower-density developments on the periphery - "streetcar suburbs" - which today are still valuable and prized places to live because they are far more walkable than your typical cookie cutter car dependent suburb sprouting up today.
In what years was that system operating? Los Angles wildly expanded in size from 1912 to 1915, and it looks like most of those systems struggled to be profitable before this point and were only further hampered by the expansion in size and the low ridership of rural lines. It seemed they were unable to accurately match rail with demand in most cases.. and most rural/suburban people were already beginning to prefer cars.
Isn't this self-evident for any town? If the local geography offers nothing in the way of convenient mobility, natural resources, easy access to trade routes, or anything else worth taking advantage of, there's no point founding a town there. Towns need to build wealth to survive and grow. One distinct drawback of ripping up streetcars and making everyone depend on the car is that you have to level massive portions of your downtown to create parking, and you have to take away tons of public space from people to make room for all the traffic. LA did both of those things and it's why it's unique among U.S. cities of its size for being horrifically sprawly and difficult to navigate.
You also need to bear in mind that car-centric development is incredibly, wildly unprofitable, and is subsidized by taxpayers. Modern low density suburban developments require absolutely enormous quantities of expensive infrastructure - pipes, asphalt, power lines, waste collection, wastewater treatment, fire, police - massive upfront capital expenditures with massive long-term liabilities. The U.S. has collectively spent many hundreds of billions of dollars building and supporting infrastructure for the exclusive use of cars. The local taxpayer base rarely if ever is actually able to offset that cost which is why A) much of the funding is from state/federal grants and B) public debt is increasing without end.
The fine exacted: $5,000 against General Motors, and $1 against its treasurer.
https://en.wikipedia.org/wiki/General_Motors_streetcar_consp...
They generally follow the natural route between large cities. This route is in the valleys which are already relatively populated because they are not the mountains which comprise most of japan. There are two, three or more types of high speed rolling stock on the same lines. The older, slower trains are cheaper between cities and have more local stops.
It complements trams (streetcars) and trolley buses in the larger cities - Zurich and Winterthur - which run in 6 - 10 (maybe 15 in Winterthur) intervals.
It further connects to a rural network of buses that serve literally every tiny village in the Canton and are timed to connect with S-Bahn trains.
The whole system is very successful and utterly useful with those frequencies.
Arguably, the city of Zurich runs one of the best public transportation networks worldwide.
You don't need a 3 - 4 minute interval if you're not connecting Tokyo with Osaka, or inner city Paris.
What you need is a well designed network, with guaranteed connectivity and predictable travel times with a simple ticketing system (independent of mode of transportation) and maybe not the fetish that it needs to be financed by ridership alone.
Silicon Valley isn't arranged like a city at all, it's almost rural except for the traffic jams. (San Francisco is another story, but even SF is a very small "big city"). Four trains per hour seems fairly frequent for that type of suburban/exurban environment.
What country has this? Definitely not USA, Canada, Mexico, Australia, Spain, France, Italy, or Portugal.
EDIT: My mistake, thank you folks! Your experience traveling abroad is different than mine. For a proper train in especially Spain or Italy during off-peak hours, there were often only one per day for many routes.
Caltrain and BART are both still utter disgraces.
Many metro lines in Paris run at less than 3 minute intervals during peak times (when there aren't any "incidents"). Even the aging line 6 has around 3 minute intervals during rush hour.
I'm not very familiar with the Bay Area, so I don't know how these would compare to the line described by OP distance-wise. Longer distance trains in Paris (RER and other suburban lines) don't run at 3 minute intervals either.
BART achieved 4 minute headways through the San Francisco subway portion. That also effectively limits headways on branch lines (absent additional trackage through SF) as when multiple 15m headway lines are combined the net headway is reduced.
For longer-haul commute service, 5--10 m headways aren't unreasonable, and a dedicated East-bayshore or Peninsula bayshore BART line might be able to accomplish this, with either a transfer or dedicated trackage in SF itself.
(Muni Metro runs on what was intended to be additional BART trackage.)
See:
or a train every 1 minute 40 seconds
(2 track railway, all station stops)