/n/, is it really necessary for a metropolitan area to have all three of the following rail transit modes?
>Metro/Subway (dense, high-capacity urban service)
>Suburban/Regional Rail (extremely high-capacity, long-distance service)
>Light Rail/Tram (medium to low-capacity, local service)

Or is it more efficient to adopt a more streamlined approach—for example, a high-capacity S-Bahn-style suburban-regional system like Berlin’s, paired with a hybrid Stadtbahn system like in Karlsruhe or Stuttgart, which blends elements of metro and tram?

It seems like running all three separate systems leads to higher costs and complexity—different rolling stock, infrastructure standards, control systems, and agencies. Wouldn’t a well-integrated two-mode setup be more cost-effective and easier to manage?

>>2040819 (OP)
It's finding the sweet spot that fits for a particular city, now and into the future.

Excessive standardisation leads to transit modes being ok at what they do, but not doing especially well. Also, in S-bahn systems, delays can spill-over very easily and Thameslink is a prime example of this. A 5-minute delay in Peterborough can result in delays happening as far away as Brighton.

With medium-sized cities, your idea might work very well. But a large city will need all the capacity it can get and only a dedicated metro system can do that and avoid delays from spilling out onto the wider network.

>>2040819 (OP)
you can drop the light rail if you have an efficienct metro system. For suburban rail the distances should be long enough to prevent the core city from growing to the sides

just ride fat people to work

At least in Germany there is a commonly accepted maxim to never combine more than two public transit systems in a town or city for local transit.

So you usually have busses and light-rail on the town level, and proper rail to connect the towns.

>>2040819 (OP)
One word: tram-trains.

if you have enough money you can just have metro and surface heavy rail that serves everything, a good example is tokyo, the rest is covered by busses or just walking, though I think some of their busses could be replaced by trams desu. there's also places like berlin where metro and interurban high speed share metro infrastructure, I think this is done all over europe, that's the best and something NA almost never does, so you have places like vancouver that have a great metro but it can't take any other type of train due to proprietary tech and track width so making new high speed (normal speed in europe, so 120-160) interurban lines is really annoying and expensive. places like poland, germany, france have a good mix of all the main modes

>>2040819 (OP)
>Light rail
Meme, just use a bus it's cheaper.

>>2040819 (OP)
I'm a staunch defender of the Zurich model: Suburban trains (with local and express services) + trams and buses.
I think for most small and medium cities this works best, and you only really need proper subways for very large cities like 3 million pop. (5 million metro pop.) upwards.

Usually you'll have a relatively compact urban core which is best covered by trams, since subways are inefficient due to the time lost getting to and from the station. See Barcelona as negative example, where trips are often just 6-7 stations by subway which point to point is barely faster than a well-prioritized tram would be. And combining suburban train with subway is similarly impractical, since you already get dropped off fairly close and will have to do a short and inefficient subway journey, often with a just as inefficient changeover.
Also when subways are built then less suburban train lines are built in the urban area (tendency towards just the trunk lines), hence making it less comfortable for people from the periphery to reach the city, instead having to rely on subways for long trips which again is less efficient than suburban trains which may even offer express services.

The train+tram approach also gives centrality to train stations, since they aren't so frequent as subway stations would be. This leads to urban development having varied density, denser near the stations and less dense further from them. Good example for this is Tokyo albeit on a bigger scale ofc so subways do make sense there.
Having areas of centrality and areas of lower density makes the combination of trains+trams very convenient, you get a hub-and-spoke transportation layout rather than a grid layout.
When the city grows, it will tend to form new centers around the train stations, instead of sprawling out. So transit would follow growth and lead growth as well.

Like I said, this is mainly thinking of small and medium cities, larger cities can and ought to use subways.