Today I'd like to raise the issue of making rail-based transportation inside (large) cities. Or, more precisely, how does one imitate the real-world systems given the conditions of OpenTTD.
As of now, I have devised four types of urban subway-like systems, that is, unless one is fine with blowing up whatever necessary and laying the tracks right on the ground, optionally visually concealing the damage using "subway/city core" tracks from NuTracks.
I assume everything takes place in a generic set of conditions: plain land and grid-based city planning, no signals on bridges and in tunnels.
1. Single tunnel subway: probably, the only advantage is that it fits rather nicely inside a 3x3 square of land, the tunnels being under the bridges. However, its performance is low, and it needs short trains (like diesel Dash-like). E.g. 2CC has some subway cars with capacity of 400-500 passangers, so those could sweeten the pill.
It needs a full 3x3 site plus two adjacent roads are to be converted into bridges.
2. Parallel track subway: is more like normal subway, but to preserve interconnection of city roads, one needs to construct additional bridges.
If the signals are placed on tracks under bridges, it requires 4-6 extra buildings to be demolished for tunnel entrances.
3. Chicago-style elevated: using bridges above city roads, it does not steal space from city buildings, although to construct elevated "piers" with signals between bridges, one needs to demolish 4 buildings (new will be build in their place), and to build a station - additional length*2 buildings. Anyway, all those losses are recoverable, except that the tunnels allow to restore only half of severed road connections.
The disadvantage is that it is one-way only by design and thus has to be built as a loop (minimal width - one block).
4. Dedicated elevated zone: in terms of required demolition, it is no better than building right on the surface. However, it does have an advantage of being naturally isolated from ground traffic, and thus crossing any existing road or rail on the land level is painless and does not require the trains to lose speed due to slopes.
Although I tried to think of any other ways to integrate rails into city fabric with minimal losses, I wasn't able to think of any other options beyond those above. I believe the other players of OpenTTD are likely more experienced and inventive and could share their ideas on the issue.
UPD: Since I apparently did not make it clear enough, let me rephrase the question:
Are there any "better" (in terms of required demolition and achieved performance) construction patterns for a rail-based intra-city public transit system, that actually resemble a real subway?
A a side note, I know about trams, bagic bulldozer, patching the game's source code and suchlike, thank you. The question is about design, not implementation.
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