Help me understand city growth

[Bear789]

I consider myself a Simutrans veteran (even though I joned the forums only recently, I'm playing the game since 0.8something), but I'm by no means an expert, and there are things that still elude me.

Currently, the thing that bugs me is city growth. I'm playing this map, if that matters.
I know that city growth is triggered by passengers trips and passengers and goods deliveries to the factories which employ people from the town, but I can't understand why sometims two towns with similar transport services have largely different growth rates.

Exhibit A. Colchester.

It's one of the first cities connected to the network, for both passengers and goods. I know that city growth can have a hard time crossing double railway tracks, so I took care to build through areas already claimed by the town and leave openings where the city could grow beyond the tracks. It's served by only one station, but it's the huge port hub, which covers most of the town; it's served by 15 lines, with direct routes for the most important destinations (at least judging by the minimap in the city dialogue window). Yet, it's still a fairly small town.

Exhibit B. Grangemouth.

Grangemouth - Colchester was the second line I ever created on this map, originally via ship, now via train, so both towns have been served by my company for the same amount of time. I also developed both ends of the network somewhat evenly. Originally, both towns were roughly the same size. I consider them twin cities for both starting point and transport services.
Similar starting situation: the old city center is sorrounded by tracks, I took care to let the city "escape" the barriers; one big central hub for both goods and passengers, no urban transport system; 15 lines serving it, direct routes for most big destinations. Same goods overcrowding problems. As you can see, Grangemouth has grown a lot more than Colchester.

Exhibit C. Kirkcaldy.

This is the worst "offender". It's a town just west of Grangemouth, served only by one passenger line, so it has a limited array of destinations and a larger amount of "no routes" (I suppose because of the highest number of transfers required to reach the farthest parts of the network). It's connection to the freight network happened much later despite having a market from the early years (I kept ships for intercity freight lines for a lot more time than passengers and Kirkcaldy lacks waterways and I didn't want to build a canal because I knew that sooner or later I would have switched to trains). Originally the town was way smaller than Grangemouth and Colchester, yet it's now nearly as big as Grangemouth, bot in population numbers and actual number of buildings.

There are a lot of other examples on the map, but I don't want to get repetitive.
Can you please explain me this differences?

[prissi]

The answer is not very straight forward. In the first example, the city can only expand in the top and bottom along one road. Since the places for expansion are taken randomly, the chance of picking a right place are slim. I would suspect the city info show many home and jobless numbers.

How much a town expand depends also on the highest available level of the buildings. Thus in earlier year (before e.g. 1900) towns spread out more, since the level caps off earlier (dpends obviously on pak sets). Finally, if there are many roads built, the house construction will be more likely too.

[Bear789]

Thank you!

While I'm at it, another couple of things:
- You mentioned homeless and unemployed. I always considered those somewhat cosmethic infos, at most telling me that the city wants to grow but cannot. Do they affect anything else?

- I know that serving the city hall gives a great boost to the growth, but I can't understand via testing how effective it is and whether the hall (if larger than one tile) must be entirely covered, like an attraction, or any tile will do.

[greenling]

Hello Bear789
Your city can not growth there it gives no free place to build new buildings.
Try to lay the Railroad in the underground that gives the Citys space to growth.

[Combuijs]

- I know that serving the city hall gives a great boost to the growth, but I can't understand via testing how effective it is and whether the hall (if larger than one tile) must be entirely covered, like an attraction, or any tile will do.

City halls and atrractions should be covered fully. For factories that is not necessary.

[Fifty]

One thing to note is that cities only expand their boundaries when a certain percentage of the tiles within a city are occupied. I don't know if this has changed, but Simutrans counts water tiles as "free" in the rectangular city boundaries. Thus the cities that include coastline, like the first two, are not expanding as they would normally, as the game engine thinks there is free space in the water and is not expanding the boundaries.

Also- growth is percentage based. If a city has one market 100% supplied, it will grow faster than one with two markets 50% supplied. If certain goods types cannot be produced in-game yet, it will still be counted as a percentage not supplied if the consumer could consume it. For example, in pak 64 a Materials Wholesale can consume planks, steel, and concrete. If you start in, say 1880, you will get the first two chains, but not the third, so that factory can only be supplied up to 66%

If you have high homeless and unemployed numbers best is just to build a low-level building outside the city limits to expand them, then the city will start growing into the expanded area.

Your map looks very nice and complex 

[jamespetts]

One thing to note is that cities only expand their boundaries when a certain percentage of the tiles within a city are occupied. I don't know if this has changed, but Simutrans counts water tiles as "free" in the rectangular city boundaries. Thus the cities that include coastline, like the first two, are not expanding as they would normally, as the game engine thinks there is free space in the water and is not expanding the boundaries.

Hmm - I wonder whether this should be changed...?

[Fifty]

Hmm - I wonder whether this should be changed...?

If it hasn't already it would be nice!

[prissi]

Also streets and ways are not counted. It is just the total area of the city divided by the number of houses.

[Bear789]

Thank you all for the answers.

Your map looks very nice and complex 

Thanks. I'm thinking about starting a map journal, but I play very randomly, sometimes every day, sometimes I don't touch the game for months.