NewTownGrowthSwitchesdetails

How the new town growth switches work

New Town Growth Switches (details)

How the new town growth switches work

This section describes the switches that apply in "towngrowthratemode 2".  They fine tune and control every detail of town growth.

As described in the previous section, TTD internally uses an inverse growth rate, i.e. the number of 70-tick  time units between attempts to build a  new house.  However, the enhanced rate calculation uses a direct growth  rate, defined as the average number of new town buildings per 38400 time  units, which is approximately 100 years.  At the end of calculations  this rate is converted to the inverse growth rate.  If the inverse  growth rate is greater than 255, it's reduced and town growth is blocked  randomly to have the same effect on the average.

For comparison, with "towngrowthratemode 0" (TTD's original calculation),  the rates are:

||number of active stations|average rate (new houses per 100 years)

   0                 |20

   1                 |182

   2                 |256

   3                 |349

   4                 |480||

or, if a building fund is active, the rate is fixed at 640 new houses per  century.  These rates are as they're normally in TTD, except that a bug  with 5 or more stations (see the previous section) is fixed.

For the new growth rate calculation, we have the maximum and minimum rate, the towngrowthratemin and  towngrowthratemax switches.  Let -+ratediff+- be the difference between the  maximum and the minimum, i.e.

-+   ratediff = towngrowthratemax - towngrowthratemin+-

Then the base rate delta multiplier (BRDM) is calculated as follows:

-+  BRDM = (AS*ASW + PO*POW + MO*MOW + PI*PIW + MI*MIW + GI*GIW + FI*FIW + WI*WIW + SI*SIW + DI*DIW)+-

-+                / (ASW + POW + MOW + PIW + MIW + GIW + FIW + WIW + SIW + DIW)+-

where the two-letter abbreviations represent growth boost components (explained in detail below) depending on, respectively:

||-+AS+- |the number of active stations

-+PO+- |percentage of passengers transported (`passengers out')

-+MO+- |percentage of mail transported (`mail out')

-+PI+- |incoming passengers (`passengers in')

-+MI+- |incoming mail (you get the picture...)

-+GI+- |incoming goods

-+FI+- |incoming food

-+WI+- |incoming water

-+SI+- |incoming sweets/candy

-+DI+- |incoming fizzy drinks||

Each component is a number between 0 and 1, so the result (BRDM) is also  between 0 and 1.  The rest are weighting factors, represented by the  following settings in the configuration file:

||-+ASW+- |tgractstationsweight

-+POW+- |tgrpassoutweight

-+MOW+- |tgrmailoutweight

-+PIW+- |tgrpassinweight

-+MIW+- |tgrmailinweight

-+GIW+- |tgrgoodsinweight

-+FIW+- |tgrfoodinweight

-+WIW+- |tgrwaterinweight

-+SIW+- |tgrsweetsinweight

-+DIW+- |tgrfizzydrinksinweight||

The higher the weighting factor for some component is relative to the  other weighting factors, the more influence the asociated growth boost  component has on the final growth rate.  Note that it's the relation  betwen weighting factors that matters; for instance, if all the other  weighting factors are zero, the following set

-+  tgractstationsweight = 10+-

-+  tgrpassoutweight = 5+-

yields exactly the same results as

-+  tgractstationsweight = 2+-

-+  tgrpassoutweight = 1+-

The growth boost components are calculated as follows:

-+AS+- = NTB / tgrtownsizebase) * TSF) + (1 - TSF+-

where -+NTB+- is the number of buildings in the town and  -+TSF+-=tgrtownsizefactor/255 (i.e. it's a value between 0 and 1, which  determines how much of the growth rate depends on the town size, in  percent).  This can be used to add a bit of `exponentiality' to the  growth of towns (remember, the growth rate is expressed in new buildings  per time unit, so with a constant rate larger towns will appear to grow  more slowly).

Then the real growth rate is calculated:

-+   RGR = towngrowthratemin + ratediff*CRDM+-

where -+CDRM+-=-+RDM+- if -+RDM+- <= 1, and -+CRDM=1+- otherwise.

Then, if a town building fund is active in this town, 600 is added.  Then, if the town is one of those supposed to be larger (see  the largertowns switch), the rate is doubled.  And this is the final growth  rate, in new houses per century.

As a final note, the real growth of towns is a second- or third-order  effect of the final growth rate, so don't expect towns to grow exactly  at the rate you've calculated from the formulae above....  But on the  average it shouldn't be far off.