The International Simutrans Forum

/* four parts contribute to town growth:
	 * p****enger transport 40%, mail 20%, goods (30%), and electricity (10%)
	 */
	sint32 pas = (city_history_month[0][HIST_PAS_TRANSPORTED] * (40<<6)) / (city_history_month[0][HIST_PAS_GENERATED] + 1);
	sint32 mail = (city_history_month[0][HIST_MAIL_TRANSPORTED] * (20<<6)) / (city_history_month[0][HIST_MAIL_GENERATED] + 1);
	sint32 electricity = 0;
	sint32 goods = city_history_month[0][HIST_GOODS_NEEDED]==0 ? 0 : (city_history_month[0][HIST_GOODS_RECIEVED] * (20<<6)) / (city_history_month[0][HIST_GOODS_NEEDED]);

	// smaller towns should growth slower to have villages for a longer time
	sint32 weight_factor = 100;
	if(bev<1000) {
		weight_factor = 400;
	}
	else if(bev<10000) {
		weight_factor = 200;
	}

	// now give the growth for this step
	wachstum += (pas+mail+electricity+goods) / weight_factor;