cost      // running cost of the whole
unc_len   // lenght of all parts without a running cost
cal_cost  // running cost of all parts (or single part) with a running cost
unc_cost  // simulated running cost of all parts (or single part) without a running cost
divisor   // user defined value for fine tunning the simulated running cost for each part without a running cost
cal_cost += cal_cost
ind_len   // length of current part without running cost
ind_cost = (unc_len * cal_cost * ind_len) / (VEHICLE_LENGTH * divisor * 2)
unc_cost += ind_cost
cost = unc_cost + cal_cost



/**
 * Get running cost for the train consist or only for the current part.
 *
 * @param single_part whether to return the running cost of the current part or the whole.
 * @return Yearly running costs.
 */
Money Train::GetRunningCost(bool single_part) const
{
	Money cost = 0;     // running cost of the whole
	uint unc_len = 0;   // lenght of all parts without a running cost
	Money cal_cost = 0; // running cost of all parts (or single part) with a running cost
	Money unc_cost = 0; // simulated running cost of all parts (or single part) without a running cost
	uint divisor = 0;   // user defined value for fine tunning the simulated running cost for each part without a running cost
	if (_settings_game.vehicle.train_extra_runcost_divisor == 0) {
		divisor = VEHICLE_LENGTH * 2 * _settings_game.vehicle.max_train_length;
	} else {
		divisor = VEHICLE_LENGTH * 2 * _settings_game.vehicle.train_extra_runcost_divisor;
	}

	const Train *v = this;
	const Train *v1 = single_part ? v->First() : v;
	const Train *v2 = v1;

	do {
		const Engine *e = v1->GetEngine();
		if (e->u.rail.running_cost_class == INVALID_PRICE) {
			const Train *a = v1;
			do {
				unc_len += a->gcache.cached_veh_length;
				a = a->HasArticulatedPart() ? a->GetNextArticulatedPart() : NULL;
			} while (a != NULL);
			continue;
		}

		uint cost_factor = GetVehicleProperty(v1, PROP_TRAIN_RUNNING_COST_FACTOR, e->u.rail.running_cost);
		if (cost_factor == 0) continue;

		/* Halve running cost for multiheaded parts */
		if (v1->IsMultiheaded()) cost_factor /= 2;

		cal_cost += GetPrice(e->u.rail.running_cost_class, cost_factor, e->GetGRF());
	} while ((v1 = v1->GetNextVehicle()) != NULL);

	if (_settings_game.vehicle.train_extra_runcost && unc_len > 0 && cal_cost > 0) {
		do {
			const Engine *e = v2->GetEngine();
			if (e->u.rail.running_cost_class != INVALID_PRICE) continue;

			const Train *a = v2;
			uint ind_len = 0; // length of current part without running cost
			do {
				ind_len += a->gcache.cached_veh_length;
				a = a->HasArticulatedPart() ? a->GetNextArticulatedPart() : NULL;
			} while (a != NULL);
			if (ind_len == 0) continue;

			Money ind_cost = (unc_len * cal_cost * ind_len) / (VEHICLE_LENGTH * divisor * 2);
			uint cost_factor = GetVehicleProperty(v2, PROP_TRAIN_RUNNING_COST_FACTOR, ind_cost);

			/* Halve running cost for multiheaded parts */
			if (v2->IsMultiheaded()) cost_factor /= 2;

			unc_cost += GetPrice(PR_RUNNING_TRAIN_STEAM, cost_factor, e->GetGRF()) / _price[PR_RUNNING_TRAIN_STEAM];
		} while ((v2 = v2->GetNextVehicle()) != NULL);
	}

	cost = unc_cost + cal_cost;
	if (!single_part) return cost;

	const Engine *e = v->GetEngine();
	if (e->u.rail.running_cost_class == INVALID_PRICE) {
		if (!_settings_game.vehicle.train_extra_runcost) return unc_cost;

		const Train *a = v;
		uint ind_len = 0; // length of current part without running cost
		do {
			ind_len += a->gcache.cached_veh_length;
			a = a->HasArticulatedPart() ? a->GetNextArticulatedPart() : NULL;
		} while (a != NULL);

		Money ind_cost = (unc_len * cal_cost * ind_len) / (VEHICLE_LENGTH * divisor * 2);
		uint cost_factor = GetVehicleProperty(v, PROP_TRAIN_RUNNING_COST_FACTOR, ind_cost);

		/* Halve running cost for multiheaded parts */
		if (v->IsMultiheaded()) cost_factor /= 2;

		unc_cost = GetPrice(PR_RUNNING_TRAIN_STEAM, cost_factor, e->GetGRF()) / _price[PR_RUNNING_TRAIN_STEAM];
		return unc_cost;
	} else {
		uint cost_factor = GetVehicleProperty(v, PROP_TRAIN_RUNNING_COST_FACTOR, e->u.rail.running_cost);

		/* Halve running cost for multiheaded parts */
		if (v->IsMultiheaded()) cost_factor /= 2;

		cal_cost = GetPrice(e->u.rail.running_cost_class, cost_factor, e->GetGRF());
		return cal_cost;
	}
}