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Simulation Video Games

OpenTTD, part two: Economy and game mechanics

It’s been a busy couple of days, but I’m back to continue this mini-series! So, last time, in OpenTTD, part one: A history and the basics, we had a look at the history of the Transport Tycoon series, went through some basic OpenTTD railway building techniques, and then had a brief look at the industries in the game. However, there’s a lot more to OpenTTD than just that, and so, this time we will look at the in-game economy, game mechanics in relation to cargo, and towns.

OpenTTD

Economy

The existence of an economy in OpenTTD might seem foreboding, but there isn’t anything to be afraid of here at all. There five simple topics we need to cover for our bit on the OpenTTD economy and they are inflation, recession, loans, share trading, and property maintenance.

Inflation

Let’s start with inflation, and don’t worry, this won’t be a lecture in economics. Put really simply, in the real world, inflation is a sustained increase in the general level of prices for goods and services and is measured as an annual percentage increase. Similarly, in OpenTTD, there is inflation but it is much, much more simple and only exists for cargo payment rates and costs, both of which are different to each other. The inflation rate for costs is equal to the initial interest rate of the game, as determined by the game difficulty, and the cargo payment inflation is slightly below that by about one percent. Also, inflation is limited to the first one hundred and seventy years of game-play, meaning that after this period there is no more inflation.

Recession

Next, a recession is generally a significant decline in activity across the economy, lasting longer than a few months, and unless the economy in OpenTTD is set to steady there is a chance that it may go into a recession at some point. During a recession three changes will happen to the economy: the production of industries will be reduced to half of the normal value, the amount of passengers and mail produced by town houses and headquarters will be reduced to half of the normal value, and no new industries will be built. However, recessions don’t last forever and these shouldn’t cause too many problems, so it’s safe to keep them on for some more interesting events in the OpenTTD world.

Loans

OpenTTD: Loans

Loans are really simple in OpenTTD, merely the act of giving money to a another party in exchange for future repayment of the principal amount along with interest or other finance charges, and they can be taken out by any player. The maximum loan varies during the game and is dependent on the company value of the company that is taking out the loan, however, every player usually starts the game with a loan amount of £100,000 to get them started. Interest is paid monthly to the bank at the current interest rate, which does not deviate from the initial interest rate set at the game start according to the difficulty settings. Do remember, though, that buying out a company, which we will get to next, will pass their loan over to us.

Share trading

In OpenTTD, share trading allows players to participate in the financial achievements of the other companies whose shares they hold but, like the game’s other economic elements, it’s a simplified version. When those other companies are profitable and their company value is increasing, money can be made by selling the appreciated shares at a profit. The downside is that money can be lost if the companies lose money and their company value decreases and the depreciated shares are sold at a loss. As a result, these shares can be used to make a lot of money, if they are bought at the right time. For example, buying shares in a starting company is very cheap but can be risky, because the company might fail and the investment might be lost. On the other hand, if said company flourishes, the investment may be returned hundredfold or even several thousandfold.

In order to get into share trading to begin with, in single player, once a company that is at least six years old has started selling its shares, they may be bought 25% at a time by paying a quarter of the company’s labelled value. They may then be sold at a later date or 100% of the shares may be bought to take over the company, passing over all of the company’s vehicles and their debt to the new owner. However, for multi-player games, a total of 75% of a player’s company may be bought and no more than that as there is no way to take over a rival company run by a human.

Property maintenance

Finally, every company is liable for maintaining their properties and for providing the funds to cover the overheads. The expense of property maintenance is directly proportional to the company’s number of stations, regardless of their size. All this means is that that some degree of restraint needs to be exercised when building stations – only build however many are necessary for the system to run efficiently and effectively.

Company rating

OpenTTD: Company rating

Each company has a company rating, and points are added to the rating based on the performance in the components in the table below. This rating shows the performance the company is running at, with a maximum score of 1000, and a breakdown of it can be found in-game under the Detailed performance rating menu shown to the right.

Note that when calculating the number of points earned, each part of the company rating is a linear function, i.e. earning 50% of the target for a component will give 50% of the points allocated for that component. Also, where components involve monetary amounts, these are converted to the currency of the current game, whilst internally, these amounts are stored as the pound amount.

Component Target Points (min) Points (max) Percentage
Vehicle count >=120 0 points for 0 vehicles 100 points for at least 120 vehicles 0 to 10%
Number of station parts company owns >=80 0 points for 0 parts 100 points for at least 80 parts 0 to 10%
Lowest profit of vehicles at least two years old >=£10,000 0 points for loss or £0 100 points for at least £10,000 0 to 10%
Lowest quarterly revenue earned in past 3 years >=£50k 0 points for £0 50 points for at least £50k 0 to 5%
Highest quarterly revenue earned in past 3 years >=£100k 0 points for £0 100 points for at least £100k 0 to 10%
Units of cargo delivered in past year >=40,000 0 points for 0 units 400 points for at least 40,000 units 0 to 40%
Number of types of cargo delivered in past quarter >=8 0 points for 0 cargo-types 50 points for at least 8 cargo-types 0 to 5%
Current cash in bank >=£10m 0 points for £0 50 points for at least £10m 0 to 5%
Current loan from bank £0 0 points for >£250k 50 points for £0 0 to 5%
Totals 0 points 1000 points 0 to 100%

The ranges for each title bracket are shown in the table below – the left side for the Company League Table ratings, and the right side for the 2050 High Score ratings.

Rating Title Rating Title
0 to 127 Engineer 0 to 319 Businessman
128 to 255 Traffic Manager 320 to 447 Entrepreneur
256 to 383 Transport Coordinator 448 to 575 Industrialist
384 to 511 Route Supervisor 576 to 703 Capitalist
512 to 639 Director 704 to 831 Magnate
640 to 767 Chief Executive 832 to 959 Mogul
768 to 895 Chairman 960 to 1000 Tycoon of the Century
896 to 959 President
960 to 1000 Tycoon
OpenTTD OpenTTD

Station rating

Each station a company owns has a station rating, an important factor in running a successful game. This is because the amount of cargo that can be transported from an industry is fully reliant on the station rating, meaning that if the amount of cargo transported from an industry is low, it is probably because the station rating is low. Below are the factors that affect the station rating, however, all calculations are done separately for each cargo type, and we’ll get to how they work in a moment.

Factor Condition Rating points Rating %
Max speed of last vehicle entering station (to a max of 255 km/h) Above 85 km/h (52 mph) (Speed (km/h) – 85) / 4 0% to 17%
Age in years of last vehicle entering station 2 10 4%
1 20 8%
0 33 13%
Days since last cargo pick-up
Multiply days in “Condition” column by 4 if last vehicle was a ship.
Note: If a vehicle was ready to pick up a cargo but there was no cargo, it is regarded as a cargo pick-up regardless.
30 to 52,5 25 10%
15 to 30 50 20%
7.5 to 15 95 37%
less than 7.5 130 51%
Units of cargo waiting at station More than 1500 -90 -35%
1001 to 1500 -35 -14%
601 to 1000 0 0%
301 to 600 10 4%
101 to 300 30 12%
less than 100 40 16%
Statue in town of station Built 26 10%
Small advertising campaign Station within 10 tiles of town centre +64 +25%
Medium advertising campaign Station within 15 tiles of town centre +112 +44%
Large advertising campaign Station within 20 tiles of town centre +160 +63%
Road vehicle crashed Station within 22 tiles of crash -160 -63%
Train crashed Station within 30 tiles of crash -160 -63%

Now, in order to get the percent rating, the maximum possible of which is 100%, the total rating points should be divided by 255. Advertising campaigns give an instant, temporary boost to ratings of nearby stations which will gradually fall down to the calculated rating over a period of time. Also, station ratings are computed every 2.5 days and these ratings can’t change by more than two points per cycle, except after crashes. However, if rating drops to less than 50%, the station starts losing cargo.

Cargo delivery to stations

Let’s look at how the station rating will affect the delivery of cargo from industries to stations. Similar to the computing of station ratings and many other in-game calculations, a cycle of 2.5 days is used. During each of these 2.5 day cycles, for each cargo type that is produced by a supplying industry, a maximum of two stations may have cargo assigned to them. If there are more than two possible stations and they both have the same maximum rating value for the current cargo type, then the distribution of cargo depends on the internal ordering of the stations. However, if there’s only one possible station, the delivered amount is the result of the following formula rounded up to the next integer value.

produced_amount × station_rating_in_percent

This becomes slightly more complex when there are two possible stations. The second station’s rating in points is divided by two for the further local calculations, whilst the amount available to the first station is calculated as shown below.

(station_rating_in_points1 × (amount + 1)) / (station_rating_in_points1 + station_rating_in_points2)

For similar ratings this is about two thirds of the production, it increases for larger differences. The result is subject to the same calculation as in the single station case, and this is delivered to the first station. However, if the first station does not receive the full amount of cargo available to it, the remainder does not get transported to the second station. Instead the end result is that the remainder is simply not transported at all. Meanwhile, the remaining amount of the production that has not been assigned to any station yet, if any, is subject to the same calculation as in the single station case and delivered to the second station.

Local authority rating

Rating points Rating
-1000 to -400 Appalling
-399 to -200 Very Poor
-199 to 0 Poor
0 to 200 Mediocre
201 to 400 Good
401 to 600 Very Good
601 to 800 Excellent
801 to 1000 Outstanding

The local authority rating portrays the attitude of a particular town towards the company and is another important element to consider as a low rating can limit some player actions. For example, to place a station, the company must have a minimum rating of -200 (Poor). The brackets and their ranges can be seen in the table to the right, which also shows the minimum and maximum ratings possible, -1000 and 1000 respectively.

OpenTTD OpenTTD

This rating starts at +500 and can change based on some actions, as shown in the table below.

Player action Required rating* Effect on rating
Build a station -200 n/a
Destroy an ‘edge’ piece of road 16 / 64 / 112 -18, down to -100.
Destroy an ‘inner’ piece of road 16 / 64 / 112 -50, down to -100.
Destroy a city tunnel or bridge 144 / 208 / 400 -250, down to 0.
Destroy building** 40 to 300 -40 to -300
Plant tree on clear square n/a +7, up to 220.
Clear a tile with trees n/a -35
Successful bribe n/a +200, up to 800.
Unsuccessful bribe n/a Set to -50.
* “Required rating” is listed for the settings Permissive/Neutral/Hostile of the difficulty option “City council attitude towards area restructuring”.
** This is in relation to the default buildings. NewGRFs can set this number from 0 to >1000, which effectively makes the building un-removable.

Each month players’ ratings automatically change:

  • Rating goes up by 5 if it is less than 200.
  • Rating goes up by 12 for each station that has transferred cargo in the last 50 days.
  • Rating goes down by 15 for each station that has not transferred cargo in the last 50 days.

For example, if a player currently has a rating of -300 (Very Poor), two active stations, and one inactive station at a town, their rating will increase as per the formula below until one of the three conditions changes.

5pts + (2 × 12pts) - (1 × 15pts) = +14pts points/month

Industry production

OpenTTD

So we know how an industry decides to allocate the cargo that it has supplied, however, we have yet to determine how the amount of cargo an industry produces per month might change. Each month the game randomly changes the amount of production of some industries, and this can be done one of two ways depending on the rules in use – either the default/TTD-like economy rules or the smooth economy rules. We will be looking at the smooth economy rules which can be set under the advanced options menu like shown below.

OpenTTD: Smooth economy

Smooth economy rules

The chance for a production change each month is 4.5%, i.e. 4.5% of producing industries from industry list change production, and this is combined with one of three conditions.

  • Poor or no service, i.e. less than 60% of cargo transported: 33% chance of increase, 67% chance of decrease in production
  • Good service, i.e. more than 60% of cargo transported: 67% chance of increase increase, 33% chance of decrease in production
  • Excellent service, i.e. more than 80% of cargo transported: 83%% chance of increase increase, 17% chance of decrease in production

These two, the chance for a production change each month and the chance of a decrease or increase based upon service level, are multiplied together, i.e. 4.5% × 33% = 1.5%, resulting in the following.

  • Poor service: 1.5% to increase and 3.0% to decrease
  • Good service: 3.0% to increase and 1.5% to decrease
  • Excellent service: 3.75% to increase and 0.75% to decrease

With the smooth economy option enabled, production changes per month are between 3 and 23%.

Industries with very low production, i.e. 12-40 tonnes per month, will have higher changes.

Primary industries produce cargo eight or nine times a month, although forests can produce cargo up to ten times per month. Monthly production is an industries ‘base value’ × the number of times a month cargo is produced. For example, the base value for a coal mine is 15 tons, so the monthly production is 120 or 135 tons. This base value is capped at 255, so the maximum possible monthly production for any industry is 2040 or 2295 (or 2550 – again – forest).

This table lists possible starting productions governed by the smooth economy patch. Like previously mentioned, production is a multiple of eight or nine, and sometimes ten with forests.

Raw Material Industry Produced Cargo Initial production range
Coal Mine Coal 56 to 176
Forest Wood 48 to 152
Oil Rig Oil 56 to 176
Farm Grain and Livestock 40 to 112
Copper Mine Copper Ore 56 to 112
Oil Well Oil 48 to 152
Iron Mine Iron Ore 40 to 112
Bank Valuables 24 to 64
Gold Mine Gold 24 to 80
Diamond Mine Diamonds 24 to 80
Fruit Plantation Fruit 40 to 112
Rubber Plantation Rubber 40 to 112
Water Supply Water 48 to 152
Farm Maize 40 to 128
Lumber Mill Wood 180 or 225 (if trees available)
Cotton Candy Forest Cotton Candy 48 to 152
Battery Farm Batteries 40 to 128
Cola Wells Cola 48 to 136
Plastic Fountain Plastic 56 to 160
Bubble Generator Bubbles 48 to 152
Toffee Quarry Toffee 40 to 112
Sugar Mine Sugar 40 to 128

Well, that’s great and all, but it doesn’t make it any easier to visualise. So for example, say that a coal mine has 70% of its output transported, meaning that it has good service. Because of this, there is a 3% chance, because 4.5% × 67% = 3%, of a production increase from 3-23%, and a 1.5% chance, because 4.5% × 33% = 1.5%, of a production decrease from 3-23%. Let’s see how much the industry might grow after the first year. To do that, we need to take these percentages and, instead of worrying about the 3-23%, we’ll take an average of 13% for the amount of production change.

(1 + (0.03 - 0.015) × 0.13) ^12 - 1 = 0.0237

So the coal mine in question will grow an average of 2.37% after the first year. How about another example? Let’s say that the industry has a rating of more than 80%, meaning that there is a 3.75% chance of an increase and 0.75% chance of a decrease in production.

(1 + (.0375 - 0.0075) × .13) ^12 - 1 = 0.0478

In this case, the industry will grow approximately 4.78% after first year. After looking at this, it is pretty evident that it will take a while for an industry to double its production – for good service, it would take 29.6 years on average to double, and with excellent service, it would take 14.8 years on average to double. Assuming that, in game time, a day is 2.36 seconds, the doubling time with good service would take 7.1 real hours, and the doubling time with excellent service, would take 3.6 real hours.

However, in game, industries will seem to be changing their production rate very randomly when compared to what we have just covered. This is because the above examples are only true when observing many industries over the long-term, since individual industries may greatly deviate from these averages used. Statistically speaking, six out of ten industries will not go from 100 production/month to 2100 production/month even with the best service during a 65 year period, and about one out of nine industries will even lower their production when being served at 60-80% cargo transported for a 50 year period.

Delivery payment rates

Alright, so now we also know how much an industry can change their production, but what are we paid for our deliveries? This is based on a number of factors: cargo, amount, distance, and days in transit, and is the product of the cargo payment rate, amount of cargo, transit distance, and time factor determined by days in transit. Let’s have a look at each of these factors separately.

Amount of cargo

Let’s start with the easiest one – the amount of cargo. This one is really easy to figure out as it is simply the amount of cargo that we are determining the payment for. The payment rate, as we will see in a moment, measures payments for each 100 units or 10,000 litres of cargo, so the amount of cargo for use in the eventual calculation will be how many lots of 100 units or 10,000 litres there are. This means that 300 units of cargo will mean we use 3, whilst 10,000 litres will mean we use 1.

Cargo payment rate

Initial cargo payment values, shown for each cargo type in the table below, are for delivering 100 units or 10,000 litres of cargo over a distance of one tile. However, remember that the payment value will go up with inflation as the game progresses for the first one hundred and seventy years.

Cargo Units Pay. Cargo Units Pay. Cargo Units Pay.
Passengers £39 Wheat Tonnes £58 Sugar Tonnes £54
Valuables Bags £91 Paper Tonnes £66 Toys £68
Livestock Items £53 Gold Bags £71 Batteries £53
Grain Tonnes £58 Food Tonnes £69 Sweets Tonnes £75
Goods Crates £75 Rubber Kilolitres £54 Toffee Tonnes £58
Coal Tonnes £72 Fruit Tonnes £51 Cola Kilolitres £59
Steel Tonnes £69 Maize Tonnes £53 Candyfloss Tonnes £61
Iron Ore Tonnes £62 Tropical Wood Tonnes £97 Bubbles £62
Wood Tonnes £61 Copper Ore Tonnes £59 Plastic Kilolitres £54
Oil Kilolitres £54 Water Kilolitres £57 Fizzy Drinks £76
Mail Bags £55 Diamonds Bags £71

It’s possible to see the payment rate trend within the game by going to Graphs and bringing up the Cargo payment rate window, such as shown below. Like the table above, these are shown at the rate for delivering 10 units or 10,000 litres of cargo a distance of 20 squares.

OpenTTD: Cargo payment rate

Transit distance

The transit distance is measured by adding the differences in x and y tiles, not straight-line distance, between the origin station and the destination station. The tile from which this distance is measured is the name-labelled tile of each, not from the industries or by vehicle distance travelled.

This process of finding the distance is known by quite a few names, such as taxicab geometry, rectilinear distance, L1 distance or norm, city block distance, Manhattan distance, or Manhattan length, with corresponding variations in the name of the geometry. The latter names refer to the grid layout of most streets in Manhattan which cause the shortest path a car could take between two intersections to have a length equal to the intersections’ distance.

For example, the distance between the point P1 with coordinates (x1, y1) and the point P2 at (x2, y2) is

 \left|x_1 - x_2\right| + \left|y_1 - y_2\right|.

Time factor

The time factor penalises slow transportation by granting a penalty for deliveries that are considered late for the particular cargo type. Each cargo type has two numbers, days1 and days2, that determine the boundaries between fast, medium, and slow deliveries. These are shown in the table below in the Early and Late columns, with each value being presented in number of days. However, one day here is actually 2.5 days in the game, so if days_in_transit = 4, then 4 is in the calculations that follow, but the cargo is actually already ten days in transit.

Cargo Early Late Cargo Early Late Cargo Early Late
Passengers Immediate 24 Wheat 4 40 Sugar 20 None
Valuables 1 32 Paper 7 60 Toys 25 None
Livestock 4 18 Gold 10 40 Batteries 2 30
Grain 4 40 Food Immediate 30 Sweets 8 40
Goods 5 28 Rubber 2 20 Toffee 14 60
Coal 7 None Fruit Immediate 15 Cola 5 75
Steel 7 None Maize 4 40 Candyfloss 10 25
Iron Ore 9 None Tropical Wood 15 None Bubbles 20 80
Wood 15 None Copper Ore 12 None Plastic 30 None
Oil 25 None Water 20 80 Fizzy Drinks 30 50
Mail 20 90 Bags 10 None

The penalties for late deliveries have a maximum penalty of 88% and are as follows.

  • For each day after the Early delivery time that the cargo is delivered, the penalty is increased by 0.4%.
  • For each day after the Late delivery time that the cargo is delivered, the penalty is increased by 0.4%.

For example, let’s assume that there is no inflation and try to figure out the amount we would get paid for delivering 200,000 litres of oil a distance of 20 squares in ten days. We take the amount of cargo as 2 because the payment rate if per 100 units of cargo, then we take the payment rate as £54 from the table earlier, then we take the distance which is 20 squares, and because there is no late delivery for oil, our time factor is 100%.

2 × £54 × 20 squares × 100% = £2,160

Therefore we would get paid £2,160 for this delivery. Now, whilst still assuming there is no inflation, let’s try to figure out the amount we would get paid for delivering 100 bags of mail a distance of 100 squares in 100 days. Because we’re only delivering 100 pounds, we don’t need to add the initial 1 × part, so we will take the £55 payment rate from the table, the distance which is 100 squares, and then figure out the time factor because we are delivering these goods very late. The Early delivery time for mail is 20 and we are delivering it on the 100th day, so for each day after the Early delivery time, of which there are 80, we increase the penalty by 0.04%, making it 80 × 0.04%. Furthermore, the Late delivery time is 90 and we’re over that by 10 days, so for each day after the Late delivery time, we increase the penalty by 0.04%, making it there’s an additional 10 × 0.04%.

£55 × 100 squares × (1 - 80 × 0.004 - 10 × 0.004) = £3,520

And finally we see that we would get paid £3,520 for this delivery.

However, there is an exact formula for calculating delivery payment rates that is much more complicated and slightly more accurate, due to rounding error when converting from larger discrete values. What we have already covered is enough to understand how it works on a basic level, but if you’re interested in the exact formula, here it is. If you’re not, feel free to skip ahead to the next topic – vehicle speeds.

OpenTTD: Income formula

i.e. Income (cargo, amount, distance, time) = cargo payment rate. The table below presents the values that should be used for the above – Base, Days1, and Days2.

Cargo Type Base Days1 Days2 Cargo Type Base Days1 Days2
Batteries 4322 2 30 Oil 4437 25 255
Bubbles 5077 20 80 Oil (subtropical) 4892 25 255
Candyfloss 5005 10 25 Paper 5461 7 60
Coal 5916 7 255 Passengers 3185 0 24
Cola 4892 5 75 Plastic 4664 30 255
Copper Ore 4892 12 255 Rubber 4437 2 20
Diamonds 5802 10 255 Steel 5688 7 255
Fizzy Drinks 6250 30 50 Sugar 4437 20 255
Food 5688 0 30 Sweets 6144 8 40
Fruit 4209 0 15 Toffee 4778 14 60
Gold 5802 10 40 Toys 5574 25 255
Goods 6144 5 28 Valuables 7509 1 32
Grain 4778 4 40 Water 4664 20 80
Iron Ore 5120 9 255 Wheat 4778 4 40
Livestock 4322 4 18 Wood 5005 15 255
Mail 4550 20 90 Wood (subtropical) 7964 15 255
Maize 4322 4 40

Towns and town growth

Finally, let’s have a look at towns, the places where the inhabitants of OpenTTD live. Each town has a population, based on the number of buildings and how many inhabitants each building contains, which can grow or shrink depending on certain conditions. What are those conditions? Well, first, let’s see what towns are made up of.

Town buildings

OpenTTD: Station coverage

Most buildings in the towns provide a source of passengers and mail which can be transported to other towns or within the same town. However, during a recession there will only be half of the usual amount of both passengers and mail. In some cases, buildings may also accept other cargo such as goods, food, or water, depending on the environment. For a station to accept any one of these three, the buildings in the station’s coverage area must be able to accept a total of at least 8/8 of the cargo. The coverage area highlight option, shown in use to the right, will help to find out what the cargo acceptance of individual buildings would be.

Town industries

There are two town industries which are environment dependent. Firstly, Banks can be found in towns with populations of over 1,200 in Temperate maps, and in towns with any population in Sub-Arctic maps. Secondly, Water Towers may be found in desert towns in Sub-Tropical maps.

Town growth

The population of towns can increase, providing more passengers and mail to transport. The towns will grow every so often, either very slowly on their own or a bit faster with help from transport companies. The effects of town growth will be the townspeople constructing new buildings on empty tiles next to roads, or demolishing and replacing existing buildings with larger buildings, sometimes causing temporarily dips in town population while the new buildings are being constructed. Furthermore, sometimes new buildings will increase the number of cargo accepted in a town, such as goods, food, or water. Regardless of whether services are provided, towns will grow very slowly over time, however, town growth may be influenced in several ways.

OpenTTD: A town

General conditions for town growth

Finally, we’re getting to the conditions for speeding up town growth. So, town growth can be accelerated by loading and unloading at least one item of cargo at up to five stations within town influence within a two month period. It doesn’t matter which type of cargo is loaded or unloaded and extra amounts of cargo beyond the first item don’t have any extra effect. The towns will then expand physically by extending roads onto empty areas of the map and constructing new buildings next to the new roads. This means that pre-built road networks can actually speed up town growth because the town can then just build houses all the time instead of houses and roads. However, roads can’t be built over diagonal train tracks or tracks with signals on them, so be careful to not block a town in. The two images below, from the OpenTTD Wiki, show a town which is blocked in on the left and a town which may grow freely on the right as an example.

OpenTTD: A blocked in town OpenTTD: A free town

There are also cities which are a special form of town that grow twice as fast as a regular town. A big city needs plenty of space, and without obstacles, a population of one million requires around a 150-200 tile diameter.

Climate-related conditions for town growth

  • Temperate, Toyland: There are no special conditions for a Temperate or Toyland town to grow. Simply load or unload cargo as mentioned earlier to speed up growth.
  • Sub-Arctic: If the centre square, as determined by the square upon which the sign with the town name sits, is not above the snow line, food is not required for growth, although food will still be accepted. If the centre square of the town is above the snow line, at least one tonne of food per month must be delivered for the town to grow rapidly. Towns will still grow very slowly on their own, so in the case of small towns that are not large enough to accept food, it is simply a case of waiting for them to grow to a size at which they can accept food. However, the actual amount of food that is delivered will have no effect on the rate of town growth.
  • OpenTTD: Water tower
  • Sub-Tropical: If the centre square is not in the desert, food and water are not required for growth, although Water Towers may exist in the town and both food and water will still be accepted. If the centre square of the town is in the desert, at least one tonne of food and 1,000 litres of water per month must be delivered for the town to grow rapidly. The town itself will still grow slowly without food or water and the quantities of each will not have any effect on the rate of growth, just like in the Sub-Arctic environment. The supply of water, must be delivered to a Water Tower industry which may be generated automatically in towns, or one may be funded.

Tips for Town Growth

A bus service is the simplest way to increase the population of a town since the requirements for accelerated growth are “at least one item of cargo”, not the quantity of cargo being transferred. Therefore, a bus with one passenger from the other side of that same town would have the same effect on growth as a large train full of passengers from the other end of the map. Although, if this is on a Sub-Arctic or a Sub-Tropical map, the other conditions for growth still apply.

Furthermore, remember what a feeder station is from OpenTTD, part one: A history and the basics? Well, a town with a feeder station where cargo is picked up but not set down will also grow.

Also, using Fund New Buildings from the Local Authority window may result in rapid population growth for a short time, or increase the areas where the town accepts goods, food, or water, allowing more cargo types to service the town and increasing the growth rate. However, remember that delivering goods specifically does not have any extra effect on town growth in any environment other then increasing the types of cargo which are being supplied.

Town buildings will extend outwards based on the transit distance, not vector distance, along the road from the town centre, i.e. where the sign showing the town name is displayed. If you’re not sure what this means, check out the section on transit distance again. Roads which are close, but do not connect to the town centre, will have no buildings constructed alongside them because there is no way for the population to travel to such locations.

And that wraps it up for this part of my guide to OpenTTD. It looks like I should start scheduling posts less often because I’m starting to get pretty busy, but on the plus side, I can use that as an excuse to write more in-depth posts like this one which are also a lot of fun to gather information for. Anyway, that’s enough rambling from me. Until next time!

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