Passenger Stops and their coverage

Also see: Passengers

The idea of the coverage area being large is this: a person can in principle walk quite far, and will do so if there is no other means of getting to where he/she needs to go. So, for example, in a medium sized town in 1850 with only a single railway station, people living on the periphery of the town may walk several kilometers from the periphery of the town to get to the station. 'Buses were rare in the 1850s (and in any event were only affordable by the middle classes), so this would be what one might expect.

However, all passengers have a journey time tolerance. This tolerance is different for each passenger generated. Walking, including walking from the passenger's starting point to the first stop, walking between stops, transferring within a stop, and walking from the final stop to the destination building, all takes time (on the basis of a speed of 4km/h travelling in a straight line). This time is taken into account when computing whether a journey falls within a passenger's journey time tolerance.

For example, suppose that, in the town in 1850 with a single railway station, a passenger wishes to travel to a building in a neighbouring town served by that railway. The passenger's journey time tolerance for the one way trip is 1 hour and 30 minutes. The train takes 30 minutes to complete its journey, and there is an average of 15 minutes waiting between each train. The station's internal transfer time is 2 minutes. Taking out of account walking, this would give a total time of 47 minutes - well within the passenger's journey time tolerance. However, suppose that the walk from the passenger's origin building to the railway station were 45 minutes, and the walking time from the station at the other end of the line to the passenger's ultimate destination were another 15 minutes. This would give: 45+2+15+30+15=107, or 1 hour and 47 minutes - in excess of the journey time tolerance. The passenger in that instance would not travel (assuming no accessible alternative destinations).

Similarly, passengers who are able to get to their destinations in multiple ways will always choose the journey with the lowest overall time. Again, this includes walking times and internal station transfer times. This might mean that a trip by 'bus which is nearly door to door will be preferred over a trip by a faster train where the better speed of the train is outweighed by increased walking times between origin and station, and station and destination.

This means that there are many situations in which it is beneficial to build stops within the coverage area of other stops: passengers will choose a starting stop based on whichever overall journey time will be the lowest.

As to the internal transfer times of stations, you can see this in the station details window. This is determined by the area of stations, and represents the time that it takes passengers to walk within the stations. This can be increased if the station is overcrowded. This does mean that there are situations in which it is better t have several neighbouring stations rather than a single, large integrated station. (For example, an airport can be split into multiple terminals, all sharing the same runways, each a separate stop).

The idea of the Extended station coverage system is, in short, that one does not need to worry about coverage areas at all, per se, and one can just place stations and stops as one would in real life and expect more or less realistic consequences of doing so.

There is still a catchment area of sorts, but it is retained for technical, rather than gameplay reasons (viz. that it would be too computationally intensive for every passenger to have to check distance to every station on the whole map, so it is limited to a catchment area). The catchment area is deliberately made so large so as to be of little real effect in the game compared to the walking time tolerances. This system is intended to simulate much more accurately the real dynamics behind what the idea of a catchment area tries to simulate very approximately.

It is important to distinguish between the actual, technical catchment area (as represented by the square) and the effective radius of a stop (which is not graphically represented at all, but one can consider it as a circle with blurred edges).

The technical catchment area is the area within which passengers will consider travelling to the station in question. It is retained in Simutrans-Extended only because not having such a catchment area would make the game run too slowly. It is not intended to have a gameplay function. Importantly, it is not in any way related to the passengers' maximum walking time tolerance.

The effective radius is (realistically) not precisely defined, and would be very hard to represent graphically in a meaningful way because of the inherently complex relationship between journey time tolerance, walking time to the stop in question and total journey time.

As to estimating a reasonable distance between stops: look in the buildings' information window. You will see the distance to nearby stops. A higher density population will justify a denser transport network than a lower density population (a city's overall population density can be seen in its information window, but some parts of a city will be denser than others). Look for stops with a large number of passengers registering as "too slow", even when the transport connexions are good. Use the passenger destinations feature on the minimap to see where passengers who are finding that their journey times are too long ("too slow") are originating, and consider increasing stop densities in those areas. Think about what would be a reasonable spacing between stops in real life in that sort of situation. There is no general easy answer to the question of how to set stop spacing - that is the point: one has to make interesting decisions.