After some intense design work in July to remake train scheduling, it was time to implement the winning ideas during August. The core of the new design is making Schedules a new top level object and editor, and introducing Shifts, which decouple schedules from trains. Several new tools have been implemented to make creating new shifts preferable to just creating new schedules, including having per-shift specific timing of orders. Read more on how scheduling will look like in 1.14 in this month devblog:

https://carloscarrasco.com/nimby-rails-august-2024/

July was devoted to design a revamp of the train order system. The goals are to make train schedules a more visible element of the game and to make the concept of train shifts more elaborated. A "blue sky" design was discarded due to the impact it would have on existing saves, and it was replaced with a compromise design, which keeps the current order system intact, but moves it to a new game object, Schedules. There's still a lot of work left to implement this new system, so 1.14 might be some ways off. Read more at the devblog:

https://carloscarrasco.com/nimby-rails-july-2024/

Aug 4th UPDATE: The idea for dynamically assigned shifts is flawed and has been removed from the 1.14 design. The post has been updated to reflect this.

Version 1.13 has been released to the default game branch, This new version complements the changes in version 1.12 by increasing station capacity and introducing walk legs and links.


Pax are now able to plan paths including the act of walking between two stations, instead of taking a train. This includes cases where there is no possible train between stations, and when the train exists but it will faster to just walk (at least at the time of arrival). These walk legs are modeled as walking in a direct line (unrealistically fast) at 1 m/s (unrealistically slow), so it evens out.

The feature is meant to model the generic act of walking between stations, with some limited support for customization. This feature is also not able to consider things like rivers, mountains, country borders, particular streets or paths, islands, bays, etc. All these cases would require a combination of street routing and terrain routing and are an immense amount of work, and out of scope for the game.

If one or more of these cases bother you, or you just don't want to have walking legs for some stations, it is possible to disable them by changing the max walking radius of the station to 0. For a walking leg to be allowed between stations, both of their center points (the small circle displayed when you disable all station names and icons) must be within each other walking radius. A walking radius of 0 cannot contain any point so no walk legs will be possible.

The walk radius (even when set to 0) can be combined with a new special building: walk leg buildings.

This new special building can be accessed from the station creation mode (which now also contains the platform extension building). If a walk link building touches platform footprints in two (or more) different stations, these stations are considered walk linked, as long as the links from their centers is under the max radius limit (2.3km). This allows players to manually specify which walk links are allowed and which ones are not, compared to the automatic radius system.


A recurrent player complain about the station system, always supporting an active thread in the forums, is the 10k transfer pax limits in stations. In 1.13 this limit has been lifted to 25k, with a manual option to raise it to 100k, and train boarding speed has been increased by 10x to compensate. Pax will now spawn as long as the platforms are under the capacity limit, and platform capacity is now always a manual user setting. This is now possible since the original limits were put in place when the pax pathfinder was much slower. In the years since that decision was made its performance has improved immensely, and the game became deeply multithreaded.

That being said, it is the old 10k pax limit what's keeping some player saves playable at all, since they are perpetually running over capacity. With the much higher limits this problem is now visible as overloaded stations rather than refunds, which I think is better at communicating to the player what kind of problem their save has, compared to giving pax a refund and deleting them. Still, if the old mechanics are desired, it was made possible during beta to manually set a lower platform capacity limit, and to disable transfer pax overflow into the hall, enabling the refund behavior again.

Additionally, in order to support walking legs, station halls have been introduced. Stations can now store pax in 2 places: the platforms and the hall. Pax in platforms behave like always: they are eligible to board trains. Pax in the hall are not allowed to board trains. Instead they have a countdown timer, and when it reaches 0, they are moved to the platforms. If the platforms are full, they remain in the hall, waiting for a spot. Hall capacity is unlimited.


Station and train asset listings can now be displayed on the map as a "blob" overlay:

These blobs are circles whose area is proportional to the listing max value. You can change the colors, including the transparency. Adjusting the degree of transparency also enables a heatmap-like view. The map updates in realtime just like the asset listing, and it can also clamp the range to the visible objects by using the existing "on map" button in the assets panel.


For the game to support a pax simulation which scales into the millions of pax, it is necessary to precalculate a lot of data, so the sim does not slow down to 10x speed or less. The timetable and pax pathfind heuristic are such an example that has been in the game for years, and 1.12 added a new precalc for the new demand system. These precalcs are slow, but they run in the background. But even in the background they can have an impact in the UI responsiveness, especially in large saves and if the player has not reduced the amount of timetabling CPU threads. For these cases the precalcs are now paused if the game is paused, and one of the three main editors are open:

They will resume immediately if the sim is resumed, or when closing the editor.

Walk links make it more flexible to design stations. Following the same idea it is now possible to change the platform footprint (half) width. This allows to keep stations separate despite being in close proximity, for cases like having a depot next to a pax station, or separating local rail services from long distance in two stations.

Version 1.13 is now ready for testing in the beta branch. This new version is a continuation of features introduced in 1.12, which were spun off to its own version, since 1.12 was complex enough.


Pax are now able to plan paths including the act of walking between two stations, instead of taking a train. This includes cases where there is no possible train between stations, and when the train exists but it will faster to just walk (at least at the time of arrival). These walk legs are modeled as walking in a direct line (unrealistically fast) at 1 m/s (unrealistically slow), so it evens out.

The feature is meant to model the generic act of walking between stations. In particular it's not meant to model explicitly signaled OSIs, or fare zones for example. These real world cases are still a particular case of just walking between stations, so this feature aims at the more general case. This feature is also not able to consider things like rivers, mountains, country borders, particular streets or paths, islands, bays, etc. All these cases would require a combination of street routing and terrain routing and are an immense amount of work, and out of scope for the game.

If one or more of these cases bother you, or you just don't want to have walking legs for some stations, it is possible to disable them by changing the max walking radius of the station to 0. For a walking leg to be allowed between stations, both of their center points (the small circle displayed when you disable all station names and icons) must be within each other walking radius. A walking radius of 0 cannot contain any point so no walk legs will be possible.


A recurrent player complain about the station system, always supporting an active thread in the forums, is the 10k transfer pax limits in stations. In 1.13 this limit has been lifted to 100k, and train boarding speed has been increased by 10x to compensate. Additionally there's no more limits to newly spawned pax, or limits related to the number of platforms. This is now possible since the original limits were put in place when the pax pathfinder was much slower. In the years since that decision was made its performance has improved immensely, and the game became deeply multithreaded, so now it's a good time to test this increase. I say "test" because during the beta period it will be evaluated what is the performance impact if this change and it will be toned down if it's too bad for some players.

Additionally, in order to support walking legs, station halls have been introduced. Stations can now store pax in 2 places: the platforms and the hall. Pax in platforms behave like always: they are eligible to board trains. Pax in the hall are not allowed to board trains. Instead they have a countdown timer, and when it reaches 0, they are moved to the platforms. If the platforms are full, they remain in the hall, waiting for a spot. Hall capacity is unlimited.


Station and train asset listings can now be displayed on the map as a "blob" overlay:

These blobs are circles whose area is proportional to the listing max value. You can change the colors, including the transparency. Adjusting the degree of transparency also enables a heatmap-like view. The map updates in realtime just like the asset listing, and it can also clamp the range to the visible objects by using the existing "on map" button in the assets panel.

The beta development for 1.12 wrapped up in May, and it is now the default version. Some of the initial design decisions of 1.12 had to be changed in the light of existing player saves, but it in the end it held well overall, and it's a very major improvement in the simulation quality of the game.

Private 1.13 development has already started. Two major new features have already been implemented: walk legs and station halls. These correspond or solve some very often suggested features by players. To read more on how they look like read the devblog for this month:

https://carloscarrasco.com/nimby-rails-may-2024/

Version 1.12 has been released as the default game version! This version completely changes the way pax are spawned and the way they pick their destinations, and gives players and modders new tools for influencing these choices.



In 1.12 pax are spawned on specific geographical points, rather than by picking a station. And their destinations are also points in the map. Only after these points have been established are stations also picked, based on which stations can be reached from these points. Geographical points are picked based on population density. For now there is no visualization of these points so pax still just appear inside their origin stations, but the consequences of this previous step are very directly noticeable, specially when enabling the new "best path" mode.

Additionally, the way demand is generated has also changed. In 1.11 and earlier the achievable pax spawn rate of a given station was fixed, based on the station coverage. In 1.12 the pax rate depends both the population density around a station, and the reachable population from the station, subject to the distance demand curve. This means that opening more destinations in your network will not cut down on the desirability of the existing destinations as much as it did in 1.11.

All existing saves will see changes in their pax demand and generation flows, some of them very severe. A combination of changing the global demand % and the demand curves will help restore similar levels of demands compared to 1.11. For example, if more local demand is desired, you can change the destination curve to have much smaller % demand for 50km or more distances (less than 1%), then hike up the global demand %.


Since pax now spawn on map coordinates, and they have a (player configurable, limited) capability of picking their origin and destination stations, it does not make sense to divide station coverage like in 1.11. In 1.12 station coverages can overlap:

Additionally, maximum station area radius has been increased from 1.5km in 1.11 to 2.3km in 1.12.


Players can now create special sign-like buildings which add some amount of population to a point in the map:

These signs count as population points, just like the built-in population texture. They can be used to for example liven up areas which see high demand in real life but have low population, like airports.



In addition to player created POIs, mod authors can also provide map mod POI layers. Players can subscribe to these mods to immediately layers of POIs to their game map. These layers can be hidden, or have their proposed demand curve altered by players if desired.



To make the new POI feature even more powerful, it is possible pick a different demand curve for each player created POI, or globally for each mod POI layer. This allows to define POIs which have a different time based demand curve, for example a stadium only being active for a few hours a week, but having an outsized effect on its nearby stations by combining it with a large population value. Or making the distance demand curve of an airport much less dependent on the distance, compared to the default curve.

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For more information check the blog posts:

https://carloscarrasco.com/nimby-rails-february-2024/

https://carloscarrasco.com/nimby-rails-march-2024/

https://carloscarrasco.com/nimby-rails-april-2024/

Version 1.12 is now ready for testing in the Steam beta branch. This version completely changes the way pax are spawned and the way they pick their destinations.



In 1.12 pax are spawned on specific geographical points, rather than by picking a station. And their destinations are also points in the map. Only after these points have been established are stations also picked, based on which stations can be reached from these points. Geographical points are picked based on population density. For now there is no visualization of these points so pax still just appear inside their origin stations, but the consequences of this previous step are very directly noticeable, specially when enabling the new "best path" mode.

Additionally, the way demand is generated has also changed. In 1.11 and earlier the achievable pax spawn rate of a given station was fixed, based on the station coverage. In 1.12 the pax rate depends both the population density around a station, and the reachable population from the station, subject to the distance demand curve. This means that opening more destinations in your network does not cut down on the desirability of other destinations, it will just make existing stations generate more pax (always in proportion to the demand curves).



Since pax now spawn on map coordinates, and they have a (player configurable, limited) capability of picking their origin and destination stations, it does not make sense to divide station coverage like in 1.11. In 1.12 station coverages can overlap:


Players can now create special sign-like buildings which add some amount of population to a point in the map:

These signs count as population points, just like the built-in population texture. They can be used to for example liven up areas which see high demand in real life but have low population, like airports.



To make the new POI feature even more powerful, it is possible pick a different demand curve for each POI. This allows to define POIs which have a different time based demand curve, for example a stadium only being active for a few hours a week, but having an outsized effect on its nearby stations by combining it with a large population value. Or making the distance demand curve of an airport much less dependent on the distance, compared to the default curve.

---
For more information check the blog posts:

https://carloscarrasco.com/nimby-rails-february-2024/

https://carloscarrasco.com/nimby-rails-march-2024/

https://carloscarrasco.com/nimby-rails-april-2024/

Work continued with the new pax demand generation system in 1.12, with the introduction of multiple custom demand curves and player defined POIs. In 1.12 it will be possible for players to define custom time based and distance based pax demand curves, to control pax spawn and pax picking of destinations. These curves can alter the built-in population layer, and they can also alter a new kind of game object: points of interest. These POIs will be a special kind of building players can place anywhere on the map, and then assign a population value and a demand curve to them. They then become part of the pax generation for all the stations covering them, and also an attractor for pax demand from other stations. Check the blog post for more details and other new features:

https://carloscarrasco.com/nimby-rails-march-2024/

February saw the final releases of the 1.11 beta series, and the start of internal experimentation and development for 1.12. I originally intended for 1.11 to also feature pax generation changes, but the scope of the changes became too big to just be a "plus one more thing" feature during a beta period, so it has now been reassigned as the major feature of 1.12.

Work on the new pax generation system has begun, with many experiments done in February, to put some ideas to the test and see which ones are practical and which ones are not. The guiding principle is to try to model natural demand for pax trips, and then adapt the designs to the reality of a real time game. Solutions have been found for some the challenges of adapting this idea to the game, but a lot of work still remains to be done.

https://carloscarrasco.com/nimby-rails-february-2024/