Standardized Roadtype Scheme
Not in a useable state do not use
There is currently not enough clarification on how the standard is meant to be used along with other major issues
Surface / Type [X***]
Describes the road surface / rail type and thus the vehicle type.
Roadtype:
| Letter | Meaning (Road) | Powered Roadtypes | Recomended vehicle set fallbacks |
|---|---|---|---|
| R | Regular Road | RI(S) | |
| P | Passenger-only | RPI(S) | R |
| G | Guided busway | RPG | P then R |
| I | Industrial Site (ISR) | I | R |
| B | Bicycle Lane | RB(Z) | R |
| W | Waterway | W | |
| A | Amphibious on road (hidden) | RPI(S)W | R |
| S | Snowy or Iced Track | S | |
| a | Amphibious on snow (hidden) | SW | S |
| Z | Pedestrian Zone | Z | |
| E | Eyecandy | E | |
| p | Pump/Pipeline | p |
Tramtype:
| Letter | Meaning (Tram) | Powered Tramtypes | Recomended vehicle set fallbacks |
|---|---|---|---|
| R | Regular Rail | RI(M) | |
| P | Passenger-only | RPI(M) | R |
| I | Industrial Site (ISR) | I | R |
| B | Bicycle Lane | (R)B | |
| S | Suspended Monorail | S | |
| M | Metro | M(RP) | |
| O | Trackless trams | O | |
| E | Eyecandy/Electrical infrastructure | E |
It is the vehicle set's responsibility to implement fallbacks to other appropriate surfaces. It is also up to the author to decide if they want to do it or not. This means that road/tramtrack sets shouldn't add these to their alternative_roadtype_list (NML) and alternative_tramtype_list (NML)
It is up to the track set to implement all powered roadtypes in the powered_roadtype_list (NML). The same goes for tramtypes: powered_tramtype_list (NML). It is further advised to implement support for the roadtypes/tramtypes in brackets, if applicable.
Hidden roadtypes for compatibility should be implemented by road sets. It is up to the author to decide if they want to implement it as a hidden roadtype or not.
Speed / Feature [*X**]
Any character may be used for roads, but at least one road must have "A".
Vehicles should use "A".
Terrain / Stability [**X*]
Describes the roughness of the road surface / trackbed stability, and thus the vehicle tier.
| Letter | Meaning | Powered Roadtypes |
|---|---|---|
| a | Very slow / rough / light | aA |
| A | Slow / rough / light | aAB |
| B | Regular | ABC |
| C | Fast / stable | BCc |
| c | Very fast / stable | Cc |
If all classes aren't defined by the road set, the other ones should be in the alternative_roadtype_list (NML). The same goes for tramtypes: alternative_tramtype_list (NML).
Road vehicle sets should not implement fallbacks for terrain / stability.
Classes "a" and "c" are entirely optional for road/tramtype sets and should under no circumstances be used by vehicles.
Energy [***X]
Describes the energy source of the track / vehicle.
Generic classes:
| Letter | Meaning (Road) | Meaning (Tram) |
|---|---|---|
| N | None | None |
| E | Overhead electrified (Catenary) | Overhead electrified (Catenary) |
| G | Ground electrified | Ground electrified |
| Z | Ground and overhead electrified | Ground and overhead electrified |
Specialized classes:
| Letter | Meaning (Road) | Meaning (Tram) | Vehicle set fallback |
|---|---|---|---|
| 3 | n/a | Third Rail | G |
| 4 | n/a | Fourth Rail | 3 then G |
| C | n/a | Cable | G |
A tramtrack set that only uses specialized types, should map the generic types to the most suitable specialized type in the set with the help of the alternative_tramtype_list (NML).
The default labels (ROAD, ELRL) and non-standard labels
OpenTTD will allways define ROAD and ELRL incase there are vehicles for them. It is therefore recomended to have these present in the set so that you can map them to appropriete labels from the standard. There are a few ways of doing this:
- Replacing one of the standardised types with the default label and putting the standardised label in the alternative_roadtype_list (NML) or alternative_tramtype_list (NML).
- Defining ROAD and/or ELRL separately from the standardised labels and adding the standard ones to the powered_roadtype_list (NML) or powered_tramtype_list (NML). The main advantage of this is that you can use a parameter to map ROAD and/or ELRL to the standardised labels. This allows the player to chose where there non standardised vehicles will be able to go.
Vehicle set authors might want to add the default labels and non-standard labels as a fallback. If not implemented for the defualt labels, their vehicles won't show up on the default roads and/or tracks, leading to countless bug reports from players. Non standard labels that might be worth adding fallbacks too are: ELRD, RAIL, HAUL and probably some more.
Summary for Road/Tramtrack sets
This section summarizes the above for road/tramtrack sets.
- [X***] Track gauge and type class
- Define at least one track type for every track gauge/type class you want in your set.
- If you only provide tracks for one gauge/type, consider leaving some free railtypes so a player can load an additional set for some other type.
- [*X**] Speed limit class
- Make sure class A is always available, either directly or via an alternate label.
- Use only class A if you don't want speed limits;
- With speed limits, A is the lowest speed limit. Continue with B, C, etc. for increasing speed limits;
- The speed class can also be used to implement additional eye-candy track types, use letters higher in the alphabet for this.
- [**X*] Axle load class
- Always define all classes A through E for every track type class / electrification combination, either:
- Directly via a real railtype definition;
- Indirectly via the alternate rail type label list, property 1D (NFO) or alternative_railtype_list (NML).
- Extend the predefined classes only if you also provide a train set that makes use of these.
- [***X] Energy source type class
- If your set only uses specialized classes, always map the generic classes to the closest matching specialized type via property 1D.
- Standard labels [RAIL, ELRL, MONO, MGLV]
- Always define the standard labels when possible, instead of what would be the equivalent of the standard label in this scheme.
- Map the equivalent labels from this scheme to the standard labels using property 1D (NFO) or alternative_railtype_list (NML).
Or, put differently, for each gauge/type, select one or more energy source types. For each type/energy combination provide all axle load classes for the speed class "A", either as a real type or as an alternate of another type. Provide more types with a different speed letter if you want to provide several different speeds or other eye-candy tracks.
Summary for vehicle sets
This section summarizes the above for vehicle sets.
- [X***] Surface / Type
- Use the surface / type class that matches the vehicle;
- Define a fallback type via the road/tramtype table in case you want the vehicle to be available on a different road or tramtrack if no matching road/tramtrack set is loaded.
- Specialized subtypes like "G" might not always be available. If you want those vehicles to be still available then, fall back the the generic class (e.g. "P" or "R").
- [*X**] Speed / Feature
- Always use class A for every vehicle.
- [**X*] Terrain / Stability
- Use A, B or C depending on where you want your vehicles to be able to drive.
- A is used for slow offroad capable vehicles which aren't allowed on Motorways and similar Roads
- B is used for vehicles which can drive offroad but are also allowed on Motorways.
- C is used for vehicles which can't go offroad or similar.
- Use B if you aren't sure what to chose.
- Never use a or c.
- [***X] Energy source type class
- Use the energy source type class that matches the vehicle;
- When using specialized classes, define a fallback type via the railtype table in case you want the vehicle to be available if no matching track set is loaded.
- Default labels [ROAD, ELRL]
- Define a fallback type to the default labels via the road/tramtype table in case you want the vehicle to be available on the defualt roads/track if no matching set is loaded.
Be as specific as you want when selecting the road/tramtype, it is the job of the road/track set to select a playable, reduced subset out of all possible type combinations.
