NML:Railtypes

Railtype IDs are limited to 64 in total. NewGRF-local IDs may freely be chosen, but must be in the 0..63 range. If other railtype GRFs are loaded, it may be that there are not enough railtype slots available. To prevent your entire NewGRF from being deactivated with the 'Attempt to use invalid ID'-error, you can use the following code:

if (railtype_available("LABL") || loading_stage == LOADING_STAGE_RESERVE)
    ... item definition ...
} else if (loading_stage == LOADING_STAGE_ACTIVATE) {
    ... warning / error ...
}

The warning / error is optional, but can be used to inform the user about the missing railtypes.

Vehicle and Railtype availability

Vehicle and railtype availability and compatibility is influenced by multiple properties. Generally, the vehicle defines which railtype it is, and the railtypes define the compatibility between each other.

A vehicle exists, if its railtype (train property track_type) is defined. Otherwise the vehicle is disabled.
When a vehicle is introduced, it always introduces its railtype (train property track_type).
A railtype is introduced, if at least one of the following conditions is met:
- A vehicle is introduced, that references the railtype (train property track_type).
- Another railtype is introduced, that references the railtype via the introduced railtype list (railtype propery introduces_railtype_list).
- The introduction date (railtype property introduction_date) is passed and all required railtypes (railtype property requires_railtype_list ) are available.

Via railtype property compatible_railtype_list multiple railtypes can be defined, which shall be considered equivalent to a railtype. This affects the interpretation of train property track_type. If train property track_type references an undefined railtype, then railtype property compatible_railtype_list is checked for all defined railtypes, whether the vehicle can be reassigned to some other railtype. Otherwise the vehicle is disabled. However note also that alternative_railtype_list provides an alternative/complementary approach to handling undefined railtypes.

Note that when routing trains onto railtypes, the compatibility is only evaluated for the lead engine of a consist. This means that trains will run on incompatible rail types if they are in a consist where the lead engine is compatible with the rail type. This applies to both engines and wagons.

Railtype properties

property	value range	comment
label	4-byte string	names of default rail types: "RAIL", "ELRL", "MONO", "MGLV". See the List of railtype labels in the NewGRF Specs for currently defined custom labels.
introduction_date	date(yyyy,mm,dd)	1.1 Valid range for yyyy is 0 ... 5000000.
name	string	Name of this railtype
toolbar_caption	string	1.2 Caption of the build rail toolbar. In earlier versions this is the same as the 'name'
menu_text	string	Shown in the dropdown menu for all railtypes
build_window_caption	string	Caption of the build vehicle window
autoreplace_text	string	String for the autoreplace window
new_engine_text	string	String for the "We have invented a new <rail type> engine" news message
compatible_railtype_list	list of railtype labels	Provide a list of rail types that trains of this type can also run on. e.g. ["RAIL", "ELRL", "MONO"]. Note that when routing trains, the compatibility is only evaluated for the lead engine of a consist. This means that trains will run on incompatible rail types if they are in a consist where the lead engine is compatible with the rail type. This applies to both engines and wagons.
powered_railtype_list	list of railtype labels	Provide a list of rail types that trains of this type are powered on.
railtype_flags	bitmask(RAILTYPE_FLAG_XXX, ...)	CATENARY Enable catenary NO_LEVEL_CROSSING Disable level crossings HIDDEN 1.9 Hides railtype from player PRECOMBINED 1.10 Enable use of precombined overlay sprites ALLOW_90DEG 1.10 Always allow 90 degree turns DISALLOW_90DEG 1.10 Always prohibit 90 degree turns (takes precedence over ALLOW_90DEG)
curve_speed_multiplier	0...255	max curve speed is defined as multiple of the base curve speed (see below)
station_graphics	RAILTYPE_STATION_NORMAL, RAILTYPE_STATION_MONORAIL, RAILTYPE_STATION_MAGLEV	Type of station graphics to use for the default stations
construction_cost	0 ... 65525	1.1 per piece of track as multiplier to PR_BUILD_RAIL base cost. Default cost factors are 8, 12, 16 and 24 for RAIL, ELRL, MONO and MGLV.
speed_limit	0 ... 65525 km/h (speed units)	A speed limit of 0 means unlimited speed
acceleration_model	ACC_MODEL_RAIL, ACC_MODEL_MONORAIL, ACC_MODEL_MAGLEV	ACC_MODEL_RAIL and ACC_MODEL_MONORAIL behave the same currently
map_colour	0 ... 255	1.1 entry in the colour palette.
requires_railtype_list	list of railtype labels	1.1 List of rail types on that need to be available to the company of the player for this rail type to be introduced at (or after) the introduction date. This limit does not apply when the rail type is introduced by the introduction of a vehicle.
introduces_railtype_list	list of railtype labels	1.1 List of rail types that get introduced when this rail type is introduced. For example, to make sure that when a fast rail type is introduced the slow variant exists.
sort_order	0 ... 255	1.1 number which defines the sort order among rail types. If this entry is not defined, it gets assigned sort order n*10+7 for the n-th railtype.
maintenance_cost	0 ... 255	1.2 Maintenance cost factor for each piece of tracks of this railtype. Default cost factors are 8, 12, 16 and 24 for RAIL, ELRL, MONO and MGLV.
alternative_railtype_list	list of railtype labels	1.2 List of rail types which this rail type will act as fallback for, if the corresponding rail type is not defined separately

Sort order

The sort_order influences the sort order of the drop down lists with rail types. Default values are as follows:

Value	Meaning
07	normal rail
17	electrified rail
27	monorail
37	maglev
n7	railtype #n

Thus the rail type that (internally) gets index 8 will get a default value of 87. These defaults are to keep the ordering when this property is not supported as they were.

Base speeds for curves

The base speeds relevant for the curve_speed_multiplier are:

curve length	base speed [km/h]
0 (90 degree turn)	30
1	44
2	55
3	66
4	75
5	84
6	91
7	98
8	103
9	108
10	111
11	114
12+	115

Railtype variables

name	value range	comment
terrain_type	TILETYPE_NORMAL, TILETYPE_DESERT, TILETYPE_RAIN_FOREST, TILETYPE_SNOW
enhanced_tunnels	0	Reserved for future use, always returns 0 in OpenTTD. Should custom tunnel entrances be implemented, other values than 0 might be returned
level_crossing_status	LEVEL_CROSSING_CLOSED, LEVEL_CROSSING_OPEN
build_date	0 .. 5000000	for depots only: build date of the depot in days since 0
town_zone	town zone	Town zone of the tile. (Only available for level crossings and depots.)
random_bits		2 pseudo-random bits, based on tile location

Railtype callbacks

For rail types a number of callbacks are used to define rail type graphics. Each should refer to a sprite set containing the relevant sprites. Refer to the example sprites or the example railtype grf in the NML repository, for an example on what sprites are needed in what order.

callbacks	number of sprites	meaning
gui	16	4 rail directions, autorail, depot, tunnel and convert rail sprites for rail menu.
track_overlay^[1]	10	6 flat and 4 slope sprites. Track without landscape. Used in junctions, and also with path signals, if the "Show reserved tracks" option is enabled in the game settings.
underlay^[1]	16	6 flat and 4 slope, one crossing WITH track, 5 junction pieces without track. Tracks with ballast but without landscape.
tunnels^[1]	4	1 sprite for each direction. Sprite is overlay for track in existing tunnel graphics. The original ground sprite is drawn, then the overlay, then possibly a train and the original tunnel head is drawn over the top. This keeps compatibility with different landscape types. Sprite order: SW, NW, NE, SE.
catenary_wire	28
catenary_pylons	8
bridge_surfaces^[1]	6
level_crossings^[1]	10	For each direction: one track sprite and 4 sprites for road lights etc
depots^[2]	6	2 sprites for each south-ish, 1 sprite for each north-ish depot. Like original depots.
fences	8 / 16	x, y, vertical, horizontal, SW, SE, NE and NW slopes like original fences at sprite 1301. 1.6 Since OpenTTD r27343 there is also a 16 sprites version, see below.
tunnel_overlay^[3]	4	If this callback is defined, tunnels for this railtype will be drawn differently. First, a grass underlay base sprite is drawn, then the 'tunnels'-sprite. Next, train sprites if applicable and then a grass overlay and finally the sprite from this type (tunnel_overlay). The grass sprites are defined in the base set and do not contain any parts of the tracks or portal, so these have to be fully provided by the railtype sprites. `getbits(extra_callback_info1, 0, 8)`: 0 for normal tunnels, without any extra features (like tracks above). All other values are reserved for future extensions.
signals	8	1.3 1 sprite for each direction, order is SW(-facing), NE, NW, SE, E, W, S, N. For more information, see below
precombined^[1]	63	1.10 1 sprite for each combination of track on a tile. The index is determined by treating each track piece as a bit in the order X Y N S W E, subtracting 1, see below

↑ ^1.0 ^1.1 ^1.2 ^1.3 ^1.4 ^1.5 Either all or none of these sprites should be provided.
↑ 1.2 In OpenTTD prior to r22854, depot sprites would not be used if the above 'all or none' sprites were not supplied.
↑ Above 'all or none' sprites must be supplied, if these sprites are to be used.

If a callback is not implemented or fails, graphics from the fallback railtype (picked via the station_graphics property) will be used instead.
Note that there is no "default graphics"-callback.

Example sprites

gui

track_overlay

underlay

level_crossings

You can define a special track piece which crosses the road and for each of two directions and each of the corners of the tile a separate sprite for a light, sign, or whatever should go there.

Sprite number for X	Sprite number for Y	Useage
0	1	Rail overlay
2	3	North light
4	5	East light
6	7	West light
8	9	South light

depots

Sprite Number	Usage
0	NE wall for SE-entry depot.
1	Depot building for SE-entry depot.
2	NW wall for SW-entry depot.
3	Depot building for SW-entry depot.
4	Depot building for NE-entry depot.
5	Depot building for NW-entry depot.

fences

1.6 Since OpenTTD r27343 there is also a 16 sprites version, this allows to use different sprites resp. offsets for the fences on either track side.

Sprite number	Tile slope	Track bit	Fence position	Version
0	flat	X	NW	1.0
1	flat	Y	NE	1.0
2	flat	left	E	1.0
3	flat	upper	S	1.0
4	SW	X	NW	1.0
5	SE	Y	NE	1.0
6	NE	X	NW	1.0
7	NW	Y	NE	1.0
8	flat	X	SE	1.6
9	flat	Y	SW	1.6
10	flat	left	W	1.6
11	flat	upper	N	1.6
12	SW	X	SE	1.6
13	SE	Y	SW	1.6
14	NE	X	SE	1.6
15	NW	Y	SW	1.6

tunnel_overlay

If this callback is defined, tunnels for this railtype will be drawn differently.

First, a grass underlay base sprite is drawn, then the 'tunnels'-sprite. Next, train sprites if applicable and then a grass overlay and finally the sprite from this callback. The grass sprites are defined in the base set and do not contain any parts of the tracks or portal, so these have to be fully provided by the railtype sprites.

Illustration:

signals

This callback can be used to supply custom signal graphics.

The resulting sprite set must consist of 8 sprites, corresponding to the following signal directions: SW-facing, NE-facing, NW-facing, SE-facing, E-facing, W-facing, S-facing, N-facing. If resolving fails or results in an empty sprite group, the matching base set sprite will be used instead.

Variable extra_callback_info2 contains the state, variant and type of the signal. Use the builtin function getbits() in the following fashion to access the information:

Signal state: getbits(extra_callback_info2, 0, 8):

Result Meaning

00 Red signal

01 Green signal

all other values Reserved
Signal variant: getbits(extra_callback_info2, 8, 8):

Result Meaning

00 Light (electric) signal

01 Semaphore

all other values Reserved
Signal type: getbits(extra_callback_info2, 16, 8):

Result Meaning

00 Normal block signal

01 Entry pre-signal

02 Exit pre-signal

03 Combo pre-signal

04 Two-way path signal

05 One-way path signal

all other values Reserved

Variable extra_callback_info1 contains the drawing context.

getbits(extra_callback_info1, 0, 8):

Result	Meaning
0	Signal is drawn in a viewport, i.e. on the map.
0x10	Signal is drawn in the signal GUI. The returned sprite set must still have 8 sprites, but OpenTTD will only use the 7th sprite, so all other sprites can be empty.
all other values	Reserved

Precombined overlay sprites

Example code

A typical implementation for railtypes can look like:

 item(FEAT_RAILTYPES, elrail, 0x01) {
     property {
         label:                      "SHIN";
         name:                       string(STR_EL_RAIL);
         menu_text:                  string(STR_EL_RAIL);
         build_window_caption:       string(STR_BUILD_CAPTION);
         autoreplace_text:           string(STR_AUTOREPLACE);
         new_engine_text:            string(STR_NEW_ENGINE);
         compatile_railtype_list:    ["SHIN","RAIL","ELRL"];                   // Tracks of rail and electrified rail are compatible
         powered_railtype_list:      ["ELRL","SHIN"];                          // But we only have power when we have electricity
         railtype_flags:             bitmask(RAILTYPE_FLAG_NO_LEVEL_CROSSING); // High speed tracks should not have level crossings
         curve_speed_multiplier:     1;
         station_graphics:           RAILTYPE_STATION_MAGLEV;                  // We want the most modern stations
         construction_cost:          32;                                       // should be pretty steep
         speed_limit:                500 km/h;
         acceleration_model:         ACC_MODEL_RAIL;                           // This is still rail, though
     }
     graphics {
         track_overlay:   ground_switch_overlay;     // defines the sprites drawn as overlay for junctions and highlight
         underlay:        ground_switch_underlay;    // defines the usual tracks and the underlay for junctions
         level_crossings: level_crossing_switch;     // defines level crossings including traffic lights and blocking bars
         tunnels:         tunnel_switch;             // defines the tracks drawn on a tunnel tile
         depots:          depot_switch_electric;     // defines the depot sprites
         bridge_surfaces: bridge_terrain_switch;     // defines the overlay drawn over bridges
         fences:          fences_set;                // defines the look of fences
         // we don't define catenary wire and pylons, thus we use the default which comes with the base graphics.
     }
 }

The switches and graphics blocks are defined in the usual way as described in sections switches, random switches and graphics block sections.

[leftout-1] 1.0 ^1.1 ^1.2 ^1.3 ^1.4 ^1.5 Either all or none of these sprites should be provided.

[depotr22854-2] 1.2 In OpenTTD prior to r22854, depot sprites would not be used if the above 'all or none' sprites were not supplied.

[tunnel_overlay-3] Above 'all or none' sprites must be supplied, if these sprites are to be used.

[1]

[2]

[3]

NML:Railtypes

Contents

Railtype IDs

Vehicle and Railtype availability

Railtype properties

Sort order

Base speeds for curves

Railtype variables

Railtype callbacks

Example sprites

gui

track_overlay

underlay

level_crossings

depots

fences

tunnel_overlay

signals

Precombined overlay sprites

Example code

Navigation menu

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Result	Meaning
00	Light (electric) signal
01	Semaphore
all other values	Reserved

Result	Meaning
00	Normal block signal
01	Entry pre-signal
02	Exit pre-signal
03	Combo pre-signal
04	Two-way path signal
05	One-way path signal
all other values	Reserved