General WAG File Settings

Aim - this section provides an overview of some of the more general parameters needed within a WAG file.

If you wish to provide any feedback on this page, please use the contact page. It would br great to have some feedback as this helps to ensure the accuracy of the information and models.



Axle Adhesion

Derailment Coefficient

Wagon Steam Heating

General Open Rails Parameters for Wagons


This page describes some of the simpler settings potentially required in the WAG. Some of the more important settings are found on pages purely dedicated to their description.


Axle Adhesion

Individual wheelsets (axle groupings or wheelset groupings) can be set up to operate independently as far as adhesion (wheelslip) is concerned. This is especially valuable when setting up a Duplex steam locomotive as the wheelsets can operate independently of each other, and slip at different times.

Modelling of different wheelsets in OR can be done by using the following format.

ORTSAdhesion (

    Various parameters for each axle in the wheelset as described below.


AnimatedParts - indicates the parts that are associated to the wheels in the wheelset. In the case of a steam locomotive, this might be the connecting rods and reciprocating connections.
Weight - weight on the full wheelset.
ORTSRadius - radius of the wheels.
NumberWheelsetAxles - number of wheel axles in the wheelset.
ORTSFlangeAngle - flange angle of wheels in the wheelset.
ORTSInertia - inertia of the wheels in the wheelset.


Derailment Coefficient

The Derailment Coefficient is defined as the ratio between the Lateral (L) Force on a car or wagon, and the Vertical (V) force on the car, ie Coeff = L / V.

The coefficient gives an indication of the likelihood of a car coming off the tracks in certain circumstances, and most railway companies select a coefficient value that they use to set the conditions that a train may travel around a curve or through a turnout.

There are many factors which will influence the calculation of the derailment coefficient, and OR attempts to capture some of the more relevant aspects without over complicating the information required.

Open Rails will attempt the calculations using default values calculated from the existing Size statement in the WAG file.

However for the most accurate outcome the following parameters can be included in the wagon section of the ENG or WAG file.

ORTSLengthBogieCentre - length between bogie centres.

ORTSLengthCarBody - Length between car ends (For most accuracy, use the coupler pivot point).

ORTSLengthCouplerFace - length between coupler faces.

ORTSNumberAxles - number of axles on the car.

ORTSNumberBogies - number of bogies on the car.

The following diagram illustrates the key distance measurements.

Car measurements

In addition the following settings should be set to define the wheel profile.

ORTSWheelFlangeLength - Wheel flange length is defined as the length of flange starting from the beginning of the maximum flange angle to the point where flange angle reduces to 26.6 degrees. Some railway companies use a point 70mm from the internal face of the wheel, and the intersection with the wheel tread. Wheel wear may also impact the Flange height. The Flange length is the value marked "Fh" in the diagram below.

ORTSMaximumWheelFlangeAngle - Wheel flange angle is defined as the maximum angle of the wheel flange relative to the horizontal axis. The Flange angle is the value marked "Fang" in the diagram below.

wheel profile

For a more detailed description of the phenomenon of derailing, refer to the derailment page.


Wagon Steam Heating

The main purpose of the OR Wagon Steam Heating Model is to "generate" steam usage on steam locomotives, a reduction in the mass of respective vehicles as water and fuel is used, and generate some visual effects in the game. The model was built using information sourced from the articles found on the Wagon Steam Heating Information.

Steam for steam heating of trains can be provided by steam locomotives, diesel locomotives fitted with a steam generator or by separate steam generator wagons. Electric locomotives and trains can have steam heating added by the inclusion of a steam heating wagon in the consist.

To enable steam heating to work in Open Rails for locomotive fitted boilers, the following parameter needs to be included in the engine section of the steam locomotive ENG file:

MaxSteamHeatingPressure( x )
x = maximum steam pressure in the heating pipe - this is generally 40 to 80 psi in UK, but can be as high as 180 to 250 psi in USA

If the above parameter is fitted to the locomotive, then an extra line will appear in the extended "LOCOMOTIVE INFORMATION" HUD to show the temperature in the train, and steam heating pipe pressure, etc. Diesel locomotives should also have the steam generator defined in the wag section of the ENG file.

Steam heating will only work if passenger cars are attached to the locomotive, (or for wagons that have been defined as heated). Warning messages will be displayed if the temperature inside the carriage falls below 45 degF (10 degC).

The player can control the train temperature by using the following controls:
Alt-U - increase steam pipe pressure (and hence train temperature)
Alt-D - decrease steam pipe pressure (and hence train temperature)

The impact of steam heating will vary depending upon the season, length of train, etc.

Some special visual effects can also be implemented as part of carriage heating. These include steam leaks in the steam pipes, and heating boiler exhausts, etc. Further details can be found on the Visual Effects page.

By default steam heating should work with standard defaults already included in OR, however if you wish to customise your configurations, the follwoing parameters are available for this purpose.

Steam Heated Cars

ORTSHeatingCompartmentTemperatureSet ( x ) - defines the thermostat temperature, above which the compartment heating will be turned off. In the early days of steam heating the GWR considered it sufficient to maintain a temperature of 55 F (13 C), in the later part of the twentieth century British Railways 65 F (18 C) was the expected standard of heating for a passenger coach.

ORTSHeatingCompartmentPipeAreaFactor ( x ) - controls the amount of heat transferred from the steam to the compartment via radiators. Lower numbers give greater heating. Values between 3.0 and 2.0 work well for pre-nationalisation British carriages. Values between 2.5 and 1.5 are more appropriate for later British Railways stock. For mid-late 20th century stock values between 0.6 and 1.0 could be used.

ORTSHeatingWindowDeratingFactor ( x ) - is the proportion of the carriage sides (between 0 and 1) taken up by windows. A larger value of this factor results in greater heat losses.

ORTSHeatingTrainPipeOuterDiameter ( x ) - can be increased to represent thicker insulation around the steam pipes, however a larger surface area may increase the heat loss.

ORTSHeatingTrainPipeInnerDiameter ( x ) - reprents the bore of the main steam pipe. Most British carriages built prior to nationalisation had 1.5 inch internal diameter steam pipes. Later steam heated stock built by British Railways used 2 inch internal diameter pipes, which allowed a higher standard of heating to be achieved for longer trains without the need to use a higher supply pressure. Higher steam pressures and larger steam pipes were employed in USA to enable larger carriages and longer trains to be adequately heated in a colder climate.

ORTSHeatingConnectingHoseOuterDiameter ( x ) and ORTSHeatingConnectingHoseInnerDiameter ( x ) similarly represent the connections between the cars. In UK connecting hoses were of 1.75 inch diameter.

The steam heating model increases heat losses due to the apparent wind as the train moves, so it will be noticed that heat losses will increrase up to about 45mph (20m/s). So when tuning the steam heat model, it is suggested that the ORTSHeatingCompartmentPipeAreaFactor ( x ) be reduced until the temeprature remains constant at approximately 50mph.

Example British passenger carriage:

   ORTSHeatingCompartmentTemperatureSet ( 65degf )
   ORTSHeatingCompartmentPipeAreaFactor ( 2.0 )
   ORTSHeatingWindowDeratingFactor ( 0.30 )
   ORTSHeatingTrainPipeOuterDiameter ( 2.875in )
   ORTSHeatingTrainPipeInnerDiameter ( 2.0in )
   ORTSHeatingConnectingHoseOuterDiameter ( 2.05in )
   ORTSHeatingConnectingHoseInnerDiameter ( 1.75in )

Example US passenger carriage:

   ORTSHeatingCompartmentTemperatureSet ( 65degf )
   ORTSHeatingCompartmentPipeAreaFactor ( 0.5 )
   ORTSHeatingWindowDeratingFactor ( 0.25 )
   ORTSHeatingTrainPipeOuterDiameter ( 3.25in )
   ORTSHeatingTrainPipeInnerDiameter ( 2.50in )
   ORTSHeatingConnectingHoseOuterDiameter ( 3.00in )
   ORTSHeatingConnectingHoseInnerDiameter ( 2.5in )

Specially heated freight vans, such as Banana Vans or Non-passenger coaching stock and goods wagons with through steam pipes:
For example, in the UK some types of banana vans were steam heated during the winter months, to help with the ripening of the bananas.

ORTSWagonSpecialType ( Heated ) can be used to add steam heating or a through steam pipe to goods wagons.

Non-passenger coaching stock such as parcels and luggage vans had through steam pipes, but no heating. To represent this in OpenRails a large value of ORTSHeatingCompartmentPipeAreaFactor can be used.

Example Banana van:

   ORTSWagonSpecialType ( Heated )
   ORTSHeatingCompartmentTemperatureSet ( 60degf )
   ORTSHeatingCompartmentPipeAreaFactor ( 3.0 )
   ORTSHeatingWindowDeratingFactor ( 0.00 )

Example Baggage car:

   ORTSHeatingCompartmentPipeAreaFactor ( 100 )
   ORTSHeatingWindowDeratingFactor ( 0.01 )

Diesel and Electric Locomotives

Also in the eng section of the ENG file the MaxSteamHeatingPressure( x ) line must be included.

Diesel locomotives that are fitted with steam heating boilers need to have the following parameters added to the wag section of the ENG file.

ORTSHeatingBoilerWaterTankCapacity ( x ), where x = water tank capacity
ORTSHeatingBoilerWaterUsage ( x1 y1 xn yn ), where x = steam usage rate, y = water usage rate
ORTSHeatingBoilerFuelUsage ( x1 y1 xn yn ), where x = steam usage rate, y = fuel usage rate

For Bristish Railways modellers, this information on steam heating boilers fitted to diesel locomotives, has been compiled to assist in configuration.

A small number of British diesel locomotives were fitted with scoops to replenish the boiler water tanks from water troughs. These should be defined in the eng section of the ENG file in the same way as water scoops for steam locomotives.

Steam Heating Wagon

A "stand alone" car can also be set up with a steam heating boiler for heating the train when hauled by a locomotive not configured for steam heating, using the above paramaters and the followingan example entry for the wag section for this type of wagon is given below:

   ORTSWagonSpecialType ( HeatingBoiler )
Comment ( Heating boiler water capacity 840g-uk sufficient for approx 4 hours )
Comment ( * Spanner Swirlyflo heating boiler produces steam at max 2000lb/h * )

   ORTSHeatingBoilerFuelTankCapacity ( 840g-uk )
   ORTSHeatingBoilerWaterTankCapacity ( 840g-uk )
   ORTSHeatingBoilerWaterUsage ( 0 0 2000 200 )
   ORTSHeatingBoilerFuelUsage ( 0 0 2000 20.5 )

Similar information can be added to any wagon to convert it into a steam generator.

Steam Heating Demonstration Activity

To demonstrate a working example of some of the different steam heating configurations a Steam Heating Demonstration activity is available.


General Open Rails Parameters for Wagons

The general parameters that define the features described on this page are tabulated on the following web page.

General Parameters for WAG and ENG files (updated May 2020)