22. Appendices

22.1. Units of Measure

Open Rails supports the same default units of measure as MSTS which are mostly, but not exclusively, metric.

When creating models just for Open Rails, we recommend you do not use defaults but specify units for all values that represent physical quantities.

As shown below, Open Rails provides a wider choice of units than MSTS.

Measure	Default unit	Applies to	OR accepts	MSTS accepts	Comment
Mass	kg		kg	kg
			t	t	metric tonne (1000 kg)
			lb	lb
			t-uk		Imperial ton (2240 lb)
			t-us		US ton (2000 lb)
Distance			mm
			cm	cm
	m		m	m
			km
			in	in
			in/2	in/2	half-inch – historic unit for tyre diameters
			ft
			mile
Area			m^2
			*(m^2)	*(m^2)
	ft^2		ft^2
		*(ft^2)	*(ft^2)
Volume	l	diesel fuel	l		liter
			m^3
			*(m^3)
			in^3
			*(in^3)
	ft^3	other	*(ft^3)	*(ft^3)	e.g. BoilerVolume
			g-uk		Imperial gallons
			g-us		US gallons
			gal		US gallons
			gals	gals	US gallons
Time	s		s
			m
			h
Current	amp		amp
			A
Voltage	volt		V
			kV
Mass Flow			g/h
			kg/h
	lb/h		lb/h	lb/h
Speed	m/s	other	m/s	m/s	meter per second
			km/h
			kph	kph	kilometer per hour
			kmh	kmh	misspelling accepted by MSTS
		kmph
	mph	dynamic brake	mph	mph	miles per hour
Frequency	Hz		Hz		Hertz
			rps		revolutions per second
			rpm
Force	N		N	N	Newton
			kN	kN
			lbf		Pounds force
			lb
Power	W		W		Watt
			kW
			hp		horsepower
Stiffness	N/m		N/m	N/m	Newton per meter
Resistance	N/m/s		N/m/s	N/m/s	Newton per meter per second
			Ns/m		Newton seconds per meter
Angular Resistance	N/rad/s		N/rad/s
Pressure	psi	air pressure	psi		pounds per square inch
			bar		atmospheres
			kPa		KiloPascal
	inHg	vacuum	inHg		inches of mercury
Pressure Rate of Change	psi/s		psi/s
			bar/s
			kpa/s
			inHg/s
Energy Density	kJ/kg		kJ/kg		kiloJoule per kilogram
			J/g
			btu/lb		Board of Trade Units per pound
Temperature Difference	degC		degC
			degF
Angle	radians		–
			deg
Angular Speed	rad/s		–	rad/s
Other			–	lb/hp/h	e.g. CoalBurnage