Formula Used
The basic constant-deceleration relation is d = (v₀² − v₁²) ÷ (2a). Reaction distance uses dᵣ = v₀tᵣ. This calculator extends those equations with a time-step simulation.
Brake force is limited by wheel-to-rail adhesion. Track resistance and aerodynamic drag add deceleration. Downhill gravity reduces effective deceleration.
Brake propagation delay uses train length divided by propagation speed. Build-up force increases gradually before full braking. Multi-stage mode applies three selectable braking levels.
How to Use
- Select a calculation mode and train preset.
- Enter speed, mass, braking, delay, and track values.
- Choose gradient, adhesion, weather, and unit options.
- Enter available distance for safety comparisons.
- Press calculate and review warnings, charts, and scenarios.
Example Data
| Train | Speed | Mass | Deceleration | Track | Use |
|---|---|---|---|---|---|
| Passenger | 100 km/h | 600 tonnes | 0.75 m/s² | Level, dry | Service estimate |
| Freight | 80 km/h | 2,500 tonnes | 0.45 m/s² | 1% downhill | Long-train estimate |
| Metro | 80 km/h | 300 tonnes | 1.10 m/s² | Level, dry | Urban stop |
| High-speed | 250 km/h | 450 tonnes | 0.90 m/s² | Level, dry | High-speed estimate |
Frequently Asked Questions
Does this calculator replace certified railway braking analysis?
No. It provides engineering estimates for study and comparison. Operational use requires validated railway models and approved procedures.
Why does downhill gradient increase stopping distance?
Gravity acts along the direction of travel. It reduces the net deceleration available from braking and resistance.
What is brake propagation delay?
It is the time needed for braking commands or pressure changes to reach the train. Long pneumatic freight trains can experience significant delay.
How does adhesion affect braking?
Adhesion limits transferable wheel braking force. Wet, icy, or leaf-contaminated rails can reduce that limit.
What does wheel-slide protection do?
It helps wheels remain near useful adhesion. The calculator applies a higher adhesion utilisation when protection is enabled.
Does train mass always increase braking distance?
It depends on how braking force scales with mass. Force-based calculations often show greater distance for heavier trains.
What is rotational mass allowance?
Rotating wheels and drivetrain parts store kinetic energy. The allowance increases effective dynamic mass for braking calculations.
How is aerodynamic drag handled?
Drag changes with air density, drag area, wind, and speed. The model recalculates it throughout the stop.
What is the recommended safety distance?
It is calculated stopping distance multiplied by your safety factor. It is not an official signalling or operating margin.
Can the calculator compare service and emergency braking?
Yes. The comparison table recalculates both using their entered deceleration values.