Tools › User guides › Railway Cant & Transition
The Railway Cant & Transition Calculator works out the equilibrium cant, the cant to adopt, cant excess, transition length and shift for a curved broad-gauge track following Indian Railways Permanent Way Manual (IRPWM) practice.
Open the Railway Cant & Transition Calculator ›
| Field | What to enter | Typical value | Tip |
|---|---|---|---|
| Radius, R (m) | Radius of the circular curve. | 600 m | Degree of curve D = 1750 / R. |
| Maximum speed, Vmax (km/h) | Maximum sectional / booked speed on the curve. | 100 – 130 | |
| Minimum / goods speed, Vmin (km/h) | Speed of goods trains (or booked minimum). | 50 – 65 | Used for cant excess. |
| Adopted cant deficiency, Cd (mm) | Cant deficiency you allow. | 75 mm | Maximum 75 mm allowed in the tool (BG). |
| Result | Meaning | Limit | Tip |
|---|---|---|---|
| Equilibrium cant at Vmax / Vmin | C = GV²/127R with G = 1750 mm. | ||
| Adopted actual cant, Ca | Cant to provide = equilibrium cant at Vmax − Cd, limited to the maximum cant. | ||
| Cant excess at Vmin | Ca − equilibrium cant at Vmin. | ≤ 75 mm (BG) | |
| Maximum speed | Speed that the adopted cant and deficiency permit. | ||
| Transition length | Largest of the three IRPWM criteria (cant gradient, rate of change of cant and of deficiency). | ||
| Shift | S = L²/24R. |
The difference between the equilibrium cant needed at the maximum speed and the cant actually provided. Indian Railways allows up to 75 mm on BG for normal tracks.
It lets cant and curvature build up gradually so the change of cant and of lateral acceleration stays within limits; the shift is how far the circular curve moves inward.