Resistance Due to Starting and Accelerating

Trains face these resistances at stations when they start, accelerate, and decelerate. The values of these resistances are as follows:

Resistance on starting, R6 = 0.15 + 0.005 W2 (25.10)

Resistance due to acceleration, R7 = 0.028aW (25.11)

where W1 is the weight of the locomotive in tonnes, W2 is the weight of the vehicles in tonnes, W is the total weight of the locomotive and vehicle in tonnes, i.e. W1 + W2, and a is the acceleration, which can be calculated by finding the increase in velocity per unit time, i.e., (V2 - V1)/t, where V2 is the final velocity, V1 is the initial velocity, and t is the time taken.

Table 25.1 summarizes the various resistances faced by a train.

Table 25.1 Details of various resistances

Nature of resistance

Value of resistance


Resistance due to friction (Rj)


Resistance independent of speed

Resistance due to wave action

0.00008 WV

Resistance dependent on

track irregularities, and speed



Resistance due to wind, or

0.0000006 WV2

Resistance dependent on

atmospheric resistance (R3)

square root of speed

Resistance due to gradient (R4)

W x % of slope 100

Resistance dependent on slope

Curve resistance for BG (R5)


Resistance dependent on degree of curve

Resistance due to starting (R6)

0.15 Wj + 0.005 W2

Resistance dependent on weight

Resistance due to acceleration


Resistance dependent on


weight and acceleration

Resistance Due to Curvature | RAILWAY ENGINEERING - Contents | Tractive Effort of a Locomotive