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, R_{6} = 0.15 + 0.005 W_{2} (25.10)
Resistance due to acceleration, R_{7} = 0.028aW (25.11)
where W_{1} is the weight of the locomotive in tonnes, W_{2} is the weight of the vehicles in tonnes, W is the total weight of the locomotive and vehicle in tonnes, i.e. W_{1} + W_{2}, and a is the acceleration, which can be calculated by finding the increase in velocity per unit time, i.e., (V_{2}  V_{1})/t, where V_{2} is the final velocity, V_{1} 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 
Remarks 
Resistance due to friction (Rj) 
0.0016W 
Resistance independent of speed 
Resistance due to wave action 
0.00008 WV 
Resistance dependent on 
track irregularities, and speed (R) 

speed 
Resistance due to wind, or 
0.0000006 WV^{2} 
Resistance dependent on 
atmospheric resistance (R_{3}) 

square root of speed 
Resistance due to gradient (R_{4}) 
W x % of slope 100 
Resistance dependent on slope 
Curve resistance for BG (R_{5}) 
0.0004WD 
Resistance dependent on degree of curve 
Resistance due to starting (R_{6}) 
0.15 W_{j} + 0.005 W_{2} 
Resistance dependent on weight 
Resistance due to acceleration 
0.028aW 
Resistance dependent on 
(R7) 

weight and acceleration 
⇐Resistance Due to Curvature  RAILWAY ENGINEERING  Tractive Effort of a Locomotive⇒