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TECHNOLOGY ROADMAP: TRANSPORTATION

TABLE 2.2: MAXIMUM FREIGHT LOAD CARRIED BY A SINGLE DISTRIBUTED POWER TRAIN

AUSTRALIA SOUTH AFRICA CHINA
Railway/Service BHP Spoornet Daqin

Haulage distance (km) 276 861 655
Train Load (t) 99,732 41,000 20,000
NA ______________________
Train Length (km) 7.3 ______________________ NA
No. of wagons 682 342 208
No. of Locos 8 11 8

Remarks Diesel Locos Diesel+Electric Locos mix Electric Locos

2.3 AXLE LOAD enhanced design features, which adds to input cost.
The axle load of a wheeled vehicle is the fraction Hence, compromise is sought for an optimum
of total vehicle weight resting on a given axle. axle load.
Axle load is an important design consideration
in the engineering of railways, as exceeding the Many developed railways have adopted axle loads
maximum rated axle load will cause damage to that are much higher than the axle load limits
the tracks. A given section of track is designed for used in Indian railways. Increased axle load directly
a prescribed maximum axle load. The maximum increases the throughput, as can be seen from
axle load is related to the strength of the track, Table 2.3[15]. For the same length of trains (58
which is determined by weight of rails, density wagons), the throughput increases considerably.
of sleepers and fixtures, train speeds, amount of
ballast, and strength of bridges. Because track and Table 2.4 shows the axle loads prevailing in
especially the rails are expensive, it is desirable to some of the highly developed freight operating
optimise the track for a given axle load. If the track railways[16]. In contrast, Indian Railways operate at
is overloaded by trains that are too heavy, it can be an axle load of 20.5 tonne. Efforts are being made
damaged in a short time[14]. now to increase the axle load to 22.9 tonne and
later to 30 tonne in the dedicated freight corridor.
Increasing the axle load means increasing the Even after achieving this, there is still a gap when
load carrying capacity of the wagons. At the same compared with countries like the USA and South
time, it further stresses the track. This demands Africa.

TABLE 2.3: AXLE LOAD VIS-A-VIS THROUGHPUT

AXLE LOAD IN TONNES TRAILING LOAD IN TONNES TRACK LOADING DENSITY t/m
20.32 4831 7.67
22.9 5410 8.25
25.0 5800 8.82
30.0 6960 10.58

TABLE 2.4: AXLE LOAD IN FREIGHT OPERATING RAILWAYS

US Rail Roads 32-35 tonnes
Australia 22 tonnes

Chinese Railways 25 tonnes

South Africa 30 tonnes

India 20.5 tonnes

RAILWAYS 141