This refers to "Can the railways sweat its assets better" (Business Line, December 23). Indian Railways (IR) has been repeatedly announcing its goal to run freight trains at 100 km per hour. The present average operating speeds of freight trains is around 20 km per hour. Statistically, a freight train runs 400 km per day which means 20 hours of effective operating time.

To achieve greater average speeds, a number of proposals have been put forward in terms of additional capital assets in signalling, track modernisation, rolling stock upgradation and so on. The golden quadrilateral railway network is considered the most strategic and heavily used routes for passenger and freight traffic. On closer examination of parameters required to operate at 100 km per hour, it is found that standards are set for speeds of 120 km per hour. Most routes are equipped with multiple aspect colour light signalling and token-less block working. The locos and wagons are designed and manufactured for 100 km per hour. Yet the speed of the freight trains is still of the order of 30-40 km per hour. The main reason for this difference is the power employed to haul freight trains.

Loop-lines at all stations on the main lines are capable of accommodating 58 BOX-N type wagons, which form the bulk of the rolling stock. The carrying capacity of these wagons is marked as 58 tonnes but IR allows loading up to 60 tonnes.

The gross weight of a fully-loaded BOX-N is about 86 tonnes. Thus, the load to be hauled by the motive power comes to about 4,840 tonnes. The terrain on the various trunk routes is generally made up of plateaus, hilly regions and mountain ranges. Some sections are flat such as the Gangetic Plains between Delhi and Kolkata. Almost all other routes from North to South pass through the Vindhya-Satpura ranges and the Eastern and Western Ghats.

The gradient on all these routes is of the order of 1 in 250 to 1 in 400 in most sections. Though the permissible speed on almost all rail routes is 100-120 km per hour, the passenger carrying trains are able to achieve this speed due to their lower weight. The much heavier freight trains are able to maintain speeds of only 35-40 km per hour even on non-stop runs. This is on account of the inadequate motive power hauling these trains. The balancing speed of a freight train worked by two standard diesel locomotives of WDM2 is of the order of 30-35 km per hour, implying that achieving speeds in the region of 100 km per hour is not feasible by two loco operation.

With three locos it may be possible to achieve speeds of 50-60 km per hour on an average. These speeds may be comparable to that of express and mail trains and section capacity can be greatly improved due to less time of occupation of block sections.

The most important parameter for transportation is the power employed per unit weight of the hauled load. The double-headed goods trains with 58 BOX wagons, 86 tonnes each, or a train-load of 5,000 tonnes, have installed power of about 6,400 horse power (hp) with two locos of 3,200 hp. This gives a ratio of 1.4 hp per tonne. The ratio must be at least 2 hp per tonne.

So instead of investing on heavy capital expenditure on fixed assets to improve track standards and the like, it will be worthwhile to pulling all freight trains with three locos instead of the present two; this will give it a power weight ratio of 1.92 hp per tonne.

With more 4,000-hp locos of WDG 4 class locos being inducted into the system, three locos of aggregate 12,000 hp hauling 5,000 tonnes will give 2.4 hp per tonne. This will improve greatly the operating speeds of freight trains comparable to that of express trains making it operationally possible to eliminate precedences and consequent stopping and starting of heavy freight trains wasting lot of time and fuel as well as section capacity.

M. P. Sankaranarayanan,

Railway consultant,

Secunderabad

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