Once we clear the sections faster we can not only accommodate more trains, we can also plan for better maintenance time slots
Tracks need to be available for maintenance. This means that trains need to move over them fast. This in turns means that performance of locomotives needs to be improved. Above all this, there is the need to ensure safety.
Here’s how this complex problem is tackled.
While the Indian Railways (IR) struggles to retain relevance in tomorrow’s economy, frequent accidents on the railway network have exposed that it is operating under severe stress. This has led to a situation where needs of punctual running can no longer be balanced with a need to carry out critical, safety-related maintenance activities, which require stopping of train movement. Most of the maintenance activities need physical stoppage of trains, with the period for this being called a traffic block. The Railways has reached a stage where the physical time available is not commensurate with required maintenance in several locations.
This is the case on several of the routes. This has led to an adoption of expedient processes under duress and a general sense of exasperation.
Given that laying of new tracks is an expensive and long term proposition, what can be done to accommodate more trains? Conventionally, the issue was tackled by signaling innovations, investing more in awareness and grading the speeds of trains which follow each other. This brought in four aspect signaling, automatic signaling etc. However, there is a limit to how much innovations can help and that limit has also been exhausted at several high traffic density routes.
Fundamentally, we can tackle the issue in the good old way - clearing the sections faster so that either more trains can be accommodated or the track is available for maintenance for a longer time.
This calls for more motive power and that has been the key justification for inducting more powerful locomotives. Figure 1 shows how the power of electric locomotives evolved historically (IR has already made the bold decision of going 90 per cent electric in another few years).
Figure 1: Electric locomotives over the years
Historically, the world over, multiple locomotives have been concatenated together to give more tractive power. This solution causes the couplings closer to the locomotives getting stressed more and being vulnerable to breaks, which can eventually result in a parting of the train. This limits number of locomotives that can be joined together. In India, this is limited to two for higher power electric locomotives and to three for lower power electric locomotives.
The ideal solution is to haul the load with locomotives interspersed in the train, which reduces the coupler forces and also permits more effective and efficient braking. Here, the challenge is of having a remote control which can link up all these locomotives and permit operation by the crew in the lead locomotive.
So, What Is The Proposition?
Before induction of what are known as three-phase locomotives, India had a fleet of 5,000 horse power (hp) locomotives, referred to as conventional locomotives. These suffered from lack of regenerative braking ability.
Regeneration is the process where the train is braked electrically and the locomotive is made to act as an electricity generator, feeding power to the overhead conductors. This brings down energy consumption. However, this advantage accrues from the frequent need of breaking. Once speed restrictions and differential speed between trains is reduced, this advantage would be mitigated to some extent.
The conventional locomotives have several wearing components too, which handle electrical power, necessitating periodic maintenance.
A 5,000 hp conventional locomotive typically costs Rs 7.5 crore and a 6,000 hp, three-phase, regeneration-capable, locomotive costs about Rs 15 crore. Recently, IR has awarded a contract for procuring 12,000 hp locomotives from Greenfield factory at Madhepura, Bihar, which would cost about Rs 28-30 crore, each. The 12,000 hp locomotive essentially has two back-to-back units of 6,000 hp permanently coupled.
A 12,000 hp back-to-back unit also would suffer from the issue of high coupler forces near the locomotive.
If we can somehow pair a 6,000 hp, three-phase locomotive, with a 5,000 hp conventional locomotive, we would get an 11,000 hp formation but at about Rs 22-23 crore as against a 12,000 hp, three-phase unit, costing between Rs 28-30 crore. By intelligently pairing the three-phase and conventional locomotive, one can retain the regenerative capability of the ‘train’ and save Rs 6-8 crore in upfront capital expenditure.
This brings forth a very interesting proposition. We no longer would see a locomotive in isolation. We can see each 6,000 hp loco paired with a 5,000 hp loco always at each end of the load forming a motive power combo. These locomotives at the two ends of the train can dramatically reduce coupler forces and brake application and release times. To get an idea of the advantages, consider the following. A simulation was done on freight trains as they bring down section capacity drastically due to extremely poor average speeds and poor acceleration. The lessons from it apply equally powerful passenger trains and we move towards a regime where a passenger and freight train do not get differentiated on control charts as they move comparably.
Figure 2: Simulation run of a standard freight train in different scenarios
This graph brings very interesting results: an 11,000 hp combo costing Rs 6-7 crore less does offer a comparable performance to 12,000 hp combo.
Instead of 162 seconds, cheaper option takes 187 seconds for a 4700-tonne freight train to accelerate from 0-75 kilometer per hour (kmph). This should be contrasted with 377 sec taken by a 6,000 hp single locomotive as against 517 sec taken by a 5,000 hp conventional locomotive for the same load to accelerate between 0-75 kmph - which is the current practice.
Seeing An Opportunity For Jobs And Safety
At the cost of one three-phase locomotive, we can acquire two conventional locomotives. Once we pair a conventional and a three-phase locomotive together, we mitigate the disadvantages associated with conventional designs-that they can not regenerate. Also, as duty cycle on locomotives can be altered at will, the same equipment can be made to perform better.
IR has a fleet of nearly 5,000 electric locomotives of which one thousand are of three-phase type and rest are conventional. If we adopt the policy of pairing a conventional with a three-phase locomotive, we have immediate requirement of five thousand additional locomotives right away, of which four thousand would be the three-phase type and balance conventional. This would progressively release more section capacity as can be seen from the graph above. In fact, its impact on passenger trains would be even more dramatic as each train would in effect become a train set. This piece has considered only existing fleet, Chittaranjan Locomotive Works (CLW), the electric locomotive factory of our country, manufactures more than 250 three-phase locomotives a year, which would need matching conventional locomotives.
Once we clear the sections faster we can not only accommodate more trains, we can also plan for better maintenance time slots.
CLW takes about 60,000 man-hours to produce a locomotive (this includes major mechanical assemblies like chassis, carboy, bogies but does not include large assemblies like traction motors, transformers, converters etc.). The factory is fully loaded and trying hard to meet the requirement of electric locomotives. Once we look at the additional requirement of 5,000 locomotives to pair with existing fleet, work would need to be outsourced to another facility. If we use innovative manufacturing techniques and clever outsourcing, this time can be brought down to say a third of existing time i.e. 20,000 man-hours. Taking a working day of eight hours each, we conservatively create 1.25 crore man-days of quality employment. Though, one can conservatively assume that time needed for manufacturing extra equipment not included can be absorbed by existing employed manpower. Each of these items would give strong downstream stimulus (say one makes a transformer in an existing factory, but then someone supplies the tanks, stampings, conductors etc.).
R Jagannathan recently argued for a stimulus to the economy. Five thousand locomotives present an investment opportunity of nearly Rs 67,000 crore which can be spread over the period of their manufacture. This money would readily pay for itself as substantial capacity would be released to accommodate more maintenance blocks and possibly more trains. Though existing designs can be readily put into manufacture, such a plan can also factor in a strong redesign of electric locomotives ground up after a few years, without impacting the initial deliveries.
These 5,000 locomotives would have their own maintenance needs. One can consider creating one facility for 250 locomotives which translate to twenty locomotive sheds, each needing certain manpower. Innovative financing and contracting models can be thought of to create these.
Naysayers And Skeptics
The first expected reaction would be an aversion to the use of old technology locomotives. This can be readily answered on back of their performance and the fact that each class of locomotive has a big room of improvement which can be addressed without the need of a fundamental discovery. Conventional locomotives are made up of readily available material and are extremely simple to make and maintain. Being electric locomotives, they do not suffer from any tail pipe emission issue.
The ministry took the decision to discontinue manufacturing of conventional locomotives, but that decision may need to be revisited. The drawback of not being able to regenerate gets mitigated as one locomotive in each train can regenerate. Also, the conventional locomotive can be selectively fired whenever the operational need arises (for example one would not need it while cruising). New control techniques can even mitigate issues like lower power factor of conventional locomotives.
This brings us to the final likely concern. Where is the control to manage two locomotives at each end of the train with one set of the crew? This issue is now the coca cola problem - the issue is now just of packaging an available solution which has higher end specifications.
The merit of pairing a locomotive in order to provide one at each end of the train is now an operational and safety imperative and the only decision directly impacting actual train running and relieving the stress on lines.
The time for this idea has come. While relieving the stress on the network this would create a high volume of high-value employment in manufacturing, and in services, of locomotives.
Can this be part of the stimulus argued for by 'Swarajya' here?
* The author (@sujeetmishra, firstname.lastname@example.org) is a railwayman currently on sabbatical from railroads, based in New Delhi, and a Research Scholar at IIT(BHU). Views expressed are personal.