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Economics/Track Ballast - Alternative Materials.


QUESTION: Dear Dr Raza

Which could be the alternative materials which can be used / tried out instead of Ballast or crushing stones ?. viz Cement, plaster of Paris, sand, metal, non metals etc for railway tracks ?.

Awaiting your reply,

Thanks & Regards,
Prashant S Akerkar

ANSWER: Hi Prashant,

This is a big question which requires substantial research in terms of the following:

1.   Use of the alternative materials
2.   Relative availability of the alternative material (compared with existing ballast)
3.   Applicability of the alternative material
4.   Sustainability of the material against rolling of trains over time
5.   Cost of embedding and maintenance of alternative materials

I don’t claim to possess any robust knowledge on the above or more factors responsible for consideration. In fact, this study need be conducted jointly by engineers, financial analysts and economists –something like the feasibility reports produced by the World Bank or by India’s IDBI or ICICI [If you happen to be near Mumbai, please visit the IDBI, an excellent institution where I worked for a short time a long while ago under the United nations Development Project; they are very knowledgeable]. I would, however, like to put you on to following important factors regarding the tackbed:

1.   The trackbed has to be laid out so that the ground on which sleepers are placed are not only tough to a certain degree (but not excessively) but also resilient enough to meet the “stress” which is inevitable when wheels roll with heavy load and the “elasticity” which is called for under varying climatic conditions.
2.   There has to be sufficient “porosity” in the materials to allow proper “seepage” of rain water (such as in Kolkata), mud (such as in Ajmer) or sludge (such as in some Northern regions). This “porosity” is essential for extending life of sleepers.
3.   The materials should have the property to extirpate growth of vegetation or at least to keep down vegetation, especially in non-desertic areas.
4.   Whatever goes to make the trackbed need be available in ample supply and available at affordable cost. That must also be in constant supply.

On the face of it, crushed stones in India seem to yield the following advantages: (a) there are available, though not in all places, in sufficient quantities; (b) labour-intensive methods may be gainfully employed; (c) transportation along roads and railway is possible; and (d) allows good porosity and strength. These, to me, also have the disadvantages: (a) these materials do not have the necessary “cohesion” and may undergo disintegration and ultimate reduction in requisite magnitude; and (b) there is created bedrock propitious to vegetation that is a big problem for maintenance.

We have to consider the advantages and disadvantages of the other materials side by side.

Cement, to be, does not pass the test. Cement mixing with earth forms strong, solid boulder-like piece. If this were for a small area, cement could probably be the ideal thing. However, the trackbed goes into kilometers after kilometers of narrow solid. Cement is unlikely to produce the requisite “level” bed. One way could be using big slabs with gaps in between. But the question is, how far this is possible and feasible. Secondly, railway sleepers “need” resilience as the trail rolls on, and cement is a bad material for that. Further, we may not rule out the cost factor.

Metals may pose the same problem. But there is more to it. Engineers may have to consider the “conductivity” when laying the metal bed. Both climatic conditions and static electricity effects are some outwardly prohibiting factor.
Plaster of Paris may pose cement-like problem to a certain extent. But the “brittleness” may pose another problem, especially in respect of “maintenance” and “denudation.” Plus, it is not going to be cheap.

I have the feeling that, given technology permits, sand could be a good alternative. Yet sand has the possibility of sand blown away into dunes in certain weather. However, with mix of other materials like crushed stones or mud-like materials (such as adobe is the U.S.), sand could be an alternative. The advantages are: (a) good porosity; (b) inhibition of vegetation; (c) good resilience; and (d) good for sustaining sleepers (even wooden sleepers).

You have to properly weigh both the advantages and disadvantages of these materials from the perspective of an engineer, a financial analyst and an economist. I hope,Prashant, this gives you an inkling of how you may proceed with your interesting investigation. Best.  

[an error occurred while processing this directive]---------- FOLLOW-UP ----------

QUESTION: Dear Dr Raza

Thank you.

If we create a Word document with four columns viz. Material, Advantage, Disadvantage and Conclusion, will this be a good reference for Materials evaluation as a alternative to Crushing stones ?.

The Train should run more efficiently on the railway tracks with the New Material installed viz Cement, Sand, Plaster of Paris, Coal, Metal, Non Metal etc instead of the crushing stones. Maintenance has to be taken into picture.

I also feel Rutherford's periodic table could be a useful reference.

Awaiting your reply,

Thanks & Regards,
Prashant S Akerkar

Dear Prashant,

I think you are on the right track. With my limited knowledge, I would be inclined to consider this a good first step towards comparative analysis of crushing stones and substitutes as building materials of suitable bed for laying railway tracks along routes that may vary in natural constituents and in divergent climatic conditions.

Advantages and Disadvantages may each have appropriate sub-columns showing well-defined suitable rubrics. For example, under the Advantage column, we may set forth (a) relative availability, (b) relative properties (you may put the name/names from the periodic table), (c) renewable or nonrenewable, (d)  marginal benefit in use for railroad bed over marginal benefit in use for other purposes (such as use in reservoirs, house-building,macadamized roads, etc.), (e) conformability to desirable environmental standards (such as sand or cement or that improper coal use could cause surphur dioxide emission but use in railroad bed could forestall acid rain by extirpating formation of particulates), and so forth. Under the Disadvantage column, we may set forth (a) relative scarcity, (b) relative  irreversibility of depletion, relative consequences of environmental damage, (c) cost of transportation, (d) relevance to negative externality or spillover effects (such as deforestation or denudation of alluvial soil), etc.

Under conclusion, you may as well bring our "future benefits" and "industry linkages" (such as a boost to transport industry, employment generation and diversity, and so forth).

I have a feeling reference in appropriate instance to a table like that from the modern periodic table (not only from Rutherford but also from Chadwick and others). This may be very interesting but difficult for people who like me are not experts in chemistry.

I wish you success in this new line of thinking.  


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Eklimur Raza


It appears some students in this website are confused about elasticity of demand and the slope of the demand curve when they are trying to figure out why rectangular hyperbola comes up in case of unitary demand curve. First, they don't know that RH can be depicted in a positive quadrant of price,quantity plane. Secondly, they make the mistake that the slope of RH is constant at -1. Two points could help them: first, e=1 at each and every point of the RH, because the tangent at any point shows lower segment=upper segment (another geometric definition of e); yet slopes at different points,dQ/dP, are different; second, e is not slope but [(Slope)(P/Q)]in absolute terms. Caveat: only if we measure (log P) along the horizontal axis and (log Q) up the vertical axis, can we then say slope equals elasticity --in which case RH on P,Q plane is transformed into a straight-line demand curve [with slope= -tan 45 deg] on (log Q),(logP) plane, and e= -d(log Q)/d(log P). [By the way, logs are not used in college textbooks --although that is helpful in econometric estimation of elasticity viewed as an exponent of P, when demand equation is transformed into log-linear form.] I have not found the geometrical explanation I have given in any textbook followed in undergraduate and college classes in Canada (including the book followed in a university where I taught for a short time and in the book followed in George Brown College, Toronto, where I teach.


About 11 years' teaching economics and business studies, and also English, history and elementary French.Practical experience in a development bank, working with international donor agencies like the World Bank and the ADB. Experience in free-lance journalism, including Canada's "National Post."

I teach micro- and macroeconomics at George Brown College (continuing education), Toronto, ON, Canada.

Many articles and editorials, on different subjects, in English newspapers. Recently an applied Major Research Paper, based on a synthesis of the Solow growth model and the Lewis two-sector model, has be accepted by Ryerson University, Toronto. Professors Thomas Barbiero and Eric Cam, Ryerson University, accepted the paper.

Master degree in Interantional Economics and Finance and diploma with honours in Business Administration from Canada.

Awards and Honors
Received First Prize in an inter-university Literary Contest.

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