Project Unigauge

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Comparison of different gauges common in India with the standard one, which is not common in Inda

Project Unigauge is an ongoing exercise of the Indian Railways to standardise most of its railway lines towards a single 1676 mm (5 ft 6 in) wide broad gauge network.

Indian currently has significant quanities of four different incompatible gauges. The railways consist of around 42,000 km of broad gauge (BG) railway, 17,000 km of metre gauge and an assortment of narrow gauge lines.^[1]

1 Early History
2 Project Unigauge
3 Maps
4 See also
5 References

[edit] Early History

The project started around 1980. It was concluded that towns and cities on the metre (MG) and narrow gauge (NG) lines had a poorer service than equivalent towns on the broad gauge system. Conversion of lines to broad gauge would make the broad gauge more efficient and with more capacity, with many regauged links providing short cuts for broad gauge traffic.

[edit] Broad Gauge

Broad gauge was chosen for India in the 1850s by the then Governor-General rather than the standard gauge, with two main reasons given:

greater stability during periods of high wind and unpredictable weather.
greater space between the wheels for bigger inside cylinders, although this ceased to be a problem when outside cylinders were introduced.

The inability to source standard equipment wasn't seen to be a problem, or was overlooked. The extra cost of longer sleepers wasn't considered to be a problem, though later on the cost saving of shorter sleepers with metre gauge was considered to be an advantage.

[edit] Standard Gauge

Very small amounts of standard gauge (1435 mm) have existed in India for one-off projects and short line lengths. The only surviving example of which is the Kolkata (Calcutta) Tram system

[edit] Metre Gauge

In the 1880s, when the basic broad gauge system was looking reasonably complete, another Governor-General considered the introduction of infill metre gauge lines as this appeared to be achievable at reduced cost.

[edit] Narrow Gauge

Even narrower gauge lines were constructed on the basis of saving more money and simplifying engineering. The mentality was that if money could be saved building metre gauge rather than broad gauge, then presumably more money could be saved by building in a narrow gauge.

[edit] Absurdity

The design process during construction was taken to its extreme, with the gauge being carefully chosen to optimise costs for the traffic offering. The result being that each line might be a different gauge, even if it would have been more useful to have a through service.

[edit] Weight of Rail

An alternative way to reduce construction costs during is to use lighter track and lighter rails. Railway rails are expensive and lighter rails achieve significant cost savings.

Lighter rails can only carry lighter engines and rolling stock, but since traffic is generally less, this is not a problem. Light engines can travel on heavy main lines, but not visa versa. If needs be light track can be gradually upgraded to heavy duty track. An intermediate stage is to allow heavier engines to operate on lighter track at reduced speed.

Varying the strength of the rails, but keeping the gauge constant, could have been done instead and potentially avoiding the current break of gauges.

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[edit] Project Unigauge

Undertaking project Unigauge requires more than just changing the spacing between the rails. Existing sleepers may be too short and have to be replaced, even though these sleepers may not be life expired. Bogies on rolling stock would have to be replaced to fit the new gauge. Since the width of the previous passenger carriages are narrower than broad gauge ones, the gap between the platform and carriage may cause problems. Either the gap may be too large and thus unsafe, or broad gauge rolling stock is likely to hit the old platforms.

However, eliminating breaks of gauge improves rolling stock utilisation and therefore saves on the quantity of rolling stock required. Excess metre gauge rolling stock, much of it modern and in good condition, has a ready second-hand market in many other metre gauge railways around the World.