The gauge of Chinese and Russian railways differs, posing a significant risk of derailment if the train wheels aren't changed. Why do the two countries have this difference in gauge? How was the world standard gauge established?

World Standard Gauge:

There are currently over 30 different gauges worldwide, broadly categorized into narrow gauge, standard gauge, and broad gauge. Gauges smaller than 1435 millimeters are considered narrow gauge, with main sizes including 1067 mm, 1000 mm, and 762 mm, used primarily in countries like Japan, Vietnam, the Congo, and Zambia. The standard gauge is precisely 1435 millimeters, used by the majority of countries, comprising around 60-70% globally, including China, the UK, and the USA. Gauges larger than 1435 millimeters are classified as broad gauge, predominantly represented by Russia, Argentina, and Chile.

Why standard gauge 1435 Millimeters?

Why was 1435 millimeters chosen as the boundary between broad and narrow gauges? Why is this gauge considered the "standard gauge"? The answer lies in the width of two horse's backsides over 2000 years ago.

Over 2000 years ago, Roman chariots pulled by two horses were prevalent in Rome, with the distance between the two wheels coincidentally matching the width of two horse's backsides – "4 feet 8 1/2 inches," which equates to 1435 millimeters. Subsequently, the designer of electric trams, influenced by his work with horse-drawn carts, adopted the same gauge for tramways. When the railways were developed in England, they initially followed this standard, and later, the UK assisted the USA in constructing railways, where they also adopted the same gauge. Over time, 1435 millimeters became established as the standard gauge.

Is There a Difference in the Advantages of Broad and Narrow Gauges?

Let's first consider the load-carrying capacity. Despite having a gauge of only 1067 millimeters, typical of narrow gauge railways like those in South Africa and Queensland, Australia, the amount of cargo carried by trains in each run is still substantial, comparable to the load-carrying capacity of Russia's broad gauge. As for the load capacity of narrow gauge versus standard gauge, there is virtually no difference.

Next, let's look at construction costs. Although narrow gauge railways have smaller gauges, they still require substantial track laying. Therefore, overall, the construction costs of narrow gauge railways are similar to those of standard gauge light railways. Only when the gauge is less than 3 feet can significant cost savings be realized, but railways with such gauges have limited carrying capacity and are primarily used in sections like mountain railways with restricted capacity, and are rarely used in normal sections.

As time progresses, countries are gradually seeking to expand and integrate their railway networks. It's expected that the gauges of various countries may further converge towards the standard gauge in the future. However, achieving global standardization in the short term may be challenging, and there is still a long way to go on the road to global railway integration.