Trains

On a stormy night, the N2 train trudged silently through the dense jungle, completely indifferent to the wind and rain outside. Tung, the train's locomotive driver, felt uneasy, fearing that a fallen tree might block the tracks ahead. Occasionally, he stuck his head out of the window, trying to see, but the forest road was too dark, and he couldn’t make out anything.  Suddenly, it seemed as though a woman was clinging to the front of the locomotive, frantically waving a white scarf, as if desperately pleading for help. The image became clearer and clearer, making Tung’s heart sink. He decided to stop the train to see if he could help the woman. Stepping off the train, he wandered around searching for her. But there was no one in sight, except for a large leaf caught on the front of the locomotive, still fluttering in the wind. Tung shuddered, feeling as though he had seen a ghost.  Since the train was already stopped, Tung decided to walk along the tracks ahead to check if there was a fallen tree. Suddenly, he panicked when he discovered that the bridge ahead had collapsed! He had almost driven the train into the river below. This is part of a short story published many years ago in Saigon (perhaps inspired from The Signal-Man by Charles Dickens).

The idea of a train driver being able to stick his head out of the locomotive is truly from a bygone era, as modern train cabins are now completely enclosed, and trains no longer run on “fire” (though we still refer to them as “xe lửa” or “tàu hỏa” in Vietnamese, meaning “fire train”). Since the Middle Ages, humans were able to transport large amounts of goods via waterways. By the time of the Industrial Revolution, when massive amounts of coal needed to be transported overland, trains were invented. Later, trains were modernized to carry people, and since then, they have continued to improve into the modern era. The first steam locomotive (named New Castle, designed by Richard Trevithick in 1803 in England) was powered by steam. Notably, it utilized a crankshaft, which transformed the piston’s linear motion into the wheels’ circular motion. This method was later applied to vehicles using combustion engines. The diagram below illustrates the operating principle of a steam locomotive. You can refer to How a Steam Locomotive Works for further details.

New Castle

In Vietnam, the first steam train ran on December 27, 1881, on the Saigon - Chợ Lớn route (which ceased operation in 1953) and on July 20, 1885, on the Saigon - Mỹ Tho route (which ended operation in 1958). In Northern Vietnam, steam trains were once manufactured based on Chinese designs, such as the locomotive named Tự Lực, which was produced in the 1960s.

Sài Gòn - Chợ Lớn route

Sài Gòn - Mỹ Tho route

On the right is an image of the Vietnamese steam locomotive named Tự Lực, with the identification number 141-179, which is currently being restored (in 2024). When mentioning steam trains, many people may recall the sound of a train laboring up a slope in the song Xe Lửa Mùng 5 by Trần Văn Trạch. For more information about locomotives in Vietnam, you can refer to Types of Locomotives and Carriages Used in Vietnam.

Believe it or not, steam locomotives are still runnung in 2025 in OHIO Cuyahoga Valley Scenic Railroad: Steam in the Valley!.  

                 

In 1897, Dr. Rudolf Christian Karl Diesel (a talented yet ill-fated man) invented the locomotive powered by residual oil (also known as Diesel oil) to improve the efficiency of the combustion engine. Diesel-powered locomotives operate similarly to steam locomotives, as illustrated in the diagram below.

In 1837, the world saw the first battery-powered locomotive, invented by Robert Davidson in Scotland, but it was very weak. By 1879, Werner von Siemens introduced the first passenger electric train in Berlin, powered by 150 VDC electricity supplied through a third rail. The image on the right illustrates a type of third rail.

In 1891, Charles Brown from Switzerland built the first three-phase AC electric locomotive, with power supplied through overhead wires above the locomotive. The structure of an electric locomotive is illustrated in the diagram below.

When trains transitioned from “steam” to “electric,” the crankshaft disappeared because the wheels were turned directly by electric motors. Modern electric trains can achieve high speeds in part due to the new aerodynamic design of the locomotive, which reduces wind resistance (aerodynamic drag).

More recently, trains can even "fly" because they are lifted a few millimeters above the tracks while running! This type of train is called a maglev (magnetic levitation) train, as magnets on the train and the tracks are used to lift and propel the train. The diagram below illustrates the structure of a maglev train.

If you want to learn which countries in the world have used trains to transport passengers, please refer to The History of Train Development and How Trains Work.

In addition to the locomotives mentioned above, there were also attempts to develop other types of train engines, such as:

·        Atomic-powered locomotives (Dr. Lyle Borst, Utah University) in the early 19th century; ultimately abandoned as it was not practical.

·        Petroleum-powered trains (invented by Gottlieb Daimler in 1887).

·        Gasoline-powered trains (developed by the Maudslay Motor Company in England in the early 20th century).

·        Diesel-electric trains, which generate electricity using diesel engines to power the wheels, introduced in the late 20th century. (As of 2024, Vietnam still uses this type of locomotive). Do not confuse this with electro-diesel locomotives, which can operate using either diesel fuel or electric power.

·        Gas turbine-electric trains, which use gas and electricity.

·        Hydrail: Trains that use hydrogen either to power an internal combustion engine or to generate electricity.

Over the past centuries, trains have become increasingly faster. Please refer to the table below for the record speeds of various types of trains.

Record train speed

Locomotive	Record speed	Date	Nation
Steam “4468 Mallard Class A4”	160 km/h	1938	England
Diesel (InterCity 175)	201 km/h	1976	England
Electric TGV  (Train à Grande Vitesse)	574.8 km/h	3 April, 2007	France
Maglev	603 km/h	21 April, 2015	Japan

For further details, check out TRACK 101: How does track work? and How Railroads Design Grades and Curves to learn about:

·        How railway tracks are assembled (see Railway Track for more details);

·        How tracks are placed through city intersections (so that the tracks remain level with the road surface);

·        How the fixed distance between two rails is maintained;

·        How rail curvature is measured;

·        In curved sections, why one rail is raised slightly higher to counteract centrifugal force and prevent the train from tipping over;

·        Why train wheels made of steel (EA1N grade steel) have varying thickness in different parts;

·        The gradient of railway tracks (typically less than 2%).

For mountain-climbing trains, the gradient is often very steep, so additional cogs are installed on the track (and the train) to help the train grip the rails. To learn more, watch Riding the World's Steepest Cogwheel Railway in Switzerland's Alps | Pilatus Bahn. Regular trains that operate on moderately flat tracks are called adhesion railways (relying on friction between the wheels and rails), while mountain-climbing trains are known as cogwheel railways. Vietnam had a mountain railway that connected Tháp Chàm station (Binh Thuan) with Da Lat station. Construction of this railway began in 1908, and it wasn’t fully completed until 1932, spanning a total length of 84 kilometers. After 1975, the Tháp Chàm – Da Lat railway was dismantled; the trains were disassembled and sold to Switzerland. Switzerland restored the locomotives and now uses them to serve tourists in the Alps. Below are a few rare images of this unique railway.

Steepest Cogwheel

The Swiss-made HG 4/4 train is operating in the Ngoan Muc Pass area around 1930	Sawteeth on the rails	Train restored from an old Vietnamese locomotive

You, like the writer, may assume that trains typically run on two rails. Few people know that in 1903, engineer Louis Phillip Brennan patented a train that ran on a single rail (monorail) using the gyroscopic principle to maintain balance. On November 10, 1909, he presented his invention to the amazement and admiration of onlookers. Experts noted that this type of train was only suitable for passenger transport because the entire weight of the train was concentrated on a single rail, which could easily wear down both the wheels and the rail.

Since then, rail construction techniques and train balancing systems have been modernized up to the present day. In entertainment areas (such as Disneyland) or large airports with multiple terminals, automated electric trains—known as automated people movers—are used to transport passengers between different points. There are also suspended monorails that run overhead, as shown in the image below. It is noteworthy that monorails are designed exclusively for passenger transport and cannot carry heavy freight. You can watch the monorail in Wuhan, China, in the YouTube video The World WON'T Believe China's New Infrastructure.

	Disneyland Monorail	Japan's Suspended Train Like a Thrill Ride

To learn more about how modern diesel-electric trains work, refer to How a Diesel-Electric Locomotive Works, which covers topics such as:

·        The components of a locomotive and specialized train terminology in English;

·        Couplers that connect the locomotive to the carriages;

·        How diesel engines operate;

·        How motors power the wheels;

·        The braking system;

·        The driver’s cabin;

·        The driver’s rest area.

To understand how trains switch tracks, see How do TRAINS STEER? | Switches 101.

On October 14, 1966, the Montreal Metro inaugurated the world’s first rubber-tired underground rapid transit system. The rubber wheels, positioned on both sides of the train car, run on concrete tracks and produce much less noise compared to steel wheels on metal rails. However, this type of metro still uses guiding rails to keep the train on its designated path.

Instead of using iron rails, monorails (powered by electricity) use a single concrete guideway to direct their path. Similarly, maglev trains also use a concrete guideway for direction, but while in motion, the train does not actually touch the guideway.

If you’re curious to learn more:

1.     To find out how train brakes work, watch How Train Brakes Work: A Comprehensive Guide.

2.     To understand how automatic railroad crossing signals operate in the United States, compare it with manually controlled signals in Hanoi by watching How Railroad Crossing Signals Work (as seen in Hanoi train street).

3.     To see how rail traffic management has been modernized, check out How Centralized Traffic Control Makes Rail Traffic More Efficient.

4.     To learn why modern trains no longer produce the rhythmic sound they used to, watch Why Railroads Don't Need Expansion Joints.

5.     For the history and recent developments of Chinese railways, watch Chinese Railways: The World's Fastest Growing Railway System.

6.     To see how China builds modern railways, check out Monster Vehicles on High Speed Railway Construction.

7.     To explore a unique tourist attraction where a railway runs through a busy market in Bangkok (similar to Hanoi), watch Maeklong Railway Market in Bangkok, Thailand.

8.     To discover the world’s most dangerous railway tracks, watch 20 Most Dangerous Railway Tracks in the World.

9.     To play train-driving simulation games, watch Train Sim World.

After learning a bit about trains, you may be wondering how trains will evolve in the future. If so, check out TOP 15 Future Train Concepts. At the beginning of this video, Hyperloop trains are mentioned as an advanced type of “train” of the future. In reality, the concept of this train was proposed and successfully proof-tested (proof of principle) by a group of students at McGill University, Montreal, in early 1968, as recorded on the final page of the McGill Homecoming 2023 Reunion Address.

Finally, as a closing thought, do you know why the SRB (Solid Rocket Booster) used in the Space Shuttle program wasn’t made with a larger diameter? At first glance, this might seem like a question that’s “off track.” But in reality, it’s not. The Thiokol company manufactured the SRBs in the state of Utah, and they had to transport the boosters to Florida by train. Along the way, the train had to pass through tunnels, and the tunnel size was only slightly larger than the distance between two train rails (56.5 inches). Interestingly, this measurement dates back thousands of years - it originated as the width of a Roman chariot, which was based on the size of two horse rear ends!

	2 Solid Rocket Boosters