While the conventional railway system of using trains on steel tracks is an excellent way to travel longer distances within and between cities, for some occasions, different types of railway systems might be a better solution. For instance, they might be faster, cheaper, safer or require less maintenance.

Monorails, for example, are a popular for smaller distances within a city. Consider the famous San Francisco cable car, which has a unique system to cope with the hilly areas in the city – this is just like mountain railways that need a special system to ride on steep grades above 7 to 10%. Or think of the Maglev train in Shanghai, the fastest commercial high-speed electric train, which uses its ability to transport passengers to and from the Pudong International Airport. In this unit, each special system will be further explained, but first a short evaluation of each is given, answering why certain systems were developed, and why they are still used nowadays. 

Type of system	Monorail	Suspended monorail	Straddle monorail	Cable car	Rack railway	Maglev
Name	Schwebebahn	Siemens H-Bahn	Seattle Center Monorail	San Francisco Cable car	Middleton Railway	Shanghai Transrapid
Place	Wuppertal, Germany	Dortmund, Germany	Seattle, USA	San Francisco, USA	Middleton, UK	Shanghai, China
When was this system implemented?	1901	1984	1962	1873	1812	2004
Why was it implemented?	There was a need for large scale transport, and the space above the River Wupper was the only available, and thus a monorail was built above it.	To connect the north and south campuses of the University of Dortmund.	Used to transport guests of the 1962 World’s Fair.	The first cable car was introduced after Andrew Hallidie saw a horse-drawn streetcar slide backwards on wet cobblestone, killing the horses.	The rack railway was added when steam locomotives were introduced and more traction was needed to carry the heavy coal loads on the track.	Fast connection to transport passengers from the Shanghai Pudong International Airport to the city centre.
Advantages	It is elevated and thus does not interfere with other transport.	The suspension and propulsion system of the monorail is covered by the railway and thereby protected from the weather.	The narrow beams of the monorail cast a smaller shadow, and thus it is more pleasant for residents.	Used to make ascending and descending hilly areas of the city more easily.	Enables trains to climb steep hills of approximately 7 to 10%.	Fast transportation.
Disadvantages	Derailment of the monorail can occur more easily, although only one fatal accident has happened.	Turnouts and junctions are costly to built and operate.	Requires special accommodation for disembarking passengers during an emergency.	Transport relies heavily on skilled gripmen.		Only suitable for long distances and expensive to built.
Why is this system still relevant today?	Still used by 24 million passengers each year to travel between Oberbarmen and Vohwinkel.			Although often not used by locals, it is a major tourist attraction in San Francisco.	Rack railways are still used to travel along steep grades to provide extra traction.	Fastest rail transportation method in the world.

In 1821 Henry Robinson Palmer was the first man to patent an elevated railway. It was a monorail suspended on 2 wheels above a cable with a carriage hanging on either side of the cable. The carriage was pulled forward by a connected rope between the carriage and horses. When Palmer presented his study, he wrote: 

“In order to retain a perfectly smooth and hard surface, unencumbered with extraneous obstacles to which the rails near the ground are exposed, it appeared desirable to elevate the surface from the reach of those obstacles and at the same time be released from the impediments occasioned by snows in the winter season.” 

Source quote: Palmer, H. R. (1823). Description of a Railway on a New Principle. London: J. Taylor. pp. 1, 2, 33-35

 Image on the right: Henry Palmer’s elevated railway pattern

Although monorails are not towed by horses anymore, the monorail still has some resemblance of his design, especially the Wuppertal Schwebebahn which is called the ‘only real’ monorail. However, the term monorail has been broadened and is nowadays defined as a “single rail serving as a track for passenger or freight vehicles. In most cases rail is elevated, but monorails can also run at grade, below grade or in subway tunnels. Vehicles are either suspended from or straddle a narrow guideway. Monorail vehicles are wider than the guideway that supports them.” 

As monorails are often elevated, they do not interfere with other traffic flows and does not have to deal with intersections, traffic jams, red lights and such, giving them an advantage over for example trams and busses. Likewise, it makes them safer, as the only collisions that can occur are those with other vehicles on the same track. Furthermore, these elevated tracks can often be built above existing roads or rivers making it an excellent solution in busy cities. 

There are three basic types of monorails used in the world. The so called ‘only true’ monorail, the Schwebebahn in Wuppertal, Germany, the suspended monorail and the straddle monorail. In the next section, each monorail is described in more detail. 

The Schwebebahn is the ‘only true’ monorail in the world riding in Wuppertal, Germany since 1901. It is a suspension railway riding 12 meters above and along the Wupper River for 13.3 kilometers transporting nowadays almost 24 million passengers per year. The monorail was built above the river Wupper when a need for a large scale transportation system arose, but a lack of space was present in the area. So it was decided to use the space above the river to create the Schwebebahn monorail. 

Picture: Original Keiserwagen of the Schwebebahn in Wuppertal

The train cars run on two dual wheeled bogies, which carry both the load and propulsion of the train car. The double flanged steel wheels run on a single steel rail powered by a single motor. This system was developed by Carl Eugene Langen. The flanged wheels are what keep the vehicles on track. However, by only having one wheel, the monorail is more prone to derailment. Although this only happened once during the existence of the Wuppertal Monorail, it caused a fatal accident in 1999, when one of the maintenance workers left an instrument attached to the rail, causing the vehicle to fall off its track and plunge into the river below.  

Left: Keiserwagen Schwebebahn (picture by Rob Dammers)

Right: Suspension of Schwebebahn monorail (picture by Matthias Böhm)

Elephant jumps out of monorail

Although the Schwebebahn and suspended monorails hang beneath their tracks, both have very different suspension mechanisms. As mentioned before the Schwebebahn has a steel wheel rolling along a steel track whereby the double flanged wheels guide them along the track. Suspended monorails, however, often have multiple bogies with rubber wheels that drive inside concrete beam boxes. The vertical oriented wheels drive on the lower face of the hollow box and are used to suspend the monorail, while the horizontally orientated wheels provide guidance and stability along the track. The vehicles can reach up to 60 km/h, while keeping noise levels very low due to the rubber tires. The enclosed hollow box, however, has its advantages and disadvantages. It keeps the bogies protected from any weather conditions, whether it is rain, snow or frost, but it makes turnouts and junctions costly to built and operate. This makes maintenance to the bogies more difficult. 

 Picture on the right: Suspended monorail

One example of a suspended monorail is the Siemens H-Bahn in Dortmund, Germany, used to connect the north and south campuses of the University of Dortmund. This monorail made use of SAFAGE’s system, where a bogie from the Paris metro was converted to suspend vehicles from a track, thus making it an aerial railway. The railway service began in 1984, only covering 1.05 kilometers with 2 trains. Later the track was expanded and now consists of 3.16 kilometers of track. 

One example of a straddle monorail is the Seattle monorail. This track was developed to transport passengers to and from the World Fair in 1962, and was later bought by the city of Seattle. The track is only 1.54 kilometers long and has 2 vehicles driving up and down their own tracks. It connects the Seattle Center with the Westlake Center, transporting around 2 million passengers each year. 

Picture: Illustration of a straddle monorail

As each vehicle travels along its own route, you would think that no accidents could happen. However, after the space between the tracks had to be reduced to make room for the Westlake Center, insufficient room was left for two vehicles pass each other, resulting in a collision in 2005. 

Left: Seattle Monorail leaving the museum of pop culture (picture by Steve Ginn)

Right: Seattle Monorail accident (picture by Garrett Fitzgerald)

The cable cars are pulled by a cable running just underneath the city floor, held by a grip, which grips the cable to move forward. The cable is powered by a power house where it is kept running at a constant speed of 15.3 km/h. A ‘gripman’, whose skills are heavily relied upon, uses the grip to hold onto the cable and to move forward, both on level ground as well as up and down a hill. S/he then releases the cable to be able to break for passing traffic in front of them. The gripman needs to perform different tasks depending on the situation the car is in. 

Picture: San Francisco Cable Car

Picture: Grip mechanism cable car (shown closed without cable) (picture by HaeB)

Picture: San Francisco cable car (picture by Garrett Fitzgerald)

In the image below, the gripman would perform a partial release. During passenger and other stops, the grip is opened up slightly so that the cable is still inside the grip but slides freely so the car does not move. This allows for stops without the grip man having to pick up the cable each and every time.

Partial release of the cable

Next, the cable car needs to pick up speed to travel forward. As the grip level is pulled back, the grip clutches the cable, accelerating the car up to its maximum speed (see second and third image). The acceleration is a smooth process as the cable is lubricated with pine tar that evaporates under the heat and pressure of the grip, giving a metal to metal contact that allows for a strong grip. 

Accelerating up to maximum speed 

Lastly, sometimes it is necessary to drop the cable out of the grip completely. This is done by fully opening the jaws. This is necessary for cable crossings, switches, particular curves and at the end of a line. 

Full release