Although similar to trains, cable transport systems are in a class of their own. Some of you may refer to them as streetcars, but they play a decisive role in the US $80 billion public transportation industry.
The cable transport system uses an extensive array of cables to move cars around cities. Although the shape of these cars may look like trains or buses, they work very differently.
They do not have individual engines, whether internal combustion or electric, but rely on powerful central motors to pull them.
The peculiar spot cable transport systems occupy makes them fascinating. In one way, they look like trains, while in another, they look like regular buses.
We will lead you through all you need to know about them, including:
- History of the cable transport systems
- How they work
- Advantages of cable cars
With that in mind, let us get started on their history.
History of Cable Transport Systems
We will get into the nitty-gritty of this iconic transport mode soon. In the meantime, let us run through history to see how it came.
The use of cables for transportation dates back to 250 BC. This knowledge is evident in South China’s illustrations of aerial ropeway transportation frameworks.
However, it wasn’t until 1616 that the world witnessed the first mechanical ropeway, thanks to the Venetian designer, Fausto Veranzio. He might have started the design, but it took a Dutchman, Adam Wybe, to build a functional system in 1644.
The people in the Alpine areas of Europe caught on to this technology and developed it further. Subsequently, we had wire ropes and electric drives.
The gravity incline prides itself on being the earliest form of a cable transport system. It featured two parallel tracks on a steep gradient, with one rope connecting the trains of wagons.
The rope wound around a winding drum, which featured a break to control the speed. Of course, this design did not take passengers; instead, it transported goods.
The London and Blackwall Railway was the first cable-hauled street railway. However, using fiber to grip the haulage rope caused several technical issues, and these challenges paved the way for the adoption of locomotive engines.
As time passed, the technology grew, resulting in the first successful deployment in California. The world had Andrew Hallidie to thank for that when he successfully used steel cables. This move subsequently opened the Clay Street Hill Railroad.
The clever iteration used a human-operated grip, making it possible to start and stop the car securely. Also, multiple and independent vehicles could run on one line, thanks to the strength of steel.
This concept gathered attention and soon saw widespread adoption as new lines opened up in San Francisco.
How It Works
Now that we have seen a brief history of cable transport systems, we can proceed to the working principle. They are similar to train pantographs, except the cars are not electric.
The cable cars have no inherent propulsion system but depend on a central engine to pull them. With such force comes the need for a strong rope. We will get to this in a bit.
The central propulsion system could be a steam engine or any powertrain. These systems drive the supersized cables connected beneath the street with the internal wheel movement.
All the driver has to do is grip the moving cables and lose them when braking. Also, tracks run under the cars to guide them as they haul across the city from one stop to the other.
Each cable in the transport system has its configuration of winding wheels. With constant use comes expansion and loss of tension. As a result, the maintenance crew must move the wheels backward to regain pressure.
The cables can go above one inch in diameter and contain six steel strands. To further enhance the strength, 19 wires wrap around a central rope.
As mentioned earlier, the cars require a grip to latch onto the moving cables. The system uses a mechanical grip to accomplish this action, although some lines, like the California Cars, have two.
These grips look like giant pliers as they clip the robust cables. For this reason, the drivers of cable cars go by gripmen or gripwomen.
For now, the average speed of the cable transport system clocks at 9.5 miles per hour.
If you see a cable transport system going beyond this speed, it is probably traveling downhill. In such a case, the grip might not be firm. Now, let us see some specific movements.
Gripping and Letting Go of the Cable
As mentioned earlier, the car must hold on to the moving cable for movement, which is how it transports passengers and goods from one point to another.
Cable transport systems use a grip and release mechanism to achieve smooth motion. One design is where the conductor pulls a lever in the street, lifting the cable for the car to grip it.
In another design, the tracks have a dip that lowers the car and the grip below the cable. This configuration allows the conductor to stay while the car grips the steel cable.
When Two Cable Cars Cross Paths
Before we continue, we must address this peculiar situation. Cable cars cross paths, as seen on the Powell and California cable lines.
The California Line, by original design, has the upper cable, meaning the cars grip the rope as they move past Powell Street.
On the other hand, the Powell Street cars drop or release the cable before crossing the California steel tracks. Of course, the result would be catastrophic if they held on during the crossing.
To further deter the happening of a crash, the Powell Street lime has a few safeguards. First is the alarm system that alerts motorists and other road users of the incoming vehicle.
Then, an automatic release mechanism releases the cable from the car. If the Powell Street car holds on to the rope for too long, this safety feature kicks in.
Nevertheless, skilled gripmen and women are always alert to prevent an accident. They manually handle the engagement and disengagement of the cable lines.
Stopping a Car
This section in this cable transport system expository is about stopping the cars. Like every locomotive, there must be some mechanisms to stop the vehicles.
Cable cars use three different brakes at various instances to stop themselves. They include wheel brakes, track brakes, and emergency brakes.
Let’s begin with the wheel brakes. Do you remember the drum braking mechanism in some older cars? The wheel brakes in cable transport systems work similarly.
Each wheel features steel shoe operators that pull against them to stop the car. For the California line, the crew activates them from both ends of the vehicle.
The Powell cars have only one activation point. Notwithstanding, we have foot pedal activation for California and lever actuation for Powell cars.
Onto the next one, the track brakes. Each car has four pieces of wood, each two feet long, and the precise material to make them is Monterey Fir.
As the gripman pulls the track brake lever, the woods or blocks lower and press against the tracks. This action results in the car’s stoppage. Note that the track brake lever is next to the cable grip lever.
Cable transport systems feature emergency brakes in the case of, you guessed it, emergencies. This mechanism kicks in if the other braking systems fail, which they rarely do. Nevertheless, the gripman must pull the red emergency brake lever.
The emergency braking system slams an 18-inch steel wedge into the slots between the tracks. With such force and friction, the car has no choice but to stop immediately.
Turning the Cable Cars
We have addressed the essential functions of moving and stopping the cable car. It is time to see what happens to these cars when they reach the end of the line.
The turning technology will not be novel if you have seen a train turntable. While these mechanisms make turning easy, they do not turn the cable car’s entire length.
Once the cars get to the turntables, the gripmen release the cables. The latter reverses separately under the street and wraps around a large wheel in a sheave pit.
Working a turntable sometimes takes manual energy, although we have automated systems now. The conductor and the gripman often step down from the cars after mounting them in the turning mechanism.
Then, they grab a stanchion on each end, walk the car around, or use pipework to turn the mechanism. That was how the operators turned the early cable transport systems.
Newer cable cars have grips and brakes at both ends, eliminating the need for turntables. Once they reach the end of the line, the gripman switches places with the conductor and moves the car in the opposite direction.
The California street cars use this system. Also, a spring at the terminals keeps the cars from derailing during departure.
Applications that Suit Them Best
After reading this piece, you may wonder why cable transport systems exist. After all, we have cars and trains to cater to goods and passengers.
Before you think further, let us go back to the mines. Those places relied heavily on cable transport to take the miners and bring the raw minerals; you cannot use trains or buses for such functions.
Now, let’s track back to people transport. Of course, there would be no need for cable transport systems in areas with extensive and intricate road networks, which would be a poor allocation of resources.
What about remote regions with mountains and ski slopes? While we could use trains, buses would be a no-go, and cable cars are the best solution to transport people and goods in such applications.
Making and implementing cable cars creates less environmental destruction and obstruction. Unlike trains, this transport system can operate safely in streets, including heavily populated areas.
In skiing resorts, cable cars reign supreme, and they are the safest means to transport skiers to the high mountains.
Advantages of Cable Transport Systems
The cable form of transport is a crucial one for inter-city and intra-city movement. It may not have the large carrying capacity of trains or the versatility of sedans, but it has its strengths.
We have seen this system’s importance in ski resorts and mountainous regions. That is already an advantage over other transport forms, as it suits these conditions best.
Let us list some advantages of the cable transport system.
1. Less pollution
Cable cars do not have inherent propulsion systems. That is, you cannot find engines on individual vehicles. This absence, of course, means fewer emissions to the environment.
One central propulsion system can pull multiple cars, unlike sedans and SUVs with engines. Although steam or combustion engines might be the primary drivers, modern systems use more efficient engines.
2. Better suited for inconsistent terrains
As mentioned several times in this article, cable transport systems work best in inconsistent landscapes. Such situations may pose challenges for road construction.
That leaves cable cars as the only viable option to transport passengers across the terrain. Construction is more straightforward since cable tracks require less environmental impact or destruction.
Take skiing resorts that feature high mountains, for instance. It will be a poor allocation of resources to construct roads or train tracks to transport skiers up and down the slope. So, we see how viable constructing cable cars are in these challenging scenarios.
Cable Transport Systems – Final Thoughts
Cable transport systems occupy a special spot in the transportation industry. They may not have the capacity of trains and are unnecessary in well-road interconnected cities. However, they present a solution we cannot overlook in specific situations.
Such conditions include inconsistent terrain, often found in skiing resorts. Road or train track construction would be overkill and avoidably expensive.
Engineers rely on heavy-duty engines and wheels to scale through to pull cable cars up the slope. A brilliant solution, if we must say.
Cable transport systems have fewer emissions, as one engine can pull several cars. That gives room for the environment to flourish.
Do you think we need more of them in our cities? Let us hear your thoughts in the comment section.