1. How Do Builders Make a Path to Carry Materials to the Tower Site?
Before any steel can be assembled, builders must create a way to move heavy items from public roads to the construction site. There are four main methods used for this transport: temporary roads, cableways (ropeways), helicopters, and monorails [1].
Cableways have a structure similar to ski lifts or ropeways. They are said to be used often at sites that are far from public roads and have large differences in height [2]. If the terrain and distance make a monorail cheaper, builders may choose that option instead. In steep mountain areas where even cableways cannot be installed, helicopters become necessary [2].
This means the shape of the mountain and the distance from the road determine the first step of construction. Before designing the tower itself, engineers must answer the question: "How do we get the materials up there?"
2. Why Does the Transport Method Limit the Weight of Tower Parts?
Tower parts cannot be made in just any size. The weight of each piece is limited by how it will be transported. For cableways, a general guideline suggests that items should weigh about 2 to 3 tons or less [1].
Helicopters have similar limits. The weight of the parts is restricted by the carrying capacity of the specific aircraft model [2]. For example, one source notes that a Bell 214B helicopter can carry about 2 tons or less [1]. However, these limits vary by machine, so this is just one example.
Because of these restrictions, tower parts are divided into smaller pieces during design. The need for transportable weights shapes the final form of the structure.
3. Why Are Deep Cylindrical Holes Dug for Tower Foundations?
In mountainous areas with steep slopes, a method called "deep foundation" (shinso) is considered suitable [3]. This involves digging a deep cylindrical hole and filling it with concrete.
The holes have diameters of several meters. The depth ranges from several meters to tens of meters. While digging, steel plates called liner plates are inserted into the walls as workers proceed step by step [1]. Generally, foundations are about 3 to 25 meters deep. For some large towers in mountain areas, they can reach depths of tens of meters [4][3].
If concrete mixer trucks cannot enter the site, helicopters may be used to bring the concrete [3]. The construction order is: digging, adding steel reinforcement bars, pouring concrete, curing (letting it harden), and backfilling. After completion, the land is restored to a shape close to its original terrain [4].
4. How Does a Crane Grow Along With the Tower?
Placing a large crane on a mountain top is difficult. Instead, builders set up the crane’s steel column in the center of the tower. They use the already assembled parts of the tower to support and stabilize the crane [5]. As the tower is built from the bottom up, the crane’s column is extended by adding sections to make it taller [5]. The boom at the top lifts parts into their designated positions [6].
These cranes can be disassembled and transported, which makes them useful mainly for mountain assembly work [6]. However, they have limits. One construction company’s materials state that the working height is 100 to 200 meters, and each part handled should be about 1 to 2 tons or less [1].
As in previous steps, parts are divided into sizes that match what can be lifted.
5. Why Do Workers Fasten Tower Parts by Hand at High Places?
Parts lifted by the crane are secured by skilled workers waiting at high places. They use bolts and nuts to fasten them. Ultimately, the attachment is done by human hands [5].
The size of a finished tower depends on the transmission voltage and location conditions. For standard double-circuit towers mentioned in one source, 500 kV class towers are about 70 to 90 meters high and weigh 50 to 100 tons [7]. According to power company explanations, general transmission towers are about 40 to 60 meters high. In places crossing straits, some exceed 200 meters to ensure clearance for ships [8].
Helicopters may also be used when stringing the power lines themselves.
6. What Can You Look For When Checking a Tower From a Distance?
If you see a transmission tower while walking or driving, try to observe it from afar. Can you see the concrete base at the foot of the tower? Is there a nearby path that might have been used to bring materials?
Do not enter fenced areas and do not approach the tower closely. Keep your distance. If you want to learn more, you can read pages about "the role of towers" by power companies [8] or explanations of how towers are built [3].