Mountainous Terrain Challenges Korea‘s Transmission Expansion, Vertical Segmented Steel Poles Emerge as Technical Solution
I. The Reality of Construction Constraints in Mountainous Terrain
Approximately 70% of South Korea’s land area consists of mountainous and hilly terrain, forcing transmission lines to traverse major mountain ranges such as the Taebaek and Sobaek Mountains. Historically, Korea‘s transmission and distribution networks have relied on two primary support structures: lattice towers and conventional tubular steel poles. However, as voltage levels have increased, the base diameter of steel poles has expanded significantly — for 154kV and above lines, base diameters can exceed 2.6m — introducing substantial transportation challenges.
Transportation bottlenecks represent the primary constraint in mountainous construction. Korea’s mountain roads are characterized by numerous tunnels with clearance heights typically limited to 4.0–4.5m. When a steel pole‘s base diameter exceeds this limit, conventional integral transport becomes impossible, requiring either lengthy detours or segmented transport. Detours often add tens or even hundreds of kilometers of extra distance, significantly increasing both transport time and cost under mountainous road conditions.
Installation site limitations pose a second critical challenge. Construction sites in mountainous areas rarely offer sufficient working space for large cranes and heavy transport vehicles. Traditional construction methods rely on large cranes for integral hoisting, yet on narrow ridges or slopes, such equipment simply cannot access the site. This conflict has become particularly acute in Korea’s recent mountainous transmission projects — as environmental concerns tighten right-of-way corridors, available working space has further diminished.
II. Vertical Separated Tubular Steel Pole: Technical Solution Explained
In response to these constraints, the KEPCO Research Institute formally proposed the Vertical Separated Tubular Steel Pole in 2019. The core concept involves longitudinal segmentation and modularization of the pole‘s cross-section, decomposing the conventional monolithic large-diameter pole into multiple prefabricated modules that can be assembled on-site.
Modular design ensures that each unit‘s dimensions and weight remain within the capacity of medium-sized transport equipment. Specifically:
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Road transport scenarios: Segmented modules can be delivered via medium-sized trucks to previously inaccessible sites, eliminating the need for oversized flatbed trailers.
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Roadless mountain scenarios: Each module‘s weight can be controlled within helicopter lifting capacity (typically 3–5 tons), enabling air transport directly to the installation point.
Assembly methodology has also been redesigned. Traditional integral hoisting is replaced by a “pole-self-supporting” segmental lifting method. The specialized assembly equipment developed by the KEPCO Research Institute is installed inside the steel pole, using already erected lower sections as support foundations to sequentially lift and connect upper modules. This design completely eliminates reliance on large cranes, enabling construction to proceed normally even at sites without road access or where heavy equipment cannot enter.
III. Technical Parameters and Standards Reference
The design and manufacture of vertical separated tubular steel poles strictly comply with KEPCO‘s current technical standards framework:
GS-5445, published in 2018, represents KEPCO‘s most current technical requirements document for steel pole products, covering design loads, material properties, manufacturing tolerances, galvanizing corrosion protection, and inspection methods. The vertical separated tubular steel pole was designed within this standard framework.
IV. Application Prospects and Industry Significance
The technical value of vertical separated tubular steel poles extends beyond solving mountainous construction challenges — the solution is broadly applicable. The same approach is viable for urban dense areas, environmentally sensitive zones, and any confined site where large construction equipment cannot access.
From a market perspective, KEPCO has continued to expand transmission infrastructure investment in recent years. In September 2024, KOSDAQ-listed Boseong Powertech signed a KRW 24.4 billion contract with KEPCO for steel tower pole supply on the East Coast-Singapyeong transmission line. That same month, KEPCO initiated procurement of approximately 5,277 tons of steel pipe towers for the 500kV HVDC Donghaean-Singapyeong line. These projects involve line routing through mountainous terrain, where vertical separated tubular steel poles are poised to play a critical role.
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