Why do cities use power steel poles instead of angle steel towers for power transmission?
In the construction of urban power transmission lines, power steel towers (steel pipe towers) have gradually replaced traditional angle steel towers as the mainstream choice. The main reasons can be analyzed from multiple perspectives as follows:
1. Spatial Adaptability Advantage
Small in size
Urban land resources are scarce. For power poles, single-column or compact designs are adopted, and the foundation area is usually only 1/3 to 1/2 of that of angle steel towers. This design is particularly suitable for narrow spaces such as road green belts and sidewalks.
Example: The diameter of steel pipe poles is usually 0.5 to 1.2 meters, while the foundation of angle steel towers requires an area of 3 to 5 square meters.
High flexibility
The steel poles can be adjusted in height by segmental assembly (15-40 meters), meeting the voltage requirements of different cities (such as 10kV to 220kV) and the shading needs of buildings. However, the angle steel towers have a fixed height and require a larger safety distance.
2. Structural and Performance Differences
Wind Resistance and Stability
The steel pipe pole has a closed cylindrical structure, and its wind resistance coefficient (approximately 0.6) is significantly lower than that of the truss structure of the angle steel tower (approximately 1.2). In areas with typhoons or strong winds, it is less likely to generate vortex-induced vibrations, thereby reducing the risk of collapse.
Reference data: The steel pipe pole can withstand wind speeds of over 40 m/s, while the angle steel tower requires additional reinforcement.
Corrosion Resistance and Lifespan
The surface of the steel poles is treated with hot-dip galvanizing or composite coating technology, ensuring a corrosion resistance lifespan of over 30 years; the connection bolts of the angle steel towers are prone to rusting, and the maintenance frequency is higher (requiring 5 to 10 years of inspection and repair).
3. Economy and Construction Efficiency
Lower overall cost
Transportation and installation: Steel poles can be transported in sections, and on-site assembly only takes 1 to 2 days. Angle steel towers require disassembly and assembly (taking 3 to 5 days).
Maintenance cost: Steel poles do not need to be regularly tightened with bolts, reducing the inspection workload by more than 50%.
Landscape and Policy-driven
Most urban regulations require the "invisibility" of power transmission facilities. Steel poles can be integrated into the environment through painting or greenery wrapping, while angle steel towers are visually conspicuous and may cause complaints from residents.
4. Applicability in Special Scenarios
Avoidance of Underground Pipelines: The steel pole foundation is a bored cast-in-place pile, causing minimal interference to underground pipelines;
Multi-loop Installation: The steel pipe pole can be designed as a multi-angled or multi-loop structure (such as double-loop or quadruple-loop), saving the width of the corridor.
Exceptional cases
Steel tube towers are still applicable in the following scenarios:
Ultra-high voltage (500kV and above) power transmission requires higher mechanical strength;
Areas with low aesthetic requirements such as mountains and outdoors;
Temporary lines or projects that need frequent renovations.
Summary
The choice of power poles by cities is the result of the combined influence of spatial constraints, safety requirements, economy and policy orientation. The modular design of these poles also aligns with the upgrading trend of future smart grids.
