Power Line Surveying
Surveying for power transmission routes and towers. El-Eman Office provides infrastructure surveying.
Choosing the route and reducing impact
In power line surveying, route selection is the most important decision, because it determines the number of towers, the length of the line, the construction cost and the number of landowners affected. Selection begins with alternative routes on maps and satellite images, which are then reconnoitred in the field and compared by terrain and obstacles such as buildings, roads, canals, farms, airports and other lines. The route should be as straight as possible to reduce angle towers, which are more expensive, while avoiding high-water land or weak soil.
The longitudinal profile and tower heights
The surveyor draws the longitudinal profile of the ground along the route, and the engineer uses it to fix tower positions and heights so that the conductors keep a safe clearance above the ground and obstacles, even when they sag and expand in the heat. Inaccurate levels directly affect the safety of the line: an error in the level of a road crossing could mean inadequate clearance.
- Crossings of roads, railways, rivers and other lines are measured with extra accuracy.
- Trees and buildings close to the corridor are recorded.
- Tower positions are set at suitable levels, avoiding the bottoms of drainage channels.
Setting out, documentation and land ownership procedures
During construction, tower centres are set out by coordinates and the limits of their foundations are marked, and fixed points are established for reference during erection. A schedule is also prepared of the land and structures the line passes over or whose corridor falls on them, which is the basis for ownership and compensation procedures. After completion the line is documented as built, with tower coordinates and levels, and serves as a reference for maintenance and for neighbouring urban planning so that nothing is built inside the corridor.
- Study route alternatives on maps and identify obstacles.
- Carry out the reconnaissance and longitudinal profile with progressive accuracy.
- Set out tower centres and check the distances between them.
- Deliver an as-built map with detailed coordinates and levels.
The line and its surroundings
Lines pass through farmland, built-up areas and desert, each with its own challenges. On farmland, the aim is to reduce the number of towers and avoid crop damage. In built-up areas, the line should not pass over buildings and must respect the electrical corridor. In desert areas the difficulty may be access and moving dunes. Bird flight paths in some areas and nearby airports must also be considered. The surveyor is the link between the electrical engineer and the environment, supplying the maps and profiles that help in the choice.
Frequently asked questions
Why does a line need a longitudinal profile?
Because the height of the conductors above the ground changes with tower height and the sag between two towers, and the profile shows the real shape of the ground.
What is LiDAR used for on existing lines?
It records conductors, towers and nearby trees accurately, showing where vegetation or buildings are getting close to the line.
Is a drone used alone?
It is useful for quick surveys but needs ground control points, and important measurements such as crossings are still made with precise ground instruments.
