Route maintenance: biotopes along the transmission routes

Our integrated vegetation management (IVM) planning is an innovative concept for power line route maintenance that unites both ecological and economic benefits. At the heart of this concept is the basic principle of maintaining existing biotopes in such a way that operation of the line is not disrupted and the natural habitats along our routes can develop sustainably. To this end, the concept comprises maintenance measures designed to foster and develop vegetation that is typical of the respective region.

Implementation of these measures is based on our IVM plans, in which all areas of our overhead line routes are mapped and divided into ‘maintenance units’. The plans for integrated vegetation management are put together in close collaboration with external experts, such as biologists, nature conservation and forestry authorities. We consult with local associations and landowners on a case-by-case basis. The respective maintenance measures are planned for a period of ten years and documented accordingly. Our key guiding principle, therefore, is to carry out maintenance measures more frequently, in smaller areas and more gently instead of infrequently and intensively. We put this proven approach into practice throughout our entire grid.

An opportunity for nature conservation

Through our measures, we’re promoting vulnerable habitats such as arid biotopes and wetlands. But our maintenance concept is also bearing fruit along the 2,000 kilometres our routes cut through woodland. It has led to the rise of stable and highly structured borders to the woods and forests that offer varied habitats for a multitude of species worthy of being protected. The fact that a number of our route sections have been designated as German or even European nature reserves (Fauna Flora Habitats = FFH areas, for instance) confirms how effective our maintenance measures are. The construction and operation of power lines, therefore, by no means has to conflict with nature conservation, landscape protection and the protection of birds.

The basic principle of integrated vegetation management

Maintaining our power line routes and protecting nature go hand in hand for us. The principle we follow is to cut back trees and shrubs as selectively, carefully and with as much foresight as possible. The main aim of our maintenance measures is to create an adequate safety clearance between the conductor cables and the vegetation. To this end, we remove fast-growing species of tree and shrub and promote slow-growing varieties.

A description of the picture follows:
The information graphic in landscape format with a white background shows a cross-section through a route. In the middle of the picture there is a stylized mast.
Below the mast the bottom of the ground is coloured purple and named "Normalschutzstreifen". The area to the left and right of the normal protection strip is considerably larger and named "forest protection strip".
The vegetation in the area of the normal protection strip is kept low. The height of the wider forest protection strip is cut wedge-shaped from the central axis of the route to the outside.
Stylized insulators are also drawn hanging on the trusses of the stylized mast. A dotted line from top to bottom is drawn under the masts, which ends at some height above the ground. The corresponding legend states: "sag of the resting ladder rope".
Based on this line a 45° angle is drawn. The corresponding legend indicates: "sag of the swung out conductor rope".
At the left edge of the infographics a high tree is drawn, from the top of which a curve goes in the direction of the mast and ends with some distance beside the foundation. The corresponding legend indicates: "Fall curve of the marginal tree with reached final growth height".
At the right edge of the infographics a high tree is drawn. The legend indicates: Limitation of the final growth height by promotion of forest edge structures.
End of the picture description.

At the same time, we do take regional differences into account. At the periphery of the protection strip and close to the pylons, trees and shrubs may grow considerably higher than in the middle of the span; this allows a smooth transition between the route vegetation and the adjacent commercial woodland. The stepped, stable and highly structured peripheries of the woods and forests offer varied habitats for a multitude of species worthy of being protected. In this way, we make sure that our overhead lines operate reliably and preserve and foster existing biotopes.

Route maintenance today: more frequent and less intensive intervention

A description of the picture follows:
The information graphic in landscape format with a white background shows a cross-section of two lines with a stylized mast in the middle. On the left, it is surrounded by stylized trees, some pale blue, some pale red.
Below it is written: "Before the care measure".
The pale red coloured trees are missing on the right graphic.
Below it is written: "After the care measure".
End of the picture description.

In order to create an adequate safety clearance between the conductor cables and the vegetation, we now intervene more frequently. We cut back trees and shrubs as carefully and with as much foresight as possible.

Route maintenance previously: infrequent and intensive intervention

In the past, maintenance measures were carried out infrequently but intensively. All of the trees and shrubs along the route were removed completely and an aisle was cut through the forest.

Route maintenance with underground cables

Routes with underground cables generally need to be cut back even more than those with overhead lines. Since the routes in forest areas also need to remain free of deep-rooting trees and shrubs and the cables have to be readily accessible in the event of a fault, the amount of maintenance work necessary is much higher.