HighStep for electricity pylons
Requirements from a constructor of new wind power plants perspective
Modern wind power plants have hub heights of 150 metres or more. During the construction of the towers, the erectors have to climb to the actual highest point to perform their tasks, such as bolting tower segments together. Conventional systems only allow the erectors to climb up using their own muscle power, so they have to climb up to an ever increasing height several times a day.
The first case concerns hybrid towers, the first 80 metres of which are concrete. Such towers take up to 9 weeks to construct, during which time the concrete segments are cast on-site. The tower grows a little each day. The steadily increasing height of the tower makes it impossible to use a conventional lift operated via rope hoists. Instead, a swaying work platform is hoisted via a motorised rope winch. On arriving at the top, the erector has to use a ladder to reach the work platform. All in all it is a very unsafe solution.
The second case relates to the construction of full-section steel tube towers, which are delivered at the height of the flange without platforms. During construction, the platform provides a standing area from which each bolt of the flange can be reached. If there is no platform, several ladders have to be extended up the tower so that the erector can reach all the bolting points at the top end of the tower. Here again, climbing has to be done manually, it is impossible to use conventional service lifts.