Catenary mast
A catenary mast or catenary support is a mast for the mounting of the overhead line of electrified railways or Oberleitungsbusstrecken . In Germany, the maximum distance between two support points is 80, the standard distance on high-speed routes is 60 meters.
Types
Catenary masts can be made of wood, reinforced concrete or steel. Wooden catenary masts are no longer used in Germany, but they are still widespread in Norway, for example. Most Oberleitungsmasten of Deutsche Bahn AG are steel masts, but are at Neuelektrifizierungen and the replacement abgängiger Oberleitungsmasten majority of reinforced concrete poles made of spun concrete used. In some cases, however, new steel masts are also erected. This is particularly the case if special designs are required (e.g. on bridges or in train stations) or if the section of the route lies in a confusing curve. The latter is related to the fact that steel masts can be designed as lattice masts, which allows the driver a better view of the route than the relatively thick spun concrete masts, especially when erecting masts on the inside of a curved track. In many countries, for example in the Czech Republic, Slovakia and Italy, tubular masts are also common. Tower masts for transverse support structures or multi-track cantilevers are usually angle masts made of steel, rectangular concrete masts are the usual design in Austria, but could not prevail in Germany. However , they are still in operation in several stations on the Halle – Cottbus railway line . As the first German railway infrastructure company , the Albtal-Verkehrs-Gesellschaft has been using catenary masts made of glass fiber reinforced plastic (GRP) in the area of the Ettlingen turning loop since August 2018 . They have been in use on the Belgian Kusttram since 2013 .
The oldest types of construction, both concrete and steel masts, were insert masts. They were placed in previously excavated construction pits, then filled with concrete. The advantage is a simple construction, but it is hardly possible to replace a damaged mast in the same place. In addition, the construction pits must be secured with shoring because of the necessary depth. The excavation was often only possible manually and the masts had to be supported while the concrete was setting. To simplify matters, attachment masts were created later. Its lower end is a flange that is bolted to the foundation with studs. With these it is possible to concrete the foundations beforehand. The installation of precast foundations is also possible, especially for support points that are not loaded in the longitudinal direction. Spun concrete poles were inserted into previously laid concrete sleeves, wedged and also concreted in. If possible, driven piles are used today. For steel masts, the driven piles are provided with a concreted mast head, driven piles for spun concrete masts have a welded tube on the top. The mast is placed on top of this and the space in between is filled with concrete. The pile foundations drastically reduce the civil engineering work.
In modern overhead line masts, a guyed or supported tubular slewing jib carries the suspension rope of the catenary system, and a side bracket linked to it directly or via a support tube guides the contact wire in the necessary zigzag. In the past, other designs were also common, for example rigid booms; in addition, many countries have their own designs due to separate development. For the pantograph to run properly, the contact wire must be properly tensioned. Post-tensioning is common, but in Spain and France, for example, there are still long stretches of track with permanently tensioned catenary. Guy masts must also be able to absorb forces in the longitudinal direction, which is why angle masts or spun concrete masts with an enlarged diameter are used. If flat masts have to be used as guy masts, for example to span construction point connections, then they are additionally stiffened with anchor ropes, similar to contact line fixed points.
Catenary masts can carry other cables in addition to the catenary. Occasionally they carry feed lines on trusses above the conductor cables to more distant catenary sections that are to be fed separately.
There are also overhead line masts with a traverse for a railway power line attached to the top . For static reasons, either only one circuit is laid on the mast (on double-track lines, each overhead line mast has a crossbeam for a traction current line) or the traction current line is suspended on the crossbeams in a two-level arrangement, with each circuit taking up one half of the mast.
The connections between the sub-centers and remote computers of electronic interlockings and between the sub-centers are usually established using fiber optic cables. For reasons of failure safety, two cables are laid in a spatially separate location. In many cases, one strand is routed in the cable trough channel and the other on trusses on the outside of the contact line masts.
Web links
Individual evidence
- ↑ Powerlines: AVG is testing contact line masts made of glass fiber reinforced plastic. In: LOK Report . August 3, 2018, accessed August 23, 2018 .