This invention concerns a safety fence for roads consis¬ ting of poles inserted in the ground and buffer rails extended between the poles and attached to one side of the poles, said buffer rails being tubular structural steels, which are placed on one, two or more levels above the ground.
The object of the present invention over the known art is to increase the flexural resistance of the longitudi- nal buffer rails, which makes it possible to increase the distance between the central points of the poles * The invention will also make it possible to arrange the poles with optional relative distance independent of the length of the tubular structural steels. With the means of attach¬ ment it is also possible to easily adjust the distance of the buffer rails over the ground. A further object of the invention is to make it less time consuming to assemble the safety fence and also to make it less time consuming to exchange damaged parts of the fence.
The invention is characterized by that the outer contour of the section of the tubular structural steel includes two parallel extended lines, which are joined by a third line to form an U-shaped section, the syπir.etry line of which coincides with an extension of the symmetry line of the section of the tubular structural steel so that along the steel it is formed an U-shaped rib, which is directed towards the poles and is attached to the poles by a screw mechanical joint attached to the poles. In the following the invention will be described with reference to the enclosed drawings.
Fig. 1 shows a section of one buffer rail and a part of a pole according to the invention.
Eig. 2 shows a view A-A from above of the buffer rail end pole.
Fig. 3 shows a section of an alternative form of the buffer rail.
The buffer tube 1 and the pole 3 are formed from tubular structural steels. When assembling a new fence a hole is taken up in the ground for the poles in a known manner.
The buffer tubes are placed in correct height over the ground and in correct lateral position on temporary supports,which are placed between the holes in the ground. The poles are therefore attached to the buffer rails or buffer tubes by means of a mechanical joint 2 and adjustment is carried out in level and lateral posi¬ tion before the screws 5, 6 respectively of the mechani¬ cal joint are tightened. The fence has now its correct position in height and lateral position.Injected concrete is now pumped into eachpole so that the space between the pole and the side of the hole is filled up. When the ■' .concrete has set.the support between the holes or rather the poles can be take.n away and the fence is ready to be used. It is possible to reinforce the pole, i.e. by inserting a perforated structural steel when the injected concrete has been pumped into the pole. It is also possible to reinforce the buffer tubes by filling the tubes with injected concrete or with in¬ jected concrete and sheeting.
If one wishes to increase the gripping between the pole, the sheeting and the concrete, the sheeting is preferably welded to the pole before being galvanizated.
As can be seen from Fig. 1, the buffer tube 1 has the form of a tubular structural steel with a U-formed rib 4,
which is extended along the length of the buffer tube. The mechanical joint is attached displacable on the pole 3 and consists of a clamping opening in which the rib of the buffer tube is inserted and 'clamped with a screw 7.
In order to adjust the buffer tube in height, the mechanical joint 2 is released from the pole. If a part of the tube of the buffer has to be exchanged after being damaged the tube is cut with a saw and a new tube part is inserted instead of the damaged part by using a welding and/or and interior smaller pipe.
The buffer rail can consist of one or several longitu- dinal tubular structural steels. With the expression tubular structural steel is meant not only structural steels having a circular cross section.
Fig. 3 shows an another embodiment of the rib 4.