Field and background of the invention The present invention relates to a safety arrangement in the form of a guide rail for fixing to a plurality of posts along the boarder of streets. The guide rail is composed of a series of longitudinal rail segments fixed end to end by fastening means. The segments have a C-shaped cross section or are pipes with rectangular cross section.

In prior art guide rails the individual segments are con- nected together by prismatic tongues whose outside dimen- sions correspond to the interior cross section of the rail segments. They are fastened to both adjoining ends of the rail segments by screws.

This type of mounting is expensive and time consuming on the construction site. Dismounting, as well, is time con- suming since for removing a single rail segment about 40 screw connections have to be removed. After accidents on divided highways this often is not possible because of the urgency to remove parts which would endanger traffic. For this reason the damaged guide rails at the site of the accident are often simply cut off with welding torches or cutting discs.

Summary of the invention The present invention substantially reduces or avoids the above mentioned disadvantages of prior art safety arrange- ments. The required number of fastening means is substan-

tially reduced as well as the time for mounting and dis- mounting which is simplified. Nevertheless the strength of the connection is at least as high as or higher than in prior art systems.

A prime aspect of the present invention consists of a safety arrangement in the form of an elongated guide rail for fixing on posts. The guide rail comprises a plurality of longitudinal rail segments connected together end to end by fastening means. The segments have a C-shaped cross sec- tion or are pipes with rectangular cross section. Each seg- ment has on one end an end section with reduced cross sec- tion the outside dimensions of which corresponding to the inside dimensions of the opposite end such that adjoining rail segments can be connected by telescoping and fasten- ing.

By this means an easy joining of the rail segments is achieved. No prismatic tongues are required and only half of the fastening means, e. g. bolts and nuts, are necessary.

The reduced number of fastening means also reduces the risk of vehicles getting caught in an accident.

The reduction in cross section of the end section may be achieved by cold forming, preferably by forging in a die.

The resulting interior structural deformations and aniso- tropic properties lead to an increased strength of the end section. Therefore the strength of the connection of ad- joining rail segments is at least as high or higher than the prior art connection with a separate tongue.

Preferably the end section is at least twice as long as the overlapping length of adjoining rail segments. This way a

single rail segment can easily and quickly be removed from a row of rail segments and be replaced by a new rail seg- ment in a case of damage.

If the overlapping length is defined by aligned bores no additional makings are required to define that length.

Preferably the fastening means are screw elements, e. g. bolts and nuts. These screw elements are readily available in the required strength and shear resistance, if required in stainless steel. Other fastening means are also possible but are more cumbersome in use and/or have a lower strength.

Preferably the C-cross section comprises an upper and a lower thigh which are connected on one side by a strap and extend on the other side into flanges which are parallel to the strap. This shape results in optimum strength at low weight per unit length.

If some of the screw connections are offset from a common plane of the others the strength of the connection can be increased because more screw connections can be arranged without hindering the mounting.

Brief description of the drawings A preferred embodiment of the invention is described here- inafter with reference to the drawings in which: Fig. 1 shows a guide rail along a street, Figs. 2 to 4 show the top view and the side views, and

Fig. 5 is a cross section of the connection of adjoining rail segments.

Detailed description of a preferred embodiment The safety arrangement according to the present invention is a guide rail 1 shown in Fig. 1 as it is installed along a dividing strip of divided highways or along the boarders of streets. The segments 3 of the guide rail 1 are mounted on posts 2 in known manner. Each segment 3 has on one of its two ends an end section 4 with reduced substantially cylindrical or prismatic cross section of a length 2A. this end section 4 forms a single piece part with the C-shaped profile of the main part of the segment 3 via a frustro- conical or frustro-pyramidal transition section K. The end section 4 is inserted or telescoped into the non-reduced end 5 of an adjoining segment 3 with an overlapping length A which is at most half the length 2A of the end section 4.

The C-shaped profile of the segments 3 comprises an upper thigh 6, a lower thigh 8 and a strap 7 connecting the thighs 6,8 on one side.

For mounting, a first segment 3 is screwed to its posts 2.

The end section 4 of the next segment is inserted into the unreduced end 5 of the first segment 3 by the overlapping length A and fixed to the first segment with screws 10 in a plane s perpendicular to the longitudinal extension of the segments 3. The second segment 3 is also screwed to its posts 2. In that way guide rails 1 of any desired length can be mounted. Each of the segments 3 can be replaced in- dividually in the guide rail 1 in that on both of its ends the screw connections 10 are removed as well as the connec-

tion to the posts 2. The segment 3 to be replaced is then slid longitudinally up to the transition section K into the adjoining segment 3. A slight play between the outside di- mensions of the end section 4 and the inside dimensions of the unreduced end 5 of the segments 3 allows tilting of the segment 3 to be removed and removal. The required play can easily be calculated based on the length L of the segments 3 and the overlapping length A.

The enlarged representations of Fig. 2-5 show further de- tails. On the side opposite the strap 7 the thighs 6,8 have flanges 9 which are substantially parallel to the strap 7.

These flanges 9 serve as lateral guides in the telescope connection and increase the bending strength of segments 3.

As can be seen in Fig. 3 and 4 the screw connections in the flanges 9 are spaced from the plane s of the other screws 10. This simplifies mounting and improves use of space and strength of the connection.

The cross sectional view of Fig. 5 along line V-V in Fig. 4 shows the massive interlocking connection of two adjoining segments 3 with their end sections 4,5.

In a practical example of a straight guide rail 1 the seg- ments 3 have a length L of 3996 mm, a length 2A of the end section 4 of 260 mm and an overlapping length A of 120 mm.

The strap 7 is 180 mm high, the thighs 6,8 are 150 mm wide and the flanges 9 are 34 mm high. The segments are of zinc- plated steel S235 IRG 2. The guide rail meets all the re- quirements laid down in the guide line LS ISO'180, part B of the Swiss federal department of environment, traffic,

energy and communication, section streets, ASTRA, Bern, Switzerland.

Of course the invention can also be used along curved streets. For small radii of curvature bent segments 3 can be used.