Composite road safety slip rails made from metal and reinforced wood

Composite slip rails for road safety made from round wooden bars reinforced with iron and comprising posts made from sectional iron and supporting each one a spacer carrying a horizontal guard rail consisting of previously slotted round wooden beams reinforced with embedded metal fishplates providing for the cohesion of the wood and the connection of the elements.

BACKGROUND OF THE INVENTION 
The present invention relates to safety slip rails made from round or 
cylindrical wood adapted to be placed in all the places where vehicles are 
likely to move deliberately or accidentally away from the tracks or 
traffic lanes which are assigned to them, in particular along roads and 
motorways or turnpike roads or at the borders of car parks and parking 
lots. The technical field involved therefore is the one of the manufacture 
or building of road safety devices. 
OBJECT AND SUMMARY OF THE INVENTION 
A known system is disclosed in the French patent of invention publication 
No. 2,663,968. 
The object of the present invention is the provision of guard rails made 
from round or cylindrical wooden beams or balks reinforced with embedded 
iron advantageously combining the complementary properties of these two 
materials, of iron-bound or hooped wooden spacers as well as a method of 
mounting and of manufacture which increases the reliability of the known 
systems and substantially decreases the manufacturing, transport and 
working costs. It adapts itself advantageously to all mounting situations: 
comers, hill tops, rail ends. 
The problems to be solved are the following: 
1. Wood is a heterogeneous natural material likely to exhibit points of 
lesser strength and under the shock of a vehicle, there is little bending 
but it may break. On the contrary the coefficient of friction between iron 
and wood is very great and this is a property usable with advantage for 
stopping the vehicles. 
2. The metal supports or holders are unaesthetic or homely. 
3. The metal supports should be spaced from the guard rail to avoid the 
shock with the vehicle. A spacer therefore is necessary. 
4. With the known methods the mounting operations are difficult and make 
use of multiple parts. It is therefore necessary to simplify the mounting 
and to make it versatile. 
To solve these problems, the following solutions have been found: 
1. The guard rails are reinforced on their sides opposite from the road by 
a sectional iron embedded or set in the wooden guard rail. The flanges of 
the section are accommodated within two slots parallel to the center line 
axis of the guard rail and thus are invisible, i.e. hidden. 
2. The spacer consists of a round or cylindrical wood arranged vertically 
between the metal support and the guard rail. In this manner the support 
is concealed but the spacer ends at 5 cm from the ground to avoid any risk 
of becoming rotted. For the same grounds the top end is cut slantwise or 
askew. 
3. To avoid hindering or impeding the slipping of the vehicle along the 
slip rail, the spacer may rotate about the center line axis of the 
fastening bolt. The structure is reinforced with a galvanized metal hoop 
to avoid any risk of projection. 
4. To facilitate the mounting, those metal fastening butt-straps or 
fishplates which are opposite from the road are made fast to an embedded 
sectional iron and mounted in the workshop or factory. All the butt-straps 
or fishplates are provided with elongated holes making the mounting 
possible in any situations whatsoever. If need be, the elements of the 
horizontal guard rail will have a length of two or four meters. They may 
also be mounted onto existing supports in replacement of metal safety slip 
rails without changing the support and possibly without changing the 
existing metal spacer. 
The safety device according to the invention may be put in place with the 
equipment available in those enterprises which are usually laying or 
installing metal slip rails without any particular training of the staff. 
The device comprises a limited number of standard parts: 
standard metal posts, 
wooden spacers according to the invention or standard metal spacers, 
guard rails according to the invention with a length of four meters for 
straight lines and corners or of two meters for special uses and sharp 
corners, 
fastening bolts with shouldered or collar nuts or with nuts and wide 
washers, e.g., commercial grade fasteners such as mushroom head bolts with 
square necks ("JAPY" bolts) having a diameter of 16 mm and a length of 200 
mm (referred to as TRCC 16.times.200 type); 
short connecting butt-straps or fishplates towards the road side.

DETAILED DESCRIPTION OF THE INVENTION 
FIG. 1 is a perspective view of a slip rail section according to the 
invention which consists of galvanized iron posts or uprights (1) 
according to the models approved by the engineering road and motorway 
departments, carrying a pre-impregnated cylindrical wooden spacer hooped 
with galvanized iron and itself supporting a horizontal guard rail 
consisting of cylindrical reinforced wooden elements previously machined, 
pre-impregnated and previously mounted in the workshop or factory, which 
are assembled end to end by fishplates (4), (5),(6). 
FIG. 2 shows the detail of each one of the standard elements of guard rails 
such as it leaves the manufacturing plant, ready to be mounted on the 
building site. Each one of the elements according to the invention 
consists of a wooden cylinder (3) grooved with two longitudinal slots 
which are housing in embedded relationship both flanges of a sectional 
iron (9) made fast as by welding to the fishplates (4) and (5). This metal 
assembly is secured to the wooden cylinder (3) by two bolts (10) 
advantageously mounted in the workshop. The width of the U-shaped section 
should be one third of the diameter of the guard rail. The dimensions of 
the components of the illustrated guide rail elements are as follows: the 
wooden cylinder or wooden billets 3 have a length of about 2 meters (1980 
mm) or about 4 meters (3980 mm) and a diameter of 180 mm; the fishplates 
4,5,6 have a width of 60 mm and the holes in the fishplates 4,5 through 
which the bolts 10 extend into the wooden billets 3 have a diameter of 18 
mm; the diameter of the holes in the wooden billets is also 18 mm; the 
holes in the fishplate 6 are elongated and have a width of 18 mm and a 
length of 40 mm and the centers thereof are spaced 320 mm from each other; 
and the total length of the fishplate 6 is 420 mm. 
FIG. 3 shows the detail of each one of the spacers (2) consisting of a 
vertical wooden cylinder cut at its top part according to a bevel shape in 
order to allow rain water to flow off and hooped or bound with a 
galvanized iron ring 8. During mounting, the tightening or clamping effect 
of this collar will reinforce the cohesion of the wooden cylinder and 
avoid the projections in case of bursting or splintering under an impact. 
The height is designed according to the invention to avoid the contact 
with the ground. The dimensions of the illustrated spacer 2 and iron ring 
8 are as follows: the height of the spacer is a maximum of 660 mm 
decreasing to 610 mm as a result of the bevel; the diameter of the spacer 
2 is 180 mm; the holes in the iron ring 8 have a diameter of 20 mm and the 
width of the iron ring is 60 mm; and the distance between the bottom of 
the spacer 2 and the center of the holes in the rings 9 is 520 mm. 
All the wooden parts are processed after having been machined and prior to 
the mounting by injections of salts of the CCA type, class 4 according to 
the French standard NF B 50-100 (equivalent to injections of a composition 
comprising a mixture of copper oxide (CuO), chromic oxide (CrO.sub.3) and 
arsenic pentoxide (As.sub.2 O.sub.5), manufactured and sold by the British 
firm RENTOKIL). 
Each one of the guard rail elements thus described should be made fast to 
the following one, to the support 1 and to the spacer 2 according to the 
mounting depicted on FIG. 4 by bolts 7, 10 and 11 with a diameter of 16 
mm. The elongated holes in the fishplates 4, 5 and 6 depicted on FIG. 2 
allow the adjustments according to the ground, according to the curves or 
bends of the read and according to the positions of the metal supports. 
The possible rotation about the axis of connection 11 constituted by the 
bolt assembling the support 1, the spacer 2, the fishplate 4 of a 
horizontal guard rail element and the fishplate 5 of the next element 
advantageously allows the provision of the slip rail ends without any 
modification according to the description which has been made thereof with 
reference to FIG. 5.