Road structure – process – or apparatus – Traffic steering device or barrier
Reexamination Certificate
1999-09-20
2001-02-20
Will, Thomas B. (Department: 3673)
Road structure, process, or apparatus
Traffic steering device or barrier
C256S013100
Reexamination Certificate
active
06190085
ABSTRACT:
The present invention relates to a railing or barrier, which is intended especially for roads and bridges.
Barriers of the types used for roads and bridges should be highly crash-resistant. Therefore standards for such barriers have been set by road administrations in different countries. Most standards prescribe that the barrier should have elements absorbing the impact at the same level as the hub caps, i.e. a longitudinal beam positioned on the normal level of the hub caps of the vehicles. Since passenger cars and trucks have different wheel diameters, these elements must have a considerable vertical extent. The most common construction therefore is an impact-absorbing profiled metal sheet of European standard. This profiled metal sheet usually has two longitudinal ridges and an intermediate groove. The heads of the mounting bolts are arranged in this groove so as not to immediately touch vehicles sliding along the barrier. This type of barriers functions excellently as impact-absorbing elements but are unfavourable since they block the view. This is a particularly great disadvantage of bridge barriers especially in urban and motorway environments since vehicles approaching a crossing adjacent the end of the barrier are in many cases difficult to see. Also for aesthetical reasons, a clearer view should be preferred, above all in areas much frequented by tourists. It has therefore been suggested that this impact-absorbing profiled metal sheet be divided into individual impact-absorbing rods or tubes. Changing to such impact-absorbing elements, however, causes an additional problem since the road administrations in different countries require that the surface of the barrier facing the pavement be smooth and have no extensible mounting elements. As examples of this technique mention can be made of GB-A-1,209,191, GB-A-1,417,109, GB-A-2,266,910, U.S. Pat. No. 3,276,750, FR-A-2,698,643 and WO 88/00628.
With a view to improving the strength and increasing the crash resistance of road and bridge barriers, it has also been suggested that the individual impact-absorbing rods or tubes be replaced by steel cables or that steel cables be inserted in through holes in the individual impact-absorbing rods or tubes. Road fencing having bare steel cables is frequently used along motorways, whereas U.S. Pat. No. 2,907,552 can be mentioned as an example of road fencing and bridge barriers, in which the steel cables are enclosed in longitudinal tubes.
Bare steel cables are approved by the road administrations for road fencing between roadways, but not as bridge barriers. This depends on the fact that the cables often yield outwards when subjected to impact, such that in difficult cases the vehicle can temporarily move upwards almost one metre past the original position of the steel cables in their non-affected state. When the steel cables are fully enclosed in tubes as is the case in the above-mentioned U.S. Pat. No. 2,907,552, this outward flexing is reduced to a considerable extent or fully eliminated. A further reason why it is preferred to have the cables fully enclosed in a protective tube is that unprotected cables when subjected to impact mill or cut the body of the crashing vehicle open. Precisely this effect of unprotected cables has made many road administrations completely ban the use of unprotected cables on levels above the normal level of hub caps. An unprotected cable at the upper edge of a bridge barrier of normal height could cause severe personal injuries since the cable in that case would be on a level with the windows of passenger cars. To enable the use of steel cables also at levels above the normal level of hub caps, U.S. Pat. No. 2,907,552 has suggested a road or bridge barrier with specially designed posts having laterally directed U-shaped cable mountings, which besides serve as mountings for the mounting of U-shaped impact-absorbing rods.
The prior-art road fencing with fully enclosed steel cables certainly has great advantages over road fencing with bare steel cables, but also suffers from a considerable drawback. They are difficult and, thus, expensive to mount since the steel cables must be passed through the tubes and only after that be subjected to tensile prestress.
The known road fencing according to U.S. Pat. No. 2,907,552 is advantageous compared with road fencing with fully enclosed steel cables since the cables can be mounted separately in their cable mountings before the U-shaped covers or impact-absorbing rods are pushed sideways over the holders and fixed by means of bolts. A problem with the barriers or road fencing according to the last-mentioned US patent specification is, however, that the U-shaped covers or impact-absorbing rods and their fixing bolts must be mounted before the cables are tensioned, at least in connection with fencing through curves, where the fencing is positioned along the side where the cable is located on the concave side of the road fencing. In this prior-art construction, the fixing bolts for the longitudinal U-shaped covers or impact-absorbing rods in fact hold the cables in the cable mountings. Another problem of this known construction is that the holes in the longitudinal U-shaped covers must be bored in a workshop or, in most cases, on the occasion of mounting since the distance between the rods is not always exactly according to the specifications. Since the fixing bolts for the U-shaped covers also serve as fixing means for the steel cables, it is not sufficient to use merely the steel cables as temporary barriers during the building time. It is in fact an imperative labour safety requirement that at least temporary barriers are erected during this time.
If a protective barrier according to U.S. Pat. No. 2,907,552 is subjected to a light crash, which after all is most common, the steel cable is in most cases intact whereas the U-shaped protective sectional element must be replaced. If the barrier is arcuate along the concave side of a curve, the above problems arise since the fixing bolts serve to hold the steel cable sideways.
A further drawback of this prior-art construction is that the steel cables are subjected to the weather and, which is most serious, also to road salt when the opposite roadway is being cleared of snow. It is true that the steel cable can be protected with a plastic layer, but since the steel cable is not protected against sunlight from all directions, the service life of the plastic protective layer is affected.
Prior-art road fencing and barriers thus suffer from different kinds of drawbacks. An object of the present invention therefore is to provide a new barrier, in which these drawbacks have been obviated or, in any case, reduced to a considerable extent.
A further object of the invention is to provide a new barrier, in which the need of making holes adjacent to post mountings is obviated, such that the need of preparation at the working site is reduced to a minimum.
A further object of the present invention is to provide a barrier, whose impact-absorbing elements consist of one or more longitudinal, pretensioned steel cables and in which these cables can be rapidly mounted on the posts of the barrier and be tensioned to serve as temporary protection before the other barrier components are mounted.
One more object of the invention is to provide a barrier, which has longitudinal, pretensioned steel cables as principal impact-absorbing elements and in which these steel cables are essentially protected against the effect of sunlight and road salt.
Another object of the invention is to provide a barrier, which owing to its construction can be easily supplemented with an elongate fibre-optic light guide or light-emitting diode which is adapted to serve as road marking and which is protected against damage in connection with the clearing of snow and other road maintenance.
According to the invention, these and other objects are achieved if the barrier is designed as defined in the independent claim. The dependent claims define particularly preferred embodiments of this invention.
Summing up, the
BCC Baltic Construction Company AB
Luedeka Neely & Graham P.C.
Markovich Kristine M.
Will Thomas B.
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