Road structure – process – or apparatus – Traffic director
Reexamination Certificate
1999-10-28
2001-10-23
Pezzuto, Robert E. (Department: 3673)
Road structure, process, or apparatus
Traffic director
C404S012000, C359S551000, C359S552000, C359S547000
Reexamination Certificate
active
06305874
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a road-marking complex comprising at least a first and a second road-marking unit.
The invention further relates to a road surface provided with a road-marking complex.
The invention also relates to a system for marking roads comprising one or more road-marking complexes, a control system for the road-marking complexes and means for coupling the road-marking complexes to the control system.
Such road-marking complexes are used in traffic-control systems for marking traffic routes for vehicles, such as roads for cars and other road users, and runways for aircraft. One of the methods used by traffic planners in their attempts to reduce traffic jams is a so-called “tidal flow system”. In such a dynamic system, the direction of the traffic of multi-lane roads is changed at one or more lanes in accordance with the direction of the main flow of traffic. In an alternative embodiment, the number of lanes available to traffic moving in a specific direction is increased or reduced, dependent upon the amount of traffic. A problem with these methods resides in the indication in a flexible manner of the direction of the desired flow of traffic for a specific lane, or in changing the arrangement of the traffic route in a flexible manner. Known means for indicating the desirable direction of the flow of traffic include signaling lights beside or above the traffic route.
Said road-marking complexes cannot only be used as dynamic road-marking complexes; they can also be given static applications. Static applications of road-marking complexes include marking parts of traffic routes (for example straight parts or bends) so as to give guidance to the direction of the traffic under certain weather conditions, for example during fog, rain, black ice, etc., and/or under certain light conditions, such as daylight, twilight, a low position of the sun, night, etc.
Road-marking complexes can be provided in a road surface of the traffic route but also beside and/or above the traffic route, for example on a crash barrier at the side of the traffic route.
WO 87/04230 describes a system for defining and controlling traffic routes, wherein road-marking units emitting visible light are provided in the road surface at a distance from units generating said light. In addition, means are provided for transmitting heat to the road-marking units to make sure that these road-marking units function properly under different weather conditions.
A drawback of the known road-marking complex is that it is impossible to emit the light in such a way that the road user observes lines.
SUMMARY OF THE INVENTION
According to the invention, the first road-marking unit comprises a first base plate which is provided with at least a first light source,
the second road-marking unit comprises a second base plate which is provided with at least a second light source,
in a plane enclosing an angle of 0.1 to 8° with a line which connects the first light source to the second light source, light beams originating from the first and the second light source demonstrate a uniform overlap in this plane, at a distance of at least 40 meters from the first light source.
In the description of the current invention, a “light source” is defined as a unit which emits (visible) light, the origin of the light not necessarily being situated at the location of the light source. For example, light emitted by the light source may also be generated at a distant location and may be transferred by means of light guides, such as optical fibers, from a so-called light generator to the light source. The term “light source” generally does not refer to light generated by reflection of light, in particular light emitted by a vehicle which is reflected at the location of the “light source”. Furthermore, in this description, light beams which demonstrate a “uniform overlap” are to be taken to mean light beams which cannot be distinguished by the human eye under the above-mentioned conditions.
In accordance with the invention a road user, for example a motorist or a truck driver who, from his vehicle, looks ahead at the traffic on the road and the markings in the road surface, observes at a distance equal to or above 40 m that the light beams originating from the first light source in the first road-marking unit and from the second light source in the second road-marking unit demonstrate a uniform overlap. Light originating from the first and the second light source is perceived as an imaginary “white” line under these conditions. This is the case particularly if the light originates from a plurality of such light sources, for example a suitably chosen (two-dimensional) arrangement of light sources. A particularly suitable example of such an arrangement is a two-dimensional array of 6×4 light sources, wherein six light sources are arranged one behind the other in the surface of the road, in the observer's direction of view, and four light sources are arranged next to one another in the surface of the road in a direction transverse to the observer's direction of view. Said six light sources situated in the extension of the observation field of the road user are provided, in accordance with the inventive measure, in such a manner that, given the view angle of the observer, light beams originating from said light sources demonstrate a uniform overlap at a distance equal to or above 40 m. Said four light sources, which extend transversely to the direction of view of the road user, are so closely spaced that the human eye cannot distinguish these four light sources at a distance equal to or greater than 40 m. An observer situated at a distance greater than or equal to 40 m from the whole arrangement of 6×4 light beams originating from said light sources, the angle of view of the observer ranging between 0.1 and 8°, perceives said arrangement of light beams as an imaginary line in the road surface. The present invention can particularly effectively be used when the distance a between the road user and the first light source ranges from 40≦a≦100 m.
Preferably, a distance d between the first and the second light source lies in the range from 10≦d≦25 cm. In this manner, a good display of the imaginary line is obtained by means of a limited number of light sources. If the distance d is smaller than 10 cm, a large number of light sources are necessary to achieve the desired effect. For distances above 25 cm, the coherence of the light sources is such that they are no longer perceived as forming a coherent object (imaginary line) by the road user. Particularly suitable is a distance d in the range between 15 and 20 cm.
An embodiment of the road-marking complex is characterized in accordance with the invention in that the first and the second base plate of the road-marking units form a solidly constructed base module. Such base modules can be readily produced and can be bodily provided in the road surface, preferably when the road is under construction. In addition, the electric conductors or the light guides, which generate the light for the light sources, can be readily provided on or in a side of the base module facing away from the light source. The use of a base module has the further advantage that it is not necessary to provide, for each road-marking unit, a connection to the (light) generator underneath or in the road surface; instead, one connection to the (light) generator is provided for each base module comprising a number of road-marking units.
In a preferred embodiment of the road-marking complex in accordance with the invention, the base module is at least partly provided with means for increasing the skid resistance of the base module. Very advantageously, said means comprise a pattern of bumps. A high skid resistance is desirable in order to provide for under all kinds of weather conditions, a good contact between the wheels and the road surface provided with the base module, thus precluding skidding. Polyurethane is a very suitable material for the manufacture of the base mod
Custers Adrianus C. W.
Den Dulk Jacob C. P.
Kruijt Wanda S.
Meekes Gabrielle J. B. M.
Provo Kluit Pieter W. C.
Halajian Dicran
Pechhold Alexandra K.
Pezzuto Robert E.
U.S. Philips Corporation
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