Traffic Lane Marking Device

1. Field

This invention relates to the art of providing visual traffic marking devices for paved aircraft landing and takeoff strips and automobile roadways Still more particularly, the invention concerns the utilization of retroreflective and fluorescent materials and the like to provide nighttime visibility at safe distances from oncoming aircraft and ground vehicles.

2. State of the Art

Currently, the predominant material for traffic lane marking is light colored paint applied directly to the traffic surface. It is economical to apply, but is so rapidly eroded by traffic and weather that it must be replaced with costly frequency. It also suffers from inadequate visibility even at moderate distances. The patent literature describes several possibly more durable and visible traffic marking devices. U.S. Pat. No. 3,011,412 discloses a method of embedding beads or other autocollimating units into a viscous, self-hardening resin based paint. The paint is applied upstanding from the traffic surface, as a center line strip, for example, and then covered with an erodeable or water soluble layer for temporary protection from traffic during the setting period. A pyramidal roadway reflector is disclosed in U.S. Pat. No. 3,627,403, designed to extend upwardly from a roadway surface. The sloping side faces of the pyramid incorporate reflective prisms covered by a transparent plastic layer. In U.S. Pat. No. 4,279,471 an elongate transparent base member is installed extending upwardly from a roadway surface. A reflective element is inserted into a lengthwise channel in the base member. All of these reflective devices protrude upwardly, obstructing and interrupting the smooth traffic surface, and constituting traffic hazards. Further, snow plows and other cleaning machines tend to damage such upstanding devices. In an attempt to alleviate this problem, U.S. Pat. No. 4,685,824 discloses a traffic marking device embedded with its upper surface even with the traffic surface. However, the only reflectivity provided is by surface beads or the like. No vertical profile is provided, so that its visibility is greatly reduced at moderate distances from the lights of the oncoming vehicles. Thus, the prior art reflective marking devices commonly either protrude upwardly from the traffic surface or suffer seriously decreased visibility from moderate distances. The latter shortcoming is particularly serious for airport landing and takeoff strips, often requiring visibility from up to a mile or more. The prior art also falls short in providing for guiding markers operative without reliance upon vehicle lights. With malfunctioning inoperative lights, the aircraft must at present hope for a not always available illuminated landing strip. Even with functioning lights, the pilot must know the strip location well enough to position his craft to direct light upon reflective markers. No practical, economical method of independently illuminating the marker is found in the prior art. Clearly, there is a need for a traffic marking device with long distance nighttime visibility, which does not interrupt the traffic surface, and is not rapidly eroded to require frequent maintenance and replacement. A further need is for such a marker with provisions for independent, nighttime self-illumination.

With the foregoing in mind, the disadvantages and shortcomings of prior art traffic lane guide markers are eliminated or substantially alleviated in the present invention, which provides a nighttime marker to be embedded into the pavement with its uppermost surface flush with the traffic-bearing surface. The marker comprises a highly visible, light responsive component shaped to provide a substantial vertical profile from the viewpoint of oncoming traffic. A layer of transparent material covers the high profile component, extending along the pavement a substantial distance therefrom toward oncoming traffic, rendering it visible from great distances. Preferably, the reflective component is contoured appropriately to promote the impingement of light thereon at desirable angles from the varying distances occurring as the oncoming vehicle approaches. The marker preferably further comprises a lowermost layer of firmly resilient material to increase its ability to resist wheel impact from traffic.

The inventive marker may further comprise electrically powered light sources installed within the transparent layer, preferably including photo-voltaic solar generating cells, storage batteries and one or more light bulbs placed to illuminate the light responsive component.

It is therefore the object of the invention to provide a highly durable traffic lane marker which does not protrude above the traffic surface, and which provides a high optical profile to be highly visible from approaching vehicles at great distances, and is visible at night without reliance upon reflection of the vehicle lights for nighttime visibility.

In the drawings, which represent the best mode presently contemplated for carrying out the invention,

FIG. 1 is a perspective view of a fragment of an aircraft runway incorporating a traffic lane marking device in accordance with the invention, drawn to a reduced scale,

FIG. 2 a plan view of fragments of a portion of the lane marker of FIG. 1, taken along line 2--2 thereof, drawn to a larger scale,

FIG. 3 a vertical sectional view of fragments of the marker of FIG. 2, taken along line 3--3 thereof, drawn to a substantially larger scale than that of FIG. 2,

FIG. 4 a longitudinal vertical sectional view of fragments of the marker of FIG. 2, taken along line 4--4 thereof, drawn to the scale of FIG. 3,

FIG. 5 a plan view of a fragment of an automobile roadway having center line reflective markers and side markers in accordance with the invention, drawn to a reduced scale

FIG. 6 a plan view of fragments of one of the center line marking assemblies of FIG. 5, drawn to a larger scale,

FIG. 7 a perspective view of one of the side markers of FlG. 5, drawn to a larger scale than that of FIG 6, and

FIG. 8 a perspective view of a fragment of the marker of FIG. 4, however incorporating a self-contained, solar powered reflective strip illuminating device, schematically shown, in accordance with the invention, installed within the uppermost transparent layer, drawn to the same scale.

An embodiment of the traffic lane marking device 10 in accordance with the invention is shown in FIG. 1 embedded into an aircraft landing and takeoff strip 11 flush with the traffic surface 12. (FIG. 3) Transverse elongate light responsive components 13 are in this application preferably spaced at intervals 14 of approximately 30 feet, as required by the high speeds of landing and departing aircraft. Lane marker assembly 10 is constructed in large part of plastic materials. Because of mold size limitations, the elongate marker strip 10 may comprise, for example, six individual segments 15, each with interlocking notches 16 and mating projections 17. (FIGS. 2 & 4) For this application, only three segments 15 incorporate the reflective cross components 13. For even spacing, a cross component 13 is installed at the notched end of end segment 18, and at the projection carrying ends of middle segment 19 and opposite end segment 20. An interval 21 of approximately 40 feet is required between successive marking assemblies 10 by airport regulations.

Each individual segment 15 of assembly 10 comprises a lowermost layer 22 of firm resilient plastic in anticipation of aircraft wheel load impact, and a transparent uppermost layer 23. The latter may be of high strength, non-shattering glass or transparent plastic, such as Plexiglass or the like, selected for hardness, mechanical durability and long-life transparency. Bottom layer 22 of segments 18, 19 and 20 each carries an upwardly projecting transverse ridge 24. The cross components 13 each comprise a ridge 24 with light responsive material 25 secured to its upstanding surfaces. A downwardly opening channel 26 in transparent top layer 23 accepts ridge 24. Material 25 may be fluorescent, phosphorescent or retroreflective. Prefabricated tape incorporating autocollimating reflective light beads, reflective prismatic objects or the like are all satisfactory reflective materials. Fluorescent or phosphorescent materials may also be incorporated into prefabricated tape if desired. Combinations of reflective, fluorescent and phosphorescent materials may be employed. A satisfactory reflective and fluorescent tape is part number C15FL-GRN-TC produced by General Formations, Inc., of Sparta, Mich., for example.

The light responsive ridges 24 are highly visible from great distances because they provide substantial vertical profiles to efficiently intercept light rays from distant oncoming vehicles. Ridge 24 is preferably shaped to present a curved surface, to help assure that the angles of incidence of impinging light rays from various distances will be appropriate for best reflection, retroreflection, fluoresence or the like. (FIG. 4)

Light rays from distant oncoming vehicles partially penetrate, but largely reflect from top surface 27 of transparent layer 23, because of the small angles of incidence. As the vehicles approach more closely, more penetration occurs. However, at all vehicle distances, transparent layer 23, acting similarly to light-transmitting optical fibers, retains and channels the penetrating rays toward the reflective ridges 24. The penetrating rays inside layer 23 reflect successively from the top side of the bottom surface 28 and the underside of the top surface 29, to ultimately impinge upon the light responsive material 25 on ridges 24.

For continued best visibility of ridges 24, top surface 27 of layer 23 is maintained by periodic cleaning. Snow may be removed with elastically-edged blades without damage to flushly installed strip assemblies 10. Debris may be removed by sweeping or brushing without scarring the surface.

Selected strips 23 of marker assembly 10 may include electrically powered bulbs 33 to illuminate reflective material 25 independently of vehicle lights. (FIG. 8) This magnifies the visible distances at night, and provides visibility in the event of failure of vehicle lights. Also, the illuminated ridges 24 become visible from side angles, assisting the pilot to initially align his aircraft for the landing approach, for example.

Preferably, a removable illuminating module, such as transparent block 34, is installed in a recess 35 in transparent layer 23, and carries sockets and leads 36 for the bulbs 33. A plug 37 connects with power lead 38 from a solar voltaic panel and battery pack 39, also imbedded in transparent layer 23 to be exposed to sunlight. A light sensitive switching means, not shown, may be employed to connect and disconnect the bulb circuit during darkness and daylight respectively. Existing photo-voltaic solar cell and battery technology may be employed for pack 39, such as that used, e.g., in the voltaic modules of Photocomm Division of ARCO Industries and Solarex Division of ARMCO.

If solar panel 39 is not desired, module block 34 may be adapted to additionally incorporate batteries, to be occasionally removed, recharged and replaced. Of course, sub-surface power leads from sources external to marker assembly 10, if practical to provide, could be used.

Retroflective assembly 10 may be constructed in appropriate sizes and configurations for other traffic lane marking applications. Example applications include highway center line markers 30, as well as highway side markers 31. (FIGS. 5-7) It is advantageous to provide side markers 31 with light responsive surfaces 32 arranged in pyramidal form, with appropriately colored reflective tape or the like on each separate pyramid face. For example, the faces projecting in the direction of traffic may appropriately be colored green, while the transversely projecting faces may be red or a similar warning color. Other light responsive materials 25 may be employed without departing from the spirit of the invention. For example, even state of the art highway marking paint would be visible at considerable distances with the high profiles of the marking components 24. The shape of the upstanding units 24 is also largely a matter of choice.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.