Patent Publication Number: US-6988850-B2

Title: Pavement ramp edge making

Description:
This application is a continuation-in-part of application U.S. Ser. No. 10/426,143, filed Apr. 29, 2003 and now U.S. Pat. No. 6,923,594. 

   BACKGROUND OF THE INVENTION 
   1. Technical Field 
   The present invention relates generally to paving material, and more particularly, to a pavement ramp edge maker, paving machine and related method. 
   2. Related Art 
   Typically, screed pavers include a self-propelled paving machine having a hopper for receiving paving material, e.g., asphalt, from a truck so that the truck progressively dumps its load of paving material into the hopper. A conveyor system on the paving machine transfers paving material from the hopper rearwardly for discharge onto the roadbed in front of transversely arranged screw augers, which spread the material laterally in front of a main screed. This main screed functions to compress and level the paving material to give a smooth finished road surface. The height and attack angle of the main screed may be varied to control the depth and surface of the pavement mat. The main screed may also include screed extenders to allow for a wider pavement mat to be laid. Subsequently, the paving material is compacted in position by, for example, a rolling machine or tamping machine. 
   A safety problem generated by basic paving machines are drop off edges that are left at a side or an end of a mat of paving material. Drop off edges are a safety problem because vehicles may catch a side of a tire on them, causing the vehicle to lose control. Drop off edges may range in size from a half inch to more than 2 inches, and may exist prior to and after compaction. Drop off edges can be found in highways, secondary roadways, parking areas, driveways, drainage sections, and a variety of other locations. The inherent safety issues generated by drop off edges have been identified in a report by the American Automobile Association&#39;s (AAA) Foundation for Traffic Safety that was prepared by the Transportation Center at the University of Tennessee entitled, “The Elimination or Mitigation of Hazards Associated with Pavement Edge Dropoffs During Roadway Resurfacing.” In addition, evidence of the road edge drop-off safety problem is provided by the large number of lawsuits filed against cities, counties and states as reported in the Road Injury Prevention &amp; Litigation Journal. 
   Drop off edges may be generated during paving during in, among others areas, two notable situations. First, drop off edges are frequently generated when paving multiple active traffic lanes, where it is oftentimes impossible to pave two or more lanes in a short time span. The inability to pave two or more lanes quickly may be due to a variety of reasons, e.g., traffic, equipment shortages, etc. In this case, a drop off edge is often times left between a first active traffic lane over which a new pavement mat has been laid and a second active traffic lane upon which new pavement has yet to be laid. One approach for solving this type drop off edge is disclosed in U.S. Pat. Nos. 6,238,134, 6,238,136, 6,270,284 and 6,283,672. In each of these devices, a pavement edger is fixedly mounted to a main screed or screed extension of the paving machine, and moves as an integral unit with the main screed. The pavement edger generates a stepped tapered ramp having a highly compacted step and a highly compacted upper portion of the tapered ramp. The ramp eases a vehicle&#39;s transition over the drop off edge and solves a number of paving problems relative to laying the next lane&#39;s mat. 
   Second, referring to  FIG. 1 , a drop-off edge  10  may be generated between a newly repaved area  12  and an adjacent non-repaved area  14 . Non-repaved area  14  may be, for example, an emergency lane surface  18  of a main highway, a shoulder  18  of a secondary road, an unpaved area  18 , etc. In any event, the side of pavement terminates as a drop off edge  10  having an inclination λ greater than 45°, which is generally considered an unsafe inclination. This type drop off edge oftentimes poses a significant safety problem because of obstacles such as trees, guardrails, etc., that may exist proximate the non-repaved area  14 . 
   In a worst-case scenario, this type drop off edge  10  is not corrected and the current non-repaved area  14  is left as is. One approach to diminish this type drop off edge, however, has been to spread gravel  20  from a top edge  22  of the new pavement mat  16  to the non-repaved area surface  18 . Unfortunately, this approach does not provide a permanent solution since the gravel eventually loosens and is thrown off the road. Further, this approach is fairly expensive since it requires additional passes over the area. 
   Ideally, a remedy for roadside drop off edge  10  should be provided during paving because each re-visitation to a site costs time and money. One approach used during paving has been to provide a strike off on an end of the paving machine screed to form a ramp. A strike off is a vertical plate attached to the screed or an opening in the screed that scrapes a ramp into the paving material passing thereunder. Unfortunately, a strike off does not adequately solve this type drop off edge because it provides hardly any compaction, which permits the ramp to be readily torn apart. In addition, a strike off tends to tear the edge of the mat causing a non-straight and disfigured pavement edge. Tearing of the edge of the mat also reduces the integrity of the mat, which decreases the life of the pavement. 
   The pavement edger described in the above-identified patents is impracticable relative to a drop off edge  10  adjacent a non-repaved area  14  for a number of reasons. First, the pavement edger is coupled to a main screed or screed extension of a paving machine. As a result, the pavement edger is incapable of following undulations that are common in non-repaved traffic areas. Second, the ramp generated includes vertical edges for mating with subsequent pavement mats. This ramp, although significantly better than an inclined drop off edge  10 , is not designed to be a permanent remedy to drop off edge  10 . 
   In view of the foregoing, there is a need in the art for a pavement edge maker that addresses the problems with the related art. 
   SUMMARY OF THE INVENTION 
   A pavement ramp edge maker, paving machine and related method are provided for generating a pavement edge ramp that is equal to or less than approximately 45° relative to a surface upon which the ramp is formed. The ramp reduces safety problems relative to drop off edges adjacent a non-repaved area, and increases the life of the pavement by providing a compacted edge. The edge maker generates a ramp that is partially compacted. When the pavement mat is compacted, the resulting ramp has an angle that is equal to or less than approximately 45° relative to a surface upon which the ramp is formed. In an alternative embodiment of the invention, a coupling device for a compaction member of the edge maker includes a spring bias and vertical adjustment system for mounting the compaction member to a fixed structure of the paving machine, but allowing vertical movement. 
   A first aspect of the invention is directed to a pavement ramp edge maker comprising: a compaction member have a compaction surface for partially compacting paving material received thereby into a ramp; and a coupling device for coupling the compaction member to a paving machine, wherein the compaction surface is set at an edge angle such that a final angle of the ramp after compaction is less than or equal to approximately 45° relative to a surface upon which the ramp is formed. 
   A second aspect of the invention is directed to a paving machine comprising: a screed for distributing paving material during paving; a vertically self-adjusting end gate coupled to the screed; and a pavement ramp edge maker including: a compaction member including a compaction surface for partially compacting paving material received thereby to form a ramp; and a coupling device for coupling the compaction member to the paving machine, wherein the compaction surface is set at an edge angle such that a final angle of paving material after compaction is less than or equal to approximately 45° relative to a surface upon which the ramp is formed. 
   The foregoing and other features of the invention will be apparent from the following more particular description of embodiments of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The embodiments of this invention will be described in detail, with reference to the following figures, wherein like designations denote like elements, and wherein: 
       FIG. 1  shows a prior art drop off edge adjacent a non-repaved area. 
       FIG. 2  shows a ramp according to the invention. 
       FIG. 3  shows a perspective view of a paving machine equipped with a pavement ramp edge maker according to the invention. 
       FIG. 4  shows a front perspective view of the pavement ramp edge maker. 
       FIG. 5A  shows a front view of the pavement ramp edge maker. 
       FIG. 5B  shows a side view of the pavement ramp edge maker. 
       FIG. 6  shows a profile of a pre-compaction ramp and the ramp of  FIG. 2 . 
       FIG. 7  shows a front perspective view of an alternative embodiment of the pavement ramp edge maker. 
       FIG. 8A  shows a front view of the alternative embodiment of the pavement ramp edge maker. 
       FIG. 8B  shows a side view of the alternative embodiment of the pavement ramp edge maker. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   A pavement ramp edge maker, paving machine and related method are provided for generating a pavement edge ramp that is equal to or less than approximately 45 degrees relative to a surface upon which the ramp is formed. For definition purposes herein, a “mat” or “pavement mat” is considered a layer of paving material. “Paving material” is any material used for paving roadways, such as bituminous material like asphalt. 
   Referring to  FIG. 2 , a drop off edge  110  adjacent a non-repaved area  114  is shown. Safety issues relative to drop off edge  110 , however, have been addressed by the inclusion of a compacted ramp  130  made according to the invention. Drop off edge  110 , as discussed above, is generated when a new pavement mat  116  is laid over a re-paving area  132 . Adjacent re-paving area  132  is a non-repaved area or surface  118 , which will not receive new pavement mat  116  thus generating drop off edge  110 . As used herein, “non-repaved surface”  118  is an area that is not receiving new pavement mat  116 —it may or may not have been previously paved. Non-repaved surface  118  may be angled relative to re-paving area  132 . As shown, non-repaved surface  118  is angled downwardly, for example to aid drainage away from pavement mat  116 . However, where in-road drainage is available, non-repaved surface  118  may be inclined upwardly relative to pavement mat  116  to direct drainage between pavement mat  116  and surface  118 . 
   Turning to  FIG. 3 , an illustrative paving machine  150  equipped with a pavement ramp edge maker  152  (hereinafter “edge maker”) of the present invention is illustrated. Paving machine  150  operates to spread and grade paving material  154 , e.g., a paving road mix such as asphalt, etc., on re-paving area  132  to form pavement mat  116  with a compacted ramp  130  along one side. Paving machine  150  has a rear main screed  158 . Elevation of screed  158  may be adjusted by a pair of tow arms  162  pivotally connected to a supporting frame  164 . Asphalt mix carried by paving machine  150  is spread laterally in front of screed  158  by augers (not shown), which are spaced forwardly of screed  158 . Paving machine  150  may also include an optional screed extender  168  ( FIG. 4 ) to extend screed  158 . 
   Paving machine  150  also includes a vertically self-adjustable end gate  170  (hereinafter “end gate”) at each end of screed  158 , as is commonly known in the art. Each end gate  170  may include a vertically adjustable sled  172 , as is conventional, to support end gate  170  as it traverses surface  118 . Each end gate  170  follows the contours of surface  118 , and may be biased downwardly by a biasing mechanism  174 , such as a spring loaded or hydraulically powered, suspension to maintain contact with surface  118 . 
   Referring to  FIG. 4 , edge maker  152  is illustrated in more detail. In one embodiment, the parts of edge maker  152  are constructed of steel plate of sufficient gauge to withstand the rigors of paving. It should be recognized, however, that other materials may also be used. Edge maker  152  includes a compaction member  176  including a compaction surface  180  for compacting paving material (not shown) received thereby, and a coupling device  182  for coupling compaction member  176  to one of end gates  170 . Edge maker  152  moves vertically with end gate  170 , and is not connected to screed  158  or screed extension  168 . Compaction member  176  also includes a paving material directing member  190  and a pair of support members  192  for positioning compaction surface  180 . Compaction member  176  may also include a brace member  194 . Paving material directing member  190  directs paving material toward compaction surface  180 , and prevents paving material from flowing behind compaction surface  180 . In one embodiment, compaction surface  180  is shaped substantially like an isosceles triangle, and paving material directing member  190  is a substantially vertical plate that is set at an angle of approximately 45° relative to end plate  170 . 
   Coupling device  182  includes a mounting post  200  coupled to compaction member  176 , and a mounting clamp  202  for coupling the mounting post to end gate  170 . In one embodiment, mounting post  200  is provided as a W-shaped member, and mounting clamp  202  is a U-shaped channel. Mounting clamp  202  is capable of receiving one of a first post section  206  and a second post section  208  of mounting post  200 , and a top edge  204  of end gate  170 . Mounting clamp  202  receives a number of threaded fasteners  210 A,  210 B that can be tightened to hold mounting post  200  (first post section  206  as shown) against end gate  170 . 
   Coupling device  182  may also include a vertical adjuster  212  for adjusting the vertical position of compaction member  176  relative to end gate  170 . Vertical adjustment of compaction member  176  relative to end gate  170  is advantageous to accommodate varying sizes of paving material aggregate and prevent tearing paving material mat  116  ( FIGS. 1 and 3 ). In one embodiment, vertical adjuster  212  includes a threaded vertical adjustment member  214  (hereinafter “adjustment member”) threadably coupled to compaction member  176  (e.g., via brace member  194 ), and an armature  216 . Armature  216  couples adjustment member  214  to mounting clamp  202  at a first end  218 , and rotatably receives a first end  220  of adjustment member  214  at a second end  222  thereof. Adjustment member  216  includes an engagement member  224  for turning by a user. Engagement member  224  may be any type of device for grasping and turning by a user, e.g., a bolt, a crank, screw head, etc. Brace member  194  is fixedly coupled to paving material directing member  190  and mounting post  200 . 
   In order to vertically adjust compaction member  176 , a user loosens threaded fastener  210 B and turns engagement member  224 , which turns adjustment member  214 . As adjustment member  214  turns, the vertical position of compaction member  176  relative to end gate  170  changes because of adjustment member&#39;s  214  threaded connection at brace member  194 . Once in a desired position, a user re-tightens threaded fastener  210 B to couple mounting post  200  to end gate  170 . While the adjustment range may vary to accommodate all varieties of paving material, in one embodiment, compaction surface  180  is set to be slightly (less than 0.5-inch) above a bottom edge  226  of end gate  170  and has an adjustment range between approximately 12 mm and approximately 24 mm. 
   It should be recognized that a variety of other mechanisms for mounting compaction member  176  to end gate  170  and for vertically adjusting compaction member  176  are possible, and are considered within the scope of the invention. Other possibilities for vertical adjustment include, for example, a pin and a plurality of holes, a slot and positioning bolt, etc. In addition, alterations of the described embodiment are also possible and considered within the scope of the invention. 
   Coupling device  182  allows easy and quick installation of edge maker  152 , and also allows mounting of edge maker  152  on either one of end gates  170 . In order to switch from the end gate  170  shown in  FIG. 4  to the other end gate ( FIG. 3 ), mounting clamp  202  is removed from end gate  170  (i.e., by loosening threaded fasteners  210 A,  210 B), which releases first mounting section  206 . Next, edge maker  152  is rotated to match the position of the other end gate ( FIG. 3 ) and screed  158  or screed extension  168 . Mounting clamp  202  is then pivoted about its pivotal connection with first end  218  of armature  216 , and armature  216  is pivoted about its pivotal connection with adjustment member  214  toward second mounting section  208 . Mounting clamp  202  can then receive second mounting section  208  and a top edge of the other end gate ( FIG. 3 ). Threaded fasteners  210 A,  210 B are then tightened (into threaded openings on the other side of clamp  202  from that shown) to hold compaction member  176  to the other end gate ( FIG. 3 ). While a particular coupling device has been described, it should be recognized that a variety of other coupling devices (e.g., bolting to end gate  170 ) can be used and are considered within the scope of the invention. 
   Referring to  FIGS. 4 ,  5 A and  5 B collectively, details of compaction surface  180  will be described. Assuming compaction surface  180  is provided as a flat surface, compaction surface  180  is set at a position determined, in part, by an edge angle σ 1  and a compaction angle σ 2 . Edge angle σ 1  extends between compaction surface  180  and surface  118  ( FIGS. 2 and 3 ) upon which the paving material is laid, and in a lateral direction (LH) from end gate  170 . Compaction angle σ 2  also extends between compaction surface  180  ( FIGS. 2 and 3 ) and surface  118  upon which the paving material is laid, but in a direction of travel (FH) of end gate  170 . In one embodiment, edge angle σ 1  and a compaction angle σ 2  are substantially identical, e.g., within 0–5°. This configuration is advantageous, for example, so that a single edge maker  152  can be used on either end gate  170  of a paving machine. In particular, when the position is switched, edge maker  152  is rotated 90° (clockwise in the example shown in  FIG. 4 ) such that edge angle σ 1  becomes the compaction angle, and compaction angle σ 2  becomes the edge angle. However, it is possible to have an edge angle σ 1  and compaction angle σ 2  that are different on a single compaction member  176 , if desired. In either case, changes of angles σ 1  and σ 2  may be advantageous to address different settings, for example, different paving materials, different end gates, different temperatures, etc. In this case, a set of compaction members  176  having different settings or an adjustable compaction surface  180  maybe advantageous for flexibility. It is also possible to alter the shape of compaction surface  180 , if desired. In one embodiment, compaction angle σ 2  is less than approximately 45° to provide compaction to paving material exposed thereto. 
   Referring to  FIG. 6 , a cross-sectional view of a partial-compaction ramp  230  formed by edge maker  152 , and a post-compaction ramp  130  ( FIG. 2  also) are illustrated. Partial-compaction ramp  230  illustrates how pavement material exits from edge maker  152  in a partially compacted form. “Partially compacted,” as used herein, means more compacted than paving material exiting screed  158  or screed extension  168 , but not as compacted as paving material that has been finally compacted by rolling, tamping, etc. This is in contrast to ramps that are formed by strike offs, which have no or very little compaction. Edge angle σ 1  ( FIG. 4 ) determines an angle τ of a partial-compaction ramp  230  prior to final compaction. Edge angle σ 1  ( FIG. 4 ) is set such that a final compaction angle α ( FIGS. 2 and 6 ) of paving material is less than or equal to approximately 45° relative to surface  118  upon which the paving material is laid. As used herein, “final compaction angle” refers to the angle of the ramp relative to surface  118  upon which the paving material is laid after compacting by, for example, rolling, tamping, etc. In one illustrative embodiment, edge angle σ 1  (and hence angle τ) is set at approximately 35° relative to horizontal. However, a variety of angles are possible. Final compaction ramp  130  illustrates how the height of pavement mat  116  is reduced by compaction, e.g., by rolling, and a final compaction angle α of the ramp is greater than angle τ after final compaction. A final compaction angle α of less than or equal to approximately 45° provides a sufficiently gradual transition from a top edge  122  of compacted paving material mat  116  to surface  118  such that the risk of vehicle control loss is greatly reduced. 
   Edge maker  152 , in one embodiment, can accommodate pavement lifts of 1 to 4 inches compacted (or 1.5 to 5.5 inches uncompacted height). Since edge maker  152  is coupled to vertically self-adjusting end gate  170 , it can automatically compensate for height variations between new pavement mat  116  and surface  118 . Further, edge maker  152  insures that a maximum deviation from straight-line edge of pavement mat  116  does not vary more than 1.5 inches per inch of depth change after compaction. Further, ramp  130  does not require any special rolling devices to achieve a density level adequate for an operating life equal to that of paving material mat  116 . 
   Referring to  FIGS. 7 ,  8 A and  8 B, alternative embodiments of a pavement ramp edge maker  352  will now be described. Edge maker  352  includes a compaction member  376  including a compaction surface  380  for compacting paving material (not shown) received thereby, and a coupling device  382  for coupling compaction member  376  to a fixed structure of paving machine  150  ( FIG. 3 ), i.e., not a vertically self-adjusting end gate. As a result, edge maker  352  does not move vertically with end gate  170 , as in the previous embodiments. However, coupling device  382  includes a spring bias and vertical adjustment system, as will be described further below, that allows for vertical movement of compaction member  376  so as to avoid the problems of the related art. In one embodiment, the parts of edge maker  352  are constructed of steel plate of sufficient gauge to withstand the rigors of paving. It should be recognized, however, that other materials may also be used. 
   Compaction member  376  also includes a paving material directing member  390  and a pair of support members  392  for positioning compaction surface  380 . Compaction member  376  may also include a brace member  394 . Paving material directing member  390  directs paving material toward compaction surface  380 , and prevents paving material from flowing behind compaction surface  380 . Other structure may also be added to prevent paving material from flowing behind compaction surface  380  such as a cover (not shown). In an alternative embodiment, compaction surface  380  also includes a trailing compaction surface  400  (shown best in  FIG. 8B ) extending substantially in a direction of travel from a trailing edge  402  of compaction surface  382 . In one embodiment, trailing edge  402  is rounded to assist in paving material transition from compaction surface  380  to trailing compaction surface  400 . Trailing compaction surface  400  reduces tearing and assists in generating a refined and smooth ramp. In addition, in an alternative embodiment, directing member  390  includes a trailing directing member  404  extending substantially in a direction of travel from a trailing edge  406  of paving material directing member  390 . Since each compaction member  376  of the alternative embodiment is direction specific, a compaction member for each end of a screed  358  is required. 
   Relative to coupling device  382 , an alternative embodiment provides a spring bias and vertical adjustment system  408 , as shown in  FIG. 7 . System  408  includes a mounting plate  410  for mounting to a fixed structure of the paving machine  150  ( FIG. 3 ). Accordingly, mounting clamp  202  ( FIGS. 3 and 4 ) is no longer necessary. In one embodiment, the fixed structure may be one of paving machine screed  358 , a fixed end gate  170 , screed extension  268  or a paving machine striker {not shown}. It should be noted, however, that any fixed structure of paving machine  150  ( FIG. 3 ) may be suited for this purpose. 
   System  408  also includes a threaded rod  416  slidably coupled to mounting plate  410  and threadably coupled to compaction member  376 , i.e., brace member  394  of compaction member  376 , and a spring bias  414  for biasing compaction member  376  against upward movement. Spring bias  414  includes a spring  424  mounted about threaded rod  416  and between mounting plate  410 , i.e., a mount  420  of mounting plate  410 , and a bias adjustment member  426  that is threadably coupled to threaded rod  416 . Threaded rod  416  includes an upper end  418  vertically slidable relative to mount  420 , and an end cap  421  to prevent threaded rod  416  from exiting mount  420 . A lower end  422  of threaded rod  416  is threadably received in brace member  394  such that turning of threaded rod  416  adjusts the vertical distance between compaction member  376  and mounting plate  410 . Hence, the vertical position of compaction surface  376  can be adjusted relative to the fixed structure of paving machine  150  ( FIG. 3 ). In addition, a bias required to move compaction member  376  upwardly relative to mounting plate  410  can be adjusted by adjusting the position of bias adjustment member  426  along threaded rod  416 . While system  408  has been illustrated as including a combined spring bias and vertical adjustment system, it should be recognized that separate spring bias and vertical adjustment may be provided. In addition, other mechanisms for securing the relative position of components may also be provided. For example, rather than a threaded adjustment, a hole and cotter pin adjustment or another mechanism may be used. 
   In another alternative embodiment, a support member  392 A adjacent end gate  170  is extended beyond a lower surface of compaction surface  380  and includes a rounded leading edge  440  adapted to engage a surface being paved. 
   Where possible, the above-described alternative embodiments may be provided as part of the  FIGS. 4 ,  5 A and  5 B embodiments. 
   While this invention has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the embodiments of the invention as set forth above are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention as defined in the following claims. 
   For example, paving machine  150  ( FIG. 3 ) is meant only to be illustrative. The pavement edge maker of the invention may be applied to a variety of paving machines.