Abstract:
A riser assembly and method for engaging the same to raise a manhole cover to be flush with an inclined paved surface after the application of an additional layer of paving material thereto. The riser assembly includes a first and second riser frame with a plurality of specially manufactured spacer blocks fixedly secured between them. The spacer blocks have progressively different height dimensions and sloped upper surfaces so as to create an angle between the first and second riser frames. The angle is complementary to the slope of the paved surface. The riser assembly includes an expansion device for adjusting the diameter of the second riser frame so that it frictionally engages the existing manhole frame. The fixed securement of the spacer blocks prevents relative movement between the first and second riser frames even when the diameter of the second riser frame is changed.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    This invention relates generally to manhole cover supports. More particularly, this invention relates to a separate riser assembly that is placed within an existing manhole frame to raise the height of the manhole cover to compensate for added roadway pavement. Specifically, this invention is directed to a riser assembly for use with a manhole frame positioned on an incline. The riser assembly comprises a first riser frame and second riser frame having spacer blocks fixedly engaged between them in a manner that retains the first riser frame at an angle relative to the second riser frame. The inclined first riser frame supports the full circumference of the manhole cover at an angle complementary to the sloped road surface. 
         [0003]    2. Background Information 
         [0004]    Most underground facilities such as sanitary and storm sewers, utility conduits, and the like have manhole openings to provide access thereto. These manholes usually are located in the street or roadway and consist of an inverted, generally bell-shaped metal frame, mounted onto of a brick or concrete base structure. This metal frame has an internal, horizontal ledge for supporting the manhole cover so that the top of the cover is substantially level with the top of the frame and the surrounding roadway pavement. 
         [0005]    Problems arise in the resurfacing of the roadways when a layer of pavement is placed on top of the existing pavement. This results in the manhole cover being positioned a distance below the top surface of the new pavement, causing a depression in the roadway. It is quite difficult and expensive to raise the existing manhole frame sufficiently to compensate for the added pavement. Thus, various devices and methods have been constructed and used which enable an existing manhole cover to be raised to the level of the new pavement surface without requiring the raising of the existing manhole frame. 
         [0006]    One such device is disclosed in U.S. Pat. No. 7,165,911 (Fier). The patent discloses a riser assembly which supports a manhole cover and is engaged with a manhole frame. The riser assembly raises the height of the manhole cover to the new pavement level. The riser assembly includes a circular frame formed of a metal bar and has a locking ring attached thereto which extends vertically downwardly from the frame. A plurality of outwardly projecting tabs are formed in the locking ring and are adapted to engage the manhole frame to prevent upward movement of the riser. An expansion device expands the frame and locking ring outwardly, whereby the locking ring abuttingly engages a vertical surface of the manhole frame to assist in locking the riser assembly to the manhole frame. 
         [0007]    The device disclosed in U.S. Pat. No. 7,165,911 works exceptionally well when the pavement surface surrounding the manhole is substantially flat. However, when the pavement surface is inclined, as would be the case if the manhole were located on a hill or in a valley, for example, then the riser assembly disclosed in U.S. Pat. No. 7,165,911 is not entirely adequate for the job. The reason for this is that there would be a tendency for one side of the manhole cover to be recessed into the inclined road surface or the manhole cover would tend to extend slightly above the angled pavement. Either of this situations leads to early degradation of the new pavement surface and simultaneously tends to be hazardous for vehicles traveling over the road. 
         [0008]    Various devices have been proposed in the prior art to address the issue of how to raise a manhole cover to the level of a new pavement surface when that surface is inclined. For example, U.S. Pat. No. 6,799,920 to Sondrup discloses a device comprising a pair of angled rings that are stacked one above the other and together present a lower surface that is engageable with the manhole frame and an upper surface that supports the manhole cover. The rings are rotated relative to each other to vary the angle of the upper supporting surface of the device relative to the lower surface of the device. The rings may include markings that will permit the road crew to select the angle they want to create in the device so that it is able to support a manhole cover substantially flush with an inclined surface. In order to use the Sondrup device the road crew will take a variety of distance measurements relating to the manhole and the asphalt surrounding the same and will then calculate two rotational settings for the device. The upper and bottom rings are then rotated relative to each other to match the calculated rotational settings. If additional height is required, the device may further include a third ring that is interposed between the upper and bottom rings and is rotatable relative thereto. One of the issues with this device is that it requires the road crew installing it to make a series of calculations and adjustments to the device while they are busy installing the same. This need for doing calculations in the field tends to slow the installation process down. Additionally, Sondrup&#39;s frame has to be adjusted and installed prior to pouring the asphalt. The asphalt bonds to side of the frame. Then, each time an additional layer of asphalt is added to the road surface, the asphalt surrounding the frame has to be removed in order to adjust the rings to raise and tilt the manhole cover to be substantially level with the new road surface. 
         [0009]    U.S. Pat. No. 5,944,442 (Roush et al) discloses an extender comprising two or more rings that are vertically stackable to adjust the overall height of the device so that it is able to support a manhole cover flush with a road surface. A first one of the rings has a plurality of vertical channels defined in the exterior surface of the side wall. A second one of the rings has a plurality of vertical channels on the interior surface of the side walls. The channels on the two rings are in complementary locations. Specially configured height-adjustable brackets are received in the channels of both rings to secure the rings to each other and to the base of the manhole frame. Additional rings may be similarly stacked with the first two rings. As asphalt is added to the roadway, the original rings may be disengaged from the base and be replaced with higher height rings. The side wall of each ring may be of a constant height around the ring&#39;s circumference or it may be manufactured so that it is higher at one end than at the other. At least one ring with a sloped side wall is used when the manhole is on a sloped road surface and there is a need to incline the manhole cover. Obviously, the slope of the side wall has to be calculated to fit each specific manhole so that after installation the manhole cover is flush with the inclined road surface. 
         [0010]    Bowman (U.S. Pat. No. 5,051,022) discloses a device having a cast-iron top ring and a bottom ring that engage each other. The top ring receives the manhole cover therein and may be configured to tilt the cover. The bottom ring is configured to clamp under the seat of the existing manhole frame and when this occurs, the top ring of the device is seated on the uppermost rim of the existing manhole frame. The device is therefore limited to riser heights that are greater than the thickness of the manhole cover plus the thickness of the top ring. This arrangement is impractical in many instances because the average manhole cover thickness in the United States is 1¾″ to 3½″ thick and most asphalt overlays are around 1½″ thick. Consequently, Bowman&#39;s device is only useful in very specific instances. Additionally, when the turnbuckles on the device are expanded or contracted, Bowman&#39;s riser will not provide a flat surface upon which the manhole cover can rest. In each of the expanded or contracted positions, the riser will present an uneven surface upon which the cover will have to rest, leading to rocking of the cover as vehicles travel over the same. Additionally, the design of Bowman&#39;s device requires that the existing manhole frame include a lip where the cover rests so that the bottom ring can clamp to the same. However, many manhole frames do not include these lips and then the Bowman device cannot be used with these existing manhole frames. 
         [0011]    Bowman (U.S. Pat. No. 5,143,478) discloses a riser assembly that is engageable with an existing manhole frame. The riser assembly includes a bottom ring that is seated on the horizontal support surface of the manhole frame upon which the cover previously rested. The riser assembly further includes an top ring that is linked to the bottom ring by two sets of spanners. The top ring has a greater diameter than the bottom ring and the spanners extend from the interior surface of the top ring to the upper surface of the bottom ring. Two of the spanners are welded to the interior surface of the top ring and to the upper surface of the bottom ring. These two spanners are stiff, flat steel bars that are positioned on either side of a turnbuckle device on the bottom ring. The remaining spanners are only welded to the interior surface of the top ring and are slidable over the upper surface of the bottom ring. The bottom ring will be positioned on the existing manhole frame and the turnbuckle will be adjusted to ensure that the bottom ring frictionally engages the frame. Since the two spanners adjacent the turnbuckle secure the two rings together, when the bottom ring&#39;s diameter is adjusted, the top ring&#39;s diameter is also adjusted. The remaining spanners slide over the upper surface of the bottom ring as the diameter of the top ring changes. The manhole cover is then seated on the spanners. The patent discloses that in some instance the spanners may have a top surface that is sloped. Consequently, when the manhole cover is seated on these sloped spanners, the manhole cover will be retained at an angle. This device is problematic for a number of reasons. Firstly, the top ring is positioned above the uppermost edge of the existing manhole frame. Consequently, both the uppermost edge of the manhole frame and the seat of the frame where the bottom ring sits will tend to wear and corrode. The load on the cover created when traffic travels over the same is supported by the bottom ring only. This bottom ring rests on the horizontal support or seat of the existing manhole frame. When traffic pushes down on the top ring, it creates a moment on the riser similar to a lever that creates a force to knock the cover and riser out of the manhole frame. Additionally, the cover is only supported by the spanners which are disposed at intervals between the upper and bottom rings. Consequently, as traffic moves over the cover, the cover will tend to rock on the spanners. This occurs because the cover is not supported around the full circumference thereof and when traffic runs over the edge of the cover in a location in-between the spanners it will create a force similar to a lever making the opposite side of the lid flip up. Still further, if the top surfaces of the spanners are sloped, when the size of the bottom ring is expanded or contracted the cover supported in the top ring will tend to either project above the rim of the top ring or sink inwardly relative hereto as the cover will be seated at a different location on the spanners in each of these instances. Additionally, because the top ring is disposed above the uppermost edge of the existing manhole frame, this riser assembly can only be used in specific applications because the riser heights have to be greater than the lid thickness plush the thickness of the base of the top ring. 
         [0012]    There is therefore a need in the art for a device that is suitable for raising the height of a manhole cover on sloped terrain while avoiding some of the issues found with prior art devices. 
       BRIEF SUMMARY OF THE INVENTION 
       [0013]    A riser assembly and method for engaging the same to raise a manhole cover to be flush with an inclined paved surface after the application of an additional layer of paving material thereto. The riser assembly includes a first and second riser frame with a plurality of specially manufactured spacer blocks fixedly secured between them. The spacer blocks have progressively different height dimensions and sloped upper surfaces so as to create an angle between the first and second riser frames. The angle is complementary to the slope of the paved surface. The riser assembly includes an expansion device for adjusting the diameter of the second riser frame so that it frictionally engages the existing manhole frame. The fixed securement of the spacer blocks prevents relative movement between the first and second riser frames even when the diameter of the second riser frame is changed. 
         [0014]    The method of raising a manhole cover to the level of a top surface of an additional layer of paving material surrounding an existing manhole assembly comprises the steps of:
       inserting at least one spacer block between an upper surface of an annular second riser bar and a lower surface of an annular first riser bar to create an angle between an upper surface of the first riser bar and a lower surface of the second riser bar;   securing the at least one spacer block to each of the first and second riser bars so that relative movement between them is substantially prevented;   securing a flange to the first riser bar so that the flange extends upwardly and outwardly away from the upper surface of the first riser bar;   resting the lower surface of the second riser bar against a horizontal support of the frame that is disposed adjacent the vertical support; and   placing the manhole cover into a space bounded by the flange and the upper surface of the first riser bar; and   resting a bottom perimeter of the manhole cover on the upper surface of the first riser bar.
 
The method further includes the steps of:
       
 
         [0021]    activating an expansion device on the second riser bar; and 
         [0022]    changing the diameter of the second riser bar using the expansion device so that an exterior surface of the second riser bar engages an angled flange of on the manhole frame. 
         [0000]    The method further includes the steps of: 
         [0023]    individually manufacturing a plurality of spacer blocks to have progressively different height dimensions and angled top and lower surfaces; 
         [0024]    inserting the individually manufactured spacer blocks at specific locations between the first and second riser bars that will result in the angle being created between the first and second riser bars; where the angle is complementary to the slope of the new layer of paving material. 
         [0000]    Finally, the method may further include the steps of: 
         [0025]    welding a region of the lower surface of the first riser bar to an opposing region of the upper surface of the second riser bar. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0026]    A preferred embodiment of the invention, illustrated of the best mode in which Applicant contemplates applying the principles, is set forth in the following description and is shown in the drawings and is particularly and distinctly pointed out and set forth in the appended claims. 
           [0027]      FIG. 1  is a top perspective view of a typical manhole installation in a paved surface; 
           [0028]      FIG. 2  is an enlarged perspective view of the highlighted region of  FIG. 1 ; 
           [0029]      FIG. 3  is a cross-sectional view of the paved surface, the manhole and riser assembly taken through along line  3 - 3  of  FIG. 1 ; 
           [0030]      FIG. 4  is a cross-sectional view of the manhole and riser assembly taken along line  4 - 4  of  FIG. 1 ; 
           [0031]      FIG. 5  is a perspective view of a riser assembly in accordance with the present invention and showing a manhole cover from the manhole assembly that is engageable with the riser assembly; 
           [0032]      FIG. 6  is an exploded perspective view of the riser assembly; and 
           [0033]      FIG. 7  is a cross-sectional side view of the riser assembly. 
       
    
    
       [0034]    Similar numbers refer to similar parts throughout the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0035]    Referring to  FIGS. 1 and 2 , there is shown a paved surface or pavement  10  in which is defined an access hole  12  to a manhole assembly  14 . A manhole cover  16  is engaged with manhole assembly  14  to close off access hole  12 . Pavement  10  may be any type of surface including a road, a parking lot, a sidewalk etc. that includes a manhole assembly  14  and the paving material applied to pavement  10  may be asphalt, concrete or any other type of material that is applied in layers to form a rigid surface over which people and/or vehicles travel. In particular, the area of pavement  10  surrounding manhole assembly  14  is sloped in any one of a number of directions. 
         [0036]      FIGS. 3 and 4  are cross-sections through pavement  10 .  FIG. 3  shows that manhole assembly  14  includes a manhole frame  28  disposed in a cavity  18  formed in a brick or masonry storm drain system  20  which is disposed beneath pavement  10 . Pavement  10  comprises an original layer  22  of paving material and a new layer  24  of paving material. The region of pavement  10  within which manhole assembly  14  is situated is inclined at an angle “A” ( FIG. 3 ) relative to the horizontal.  FIG. 4  shows that the original layer  22  of paving material has an upper surface  22   a  that is inclined. New layer  24  overlays original layer  22  and includes a top surface  24   a  that is inclined at much the same angle “A” as the original layer  22 . 
         [0037]    Still referring to  FIGS. 3 and 4 , manhole frame  28  consists of a bell-shaped structure mounted in storm drain system  20  and includes a generally horizontal support surface  30  ( FIG. 4 ) and a conical wall  32 . Prior to the addition of new layer  24  of pavement  10 , support surface  30  provided the seat for receiving and supporting manhole cover  16  thereon. Conical wall  32  terminates in an uppermost edge  33 . Manhole frame  28  further includes a generally vertically extending interior surface  34  which extends downwardly from support surface  30 . Interior surface  34  defines the actual manhole opening. Manhole frame  28  is configured to include an angle between the horizontal support surface  30  and conical wall  32  which matches the angled taper of the circumferential edge  16   a  ( FIG. 5 ) of cover  16 . Preferably wall  32  is tapered to be complementary to edge  16   a  of cover  16 . Preferably, the angle between surfaces  30  and  34  will be 90° to facilitate the casting of manhole frame  28  as well as providing a complementary seat for cover  16 . In accordance with a specific feature of the present invention, a manhole cover riser assembly  36  is utilized to raise up the level at which manhole cover  16  is supported when new layer  24  of pavement  10  is applied over the top surface  22   a  of the original layer  22 . Riser assembly  36  is configured so as to provide a seat for cover  16  so that it is substantially flush with the top surface  24   a  of new layer  24 . Furthermore, riser assembly  36  is provided to retain cover  16  at an inclined angle that is complementary to the angle of the inclined road surface that surrounds manhole assembly  14 . 
         [0038]    Referring to  FIGS. 5-7 , riser assembly  36  comprises a first riser frame  38 , a second riser frame  40  and one or more spacer blocks  54  that are disposed between first and second riser frames  40  and are fixedly secured thereto. Spacer blocks  54  secure first and second riser frames  38 ,  40  against relative movement. More specifically, spacer blocks  54  substantially prevent first riser frame  38  from moving one or more of laterally, horizontally, radially, and vertically relative to second riser frame  40 . 
         [0039]    Preferably, each of the first and second riser frames  38 ,  40  is circular in shape when viewed from the top. It will be understood however that other shaped riser assemblies, such as square or rectangular assemblies, are considered to fall within the scope of the present invention. Furthermore, first riser frame  38  has a first perimeter and a first diameter and second riser frame has a second perimeter and a second diameter. First diameter and second diameter are substantially the same. Riser assembly  36  preferably is manufactured from any metal that is suitable for use in roadways, i.e., the metal has to be sufficient strong enough to take the loads placed on it and must be substantially rust and corrosion free. Riser assembly  36  also defines an opening  37  through which opening in the manhole frame  28  may be accessed. 
         [0040]    First riser frame  38  comprises a substantially annular first riser bar  42  and a substantially annular flange  50 . First riser bar  42  is generally square or rectangular in cross-section and has an upper surface  42   a,  a lower surface  42   b,  an interior side surface  42   c,  an exterior side surface  42   d,  a first end  42   e  and a second end  42   f.  The first perimeter of first riser frame  38  is defined by exterior side surface  42   d.  The first perimeter is interrupted by a gap  46   a  which is defined between first and second ends  42   e,    42   f  of first riser frame  38 . When riser is fully contracted, first and second ends  42   e,    42   f  touch each other. 
         [0041]    Flange  50  extends upwardly and outwardly from upper surface  42   a  of first riser bar  42  and is secured thereto in any suitable manner, such as by an annular weld  52 . Flange  50  is secured to first riser bar  42  in such a manner that an interior side surface  50   a  of flange  50  is disposed at an angle “B” ( FIG. 4 ) relative to upper surface  42   a  of first riser bar  42 . This angle “B” is complementary to the taper of the circumferential side wall  16   a  of manhole cover  16 . Interior surface  50   a  of flange  50  defines an opening  66  that is complementary to manhole cover  16  that is to be received therein. When cover  16  is engaged with riser assembly  36 , as will be hereinafter described, lower surface  16   b  of cover  16  will be seated on upper surface  42   a  of first riser bar  42  and the circumferential surface  16   a  of cover  16  will abut interior surface  50   a  of flange  50 . It should be noted that flange  50  also includes a gap (not numbered) that is substantially aligned with gap  46   a  and has an exterior side surface  50   b  which is configured to be complementary to the access hole  12  provided in new layer  24  of pavement  10 . Furthermore, flange  50  includes an uppermost edge  50   c  that will be substantially aligned with top surface  24   a  of the new layer  24  of pavement  10  when riser assembly  36  is engaged with manhole frame  28 . 
         [0042]    Second riser frame  40  comprises a second riser bar  44  and an expansion device  48 . Second riser frame  40  preferably is formed from an annularly configured second riser bar  44  that is generally square or rectangular in cross-sectional shape. Second riser bar  44  includes an upper surface  44   a,  a lower surface  44   b,  an interior side surface  44   c,  an exterior side surface  44   d,  a first end  44   e  and a second end  44   f.  Second perimeter is defined by exterior side surface  44   d  and is interrupted by a gap  46   b  that is defined between first and second ends  44   e,    44   f  of second riser bar  44 . When riser assembly  36  is constructed, first riser bar  42  is disposed vertically above and aligned with second riser bar  44 . Gap  46   a  is also aligned with gap  46   b.    
         [0043]    In accordance with yet another specific feature of the present invention, an expansion device  48  extends between first and second ends  44   e,    44   f  of second bar  44 . Expansion device  48  is provided to enable an installer to change the width of gap  46   b  so as to fit riser assembly  36  into differently sized manhole frames  28 . Preferably, expansion device  48  is a turnbuckle that is substantially identical to the turnbuckle assembly disclosed in U.S. Pat. No. 7,165,911, the disclosure of this patent being incorporated herein by reference. As such, the expansion device  48  includes a pair of threaded rods  68  each having a flange  70  at one end. Although not shown in these figures, it will be understood that each flange  70  defines an aperture therein that is alignable with one of a pair of vertically oriented holes  72  defined in second riser bar  44  of second riser frame  40 . Holes  72  extend between upper and lower surfaces  44   a,    44   b  of second riser bar  44  and each flange  70  fits into a horizontal slot  74  cut into each of the first and second ends  44   e,    44   f  of bar  44  intermediate upper and lower surfaces  44   a,    44   b.  A pin  76  is received through the aligned holes  72  and the aperture in flange  70 . A turnbuckle  78  is engaged with the second ends of the two threaded rods  68 . Each of the second ends is received within a bore (not shown) in turnbuckle  78 . A hole  80  is defined in the turnbuckle  78  and is provided for insertion of a tool to rotate the turnbuckle  78  in either of a clockwise or counterclockwise direction and about an axis that runs through the rods  68 . When turnbuckle  78  is rotated in one of a clockwise and counterclockwise direction, the first and second ends  44   e,    44   f  of bar  44  will be drawn toward each other and the width of gap  46   b  will decrease. When turnbuckle  78  is rotated in the other of a clockwise and counterclockwise direction, the first and second ends  44   e,    44   f  will be moved away from each other and the width of gap  46   b  will increase. It should be noted that when the width of gap  46   b  decreases, the width of gap  46   a  also decreases somewhat because the first and second riser frames are fixedly secured together by spacer blocks  54  and the two riser frames  38 ,  40  move in union with one another. Gaps  46   a  and  46   b  and not necessarily of the same size but preferably are centrally aligned with each other. 
         [0044]    In accordance with a specific feature of the present invention, first riser frame  38  is disposed at an angle “A” ( FIG. 7 ) relative to second riser frame  40 . The angle “A” is complementary to the angle “A” at which the pavement  10  slopes as shown in  FIG. 3 . The angle “A” is created in riser assembly  36  by positioning one or more spacer blocks  54  between lower surface  42   b  of first riser bar  42  and upper surface  44   a  of second riser bar  44 . Spacer blocks  54  are secured to first riser bar  42  by welds  56  and to second riser bar  44  by welds  58 . Spacer blocks  54  are aligned with the first and second riser bars  42 ,  44 , i.e., blocks  54  are aligned with the regions of first and second riser bars  42 ,  44  to which they are secured. When spacer blocks  54  inserted between first and second riser bars  42 ,  44 , a gap  60  is defined between lower surface  42   b  of first riser frame  38  and upper surface  44   a  of second riser frame  40  in all regions of riser assembly  36  that are free of space blocks  54 . As is evident from  FIG. 4 , gap  60  is wider toward one side of riser assembly  36  and is narrower toward the other side thereof, i.e., the gap  60  tapers in height from one side of riser assembly  36  to the other. It should be noted that once first riser frame  38  is fixedly secured to second riser frame  40  via the at least one spacer block  54 , the angle “A” between the first and second riser frames  38 ,  40  is non-adjustable and will remain constant unless and until the welds  56 ,  58 ,  67  are broken and spacer blocks  54  are removed from between first and second riser frames  38 ,  40 . 
         [0045]    It will be understood that in accordance with the present invention, riser assembly  36  is custom made to be utilized in a specific manhole in pavement  10 . It is desirable to custom make each riser assembly  36  so that it specifically suits the terrain of the pavement  10  into which it is to be installed.  FIGS. 1 ,  3  &amp;  4  show that pavement  10  slopes downwardly in a direction that is substantially parallel to the longitudinal axis “Y” of the road  11  ( FIG. 1 ). The terrain may additionally slope at an angle relative to the longitudinal axis “Y”, but this is not illustrated on this attached figures. Consequently, in order to provide the correct angular orientation of riser assembly  36  so that it fits the specific terrain surrounding a particular manhole assembly  14 , the dimensions and shapes of the various spacer blocks  54  are calculated and each spacer block is effectively custom made to be placed at a specific location around the circumference of first and second riser bars  42 ,  44 . 
         [0046]    The location of each spacer block  54  is calculated and the blocks  54  are placed in those specific locations between first and second riser frames  38 ,  40  in order to ensure that the correct angle and pitch necessary to suit the terrain is built into the riser assembly  38 . If the spacer blocks are correctly shaped and secured between first and second riser frames  38 ,  40 , the uppermost surface  16   c  of cover  16  will be substantially flush with top surface  24   a  of pavement  10 . Additionally, if spacer blocks  54  are correctly shaped, positioned, and secured between first and second riser bars  42 ,  44 , uppermost edge  50   c  of flange  50  will be substantially flush with the top surface  24   a  of the new layer  24  of pavement  10 . If the blocks  54  are not of the correct shape or correct positioning, portions of the uppermost edge  50   c  and of cover  16  will be disposed a distance above or below the top surface  24   a,  thus creating an uneven sloped surface for vehicles to travel over or for people to walk on. 
         [0047]    In accordance with a specific feature of the present invention, the variations in shape and size of spacer blocks  54  are the features that create the particular angle “A” that is required between first and second riser frames  38 ,  40 .  FIGS. 5 and 6  show a first spacer block  54   a  provided proximate a first region  36   a  of riser assembly  36 . First region  36   a  is opposite a second region  36   b  that includes expansion device  48 . First spacer block  54   a  has a first height and both of its upper and lower surface  55 ,  57  are disposed substantially parallel to each other. A second spacer block  54   b  is provided at a third region  36   c  of riser assembly  36 . Spacer block  54   b  has a second minimum height that is smaller than the height of block  54   a.  Additionally, the upper surface  55  of spacer block  54   b  is disposed at an angle relative to the lower surface  57  thereof. Spacer block  54   c  is located in a fourth region  36   d  of riser assembly  36 . Spacer block  54   c  has a minimum height which is different to either of the heights of spacer blocks  54   a  and  54   b . Additionally, the upper surface  55  of spacer block  54   c  is disposed at a different angle relative to the lower surface  57  of block  54   c.  In the second region  36   b  of riser assembly  36 , there are no spacer blocks secured between first and second riser frames  38 ,  40  and upper surface  44   a  of second riser bar  44  is secured directly to lower surface  42   a  of first riser bar  42 , preferably by a weld  67 . The angle “A” between first and second riser frames  38 ,  40  is configured in accordance with the slope of pavement  10  that manhole cover  16  has to be made level with.  FIG. 3  shows that the slope “A” of pavement  10  is substantially equal to angle “A” and uppermost edge  50   c  of riser assembly  36  is flush with top surface  24   a  of pavement  10 . It should be noted the angles of the upper surfaces  55  of each of the spacer blocks  54   a,    54   b,    54   c  are selected so as to ensure that they support first riser bar  42  at angle “A”. Each block  54  may be manufactured to have a different height or slope on its upper surface  55 . The heights of spacer blocks  54   a,    54   b ,  54   c  grow progressively shorter as you move from spacer block  54   a  toward the region where first riser bar  42  is directly welded to second riser bar  44 . 
         [0048]    Riser assembly  36  in accordance with the present invention is used in the following manner. Firstly, a variety of measurements are taken by a road crew as relating to a particular manhole in which they wish to use an angled riser assembly  36  to raise manhole cover  16  so that it will be substantially flush with pavement  10 . These measurements, including size of access opening  12 , depth of new layer  24 , slope “A” matching the road  11 , and so on. These measurements are provided to a riser assembly manufacturer to construct an appropriate riser assembly. The manufacturer will figure out the specific dimensions of the spacer blocks  54  (namely blocks  54   a,    54   b,    54   c  and so on) that are to be used in riser assembly  36 . Additionally, the manufacturer will determine how many spacer blocks  40  have to be utilized and exactly where those spacer blocks  40  need to be placed between first and second riser bars  42 ,  44  in order to produce the angle “A” in riser assembly  36 . Once this information is determined, riser assembly  36  is constructed. The relevant number of spacer blocks  54   a,    54   b,  and  54   c  are welded to first and second riser frames  38 ,  40  in the predetermined locations between lower surface  42   b  of first riser bar  42  and top surface  448   a  of second riser bar  44 . If needed, and as shown, a region of first riser bar  42  is welded to a region of second riser bar  44 . Expansion device  48  is also engaged with lower riser bar  42 . The constructed riser assembly  38  is then shipped to the jobsite for installation in a specific manhole assembly  14 . 
         [0049]    At the jobsite the road workers or utility crew will remove the existing manhole cover  16  from the manhole opening  14 . In the attached figures, this is accomplished by inserting a lifting tool (not shown) into the apertures  64  in cover  16 . The upper surface  22   a  of original layer  22  of pavement  10  will be suitably prepared, and the new layer  24  of pavement  10  will be applied over upper surface  22   a.  Access hole  12  is then cleared to ensure that no debris or pavement material is disposed on the surfaces of manhole assembly  14 . Riser assembly  36  is then inserted though access hole  12  and lowered until lower surface  44   b  of second riser frame  40  comes into abutting contact with horizontal support surface  30  of manhole frame  28 . 
         [0050]    Riser assembly  36  is rotated, if necessary, within manhole opening  14  so that the uppermost edge  50   c  of flange  50  is substantially level with the top surface  24   a  of new layer  24  of pavement  10 . When the uppermost edge  50   c  is deemed level with top surface  24   a,  expansion device  48  on second riser frame  40  is activated to increase the width of gap  46   b.  Expansion device  48  increases the second diameter or, stated differently, increases the overall circumference of second riser frame  40  so that second riser frame  40  is tightly fictionally retained within the conical wall  32  of manhole frame  28 . (It will be understood that other components and methodologies may be employed to engage riser assembly  36  with manhole frame  38 , and these other methodologies are considered to fall within the scope of the present invention. When riser assembly  36  is correctly installed in manhole frame  28 , a worker will not be able to pull riser assembly  36  upwardly or push it downwardly. When expansion device  48  is in the expanded condition, second riser bar  44  is wedged within the opening bounded by conical wall  32 . At this stage, first riser frame  38  rises upwardly from second riser frame  40  and extends beyond uppermost edge  33  of conical wall  32 . It should also be noted that riser assembly  36  is positioned within the space defined by conical wall  32  and no part of riser assembly  36  contacts uppermost edges  33 . Flange  50  extends upwardly from first riser bar  42  and flange&#39;s uppermost edge  50   c  is substantially flush with top surface  24   a  of pavement  10 . Upper surface  42   a  of first riser bar  42  is disposed at an angle “A” relative to bottom surface  44   b  of second riser bar  44 . 
         [0051]    Manhole cover  16  is then lowered into the opening  66  defined by flange  50 . Bottom  16   b  of cover  16  is disposed in abutting contact with upper surface  42   a  of first riser bar  42  of first riser frame  38  and circumferential edge  16   a  of cover  16  will abut interior surface  50   a  of flange  50 . Additionally, upper surface  16   c  of cover  16  will be substantially flush with top surface  24   a  of new layer  24  of pavement  10 . 
         [0052]    If it is later decided to add yet another layer of pavement material to pavement  10 , riser assembly  36  may be quickly and readily disengaged from manhole frame  28 . Firstly, cover  16  is removed from its abutting engagement with first riser frame  38  by inserting a tool through apertures  64  and lifting cover  16  out of opening  66  in riser assembly  36 . Expansion device  48  is activated to reduce the width of gap  46   b  in the expanded second riser frame  40 . When expansion device is so activated, the second diameter or circumference of second riser frame  40  is decreased in size so that riser assembly  36  is no longer wedged into the space in manhole frame  28  defined by conical wall  32 . It will be understood that the at least one spacer block  54  is stationary relative to both of the first and second riser frames  38 ,  40  when expansion device  48  is activated to change the second diameter of the second riser frame  40 . 
         [0053]    Riser assembly  36  is then lifted out of access opening  12 . A newly custom-built riser assembly (not shown) that is configured to accommodate the additional layer of pavement may then be inserted through access opening  12  and then adjusted to frictionally engage manhole frame  28  in the manner described with reference to riser assembly  36 . 
         [0054]    The riser assembly in accordance with the present invention presents a cover-bearing surface (upper surface  42   a  of first riser frame  38 ) that is always disposed at the same orientation whether the expansion device  48  is in a neutral position or in an expanded condition or a contracted condition. Consequently, a cover  16  engaged with riser assembly  36  when engaged with manhole assembly  14 , and more specifically with manhole frame  28 , will not tend to rock as vehicles travel thereover. 
         [0055]    It will be understood that while the expansion device has been illustrated herein as being provided on second riser frame  40 , an expansion device may alternatively or additionally be provided on first riser frame  38  without departing from the scope of the present invention. 
         [0056]    It will be understood that second riser frame  40  may additionally include a locking ring (not shown) that extends downwardly from lower surface  44   b  of second riser bar  44  and is configured to be receivable through the opening defined by the interior surface  34  of manhole frame  28 . This locking ring may include components that will secure riser assembly  36  to manhole frame  28 . The locking ring could be of a similar configuration to that disclosed in the U.S. Pat. No. 7,165,911 (Fier) previously incorporated herein by reference. 
         [0057]    Any other suitable components for fixedly or releasably securing riser assembly  36  to manhole frame  28  are also considered to fall within the scope of the present invention. So, for example, second riser frame  40  may be welded to support surface  30  or may be secured to the annular lip which support surface  30  and interior surface  34  form part of, by fasteners, clamps etc 
         [0058]    In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. 
         [0059]    Moreover, the description and illustration of the invention are an example and the invention is not limited to the exact details shown or described.