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Figure 14-36.-Determining cut or fill from grade rod and ground rod. 3.  Compute  the  difference  between  the  HI and  finished  grade;  this  vertical  distance  is  called grade  rod. 4. Read a rod held on the hub top or ground point for which the cut or fill is desired. This rod reading  is  called  ground  rod. 5.  Determine  the  cut  or  fill  by  adding  or subtracting  the  grade  rod  and  the  ground  rod, according  to  the  circumstances,  as  shown  in  figure 14-36. 6.  Mark  the  cut  or  fill  on  the  stake. During the final grading, you will most likely be  working  with  hubs  called  BLUE  TOPS  (fig. 14-31). These hubs are driven into the ground until the  top  is  at  the  exact  elevation  of  the  finished grade  as  determined  by  the  surveying  crew.  When the top of the stake is at the desired finish grade elevation,  it  is  colored  with  blue  lumber  crayon (keel) to identify it as a finished grade stake. Other colors may be used, but be consistent and use the same color keel throughout the project so as not to  confuse  the  Equipment  Operators.  Blue  tops are  normally  provided  with  a  guard  stake  to  avoid displacement   during   construction   work.   The guard  stake  usually  shows  the  station  and  the elevation of the top of the hub. The elevation and station markings may be required only at station points; otherwise, all that is needed is the blue top and  the  guard  stake  with  flagging. The  procedure  for  setting  blue  tops  lends  itself primarily to final grading operations. It is carried out  as  follows: 1.  Study  construction  plans  and  center-line profiles  for  each  station  to  determine  (1)  the exact  profile  elevation  and  (2)  the  horizontal distance  from  center  line  to  the  edge  of  the shoulder. 2.  Measure  the  horizontal  distance  from  the center line to the shoulder edge at each station, and  drive  a  grade  stake  at  this  point  on  each side.  Sometimes  it  is  advisable  to  offset  these stakes  a  few  feet  to  avoid  displacement  during construction. 3. Set the top of the stake even with the grade elevation, using both the level and the rod. This is accomplished by measuring down from the HI a distance equal to the grade rod (determined by subtracting  grade  elevation  from  the  HI).  The target on the rod is set at the grade-rod reading; the rod is held on the top of the stake; and after a few trials, the stake is driven into the ground until  the  horizontal  hair  of  the  level  intersects  the rod  level  indicated  by  the  target.  Color  the  top of  a  stake  with  blue  crayon  (keel). 4. Where the tops of stakes cannot be set to grade because grade elevation is too far below or above the ground line, set in ordinary grade stakes marked with the cut or fill as in rough grading. However, for final grading, it is usually possible to  set  mostly  blue  tops. Where  grade  stakes  cannot  be  driven,  for example,  in  hard  coral  or  rock  areas,  use  your ingenuity to set and preserve grade markings in a  variety  of  conditions.  Markings  may  often  be made on the rock itself with a chisel or with a keel. SETTING   SLOPE   STAKES.–   SLOPE STAKES  are  driven  at  the  intersection  of  the ground  and  each  side  slope  or  offset  a  short distance;  they  indicate  the  earthwork  limits  on each side of the center line. The minimum areas to be cleared and grubbed extend outward about 6  ft  from  the  slope  stakes. 14-37

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