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Calculating the Allowable Error - 14071_128
Checking and Reducing Angles

Engineering Aid 2 - Intermediate Structural engineering guide book
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Figure 7-5.–Adjustmmt of level nets. For circuit BCDEB, the error of closure is –0.40 ft. This is distributed among the lines in proportion to their lengths. Thus, for the line BC, the correction is (Notice that the sign is opposite to that of the error of closure.) The correction of +0.07 ft is entered on the first line of the column headed CORR and is added to the difference in elevation (10.94 + 0.07 = +11.01). That sum is entered on the first line under the heading CORR DE  (corrected  difference  in  elevation).  The  same procedure  is  followed  for  the  remaining  lines  CD,  DE, and EB of circuit BCDEB. The sum of the corrections must have the opposite sign and be equal to the error of closure. The algebraic sum of the corrected differences in elevation must equal zero. The lines in circuit AEDA are corrected in the same manner  as  BCDEB,  except  that  the  corrected  value  of ED  (+27.08  instead  of  +27.15)  is  used.  The  lines  of EABE are corrected using the corrected value of EA (+17.97 instead of +17.91) and BE (+5.13 instead of +5.23). In the column Cycle II, the procedure of Cycle I is repeated. You should always list the latest corrected value   from   previously   adjusted   circuits   before computing  the  new  error  of  closure.  The  cycles  are continued  until  the  corrections  become  zero.  The sequence in which the circuits are taken is immaterial as long as they are repeated in the same order for each cycle. Computations may be based on corrections rather than  differences  in  elevation. TRAVERSE COMPUTATIONS Traverse  operations  are  conducted  for  mapping;  for large construction projects, such as a military post or an Figure 7-6.—Computations required to balance the level net. 7-7







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