• Home
  • Download PDF
  • Order CD-ROM
  • Order in Print
Solving  a  Simple  Curve - CONTINUED - 14070_245
Field Notes - 14070_247

Engineering Aid 1 - Advanced Structural engineering guide book
Page Navigation
  223    224    225    226    227  228  229    230    231    232    233  
This method gives an exact result. By converting the minutes to a decimal part of a degree to the nearest fives places,  you  obtain  the  same  result. Simple Curve Layout To lay out the simple curve (arc definition) just computed  above,  you  should  usually  use  the procedure  that  follows. 1.  With  the  instrument  placed  at  the  PI,  the instrumentman sights on the preceding PI or at a distant station and keeps the chainman on the line while the tangent distance is measured to locate the  PC. After  the PC has been staked out, the instrumentman then trains the instrument on the forward  PI to locate the  PT. 2. The instrumentman then sets up at the  PC and measures the angle from the  PI to the PT. This  angle should be equal to one half of the I angle; if it is not, either the  PC or the PT has been located in the wrong position. 3. With the first deflection angle (3°10’) set on the as the first subchord distance (42.18 feet) is measured from the PC. 4. Without touching the lower motion screw, the instrumentman sets the second deflection angle (6°55’) on the plates. The chainman measures the chord from the previous station while the instrumentman keeps the head chainman on line. 5.  The  crew  stakes  out  the  succeeding  stations  in the same manner. If the work is done correctly, the last deflection angle will point on the  PT. That  distance  will be the subchord length (7.79 feet) from the last station before the PT. When it is impossible to stake out the entire curve from the  PC,  a  modified  method  of  the  procedure described above is used. Stake out the curve as far as possible from the  PC. If a station cannot be seen from the PC for some reason, move the transit forward and set up over a station along the curve. Pick a station for a backsight and set the deflection angle for that station on the plates. Sight on this station with the telescope plates, the instrumentman keeps the chainman on line in the reverse position. Plunge the telescope and set Figure  11-11.—Inaccessible  PI. 11-10







Western Governors University

Privacy Statement
Press Release
Contact

© Copyright Integrated Publishing, Inc.. All Rights Reserved. Design by Strategico.