Survey Computations HW#9 Subdivision Cul-de-sac Return Curves, Resection
Assignment:
1. Do the following COGO problem "by hand" on computation paper showing formulas used and substitutions.
2. Also make a "COGO work sheet", a hand drawn scaled drawing of the subdivision with COGO points. Label each point with a point #. This hand drawing will accumulate the results of HW7, HW8, HW9, and HW10. Mark the coordinates of each point on your drawing something like this:
P2 12,445.23N
11,567.99E
3. Enter your computed values in the supplied "COGO Data Spreadsheet" (found on the website). In the spreadsheet, enter your calculated data by point, area, curve, or line.
4. (Optional) In addition to the hand computations, you may solve the problem a second way as a check – make and use an Excel COGO Calculator similar to lecture, use a COGO/CAD software that you may have access to. However, this is not required, but the hand computations are.
Problem: We are going add a "cul-de-sac" at the end of the road centerline and add reverse "return" curves. For this HW, do the following
1. The center of a cul-de-sac P22 is to be found by resection. At P22, the measured angle from P2 to P3 is 90 degrees, and the measured angle from P3 to P4 (not the new P4') is 125 degrees. Calculate P22 coordinates by resection.
2. The cul-de-sac with center at P22 is of R/W radius 60 ft. The centerline tangent coming into the cul-de-sac comes from P8.
3. Compute two R/W "return" curves of radius 20 ft as reverse curves between the cul-de-sac and the incoming straight R/W lines.
4. The centers of each return curve are found by intersecting a circle of radius 80 (60+20) from the cul de sac center P22 with a line parallel with and offset 60 ft (40+20) from the centerline from P8-P22.
5. The PRCs are at the intersection of the radial line between the cul de sac and return circle radius points with the cul de sac right of way of radius 60 ft.
6. The PC's are at the foot of perpendiculars dropped from the return circle radius point to the straight right of way lines.
(NOTE: there are numerous alternate COGO methods to calculate these points. Choose the method you wish to use.)
return curve RP
cul-de-sac
22
1 North R/W
7 8 PRC
6 PT
PC South R/W PC
5
Assign point numbers consistent with the COGO Data Sheet.
7. Calculate curve data for the North and South R/W return curves curves. Enter your curve data in the COGO Data Sheet.
Submit: Your updated Excel COGO Data Sheet spreadsheet attached to your assignment upload using WebCT. Insert an image of your hand solutions for this HW and your updated hand drawing. Upload a single file.