Question

AEC-357 SITE ENGINEERING NAME: I H.I. F.S. B.S. 4.61 3.01 STA BM #6 HYD #1 STA #1 BM #4 STA #6 BM #6 ELEV. | ELEV. DESCRITION / REMARKS 891.43 RIM MHC 40TH AVENUE & 65TH STREET TOP NUT - HYDRANT-SE QUAD 40TH & 65TH STREET NOTE - INVERTED ROD SHOT ON CEILING- NOTE! TOP NUT - HYDRANT - SW QUAD 40TH & 66TH STREET SE BUILDING CORNER - TOP CONCRETE FOUNDATION SAME AS ABOVE-RIM MHC 40TH AVENUE & 65TH STREET 9.11 4.03 6.73 5.45 4.91 3.66 14.91 SHOW CHECKS FOR ALL WORK!

Answer 1

B.S = Back sight

F S =fore sight

H I =Height of instrument

Height of instrument = Elevation /reduced level + BS

Elevation/reduced level = HI-FS

Station	B.S	I.S.	F.S.	H.I.	ELEVATION
BM #1	4.61			891.43+4.61 =896.04	891.43
HYD #1	3.01		9.11	886.93+3.01 =889.94	896.04-9.11 =886.93
STA #1			-4.03	889.94	889.94+4.03 =893.97
BM #4	3.66		6.73	883.21+3.66 =886.87	889.94-6.73 =883.21
STA #6	14.91		5.45	881.42+14.91 =896.33	886.87-5.45 =881.42
BM #6			4.91	896.33	896.33-4.91 =891.42
	26.19		26.20

STA #1 is inverted reading.so it is taken as -4.03.

check

for check,$\sum$BS , $\sum$ FS should be positive.

$\sum$BS=26.19

$\sum$FS=26.20 (sum of positive F.S.)

$\sum$FS - $\sum$ BS =First elevation - Last elevation

$\sum$FS - $\sum$ BS = 26.20-26.19 =0.01

First elevation - Last elevation =891.43 - 891.42 = 0.01

so $\sum$ FS - $\sum$ BS =First elevation - Last elevation

The calculation is correct