A level instrument at a height of 1.320 m has been placed at a station having a Reduced Level (RL) of 112.565 m

Q. A level instrument at a height of 1.320 m has been placed at a station having a Reduced Level (RL) of 112.565 m. The instrument reads -2.835 m on a levelling staff held at the bottom of a bridge deck. The RL (in m) of the bottom of the bridge deck is

(A) 116.720                   (B) 116.080                    (C) 114.080                    (D) 111.050

Ans: 116.720

Sol:

The correct option is C 116.720
(Bottom of bridge deck staff reading is -ve indicates inverted staff.)
Height of instrument=112.565+1.320 =113.885m
RL of bottom of bridge=113.885+2.835 =116.720m