APPLICATIONS
Transfer of Elevation
Using an Automatic Level
1. Mount the level on a tripod outside the manhole
or open cut. Adjust it to level and point at the
manhole hub. Take a reading from a rod held at
the hub. This reading is sometimes called the
“back-sight” reading. (Figure A)
2. Now take a rod reading at the manhole center. If
a manhole is in place, read the elevation of the
base. In an open cut it is necessary to place an
object in the cut which can be used as a refer-
ence. A brick, stone, or board placed at manhole
center will work for marking a reference eleva-
tion, and as a starting point for the placement of
the laser or the trivet.
Using the Special Transit and Rod Group
This is an ideal method to use when the offset hub
is too far from the manhole center to transfer
elevation with a batter-board or other means.
The Special Transit is set up using the Rod and
Crossbrace System. (Figure B)
1. Mount the Special Transit on the calibrated rod
and point it to the manhole hub. The top edge
of the transit mounting bracket is the elevation
reference and is the same as the horizontal
crosshair (centerline) of the transit.
2. Level the transit using the adjust knob and the
level vial. Use the forward marker knob to adjust
the transit so that it is pointed exactly to an
engineer’s rule or calibrated rod section held at
the manhole hub.
3. After reading the engineer’s rule or calibrated
rod, measure down from the top edge of the
transit mounting bracket (transit centerline) to
the correct invert elevation.
HI
HUB
ROD
1st reading
2nd Reading
Elevation of
Manhole Base
Figure A
Figure B
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