3. Set up an automatic level and measure the
elevation of the automatic level above the
grade hub.
4. Add elevation measurement of instrument
to “cut-to-invert” from grade hub.
5. Subtract the desired working of elevation of
laser beam above invert
6. Subtract the beam offset (0.23 ft / 70 mm).
7. Calculate new rod reading.
8. Set the rod on top of the Laser and adjust
the elevation of the laser until the correct
rod reading is observed.
9. The laser beam is now at the proper working elevation.
Example 2: Setting Grade Rod on Top of Laser
Laser beam distance
above invert
Rod reading on
top of laser
Rod reading
on grade
hub
Cut to invert
Step Description Feet /
Inch
Metric
Step 1
Decide what elevation the laser beam shall be
used above the invert.
0.5 ft 0.152 m
Step 2
Record the “cut-to-invert” information from
the grade hub.
2.64 ft 0.805 m
Step 3
Measure the elevation (HI) of the optical
instrument above the grade hub.
3.70 ft 1.128 m
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