Construction & Contractors/reading a grade rod


Hinebiter wrote at 2008-08-18 15:14:47
First of all understand what a benchmark is and how it plays into the cuts and fills. It is essential to start with a known elevation such as 327.50. What this means is your location above sea level and it start at 0 and goes up from there. So the deeper the cut the larger the number. When you shoot wiht a level the benchmark it will read your HI or height of the instrument such as 4.10 and if your are shooting the benchmark of 327.50 you add the numbers to get your HI. With the HI now established each grade you shoot on the plan elevation will match the given grade as your instrument. Learning hundreths and tenths is also essential as it is more difficult to add 11-1 3/8 to 12-2 9/16 then to add 11.11 to 12.20. If you think in these terms it may make it easy for you. What is .25 it is 3 inches and 4" is .33 and 6" is .50 and 9" is .75. Learn the rest and it is easy and quick in the field.

Dave Jennette wrote at 2014-08-10 19:39:30
if what does this mean

plan shows an elevation of 7.45 and a datum of10.0

Construction & Contractors

All Answers

Answers by Expert:

Ask Experts


Robert Cummings, P.E.


I can answer questions related to rock blasting, rock and soil excavation (such as tunnels and highway cuts), stability of such excavations, and foundations in rock and soil. I can also answer questions related to geology and mining.


30+ years as a geotechnical engineer and minerals engineer. Active consulting practice in rock blasting, geotechnical engineering, and rock mechanics for mining and heavy construction.

Society of Mining Engineers, Deep Foundations Institute, Association of Engineering Geologists, and International Society of Explosives Engineers.

Mining Engineering, AEG Bulletin.

BS and MS Geological Engineering

©2016 All rights reserved.