All About Grade Rods - EngineerSupply

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All About Grade Rods

Who uses them, and why are they used

Grade rods are mostly used by land surveyors, construction workers, concrete professionals, building contractors, plumbers, grading contractors, and farmers to determine the difference in elevation of almost any surface or utility. The definition from Webster’s Dictionary states “A graduated rod used in measuring the vertical distance between a point on the ground and the line of sight of a surveyor’s level.”

How are Grade Rods used?
For a Grade Rod to work, it must be extended to its full length and a set up of the instrument to be used with the grade rod such as an auto-level, or transit level. Next, determine the points of measurement needed. Have the rodman, person holding the rod, hold the grade rod vertically. It needs to be plumb for exact measurement. The person using the instrument can then focus on the grade rod. The rodman will then mark the measurement accordingly.

To use a direct reading laser rod with the cut/fill feature, set the rod foot on the elevation you want as your reference. Run the laser receiver up or down the side of the rod, or raise or lower the front rod section, until the laser detector signals you are “on grade.” If you are using an optical instrument, site to the rod and use the horizontal line as your grade reference. Loosen the tape lock pin, and disengage the pin from the tape grommet. Roll the tape until the detector pointer is at 5.25. Lock the tape by engaging the lock pin and tighten the knob. All future readings will be true elevation above or below 5.25. To find an elevation, simply set the rod foot at any location on the job within the range of your laser or optical instrument. Run the detector and / or front rod section up or down until you pick up the “on grade” signal from your detector. Read the number opposite the pointer. That number is your true elevation. If using an optical instrument, just read the number across the horizontal line. To use the cut/fill feature, loosen the tape lock pin, and disengage the pin from the tape grommet. Roll the tape until the detector pointer is at zero (between the blue and red sections). Lock the tape by engaging the lock pin and tighten the knob. To determine the amount to cut or fill, set the rod down and find the “on grade” signal with your detector. Read across from detector pointer. The tape will tell you how much to cut or fill. Example: Rod reading is in blue section at 1.75 feet. The existing grade is too low. Fill 1.75 feet to be at the correct grade.

Varieties of Grade Rods versus Direct Read Grade Rods
There are several different types of grade rods that are used in different situations. Some people call Grade Rods "Leveling Rods", or "Story Poles" since they tell a "story". Direct Reading Rods are read directly through the telescope of the person using the instrument. Another name for a Direct Reading Rod is a Self-reading Rod or a Cut-and-Fill Grade Rod. Many people refer to direct reading rods as a "Lenker Rod" which was a brand of rod made many years ago which is no longer made, but the direct reading cut-and-fill rods are designed much better and work on the same principle as the lenker rods did.

Types of Rods Description
Grade or Level Rods Leveling rods are typically made from aluminum or fiberglass and are graduated in feet and tenths, or feet and inches depending on the users preference.
Philadelphia Level Rods Philly Rods feature two sliding sections joined by a brass sleeve; can be used for measurements of to 13 feet; can be read with a level from a distance of up to 250 feet
San Francisco Level Rods Similar to the Philadelphia rod; features three separate, sliding sections for extending or reducing length.
Direct Reading Rods Read directly through a optical scope by the user. Direct Reading Rods are also known as self-reading rods.
Direct Elevation Rods Has a graduated strip that revolves around the rod using rollers and features numbers in reverse order which are capable of providing elevation readings without need for additional foresight and backsight calculations. This saves time and avoids most errors.
Target Rods Features a target, making it possible for the person holding the rod to double check the readings presented by the person handling them surveying instrument

An Engineer’s Rod has graduations that measure in feet and tenths and hundreds of a foot. It is marked in high contrast, allowing for easy reading. The full foot numbers are usually marked in red, while the tenths of each foot are marked in black and the hundredths are marked by a tick mark in between numbers. If the measurement lies at the top of the tick mark, the measurement is an even hundredth. If it is at the bottom of the tick, it is an odd hundredth. This type of rod uses the decimal system, making it easier for calculations.

A Builder’s Rod, or Architect’s Rod, is similar to the Engineer’s Rod. Instead of being divided into inches and decimals, this rod is divided into inches and fractions. The feet marks are still in red, but the inches are marked in black, and the eighth of an inch marks are marked by ticks. It’s necessary to convert the fractions into the lowest common denominator when adding and subtracting measurements.

A Direct Elevation Rod is more efficient at recording that the Engineer’s Rod. The Direct Elevation Rod has numbers that read down the rod. It is divided into two sections: Upper section, the front of the rod, Lower section, the back of the rod. The upper section holds a movable loop of steel measuring tape. It is marked either in decimal form of feet, tenths and hundredths of a foot, or in feet, inches, and fractions. The lower sections can be shortened or lengthened to make the marked tape more visible.

The Philadelphia Rod, or Philly Rod, is the most common engineer’s rod. It was created in Philadelphia, Pennsylvania. It contains two wooden sections. It can be extended from 7 feet to 13 feet. It has a front and back side, and each foot on this rod is divided into hundredths of a foot. The distance between the hundredths is painted black on a white background. The bottom of the black marks is odd values and the top are even values.

The Laserline GR1450 15’ direct reading laser grade rod cut/fill is a Direct Reading rod with cut and fill applications. The cut and fill feature is typically used on new job sites that are being prepared for grading. The site is balanced by moving dirt from high areas and placing it in low areas according to the engineer’s construction plans. The GR1450 has a track designed to accommodate a laser receiver for easier measurements. The direct reading tape displays measurements in both 10ths/100ths and as a cut/fill indicator. Other optional measurements are feet, inches, and fractions of an inch, or Metric. The cut/fill feature is divided into a blue and red field.

Grade Rod Manufacturers
There are many manufacturers or grade rods, but the top companies are considered to be; Seco, CST/berger, Crain, Sokkia, Northwest Instrument, and Laserline.

Grade Rod Materials
Original ones were made of wood while todays are made of aluminum or fiberglass. Aluminum is good, but fiberglass is better due to it doesn’t get bent as easy and is tougher overall.

Grade Rod Extension
It is common for grade rods to fold up, break down, or collapse into itself, which makes it easier to handle. With a wooden rod, sections can be attached to each other with sliding connections, or slip joints, or hinged to fold when not in use. Wooden rods are usually made of hard maple. Aluminum and fiberglass rods typically have telescoping sections inside each other. Fiberglass and Aluminum rods are waterproof and corrosion-resistant. Unlike the aluminum grade rods, fiberglass rods are non-conductive. The down side of wooden grade rods is that they can expand or contract in humid or wet conditions, causing inaccurate readings. Aluminum grade rods can also swell or contract in hot or cold weather. Because of these downsides, a fiberglass grade rod is better suited for harsh conditions.

Grade Rod Accessories
Accessories for Grade Rods include Prism threads on top for mounting targets or prisms. Also, cases are available and some grade rods come with a case included. A laser detector clamp that clamps by squeezing the rod and is made to hold a laser level detector.

Copyright 2015 - The Product Team
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