Unit: Surveying Lesson: Measuring Distance Ag Structures Mr. Dieckhoff PowerPoint adopted from California State Ag Mechanics Curriculum Distance Measurement Introduction Distance is one of the most basic engineering
measurements Early measurements were made in terms of the dimensions of the body Cubits - the distance between the tip of your middle finger to the elbow Typically to measure cords and textiles (another measure was 24 digits or 6 palms) Distance Measurement Introduction Fathom - distance between the tips of your
middle finger when your arms are outstretched The name comes from the Danish faedn, "outstretched arms." Distance Measurement Introduction Foot mans
distance from the tip of a big toe to the heel Rod - the sum of the lengths of the left feet of 16 men (16.5 ft) Distance Measurement Pacing The ability to pace distance is very useful A person can determine their pace by counting the
number of paces necessary to walk a distance that has been previously measured A pace is defined as one step A stride is consider two steps Calculating Pace Lab Using the tape on the asphalt determine your pace using the following method/chart. The more time you check the more accurate you will be. 100
Walk a full 100 counting the number of steps it takes you to do so. Do this a minimum of 6 times or more to be accurate. Fill in the information as required. Distance Measurement Pacing Distance Measurement Measuring Wheels Distance Measurement
Taping or Chaining For centuries engineers have measured distances with ropes, lines, or cords The term chaining is a carryover from the time when the Gunter chain was used (1600s) The 66 foot chain is made of ____ links 7.92 inches in length In 1785 U.S. a federal law stated that all government surveys must be done with a Gunter's chain
Distance Measurement Taping or Chaining It lies at the origin of the definition of an acre (43,560 sq feet). The original acre was an area of land suitable for ploughing with a defined amount of work (e.g., ten furrows long, each furrow being ten chains, permitting rests of an oxen team) It measured one chain by one furlong (totaling 10 square chains). Early twolane roads were laid out with a chain, resulting in a
66ft rightofway Distance Measurement Taping or Chaining Distance Measurement Taping or Chaining Tapes are available in lengths up to 1,000 feet; precision of 1/1,000 to 1/5,000 are commonly obtained Distance Measurement
Electronic Distance Measurement (EDM) EDMs are very useful in measuring distances that are difficult to access or long distances Distance Measurement Taping over Level Ground If the taping is done over level ground where there is no underbrush, the tape can rest on the ground A taping crew consists of two people: the head tapeperson and the rear tapeperson The head tapeperson takes one end of the tape
walks down the line towards the point If the distance is more than 100ft, then the head tapeperson places a taping pin at the 100ft interval and the process is repeated Distance Measurement Taping over Sloping Ground If the taping is done over sloping ground where there is no underbrush, the
taping must be done in sections, referred to as breaking the tape Distance Measurement Taping over Sloping Ground Holding the tape more than five feet above the ground is difficult, therefore slopes greater than 5 ft per 100 ft will require runs of less than 100 ft
Distance Measurement Taping over Sloping Ground Hold the tape level Use a plumb bob to locate the point Height less than 5 feet 40 feet
30 feet 35 feet Distance Measurements Review 1. What is a fathom? 2.
How long is a rod? 3. What is the difference between a pace and a stride? 4. What is the length of a chain?
5. How big is an acre? 6. How did furlongs help determine the length of an acre? 7.
How do you measure distance over sloping land? Lesson 1 Quiz 1. You are working on a surveying crew. The land description you are working on says the western edge of the property is 14 rods. How many feet is that? 2. What is your personal length of stride? (answer should have 1 decimal place) 3. How many square feet are in an acre?
4. What is the relationship between chains & furlongs? 5. Explain how to take distance measurements over uneven ground? Lesson 1 Answers 1. 2. 3. 4. 5.
231 feet Answers will vary 43,560 square feet A furlong is 1 chain wide, by 10 chains long Use a plumb-bob over distances where the terrain has a greater slope than 5%.