Distance Measurement Chapter 3 Mc Cormacs 5 th

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Distance Measurement Chapter 3 – Mc. Cormac’s 5 th

Distance Measurement Chapter 3 – Mc. Cormac’s 5 th

Historical Measurement n Early Survey Crews n n n Crew Chief Crew of 2

Historical Measurement n Early Survey Crews n n n Crew Chief Crew of 2 or 3 Brush Hogs Support Equipment n n Compass Chain – see page 42

Units of Measure n Mile = 5280 feet n n Divide into 1/4’s, 1/16’s

Units of Measure n Mile = 5280 feet n n Divide into 1/4’s, 1/16’s Chain: 66 feet -> 80 chains/mile n n n 100 links -> 0. 66 ft/link = 7. 92” 20 Ch, 16 Lk = 20. 16 Ch = 1330. 6 feet Rod: 16. 5 feet -> 4 rods/Ch, 320 rods/mi Engineers Chain – 100 feet Note Units – 10 th, 100 th of feet

Methods of Measurement n Indirect n n Subtense Bars – pages 39 -40 Stadia

Methods of Measurement n Indirect n n Subtense Bars – pages 39 -40 Stadia – Chapter 14 EDM – Chapter 5 Direct n n n Pacing Odometers/Wheels Taping or Chaining

Pacing (1/50) n n Try for natural pace Measure a known distance Pace a

Pacing (1/50) n n Try for natural pace Measure a known distance Pace a number of times, Average Determine: n n Length of Pace – nearest 0. 1’ Number of Paces in 100’

Pacing Example n n n Measured length = 215. 0’ Pace 4 times –

Pacing Example n n n Measured length = 215. 0’ Pace 4 times – 74, 75, 74 paces Average no. of paces = 74. 25 Length of pace = 215’/74. 25 paces = 2. 9’/pace Paces per 100’ = 100’/2. 9’/pace = 34. 5 paces

Taping or Chaining n Equipment Needed n Tape n n n n Steel Fiberglass

Taping or Chaining n Equipment Needed n Tape n n n n Steel Fiberglass Cloth Tensiometer Plumb bob Hand level Range Poles

Chaining Process n Slope Chaining n n n Plumb Chaining n n n Measure

Chaining Process n Slope Chaining n n n Plumb Chaining n n n Measure along slope Convert to horizontal Measure with chain horizontal Downhill, when possible “Breaking” chain Forward Chainer (FC) reads 1/100 ths Rear Chainer (RC) reads feet

Add vs. Cut Chains Add Chain – 1/100 th’s forward from 0 RC at

Add vs. Cut Chains Add Chain – 1/100 th’s forward from 0 RC at 71, FC at 0. 54, record 71 + 0. 54 = 71. 54’ Cut Chain – 1/100 th’s back from 0 RC at 72, FC at 0. 46, record 72 - 0. 46 = 71. 54’

Chaining Process n n n n Establish Line Level chain Tension RC – sets

Chaining Process n n n n Establish Line Level chain Tension RC – sets full foot, calls “Mark” FC – sets 1/100 ths, calls “Mark” RC calls feet – “ 86” FC – calls portion – “Point 23” RC repeats – “ 86. 23”

Electronic Distance Measurement Electronic Distance Measurement Electronic distanceElectronic Distance Measurement Electronic Distance Measurement Electronic distance
DISTANCE LEARNING DISTANCE LEARNING Distance education or distanceDISTANCE LEARNING DISTANCE LEARNING Distance education or distance
Vertical distance measurement leveling Vertical distance measurement LevelingVertical distance measurement leveling Vertical distance measurement Leveling
Measurement Scales and Error of Measurement Measurement MeasurementMeasurement Scales and Error of Measurement Measurement Measurement
RAIN MEASUREMENT RAIN MEASUREMENT RAIN MEASUREMENT RAIN MEASUREMENTRAIN MEASUREMENT RAIN MEASUREMENT RAIN MEASUREMENT RAIN MEASUREMENT
Distance Methods Distance Methods Distance Estimates attempt toDistance Methods Distance Methods Distance Estimates attempt to
Distance and Displacement Distance and Displacement Distance andDistance and Displacement Distance and Displacement Distance and
Displacement vs Distance Distance l Distance d howDisplacement vs Distance Distance l Distance d how
Distance Midpoint Pythagorean Theorem Distance Formula Distance formulausedDistance Midpoint Pythagorean Theorem Distance Formula Distance formulaused