## INTRODUCTION TO DISTANCE MEASUREMENT

### HORIZONTAL DISTANCE MEASUREMENT

In plane surveying, the distance between two points means the horizontal distance.
If the points are at different elevations, then the distance is the horizontal length between plumb lines at the points.

### METHODS OF MEASURING HORIZONTAL DISTANCES

Pacing -- accuracy 1 / 100 (1.0%)
Tacheometry (stadia) -- accuracy 1 / 500 (0.2%)
Taping -- accuracy (Standard) 1 / 5,000 (0.02%)
Electronic Distance Measurement (EDM) -- accuracy 1 / 1,000,000 (0.0001%)

### TAPING

Definition: Applying a known length of tape to a line

### HISTORICAL TAPING EQUIPMENT

• Poles
• constructed of wood or metal
length of one rod (16.5 ft)
• Gunter's Chain
• 66 ft
100 links, 1 link = 0.66 ft = 7.92 in
• Engineer's Chain
• 100 ft
100 links, 1 link = 1 ft
• Wires
• metal coils with tabs for measuring distances

### CURRENT TAPING EQUIPMENT

• Surveyor's and Engineer's Steel Tapes
• Standard lengths 100, 200, 300, and 500 ft
30, 60, 100, and 150 m
• Other Tapes
• Builder's Tapes -- common construction tape measures, usually marked in feet and inches
• Cloth Tapes -- inexpensive linen with fine copper wires for strength, not for precise work
• Fiberglass Tapes -- inexpensive flexible tapes wound on a reel, used like steel tapes
• Invar Tapes -- made of 35% nickel/65% steel and do not expand as much as steel with heat, but are 10X more expensive than steel tapes
• Lovar Tapes -- has properties and cost between steel and invar tape
• Special-Purpose Tapes

### TAPING ACCESSORIES

• Chaining/Taping Pins -- used to mark tape lengths, especially when it is required to "break tape" or when measuring over 100 feet, usually painted red and white
• Hand Level -- helps to keep tape level over sloping or uneven ground
• Tension Handles -- helps you to hold on to tape when pulling it taut
• Pocket Thermometer -- helps you figure expansion and contraction of tape due to temperature
• Range Poles -- long poles used to mark points over long distances to help keep tape aligned properly
• Plumb Bobs -- help you locate tape directly over point being measured
• ### CARE OF EQUIPMENT

Always make sure you transport and store all surveying equipment, including tapes, properly, and be familiar with their use

Steel Tapes

Don't kink
Don't pull around corners
Don't run over it
Wipe off and oil every day
Cloth Tapes
Don't cut the tape through misuse
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