Horizontal distance measurement

• Spatial Distance is distane between any two random points in 3D space
• Horizontal Distance - Linear distance between two points on any Horizontal surface; If points are at different elevations, distance is the horizontal lenght between plumb lines at the points
• Pacing consists of counting the number of steps or paces in a required distance; approximately checking more precise measurements of distance
• Pace: Length of a step in walking; measured from Heel-to-heel or toe-to-toe; relative precision 1/200 to 1/100
• Stride: two paces or double step; Relative precision 1/200 or 1/100
• Taping: direct measurement of distances with steel tapes; most common measuring or laying out horizontal distance
• Slope taping: taping measurements are made directly along the slope when the ground is of uniform inclination and fairly smooth
• Breaking Tape: measurement of shorter distances which are accumulated to total a full tape length
• When a line is measured with a tape that is "too long", corrections are added
• When Laying out a length with a tape that is "too long", corrections are subtracted
• When a line is measured or laid out with a tape that is too short, corrections applied are opposite of 1st and 2nd rules
• Tape not standard length = too long / too short

  Slope = too short

  alignments = too short

  temperature = Too long/ too short

  Tension = too long/ too short

  sag = too short

  wind = too short
• Stadia Method: uses a telescope with two horizontal cross haies called stadia hairs and a graduated rod called stadia rod
• Tacheometry: indirect method of measuring horizontal distances; based on optical geometry; relative accuracy is 1:300 to 1:400
• Global Navigation satellite systems - Fixing of satellites to determine position of points; minimum of four satellites
• EDM - measurement of distance is based on the invariant speed of light or electromagnetic waves in a vacuum