HORIZONTAL DISTANCE MEASUREMENT

Pacing

– consist of counting the steps or paces in a required distance

Pace

– defined as the length of a step which may be measured from heel to heel or from toe to toe

Stride

– is equivalent to two paces or a double step

Pedometer

• Mechanical counter for recording the number of paces

Passometer

Device for counting pace which is strapped to the leg of the pacer

• Register a pace by impact each time either foot touches the ground

distance by taping

Used of graduated tape is probably the

most common method of measuring or

layout horizontal distance

distance by taping

Consist of stretching a calibrated tape

between two points and reading the

distance indicated on the tape

distance by taping

Form of a direct measurement which is

widely used in the construction of buildings,

dams, bridges, canals, and many other

engineering as well as non-engineering

activities

Tachymetry

Based on the optical geometry of the instruments employed and

is an indirect method of measurement

Transit or Theodolite

Used to determine subtended intervals and angles on a graduated

rod or scale from which distances are computed trigonometric.

Tachymetry

Performed either by stadia method or subtense bar method

Stadia Method

Provides a rapid means of determining horizontal distances

James Watt

Stadia Method Introduced in 1771 by_____ of Scotland and was at that time

referred to as micrometer for measuring distance

stadia hairs, stadia rod

The equipment for stadia measurement consist of a telescope with

two horizontal hairs called ______ and a graduated rod called

_______

Subtense Bar Method

convenient and practical device used for quick and accurate

measurement of horizontal distance

d= L/2tan(0/2)

Subtense Bar Method formula

d= ks+c

stadia method formula

Mechanical Devices

most commonly used device are the following but

only applicable for low key precision surveys or

where quick measurements are desired.

Odometer

- simple device that can be attached to

a wheel for purpose of roughly measuring surface

distance, similar with vehicle speedometer

Measuring wheel

-similar to odometer except that

it is more portable and self-contained measuring

device; suitable for measuring distance along

irregular and curve lines and boundaries

Optical rangefinder

hand-held or mounted on a

small tripod and can be used

to determine distances

simply by focusing

Photogrammetry

the type of photograph used are those taken from an aircraft with

the axis of the camera pointed vertically towards the terrain

photographed

Photogrammetry

refers to the measurement of images on a photograph

Electronic distance measurement

allow a rapid and accurate

determination of linear distance,

horizontal and vertical angles suitable

even for large extent surveys requiring

higher orders of precision