Chain Survey Method

Chain Survey

• Gunter's Chain measures 66 feet in length, divided into 100 links.
• Engineer's Chain measures 100 feet in length, divided into 100 links.
• Revenue Chain measures 33 feet in length, divided into 16 links.
• Chains are used to take linear measurements in chain surveying.

Materials and Equipment for Chain Survey

• Steel Tapes: available in various lengths (15m, 30m, 50m, and 100m), provide more accuracy.
• Invar Tapes: used for very precise measurements, typically for high-accuracy requirements.
• Fiberglass Tapes: lightweight and flexible, suitable for general use.
• Arrows (Chain Pins): used to mark the end of a chain during measurement, typically made of steel, about 400 mm long with a pointed end.
• Ranging Rods: used to mark the positions of survey stations, typically 2 to 3 meters long and painted with alternating bands of red and white for visibility.
• Pegs: wooden stakes used to mark important survey points or station points, driven into the ground.
• Plumb Bobs: used to ensure vertical alignment of ranging rods or to project points on the ground.
• Cross Staff: used for setting out right angles and to find offsets.
• Optical Square: an instrument used to set out and measure right angles.
• Clinometer: used to measure the angle of slope or inclination.
• Field Book: a small, portable notebook used to record survey measurements, sketches, and observations.

Tape Survey

• Tape survey involves measuring distances using a tape, which could be steel, invar, or fiberglass.
• Steel Tapes: most common, used for general purposes.
• Invar Tapes: used where very high precision is needed.
• Fiberglass Tapes: used for less precise, general measurements.

Materials and Equipment for Tape Survey

• Plumb Bobs: used for vertical alignment and to ensure measurements are taken straight down to the ground.
• Tension Handles (Dynamometers): used to apply a consistent tension to the tape to avoid sagging and improve accuracy.
• Tape Clamps: to secure the tape at the endpoints.
• Chaining Pins: similar to arrows used in chain surveying to mark positions.
• Ranging Rods: same as used in chain survey to mark positions of survey points.
• Field Book: for recording measurements and observations during the survey.

Additional Tips

• Ensure tapes are properly calibrated and free of kinks or damage to maintain accuracy.
• Be mindful of temperature and humidity, as they can affect tape length (especially steel and invar tapes).
• Use plumb bobs and ranging rods to maintain straight lines and correct alignment during measurement.
• Maintain clear and accurate records in the field book to avoid errors.