Chain/Tape Survey; It is a method of Surveying in which no angles are measured but only linear measurement is taken in the field by using a chain or tape measure.It measures a series of straight lines on the ground with a chain or tape measure and all fixed points relative to theline of traverseeither by right angles (offsets) ortie lines. The following are the equipment used in tape surveying;-
1. Chain: The chain is made up of steel wire which is divided into links and togs(rings) to facilitate folding.It is sometimes used as a unit of measurement. It has brass handles at both ends for easy handling. Thelinkis 0.2m or 200mm in diameter. The length is 20m or 30m.
2. Tape/Steel tape/Linear tape: A tape is made from fiberglass or a steel strip and is 10m, 20m or 30m in length graduated in 10mm divisions and numbered at each 100mm (10) divisions.It is used for measuring short distances
3. Ranging poles:Ranging polesare made up of wood or light metal and measure about 2m long at the top. The equipment has steel shades on its legs so it can be stuck into the ground. Ranging poles are painted red and white so that they can be easily seen even from a distance. They are used for making stations.
4. Arrows; Arrows are made of steel wire of diameter 4mm and their ends are bent into a circle where red cloth is tied to facilitate visibility. They are used for showing points on the ground.They are also used for counting the number of chains while measuring a chain line.
5. Pegs; Pegs are made of wood 40mm square by 50cm long and are used for permanently marking positions during survey
6. Surveyors’ band: The surveyor’s bandis made of a steel strip which is rolled into a metal frame with a winding handle. It is 30m, 50m or 100m long. Is used in projects where more accuracy measurement is required.
7. Cross staff; The cross staffis made of metal or wood witheye slipsat right angles and is used to measure right angles from the line of traverse
8. Notebook; Note books are used during field work to record data obtained. The notebook should be of good quality and 150mm x100mm in size
9. A hard pencil and a rubber; Hard pencils are used for drawing in the field and arubberis used to erase mistakes or errors which are made. A pencil should be HB or HHB.