Basic Technical Concepts - Practical Boundary Surveying - page 25

Fig. 4.3 Breaking tape—measuring short distances on a steep slope
can be about 25 pounds. Rather than guessing at the tension, it is best to use a tension
meter (spring balance) on one end of the tape. When measuring up or down a steep
slope the person holding the tape at or over their head must be strong and in good
physical shape in order to resist the pull on the tape while holding it steady enough to
obtain an accurate measurement. The amount of tension required is dependent on the
tape length, so long tape lengths require considerably more tension than shorter ones.
When measuring long lines greater than the tape length of 100 ft, it is necessary
to set intermediate points on the ground so that there will be a point from which
the next 100 ft measurement can be made. For example, if a 200 ft line were being
measured, the front person would set a point at exactly 100 ft. The next 100 ft
would then be measured from that point. The point could be a nail pressed into the
soil or a mark set into or on the pavement. When taping was the prevailing method
of measurement, many surveyors used “ Surveyor's Arrows ” or “ Chaining Pins ”.
These are hardened steel pins a foot or so long, often painted in red and white
bands. There are 11 pins in a set. Although measuring survey lines with a steel
tape is no longer very common, the pins can still be purchased from surveying
supply houses. When a long line is to be measured, the front person sets a pin at
exactly 100 ft by pressing it into the soil. Once the front pin is set, the rear person
then removes the rear pin from the soil and keeps it. When taping long lines it is
easy to forget to count one or more 100 ft increments, so after the complete line
is measured the number of pins carried by the rear person is counted. The number
of pins multiplied by 100 ft, plus the remaining distance to the end point (a partial
tape length) is the total distance of the line being measured. For example if a line
of 535.23 ft were measured, there would be five pins and a partial tape length of
35.23 ft. The above assumes that the starting and ending points are existing survey
points such as stone bounds or wooden stakes, so no pins are used for these points.
Steel tapes used by surveyors are usually wound on a metal reel as shown in Fig.
4.3 , which shows two measurements down a steep slope. The reel has a winding han-
dle which also serves as a lock to prevent the tape from unwinding. When making