CE 134 Lecture Notes - Lecture 4: Sea Level, Geodetic Datum, North American Vertical Datum Of 1988

• School: Cal Poly Pomona
• Department: Civil Engineering
• Course: CE 134
• Professor: Lourdes Abellera

Document Summary

Elevation is referred from/based on the vertical datum. In differential leveling, the height of the instrument (hi) is referred from/based on the vertical datum. True: the turning point (tp) is where you (a) set up the instrument, or (b) hold the rod, you can have as many turning points as you like. Sources of errors: natural error, instrumental error, personal error. Types of errors: systematic error, random error. Instrumental errors: line of sight, cross hair not exactly horizontal, rod not correct length, tripod legs loose. Natural errors: curvature of the earth, refraction, temperature variations, wind, settlement of the instrument, settlement of a turning point. Personal errors: bubble not centered, faulty rod readings, rod handling, target setting. Mistakes: improper use of a long rod, holding the rod in different places for the backsight and foresight on a turning point, reading a foot too high, recording notes, touching tripod or instrument during the reading process.