Answer questions
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Fieldwork Practices-Part 2
CSMT 345
LECTURE 4
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Fieldwork Practices cont..
• Tolerance for construction layout
• Notekeeping
• Instrument care
• Use and care of hand tools
• Leveling an instrument
• Instrument set up
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Tolerance for Construction Layout
• Tolerance is how far off from the design location something can be built and still be accepted by the owner
• Tolerance controls the quality of work being performed
• Tight/small tolerance is better than large ones (precision)
• Always measure to one-half of what is coming behind you
• Tolerance vary from 0 to a foot
• Every project has designs with specific tolerance levels
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Field Note-keeping Practices
• Basic Practices
– You must leave your work on the ground for others to build or for reference purposes or defense (in courts)
– Record data exactly (honestly)..no undue erasings
– Keep field book safely
– Leave no room for interpretation
– Cite/make references (i.e., if copied from another source)
– Use a hard pencil
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Field Note-keeping Practices cont.. • Layout of field book
– Title page
• Company’s name, address, telephone number, name of field engineer and any other identifying information
– Table of content
• Following chronologically
– Legend
• Used symbols and abbreviations
– North arrow
• Useful for orientation of the layout
– Identification information
• Numbering each page/ or name of people performing work
– Provide date, time and weather data
– Use sketches freely 5
Field Note-keeping Practices cont...
• Guidelines
– Don’t crowd the data
– Do not erase
• Erased data will be thrown out in court; just cross
– Record everything
• Do it or record it if in doubt
• Leave nothing for interpretation
• Record in field book in away that anyone with little knowledge in surveying will understand
– Establish standard note forms; familiar to the company/crews
– Use standard lettering techniques
• All capital (upper case)letters be used for clarity and consistency
• Hard pencil (2h/3h or 4h) be used 6
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General Instrument Care • Surveying Instrument
– Levels, transits, theodolites, EDMs and total stations are surveying instruments which are used to measure angles, distances or elevations.
• Although basic parts are the same, each has telescope lenses, clamp, leveling screws, delicate parts that must be cared for
– A surveying instrument will only work well if in good working condition, properly calibrated
• Must be used according to procedures recommended by manufacturer
– Three areas instruments can get exposed to hazards
• Transportation – Carry in protective case and avoid bouncing it
• Use – Use according to manufacturers recommendations
• Storage – Keep in case when not in use 7
General Instrument Care
• Care and use
– Attach instrument snugly to the tripod
– Grasp the instrument firmly
– Do not touch the lenses (only with clean hands)
– Try to keep the equipment dry
– Never leave the instrument unattended
– Establish a wide foundation
– Never force the instrument
– Return the instrument to its case
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Tripods • Tripods provide a solid foundation for instrument setups
• Should always be well kept and cared for
• Two types
– Fixed leg-cannot be lengthened/shortened to assist in set of instrument
– Adjustable legs: is flexible for setting instrument
• Tripod has a head for attaching the instrument, wooden or metallic points with foot pads to help force the legs into the ground
• Always ensure a solid set up, check all screws and bolts
• Do not mishandle the equipment
• Transport it carefully, not with other equipment that can affect it
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Use and care of hand tools • Plumb bob
– Used to create vertical line or a point for reference
– Keep it clean and never use it as a hammer or a scribe
• Sight level
– Used in taping to keep the tape horizontal; and in leveling to keep from setting the leveling instrument above or below the level rod
– Wipe the lens with clean cloth and store in protective case
• Gammon reels; for storing plumb bob strings
– Keep strings clean and check for wear
• Chaining pins; for marking intermediate points on taping
– Clean pins regularly and repaint when paint fade for visibility
• Range poles
– for making points in surveying job more visible
– Store in protective case when not in use 12
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Use and care of hand tools cont.. • Prism poles
– Used with electronic instruments to measure distances and make points visible
– Are similar to range poles, except that they have hollow tube to allow graduated rods to telescope in and out allowing the rod person to establish the height of the prism quickly
– Keep the telescoping rod clean and store the prism pole in a case
• Brush clearing equipment (axe, machete and chain saw)
– Wear appropriate PPE when in use
– Store in protective cases
• Hammers/chisels/chains/tapes
• Level rods
– Probably the most abused survey equipment after tripods
– Avoid touching the measurement face, don’t abuse and keep clean
• Hand held computers 13
Use and care of hand tools cont..
• General guidelines
– Only use those equipment you know how to use
– Keep clean
– Store in protective cases
– Keep dry at all times
– Do not force if difficult to move
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Leveling an Instrument
• Ability to set up an instrument depends on availability to level it
• Remember the principle of straight, level and plumb?
• GENERAL PRINCIPLES
– Instruments are differentiated into: • One level vials, two level vials, three/four level vials
– Use the leveling screws to raise or lower the ends of the vial until the level bubble is centered
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Leveling an Instrument
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Leveling an Instrument cont.. • GENERAL PRINCIPLES
– The head of the tripod should be horizontal
• a tripod that is not horizontal requires more movement of the leveling screws which takes more time to complete the leveling process. Adjust the tripod legs to ensure accuracy
– Level vial positioning • Position the level vial over the leveling screws properly so that the
manipulation of the leveling screws is effective
– Left thumb rule
• Most people use random method of leveling which takes longer time.
• The rule is: both thumbs in, both thumbs out, the bubble follows the left thumb
– As a check, always rotate 180 degrees
– Turn leveling screws equally 17
Instrument Setup • This is a fundamental requirement of surveying
• Three types of equipment are used
– Plumb bob • Works well except that it can be moved easily by wind thereby
introducing errors in the set-up over a point
– Optical plummet (optical plumb line) • Has lenses and prism for quick set up
• Was introduced to reduce errors of plumb bob; wind does not affect it but it can get out of calibration and needs frequent check-up
– Laser plummets • Lasers can be placed inside an instrument and be used for instrument
setups over a point
• They are becoming part of the instruments and are expected to become standard feature of instruments in future
– NOTE: Tool used to setup over a point should be quick and precise18