Levelling Equipment Flashcards
What are the two broad categories of levels?
Optical aka builder’s level -> two people are needed to operate them. Looks through scope + interprets the reading.
Electronic levels -> rotate a light beam / only require one operator
Which way can a builder’s level move? (horizontal or vertical)
Horizontal
What are some fun facts about the “Dumpy” levels (aka 4-pin levels)
- Least expensive
- Least sensitive
- The hardest to correctly set up
What are 2 types of manual levels? (DT)
Dumpy
Tilting
What is split bubble or engineer’s level also called?
Tilting level.
What type of levels only have a fish - eye bubble + prism inside.
Automatic levels
What are 2 features of an Optical instruments
1) Crosshairs + stadia lines inside the viewfinder
2) An eyepiece focus (for the crosshairs)
- Reading are taken from crosshairs
What does a beam detector or sensor use to locate distances?
Infrared laser beam
What are Stradia lines used for?
To measure distance
Where are the leveling split bubble on the dumpy level?
Above or below the barrel
Where is the levelling split bubble located on a tilting level?
Alongside the barrel
What type of bolt connects the head plate to the tripod?
5/8ths NC bolt
What is Bri’s birthday?
June 17, 1988
When is Lenny’s birthday?
June 27, 2020
When is Frankie’s birthday?
November 18, 2020
What type of bolt is a NC bolt?
Course
A metric scale are shown in divisions of what?
In 10 mm (1 cm) divisions
Architect’s rod readings are in divisions of what?
1/8 in increments
Will also have 11 inch markings on it.
What are Engineer’s rods measured in?
0.01m increments
How do you set up the tripod?
Have all 3 legs closed / in contact with the ground
Bring the tripod top plate at chin level
How do you set up the tripod if the ground is sloping?
Put two legs on the downhill side and the other one uphill
If the elevation measured is higher than the instrument, how do you hold the rod?
Upside down
If the elevation is lower than the instrument, how do you hold the rod?
upright and plumb
True or false: equal length back sights + foresights will cancel errors caused by crosshairs not being in perfect adjustment?
True
What is the point of a peg test?
It is the only way to check the position of the crosshairs at the job site.
How do you get the mounting head or top plate of a builder’s level, level?
Adjusting the legs
If the tripod legs are not able to dig into anything, what must be done?
Use rubber tips or suction cups or place the tripod in a triangular frame to prevent slipping.
What happens to the air bubbles in level vials in extreme heat?
Heat can expand the air bubbles and make it very difficult to read.
to avoid heat: put some sort of sunshade over the instruments.
How are you suppose to carry the tripod outside in wide open spaces?
Over the shoulder tripod legs in front
If there are obstacles or doorways, how do you carry the tripod?
Tripod legs behind, over the shoulder with the instrument in front.
What is the most common benchmark measurement?
100ft
What establishes the height of the instrument?
The back-sight
What type of readings are taken on points of unknown elevation / used to determine the elevation of a turning point or final point in a survey?
The Fore-sight
How do you figure out the height of the instrument?
Elevation/ benchmark + Back-sight = Height of elevation
What is done with an inversion reading?
- If it’s a back-sight reading => it is subtracted from the elevation to get the height of instrument.
- If it’s a foresight reading => it is added to the height of instrument to get the new elevation.
Why do we get an inversion reading?
Because the line of sight of the instrument is above the BM
A normal reading on a builders level means what?
That the line of sight of the instrument is below the benchmark.
What is a Turning Point?
Is set when moving the instrument to a new location.
What type of beam does an electronic level use?
An infrared laser beam
With the legs closed + extended, to what height should the tripod’s top plate be adjusted before setting the tripod / mounting the instrument?
The bottom of your chin
When setting up a tripod on sloping ground, how should the legs be positioned?
With one leg uphill
What is Zero Datum?
Mean sea level (the average between high/low tide)
Explain the term - Elevation
The height of any point above zero datum.
Explain the term - Benchmark
A known elevation
Points measuring changes of elevation across the land.
What is Backsight?
Rod readings take on a point whose elevation is known.
Explain Foresight
Rod readings taken on a point whose elevation is yet to be established.
