Week 12: Engineering surveying II

Question 1

The various lines in roading alignments

Answer 1

1. Centre line
2. Shoulder road, kerb, boundary, etc
3. Edge of earthworks (top of cut, toe (bottom) of fill

Question 2

Traditional method of roading alignments

Answer 2

Work off centreline or specific position

Question 3

How to obtain coordinates in roading alignments

Answer 3

1. Engineering software pre-calcs coords
2. Set out by TS from random setup point
3. GNSS

Question 4

Machine control in roading alignments

Answer 4

No stakes at all - checks very important plus site control

Question 5

Batter staking (AKA slope staking) involves

Answer 5

Marking edge and slope of cuts and fills, which is used for roads and building platforms

Question 6

Examples of batter staking methods

Answer 6

Slope rails, sight rails, slope stakes, batter boards

Question 7

Cuts usually define

Answer 7

The actual line of the slope

Question 8

Fills usually used with

Answer 8

A boning (traveller) road or laser line

Question 9

Anywhere that there is either dirt/rock being removed or brought in requires

Answer 9

Batter stakes

Question 10

Types of cross section areas

Answer 10

Cut, Fill, Cut and fill

Question 11

Batter staking: Basic slope staking process (for a roadway) Steps 1-8

Answer 11

1. Get a first guestimate of position of catch point from X-section or from plan (i.e distance from CL or eye. This position is temporary
2. Measure to this first temporary position (Tape, TS, GPS)
3. Tie this position - determine RL and measure offset from CL (or feature if not for a road (e.g corner of building))
4. Calculate the ‘calculated’ offset at this particular RL
5. Try a new temporary position and determine new RL and offset
6. Repeat until you find the correct catch point
7. When catch point is found set a small marker stake at the catch point and label with c/f details
8. Offset the catch point with sight rails - note these offset stakes are actually more important than catch point stakes. Catch point stakes will likely get destroyed during earthworks.

Question 12

Batter staking is iterative, meaning

Answer 12

Will have to move to correct position, e.g if the position measured is at 22m and the RL calcs it to be 24m then move back 2m if ground was flat

Question 13

Process for placing sight rails (offset stakes)

Answer 13

1. Set out two stakes approx. 1 and 2m back from peg at catch point
2. Tie to the top of the stakes
3. Calculate the distance from the top of the stake to the design level

Question 14

When setting out two stakes for sight rails what three things need to be done

Answer 14

1. Need to know distance to be able to calculate RL
2. These stakes are put in perpendicular to the centreline alignment (radially in curves)
3. Allow room for earthmoving machinery

Question 15

When tying to the top of the stakes, what three things need to be done

Answer 15

1. Determine the offsets from the centreline
2. At these offsets, calc the deisgn level of batter as if it passed through these stakes
3. Allow for the boning rod length to be used (in fill section)

Question 16

When calculating the distance from the top of the stake to the design level, what three things should be done

Answer 16

1. Measure down from the tops of the stakes - aka the dip
2. Mark these levels on both stakes
3. Nail the sight rail so that its upper edge is on this design c/f line (on cut exactly, 1m above fill line)

Question 17

Reasons for marking the batter stakes consistently

Answer 17

1. To show CL offset and distance to catch point
2. Very important to note whether the cut/fill is to finish grade or subgrade

Question 18

Batter stake marking should show important information such as

Answer 18

1. Offset distance to catch point
2. C/F to toe/top from catch
3. Offset distance to CL slope batter

Question 19

You/contractor can mark the actual cut/fill line with

Answer 19

Spray paint (i.e top of cut or toe of fill on the ground)

Question 20

Make sure the contractor knows how to

Answer 20

Interpret the batter stakes to avoid any confusion

Question 21

Batter staking fieldnotes will show

Answer 21

1. Catch point - distance from CL (L or R) and RL
2. Slope rail stakes - offset and RL of front stake
3. Dip down from top of stake to design line
4. Offset from front stake to catch point (top of cut or toe of fill)

Question 22

Batter staking summary for a job, e.g stake cut batter for a building platform

Answer 22

1. Set out corners of building
2. Building platform RL from plan and distance offset to toe of slope
3. Horizontal position of top of cut determined from plot or ‘guestimate’
4. Go to this position. Determine RL of peg and then calc total distance along slope and offset from building. The calc distance and measured position distance need to be identical
5. If not found, repeat and try again
6. When you find catch point set out catch point stakes and offset batter stakes
7. Calculate height of design surface at the slope stakes and place sight rail to match batter slope

Question 23

Uses for GNSS in batter staking

Answer 23

Know whats happening on site, what are you marking out or feeding as a file into earthwork machinery

Question 24

Be careful of small/low marks because

Answer 24

They could be stripped out with topsoil at some point. Consider batter staking with GNSS even if perhaps less intuitive.

Question 25

What principle a surveyor should think of while batter staking

Answer 25

Does the plan or set out make sense 1. Look at computer plan/plan for machine guidance, check, check, check 2. Look back at marks in the field to ensure they make sense

Question 26

Uses of profile boards

Answer 26

1. Set out to mark building lines 2. Foundation lines, column lines 3. String lines between nails 4. Place outside the construction area 5. They are considered semi-permanent

Question 27

Profile boards are typically what sized wooden boards

Answer 27

150mm x 25mm (6"x1")

Question 28

Problems created from use of profile boards

Answer 28

1. Offset from corner not known 2. Can't (and don't want to) set out boards at a predetermined position

Question 29

Do the offset boards need to be at a pre calcd position

Answer 29

No

Question 30

Profile boards should be installed with

Answer 30

Nails into boards, and string between (check diagonals to confirm)

Question 31

Profile boards can be used for what control of the building

Answer 31

Horizontal and vertical control

Question 32

Always work with a ____ to give them exaclty what they need and want

Answer 32

Contractor

Question 33

Ten steps to profile boards setout (iterative)

Answer 33

1. Set out approx corner of building by coordinates, body offsets, etc 2. Build profile boards at appropriate position 3. Mark approx line of building on board (within 300mm) 4. Use instrument (orientated) then survey fix (i.e survey to) this position 5. Calc position of true line wrt this point 6. Calc small shift required 7. Mark final position on board (pencil) 8. Plaxe nail at this point 9. Survey fix this nail to check position 10. Record final position (not iterations)

Question 34

Two profile board checks on the ground (quick and simple)

Answer 34

1. String the profile boards (same as builder) and check the plan building measurements 2. Measure the diagonals

Question 35

Profile board check by calculation

Answer 35

Tie to the profile nails, compute intersections from these to determine corners of buildings. Then take a join between building corners, check distances are correct against plan dimensions, and bearings are 90 degrees different.

Question 36

In high rise buildings, three things are important to set out for and be vigilant about

Answer 36

1. Establishment and upkeep of control grid lines 2. Verticality of columns 3. Establishment and maintenance of RLs 4. Precise linework is very important

Question 37

Four methods for controlling verticality

Answer 37

1. Plumb bob 2. Theodolite 3. Specialized plummet 4. Total station

Question 38

Plumb bob verticality method

Answer 38

1. Heavy plumb bob (2 kg) is suspended from piano wire over a known location 2. Knock out or leave out holes (500mm^2) are left in a corner (s) of the building floors for observing and measuring from (4 ideal) 3. Plumb bob immersed in water or oil to dampen the movement caused by wind 4. Plumb bob line marks a baseline from which measurements are made

Question 39

Plumb bobs are used for lower height buildings of how many stories

Answer 39

3-4

Question 40

Theodolite verticality method

Answer 40

1. Set up on peg P4 and sight to peg P3 on LF 2. Transit up the building and mark on column, repeat process on RF. 3. Take mean position if the theodolite is out of adjustment 4. Set up on P2, sight P1 and repeat procedure and mark column 5. Mark the centreline intersections of the rest of the building 6. Once the CL is established, measurements are made from that to establish any position within the building

Question 41

The special theodolite attachment used to establish a vertical line and extend lines

Answer 41

Pentraprism and counterweight (balance) attached to wild T2 instrument

Question 42

The pentraprism (on eyepiece) accurately transfers line

Answer 42

Both up and down

Question 43

Accuracy of pentraprism

Answer 43

1 : 50,000 RF

Question 44

Specialized plummet is a specialist instrument that sets out

Answer 44

Vertical lines

Question 45

A specialized plummet can be either

Answer 45

Optical or Laser

Question 46

Optical plummet sights ____, while high power telescope looks ____

Answer 46

Sights downwards (nadir), looks upward (zenith)

Question 47

For specialized plummet, what is required as with any optical plummet

Answer 47

1. Holes in each floor 2. Adjustments need to be made

Question 48

For specialized plummet, forced centring requires

Answer 48

Removing plummet from tribrach and insert TS for more work

Question 49

Accuracy of specialized plummet

Answer 49

RF 1 : 30,000 +

Question 50

Issues with specialized plummets

Answer 50

1. Floor holes need to be kept open 2. Watch for refraction - more serious next to the instrument rather than the target, e.g too close to concrete holes 3. Watch for divergence of laser beam

Question 51

How to control verticality using a total station

Answer 51

Use of a free station

Question 52

Five reasons for usage of a free station for verticality

Answer 52

1. Need lots of reduncancy 2. Ten stations if possible 3. High and low targets 4. Need targets on other buildings 5. Need constant checks

Question 53

Issues of a free station

Answer 53

1. Buildings move with heat/cold 2. Concrete and steel moves 3. Control target safety

Question 54

Methods of controlling high rise buildings

Answer 54

1. Static and RTK GPS 2. Dual axis precise clinometers - measure +_ 0.2" of arc 3. Robotic total stations 4. Everything connected to computer for constant, dynamic modeling of structure as it is being built