calcs/ methods - ES Flashcards by ruby nunns

What degree of accuracy are leveling staffs read to

1mm

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how is parallax eliminated

focusing the images using the focusing lens to focus the cross hairs

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what are the three different types of readings taken when leveling

Back sight, fore sight, intermediate sight

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what are the two leveling booking methods

rise and fall and HPC

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What errors can occur in leveling (5)

collimation
parallax
staff and tripod defects
reading and booking errors
on-site equipment handling errors/ site conditions

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What are leveling staffs graduated to

10mm

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how can a collimation error be determined

two peg test

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how should leveling calculations be checked

Back sights - fore sights = rise - fall = RL final - RL initial

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Maximum error tolerance for leveling

5*sqrt(n)

n = no. of stations

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Which method of booking is best for lots of intermediate sites (not many back sights and fores sights)

HCP - height of collimation plane

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HPC calculation on booking form =

for IS of FS
for BS

HPC - IS or FS

RL + BS

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what reading should inverted staffs be treated as

intermediate sights

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what is considered to be a round of angle readings

FL and FR

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What is a large source of error with total station angle measurements - especially at short distances

miscentring/ line of sight errors

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what is the typical function of a theodolite

angle measurement

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what is the tolerance for difference between angle measurement rounds

40”/ seconds

or sometimes:
10* sqrt(n)
n = number of points

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How to calculate the reduced FL and FR - vertical circle

90-FL

FR - 270

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when targeting a prism, the total station should initially be aimed ________.

off center to the left
(plus or minus 5% incidence alignment )

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what are the two different types of tape for DDM

steel and fiberglass

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what 4 corrections should be made to slope distance measurements with tapes

slope
standardization

(+ for steel only)
tension
temperature

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slope correction formulas

L(1-cosθ)
or
-(∆h^2/2L)

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standardization correction formula

±L(I’-I)/I

I’ - standardization tape length (exact)
I = nominal tape length

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tension correction formula

±L(Tf-Ts)/ AE

Tf = applied
Ts = calibrated tension value
A = cross sectional area

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temperature correction formula

±αL(tf-ts)

α = coefficient of expansion for tape material
tf = on site temperature
ts = standard calibrated temperature

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What are the two methods of EDM?

phase measurement and timed pulse

For distance less than 1000m, ____ prisms or _______ (less than 100m) are used. Up to 3000m ______________ are used.

single, mini-prisms or adhesive prisms, triple prism sets

how is any inaccuracy of prisms reflectors combated

prism constants applied to measurements

how is a control network established

traversing

traverses must start and finish _______________.

at points of known/ fixed co-ordinates

what are control network stations typically made of

wooden pegs with nails (concrete set for long projects) wooden plinth boxes

are traverses typically taken in the anticlockwise or clockwise directions (polygon traverses)

anticlockwise

what equipment might be used for detail surveying

total station detail poles portable GNSS satellite receivers terrestrial laser scanning

in setting out, what is involved in the horizontal control techniques

control network/ co ordinate systems

in setting out, what is involved in the vertical control techniques

TBMs setup, profile boards (defines building corners), slope/ batter rails, travelers (T-shaped sight rail)

in setting out, what is involved in the accurate positioning techniques

intersection with 2 instruments bearing angles and distances (theodolite) total stations or GNSS receivers co-ordinate methods

what vertical control might be used for setting out a pipe(line)

(double or single) sight rails

what horizontal control might be used for setting out a pipe(line)

offset pegs at regular intervals (20-30m)

what piece of equipment might be used in conjunction with a sight rail to set out a pipeline

a traveller

what are the first steps in setting out a ground floor level building

mark 2 co-ordinate located corners (total station) theodolite and steel tape to plot other sides at perfect 90 degree angles

define a key check for setting out quadrilateral, symmetric shapes

check the diagonals align currently

what equipment/ key methods are used in the developing stages of setting out a ground floor level

profile boards and pegs foundations control checks against pegs/ profile formwork

how are columns and pile foundations set out - describe the general method

structural grid of pegs (sometimes string lines to level connect) theodolite used to "fix" peg centres ad transfer reference lines

what 4 main methods are used to maintain verticality when setting out multi-storey structures

plumb-bob total stations/ theodolites optical plumbing laser

describe plumb-bob methods and their use in surveying

3-20kg weights suspended on piano wire/nylon over a reference mark from a grid (oscillations damped in water or oil)

describe optical plumbing methods and their use in setting out multi-storeys

specific instruments with high accuracy openings in the floor and centring device required set over reference mark

how are total stations and theodolites used in setting out to maintain verticality

perfect adjustment and alignment of several instruments require diagonal eyepiece sometimes required

how do lasers work - physics circuit level

laser diodes powered by on-board batteries

how are invisible lasers used in setting out

rotating (ONLY) levelling, grading, internal fittings

how are visible lasers used in setting out

rotating AND alignment levelling, grading, internal fittings AND controlling verticality, pipelaying, tunnelling

what are the main applications of rotating laser instruments (3)

laser levelling controlling installation of internal fittings controlling earth-moving machinery

formula for projection scale factor(F)

F = 1 + (e^2/2R^2) e = distance from central meridian R = radius of ellipsoid at this point

formula for MSL correction to national grid distances

D*hm /R D = horizontal component of distance measured hm = mean height of point D above sea level R - ellipsoid radius at point

What formula applies the MSL correction

D(ground state) - MSL correction = D(ellipsoid) (unless line measured is below sea level then D(gs) = D(e) + MSL)

how many satellites to form co-ordinate? why?

4 x y z and time offset

what are the three types of GPS errors

satellite, receiver and signal dependent

what satellite dependent errors are typical

satellite clock error (satellite vs GPS) orbital errors (carrier phase errors) satellite geometry

what receiver dependent errors are typical

receiver clocks time differences antenna not being centered and leveled delays through altitude multi-paths caused by reflections line of sight disrupted (cycle slips)

what are the 3 high precision techniques used in site work surveying for GNSS

static surveys rapid static surveys kinematic and RTK surveys

if the plan areas are not straight sided/ geometric, what techniques can be used to determine area (5)

give take lines graphical methods trapezoid rule Simpson's rule planimetres

how can volumes of earthworks be quantified

cross-sections spot heights contours

simpson's rule can be applies to _____ number of _____________ offsets

an odd, equally spaced

calcs/ methods - ES Flashcards

(61 cards)