CN106 Engineering Surveying
s
School of the Environment & Technology
Semester 2 Examinations 2007-2008
CN106
ENGINEERING SURVEYING
Time allowed:
THREE hours
Answer ALL questions
Formula sheet provided
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CN106 Engineering Surveying
Question 1
A pipeline is to be laid between two manholes MH1 and MH2 which are 100 m
apart horizontally. A series of pegs have been set out at 20 m intervals along
the line between MH1 and MH2 and these have been levelled and the
readings given below obtained.
BS
IS
FS
Distance
1.125
TBM 19.850 m
1.984
0m
MH1
2.103
20 m
Line peg
40 m
Line peg
1.751
60 m
Line peg
1.852
80 m
Line peg
2.227
100 m
MH2
1.894
1.520
Remarks
2.220
1.687
CP
1.415
TBM 19.062 m
The invert level of the pipeline at MH1 is 17.000 m and the pipeline is to fall at
a gradient of 1 in 125 from MH1 to MH2.
Choose a suitable traveller length and calculate the heights at which sight rails
must be fixed above MH1, MH2 and each 20 m peg in order to set out the
invert of the pipeline.
(20 marks)
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CN106 Engineering Surveying
Question 2
(a)
Why is it necessary to keep sight lengths as equal as possible when
levelling?
(2 marks)
(b)
When measuring angles with a total station it is always advisable to
take face left and face right readings and to take two rounds. Discuss
the reasons for this.
(3 marks)
(c)
Explain how offsets are used when setting out.
(3 marks)
(d)
What is the difference between arbitrary north and true north? Which
one would normally be used for defining north on a coordinate grid for
construction work?
(3 marks)
(e)
Discuss the circumstances under which the rise and fall method or
HPC method would be used for reducing levels.
(2 marks)
(f)
What is a profile and how are these used in construction?
(3 marks)
(g)
Some levelling was carried out where eleven instrument positions were
used. What is the allowable error for this levelling?
(2 marks)
(h)
Discuss the circumstances under which you might choose to use a
fibreglass tape instead of a steel tape for distance measurements on a
construction site.
(2 marks)
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CN106 Engineering Surveying
Question 3
A rectangular building is to be set out on site from two control points X and Y.
The coordinates of X, Y and the building corners B1-B4 are given below.
_____________________________________________
Point or corner
mE
mN
_____________________________________________
X
215.097
177.639
Y
103.445
69.054
B1
142.304
126.503
B2
162.870
101.991
B3
182.022
118.060
B4
161.456
142.572
_____________________________________________
(a)
Describe, giving details of the equipment you would use, how you
would set out the building corners B1 and B2 only from X and Y.
Calculate the data required for this.
(8 marks)
(b)
Explain how it is possible to set out the remaining corners B3 and B4 of
the building and their offset pegs from B1 and B2.
Calculate the data required for this.
(6 marks)
(c)
Having completed the setting out, describe how you would check it.
Calculate any data that would be required to do this.
(6 marks)
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CN106 Engineering Surveying
Question 4
(a)
The coordinates of three control stations P, Q and R are given below.
Station
Coordinates
mE
mN
P
456.241
278.019
Q
258.362
303.480
R
197.854
358.257
Calculate the internal angles and lengths of the triangle PQR formed by
these stations.
(10 marks)
(b)
The following ∆E and ∆N values were calculated for a traverse
Line
∆E
∆N
WT
– 48.596
– 59.196
TA
62.790
– 6.447
AF
– 22.749
– 70.760
FM
104.483
98.061
MW
– 95.898
38.320
Calculate the fractional linear misclosure for this traverse. Is this
acceptable for engineering surveys?
(10 marks)
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CN106 Engineering Surveying
Question 5
(a)
The horizontal circle readings shown below were taken using a total
station correctly set up and levelled at point S. Book the readings in a
suitable format and calculate values for the horizontal angles AŜB,
AŜC and AŜD.
Point
Face left reading
Face right reading
A
00˚17′35″
180˚17′15″
B
38˚22′20″
218˚22′00″
C
69˚30′10″
249˚29′40″
D
137˚09′55″
317˚09′40″
A
45˚39′10″
225˚38′55″
B
83˚43′20″
263˚43′00″
C
114˚52′00″
294˚51′50″
D
182˚31′30″
02˚31′10″
(10 marks)
(b)
A digital level was checked for collimation error using a two-peg test
and the following results were obtained.
With the level midway between two pegs B1 and B2 which are 40 m
apart:
Staff reading at B1 = 1.476 m
Staff reading at B2 = 1.432 m
Level set up 10 m from B2 along the line B1 – B2 extended:
Staff reading at B1 = 1.556 m
Staff reading at B2 = 1.472 m
Calculate the collimation error for the level and the staff readings that
would have been obtained with the level in the second position close to
B2 had it been in perfect adjustment.
(5 marks)
(c)
On construction sites, it is usual that the contractor carries out all
building and other works with the engineer supervising this.
Discuss the various roles the contractor and engineer have with regard
to setting out stating clearly in your answer who does the setting out,
who should check it and who is responsible if any errors should occur.
(5 marks)
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