CURTIN UNIVERSITY OF TECHNOLOGY
Department of Spatial Sciences
PLANE AND CONSTRUCTION SURVEYING – SPAT1001
Prac: Traversing and Mapping Exercise
This is part II of the exercise
PART II (Mapping), teaching weeks 10 to 12.
PART II (MAPPING)
Objective:
To use the seven-point traverse computed and adjusted during PART I of the assignment as
control points from which a total station can be used to prepare a topographical map of the area
around Edinburgh Oval (Jack Finney Lake) including a contour map and location and RL of
all relevant features. Figure 1 shows a satellite image of the mapping work area .
Figure 1. Mapping Work Area
Pillar 18
Pillar 17
Plane & Construction Surveying – SPAT1001 2
FIELDWORK (Radiation method – the data used were collected last year)
In the performed fieldwork, and to create a topographic map of the area, the coordinates of
the key points of all existing topographical features in this area were observed, to be
determined using the radiation method.
Relevant topographical features observed, include trees, lake boundary, lights, paths, bins,
other survey marks, the WAIT model crest, in addition to points that can be used to generate
a contour map such as points of change in grade, isolated high and low points.
The attribute of each point is recorded on the attached recording sheet.
The whole area was divided into sections where points of each section are determined from
one traverse point. Each traverse point was occupied by the total station, which backsighted
another traverse point to determine the correct orientation. For example, in Figure 1, point
1 was occupied by the Total Station, backsighting the traverse point P18. The unknown
point is point (k) in the figure. In the radiation method, the coordinates of each unknown
point, such as point k, is determined by measuring the distance between the occupied
known traverse point and the unknown point (L1-k), and measuring the angle between the
traverse leg (which has a known bearing, i.e. line 1-P18 in the figure) and the line joining
the occupied traverse point and the unknown point (line 1-k in the figure).
Figure 1. layout of the occupied traverse poit (1), the backsight traverse point (P18) and
the unknown point (k). the coordinated of point k can be determined by measuring the
distance L1-k and the angle P18-1-k.
The Horizontal Directions and Horizontal and Vertical components of the radiation
distance displayed on the total station screen were manually recorded for all points
observed from the traverse points using the radiation method.
Remember that the Horizontal angle between two lines is the difference between the two
Horizontal directions of the two lines.
i.e.
the horizontal angle P18-1-k = Horizontal direction (1-k) – horizontal direction (1-P18)
(measured in a clockwise direction).
Note that, in the field one may set the first direction to zero on the total station, using a
special key in the keyboard “0-set key”, such that the second reading in the clockwise
direction represents the angle between the two lines without making any computations
(since the first horizontal direction was set to zero).
The height of the total station and the height of the target (reflector) were also recorded and
listed in the field notes.
The measurements of the work area collected last year at every point of the selected
traverse (discussed in Part I of the assignment) are recorded in the file “Topographical
Survey Coordinate Recording Sheet.pdf”. From each traverse point, the measurements
k
1
P18
L1-k
P18-1-k
Plane & Construction Surveying – SPAT1001 3
taken when occupying the point to other points of interest are tabulated in one page, and a
sketch showing the distribution of the observed points and the readings are given in a
separate page. Please use this data to complete this assignment.
OFFICE WORK
i. Compute the coordinates and RL of all unknown points manually
For each observed point do the following (see the numerical example in Bloackboard).
Multiply the measured distances by the point scale factor 0.999734.
Solve the radiation method manually to determine the coordinates of the points. (Hint: you
can do these computations using an Excel worksheet).
Please refer to Lecture no. 6.
Use the following formula to compute RL of the points (e.g. point k from traverse point
1):
RLk = (RL1 + Hi – Ht ) + VD.
where Hi is the height of the instrument (total station) and Ht is the height of the target
(reflector). Note that for the right-hand side, the three quantities (RL1 + Hi – Ht) will be the
same to all points observed from point 1. Only the quantity (VD) varies between observed
points.
The RL1 of the traverse points should be determined from a levelling traverse performed using
a double (reciprocal) run levelling. See part I of the Assignment.
The coordinates can also be stored on the internal memory of the total station. In the second
year of the surveying program, in the unit Engineering Surveying SPAT2003 you will learn
how to record in the total station and download this data directly to a PC.
ii. Prepare your plot
Prepare a map of all relevant features surrounding Edinburgh Lake.
Knowing the easting and northing coordinate ranges in your survey, you should select a
scale such that the entire plot will fit on an A3 sheet. Draw a 50m pencil grid over the
entire A3 sheet.
Plot the control traverse and show fine broken lines joining the control points. All details
should initially be plotted in pencil.
Plot in all points, write their reduced levels and symbol features.
In a separate plot, and using a copy of the first plot, write the RL of each point next to it,
and connect between the points in a form of triangles (resembling the TIN method, see
Lecture 4). Use this data to produce a contour map of the area with a contour interval of
0.5 m. Determine the location of the contour points on these lines in an approximate way
without calculations. Join the points of the same contour value (e.g. 11.0, 11.5, etc.) to
generate the contour map.
Plane & Construction Surveying – SPAT1001 4
SUBMISSION
This is an individual submission
Results of Part I and Part II should be submitted in one report.
Due Date: Friday 5 June 2020 Part I + Part II: 20% of the final mark.
Part I: 8% and Part II: 12%
For Part I, refer to the instructions of the previous part.
For Part II, the following
1. A list of coordinates and reduced levels of the control traverse.
2. Plot the traverse on A3 paper, either:
I. Using a protractor and a scale. Start from one point, measure the internal angles using the
protractor and distances using a ruler using a suitable scale (e.g. 1:500 – 1:1000). Repeat
the process for all angles until closing the traverse. or
II. Using point coordinates. Starting from one point and add the computed departure (E)
and latitude (N) to plot the next point, and repeat the process until closing the traverse.
3. A neat sketch showing locations of your mapped points, with their ID and attributes shown
next to them. The sketch should include a Legend or list of symbols that you used to identify
different attributes.
The position of each point should be plotted using either:
I. The protractor (for the measured angles from the traverse legs) and using a ruler for
the radiation distances (after multiplying the measured distances by a point scale factor
0.999734). Plot distances applying a suitable map scale (e.g. 1:500 – 1:1000).
II. Point coordinates, start by drawing a grid of suitable interval (e.g. 10m or 20m). Start
your grid from the point of integer coordinates that are close to the point of the least
coordinates (in E & N), such that the grid covers the entire area. You can plot the points
by offsetting their coordinates from the nearest grid point using a ruler.
On the Sketch
Show all coordinated points, noting their reduced levels and symbol features.
Using the gridding method (see lecture notes), interpolate contours at 0.5m contour
interval.
Use ink over contours, control points, and relevant features, then rub out all
constructional pencil lines and reduced levels.
Will need to show all computations required to plot the topographic/detail survey,
including conversion of bearing and distance to coordinates if used and calculations
for contour interpolation at a few points as an example.
* The final product and the main objective:
A suitable map neatly drawn in ink (each student submits a map).
This detail/contour plan should be drawn on a blank A3 sheet containing the location
of features using appropriate symbols (with spot heights).
contours over the lawn areas (also showing spot heights for featured points) and survey
stations.
A table showing the traverse station coordinates within the traverse plot,
The plot should show an index for the north direction, a title, and a title block containing
your name, date, scale, height datum, etc.
Plane & Construction Surveying – SPAT1001 5
Topographical Survey Coordinate Recording Sheet
Group Members: ……………………., ……………………. and …………………….
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