Transcript Profile Leveling - Oklahoma State University–Stillwater

Profile Leveling
Definition
A surveying method that yields elevations at definite
points along a reference line.
Profile leveling establishes a side view or cross sectional view
of the earth’s surface
Primary use is for utilities:
A. Highways
B. Canals
C. Sewers
D. Water mains
E. Sidewalks
F. Retaining walls
G. Fences
All of these need accurate
information about the
topography along the
route.
2
Characteristics
May be a single segment.
May be multiple segments which change
directions with angle points.
May be straight
segments connected with
curves.
3
Procedure
It is a common practice to use a procedure called stationing.
1.
Stations are established at uniform distances along the route.
2.
Standard station distance is 100 feet.
3.
Half or quarter stations are used when the topography is very
variable.
4.
The distance from the starting point to the station is used as the
station identification.
4
Procedure-cont.
Intermediate foresights are recorded at each standard station and at
additional stations as needed to define the topography of the route.
Intermediate foresights: foresights taken at stations that are not
used as benchmarks or turning points.
Purpose is to define the topography along the route.
High points
Low points
Roads
Changes in slope
Highway
Critical points
Gutters
Sidewalks
5
Defining an Object
• Because profile leveling is used to measure the cross
section of and the location of objects along a route, one
important issue is determining how many stations are
required to define the object.
• The answer is, it depends on the object and the use of the
data.
• For example: how many stations would be required to
define the cross section of a standard trapezoidal ditch?
6
6
Defining an Object-Ditch --cont
• A ditch may have been a trapezoid when
constructed, but over time it will change its
shape.
• What is the effect on the number of stations if a
channel has developed in the bottom of the
ditch?
7
7
Defining An Object-Street
• Another common object is a street.
• The number of stations required to define the
cross section of a street depends on the required
information.
– Do you need to know the height of the curb?
– Do you need to know the width of the curb?
7
8
Turning Points-cont.
When distances to foresights become too long or
when the terrain obstructs the view of the instrument,
turning points are established.
Foresights on turning points and benchmarks
are true foresights.
Profile leveling is differential leveling with
the addition of intermediate foresights.
9
Profile Data Table
STA
BS
HI
FS
IFS
ELEV
10
Example One
Determine the profile for a proposed sidewalk that connects two
existing sidewalks and bisects a road.
Step one: establish the standard stations.
Note: the last station (745.1) is established even though it
is not a standard station.
11
Example One-cont.
Step 2: Determine the sites for the critical features.
In this example, the critical features are the rapid change is slope at
337.5 and the road at 489.6.
Note a stations were established at 489.6 and 546.4
to define the width of the road and any changes in
elevation across the road.
12
Example 1-cont.
Step 3: Set up the instrument and start recording data.
The first rod reading is a backsight on the first sidewalk (benchmark)
to establish the height of the instrument.
Note: in this case the true elevation of the benchmark is unknown,
therefore 100.00 feet is used.
13
Example One Data Table
STA
0.0
BS
10.5
HI
110.5
FS
IFS
ELEV
100.00
14
Example One-cont.
Step 4: Start recording the rod readings for each station.
Note: station 100 is not used as a benchmark or as a turning point,
therefore it is an intermediate foresight.
15
Example One Data Table
STA
0.0
100
BS
HI
10.5
110.5
FS
IFS
ELEV
100.0
6.3
104.2
16
Example One-cont.
The rod reading for each station is recorded on the appropriate line of the table.
STA
0.0
BS
HI
10.5
110.5
FS
IFS
ELEV
100.0
100
6.3
104.2
200
3.9
106.6
300
4.1
106.4
337.5
7.4
103.1
400
9.2
101.3
489.6
8.0
Note: the rod reading for station 489.6 is placed in the FS
column because this station will be used as a turning point.
102.5
17
Example One-cont.
Every time the instrument is
moved, a backsight is used
to reestablish the instrument
height.
STA
0.0
Step 6: the instrument is moved so the remaining
stations can be reached.
BS
HI
10.5
110.5
FS
IFS
ELEV
100.0
100
6.3
104.2
200
3.9
106.6
300
4.1
106.4
337.5
7.4
103.1
400
9.2
101.3
489.6
6.6
109.1
8.0
102.5
500
6.7
102.5
546.4
6.8
102.2
600
4.9
104.2
700
2.2
106.9
745.1
1.5
107.6
18
Example One-cont.
The last step is closing the loop.
STA
0.0
BS
HI
10.5
110.5
FS
IFS
ELEV
100.0
100
6.3
104.2
200
3.9
106.6
300
4.1
106.4
337.5
7.4
103.1
400
9.2
101.3
489.6
6.6
109.1
8.0
102.5
500
6.7
102.5
546.4
6.8
102.2
600
4.9
104.2
700
2.2
106.9
745.1
2.3
109.9
1.5
107.6
TP2
8.3
111.4
6.8
103.1
11.5
99.9
0.0
19
Note Check & Allowable Error
STA
0.0
BS
HI
10.5
110.5
FS
IFS
ELEV
100.0
100
6.3
104.2
200
3.9
106.6
300
4.1
106.4
337.5
7.4
103.1
400
9.2
101.3
489.6
6.6
109.1
8.0
102.5
500
6.7
102.5
546.4
6.8
102.2
600
4.9
104.2
700
2.2
106.9
745.1
2.3
109.9
1.5
107.6
TP2
8.3
111.4
6.8
103.1
11.5
99.9
0.0
SUM
27.70
27.80
0.10
AE = k M =

1.0 x
=
745.1 x 2
5280
0.10
= 0.5
20
Plot of Profile Data
This is excessive slope according to
ADA standards.
Sidewalk Profile
1 0 8 .0
1 0 7 .6
1 0 7 .5
1 0 7 .0
1 0 6 .9
1 0 6 .6
1 0 6 .5
1 0 6 .4
1 0 6 .0
1 0 5 .5
Potting the data helps
answer questions such
as, “Will the slope of
the sidewalk be
acceptable?”.
Elevation
1 0 5 .0
1 0 4 .5
1 0 4 .2
1 0 4 .0
1 0 4 .2
1 0 3 .5
1 0 3 .1
1 0 3 .0
1 0 2 .4
1 0 2 .5
1 0 2 .5
1 0 2 .3
1 0 2 .0
1 0 1 .5
1 0 1 .3
1 0 1 .0
1 0 0 .5
1 0 0 .0
1 0 0 .0
9 9 .5
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
Dist ance
In this example the steepest slope appears to be between stations 300
and 327.5. The slope at this point is:
% slope =
Rise
106.4 - 103.1
3.3
x 100 =
x 100 =
x 100 = 8.8 %
Run
337.5 - 300.0
37.5
21

Excel Calculation of Slope
It is easy to calculate all of the slopes using a spreadsheet.
Station
0.0
100.0
200.0
300.0
337.5
400.0
489.6
500.0
546.4
600.0
700.0
745.1
Elevation
100.0
104.2
106.6
106.4
103.1
101.3
102.5
102.4
102.3
104.2
106.9
107.6
% slope
4.20
2.40
0.20
8.80
2.88
1.34
0.96
0.22
3.54
2.70
1.55
22
Additional uses of Profile Plot
Profile plots are also very useful for other utility routes such as drain pipes.
Drains are design with a uniform slope.
Plotting the drain on the profile gives a visual reference of the
relationship between the earth’s surface and the drain.
Assume the survey was completed for a drain pipe instead of a
sidewalk.
Also assume the starting elevation of the drain pipe is at three
feet below the surface at station 0.0 and that the desired slope is
1%.
23
Drain Plot
1 1 0 .0
1 0 8 .0
S urfac e P rofile
Elevation
1 0 6 .0
1 0 4 .0
1 0 2 .0
D rain
1 0 0 .0
It should be oblivious that this design
has problems because at station 550
the drain pipe is above ground.
9 8 .0
9 6 .0
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
Dist ance
24
One of the advantages of spread sheets is doing “What if” scenarios.
What if the drain slope was changed to 0.5%?
Drain Plot
1 1 0 .0
The way this spread
sheet was set up
changing the % slope
required changing
one value.
1 0 8 .0
S urfac e P rofile
Elevation
1 0 6 .0
1 0 4 .0
1 0 2 .0
D rain
1 0 0 .0
9 8 .0
9 6 .0
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
Dist ance
If the drain pipe will function correctly at 0.5% slope, this would be a
workable alternative.
25
What if--cont.
• If the purpose of the survey was for a drain, then additional questions
such as, What is the maximum depth of cut? Can be determined.
Drain Plot
In this example the
maximum distance
between the surface
and the drain occurs
at station 200.
1 1 0 .0
1 0 8 .0
S urfac e P rofile
Elevation
1 0 6 .0
1 0 4 .0
Depth = 106.6 ft - 98.0 ft = 8.6 ft
1 0 2 .0
D rain
1 0 0 .0

9 8 .0
9 6 .0
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
Dist ance
26
Plots of profile data can be used for many other
types of design questions.
What if the profile survey was for
an open ditch?
In this situation questions like,
“What is the maximum depth of
the ditch can be determined?”.
The top width of a ditch is determined by the depth, side slope
and bottom width.
Cross section profiles can be determined using this data and the
profile.
27
What if--cont.
How much space will be required for the ditch at the widest point?
The answer to this
question is determined by
the ditch design.
The widest point will be at
the deepest point.
1.
2.
3.
Most drainage ditches have a
trapezoidal cross section shape.
The bottom width is determined by the
anticipated flow rate through the ditch.
The side slopes are usually either 2:1
or 3:1 ratio.
Assuming a ditch bottom
width of 15 ft and a 2:1 side
slope:
The ditch at the widest point will be: 17.2 ft + 15 ft + 17.2 ft = 49.4 ft
28
Example 2
• In the first example the existing sidewalks were used as
benchmarks because they were part of the finished design.
• When there are no existing structures that can be used for a
benchmark, or when all of the existing structures will be
removed during construction, a benchmark must be established
out side of the construction zone.
• In this situation, the notes are started different.
29
Profile With Offset Benchmark
30
Step 1
•
•
The principles are the same.
The difference is that in this case the BS is taken on the benchmark not
the first station.
The notes use the same column--they just start with the BM instead of 0.0.
STA
BM1
BS
8.2
HI
108.2
FS
IFS
ELEV
100.0
31
Step 2
•
•
Record the first foresight.
In this example the first foresight (0.0) is an intermediate foresight.
STA
BM1
0.0
BS
HI
8.2
108.2
FS
IFS
ELEV
9.2
100.0
99.0
32
Step 3
Establish additional intermediate foresights as needed until the first turning
point is reached.
STA
BM1
0.0
156.5
358.6
BS
8.2
HI
108.2
FS
IFS
9.2
6.5
1.3
ELEV
100.0
99.0
101.7
106.9
33
Step 4
Move the instrument and continue recording foresights as needed to
complete the profile.
STA
BM1
0.0
156.5
358.6
458.6
522.6
598.2
BS
8.2
HI
108.2
FS
IFS
9.2
6.5
2.1
109.0
1.3
5.2
7.7
5.4
ELEV
100.0
99.0
101.7
106.9
103.8
101.3
103.6
34
Step 5
Close the loop
STA
Note: close to the benchmark not station 0.0.
IFS
ELEV
9.2
6.5
100.0
99.0
101.7
106.9
458.6
5.2
103.8
522.6
7.7
101.3
BM1
0.0
156.5
358.6
BS
HI
8.2
108.2
2.1
598.2
BM1
Sum
109.0
10.4
114.0
20.7
0
AE = K M
= 0.1 x
FS
1.3
5.4
14.0
20.7
=
598.2 x 2
= 0.047
5280
103.6
100.0
100.0-100.0
0
35
Questions?
36