Route Surveying - Slope Stakes

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Route Surveying - Slope Stakes
The University of British Columbia Departments
of Civil Engineering

• Instructor A. Bebamzadeh
• Civil 235 Plane Surveying

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Introduction
Centre-line layout is one of the first steps in
constructing a road. The road is broken into
stations. At each station, the location of the
centre-line, shoulders and slope stakes are
identified.
Slope stakes To guide the construction
process Earthwork calculation
Picture taken from http//www.tpub.com/engbas/14-3
1.htm
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Introduction
Terminology Grade Centre-line Shoulder Side-slope
Slope stake Side-hill section
Grade Rod H.I. elevation of the grade
Ground Rod reading of the rod at any point
Cut/fill Grade Rod Ground Rod
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Cut/Fill
1. Cut section
Ground rod gt 0 Grade rod gt 0
H.I. gt Grade Elev.
Grade rodgt Ground rod
2. Fill section
Grade rod lt Ground rod
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Cut Cross-section
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Cut-Fill Transition
The cross section that passes from cut to fill is
referred to as side-hill section.
Transition line is the intersection of the grade
and the natural ground.
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Side-hill Cross-section
(Side-hill section is where cross-section passes
from cut to fill)
Shoulder Stake
Centerline Stake
c
1
s
Slope Stake
f
Road Grade
w/2
d
Natural Ground
Cut Section
Fill Section
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Cross-Section Data
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Example
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Example Slope Stake
H.I. 241.90 m , grade elevation 240.36 m rod
reading on centerline 2.65 m
centerline elevation 239.25 m grade rod
H.I. grade elevation 241.90 240.36 1.54
m first trial at point 1 ground rod
3.23 f1 grade rod ground rod 1.54 3.23
-1.69 m (the negative
sign indicates a fill) Slope stake distance from
the centre-line, d1 3.5 (1.69)(2) 6.88
m measured d1 6.2 m
The rod must be moved farther from the
centerline
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Example Slope Stake
second trial at point 2
ground rod 3.62 m f2 1.54 3.62
-2.08 m d2
3.5 (2.08)(2) 7.66 m
measured distance d2 8.2 m
The rod is out too
far Eventually, by trial, the rod is held at
3 ground rod 3.40
fr 1.54-3.40 -1.86 m
dr 3.5 (1.86)(2) 7.22
m This distance agrees with the measured
distance dr hence, point 3 is the correct
location for the slope stake. The notes for this
slope stake will be
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Volume of Earthwork
Cross-sectional area is calculated from the
cut/fill data.
1. Average End Area Method (exact for A1A2)
2. Prismoidal Method
(Am obtained by averaging the linear dimensions
of the end section)
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Example Volume Calculation
For the following two stations, calculate the
volume of earthwork using the Average End Area
method and the Prismoidal method. The width of
the road-bed is 20 m and the side-slope ratio is
1.5 to 1.
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Example Volume Calculation
m2
Similarly, for station 135200
Volume from the Average End Area method
m3
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Field Exercise
Centreline stations
Shoulder stakes El.
Obtain grade El. at st. 5
Slope stakes
Transition line
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Field Books
To be included in the field books
Leveling notes
Location sketch of the road
Centreline profile of the ground and grade
Plan view of the road layout
Cut/fill data for two adjacent stations
Cross-section sketches area calculations
Volume calculation of the segment
Total volume of earthwork