Post on 04-Jun-2018
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Longitudinal and CrossLongitudinal and Cross
SectionsSections
Sr SITI NUR ALIAA ROSLANSr SITI NUR ALIAA ROSLAN
KLIUCKLIUC
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Outline of LectureOutline of Lecture
IntroductionIntroduction
DefinitionsDefinitions
MethodologyMethodology CalculationCalculation
Output / ProductsOutput / Products
ApplicationsApplications
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IntroductionIntroduction
Two other major uses of levelling are:Two other major uses of levelling are:
Longitudinal sectionsLongitudinal sections CrossCross--sectionssections
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DefinitionDefinition
Longitudinal sectionsLongitudinal sections
The existing ground profile along aThe existing ground profile along a
particular line (normally the centre line ofparticular line (normally the centre line ofexisting proposed work)existing proposed work)
Centre line of railway, road, canal etcCentre line of railway, road, canal etc
Staff reading to 0.01m is adequateStaff reading to 0.01m is adequate
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DefinitionDefinition
CrossCross--sectionssections
Are lines of levels or short profilesAre lines of levels or short profiles
perpendicular to the centre line of a projectperpendicular to the centre line of a project Provide info needed for estimating theProvide info needed for estimating the
quantities of earthworkquantities of earthwork
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MethodologyMethodology
The process of determining a series ofThe process of determining a series of
elevations along a fixed line is referred toelevations along a fixed line is referred to
as Profile Levellingas Profile Levelling Data are taken at regular intervals afterData are taken at regular intervals after
the setting out of Centre Line (CL)the setting out of Centre Line (CL)
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MethodologyMethodology
The levels for the defining of the sectionsThe levels for the defining of the sections
may be obtained by one of the followingmay be obtained by one of the following
methods:methods: Conventional levellingConventional levelling
Tacheometric methodsTacheometric methods
Interpretation from digital terrain modelsInterpretation from digital terrain models
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MethodologyMethodology
The fixed direction is usually ofThe fixed direction is usually of
significance such as the centreline of asignificance such as the centreline of a
road or riverroad or river
Cross section may be taken at rightCross section may be taken at right
angles to this direction at a constantangles to this direction at a constant
intervalintervalAlong the cross section levels areAlong the cross section levels are
measured at points, usually separated bymeasured at points, usually separated by
a fixed distancea fixed distance
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MethodologyMethodology
Similar to the usual process of levellingSimilar to the usual process of levelling
except that more readings to theexcept that more readings to the
Intermediate Sight (IS)Intermediate Sight (IS)
In order to get more info about the landIn order to get more info about the land
profileprofile
BSA
ISPISQ FS1
A
P
Q
1
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Output / ProductsOutput / Products
Longitudinal section planLongitudinal section plan
Cross section planCross section plan
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Horizontal/vertical scaleHorizontal/vertical scale
It is common to use a vertical scale largerIt is common to use a vertical scale larger
than the horizontal one (usually 10:1) inthan the horizontal one (usually 10:1) in
order to make the elevetion differencesorder to make the elevetion differencesclearclear
For eg: Horizontal scale = 1:20For eg: Horizontal scale = 1:20
Vertical scale = 1:20Vertical scale = 1:20
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CrossCross--section plansection plan
Uniform slope 3 readings sufficient
Some changes in slope e.g. 5 readings
Significant changes in slope e.g. 9 readings
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The typical cross sectionsThe typical cross sections
EXISTING GROUND PROFILE
FORMATION LEVEL
WATER LEVEL
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CalculationsCalculations
Construction levelling: often involves relativelyConstruction levelling: often involves relatively
short distances yet a large number (short distances yet a large number (nn) of) of
instrument stationsinstrument stations In this case, an alternative criterion for E canIn this case, an alternative criterion for E can
be used:be used:
Max. acceptable misclosureMax. acceptable misclosure EE (in(in mmmm):):
E =E = D D nn mmmm
5mm & 8mm: commonly adopted values for D5mm & 8mm: commonly adopted values for D
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Plotting the plansPlotting the plans
-- Longitudinal sectionLongitudinal section Define the horizontal and vertical scale (e.g. vertDefine the horizontal and vertical scale (e.g. vert 1:20 ; horz1:20 ; horz 1:500)1:500)
Can use the engine ering ruler to do the plottingCan use the engine ering ruler to do the plotting
40.
858
40.
998
0.
00
40.
773
40.
758
40.
902
40.
907
41.
001
10.
00
20.
00
30.
00
40.
00
50.
00
60.
00
Ground Level (m)
Chainage (m)
Datum = 40.000m
RL of CLs
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Plotting the plansPlotting the plans
-- Cross sectionCross section Define the horizontal and vertical scale (e.g. vertDefine the horizontal and vertical scale (e.g. vert 1:20 ; horz1:20 ; horz 1:20)1:20)
To highlight both componentsTo highlight both components
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Exercise:Exercise:
Draw both the longitudinal and crossDraw both the longitudinal and cross--
section plans in accordance to exact scalesection plans in accordance to exact scale
Use the data provided in the lecture slideUse the data provided in the lecture slide
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Advanced source of dataAdvanced source of data
LIDAR (Light Detection and Ranging)LIDAR (Light Detection and Ranging)
It is rapidly emerging technology for determiningIt is rapidly emerging technology for determining
the shape of the ground surface plus natural andthe shape of the ground surface plus natural and
manman--made featuresmade features
LIDAR is combined with Geographic InformationLIDAR is combined with Geographic Information
System (GIS) data and other surveyingSystem (GIS) data and other surveying
information to generate complex datainformation to generate complex data
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Application of Long and CrossApplication of Long and Cross--
sectionssections In the construction and design of roads,In the construction and design of roads,
highways, railways, pipelines and drainagehighways, railways, pipelines and drainage
systemssystems
Earthwork operationsEarthwork operations
Cut and fill volume calculationsCut and fill volume calculations
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Height of Collimation MethodHeight of Collimation Method
An alternative to the Rise and Fall methodAn alternative to the Rise and Fall method
Normally used when a large number ifNormally used when a large number if
Intermediate Sights are observedIntermediate Sights are observed The height of the telescope axis or heightThe height of the telescope axis or height
of collimation (HC) is measuredof collimation (HC) is measured
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ExampleExample
BSBS ISIS FSFS HCHC RLRL RemarksRemarks
2.0272.027 73.105 + 2.02773.105 + 2.027
= 75.132= 75.132
73.10573.105 BH1BH1
(73.105m)(73.105m)
2.1092.109 75.13275.132 75.13275.132 2.109 =2.109 =
73.02373.023
2.5432.543 75.13275.132 75.13275.132 2.543 =2.543 =
72.58972.589
4.6814.681 75.13275.132 75.13275.132 4.681 =4.681 =
70.45170.451
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Example (Contd)Example (Contd)
BSBS ISIS FSFS HCHC RLRL RemarksRemarks
2.1332.133 4.4274.427 70.705 + 2.13370.705 + 2.133
= 72.838= 72.838
70.45170.451 (4.681(4.681--
4.427) = 70.7054.427) = 70.705
D (CP)D (CP)
3.2463.246 72.83872.838 72.83872.838 3.246 =3.246 =
69.59269.592
EE
1.9571.957 72.83872.838 72.83872.838 1.957 =1.957 =
70.88170.881
FF
3.1593.159 0.6810.681 72.157 + 3.15972.157 + 3.159
= 75.316= 75.316
72.15772.157 G (CP)G (CP)
2.9882.988 75.31675.316 75.31675.316 2.988 =2.988 =
72.32872.328
BH2BH2
(72.328m)(72.328m)
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Arithmetic checksArithmetic checks
Sum of BSSum of BS FS = Last RLFS = Last RL First RLFirst RL
Sum RLsSum RLs First RL = [Sum (HCFirst RL = [Sum (HCii) x n) x nii]]
Sum ISSum IS Sum FSSum FS
Where: HCWhere: HCii is theis the ii th height of collimation and nth height of collimation and nii is the no. of timesis the no. of times
thethe ii th height of collimation was used to compute RLsth height of collimation was used to compute RLs
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Applications of HC methodApplications of HC method
Longitudinal and CrossLongitudinal and Cross--sectionssections
Contouring using grid and levellingContouring using grid and levelling
In general, it is applied when large no. ofIn general, it is applied when large no. of
IS are takenIS are taken e.g. in Earthwork levellinge.g. in Earthwork levelling
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Contouring byContouring by
Grid and LevellingGrid and Levelling
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ContourContour
A contour is a line drawn on a plan joining allA contour is a line drawn on a plan joining all
points of the same height above or below apoints of the same height above or below a
datumdatum
Contours cannot cross, split or join otherContours cannot cross, split or join othercontours, except in the case of an overhang.contours, except in the case of an overhang.
e.g. a cliffe.g. a cliff
The height between successive contours isThe height between successive contours is
called the vertical interval or the contour intervalcalled the vertical interval or the contour interval
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ContourContour
Contour interval value depends on the variation in heightContour interval value depends on the variation in heightof the area being contouredof the area being contoured
-- the contour interval is kept constant for a plan or mapthe contour interval is kept constant for a plan or map
The plan spacing between contour line indicates theThe plan spacing between contour line indicates thesteepness of slopessteepness of slopes
-- Closely spaced lines indicates a steep gradientClosely spaced lines indicates a steep gradient
-- Widely spaced lines indicate a flatter gradientWidely spaced lines indicate a flatter gradient
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ExampleExample
5
5
10
10
15
25
20
15 2025
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Productions of contoursProductions of contours
Direct methodDirect method
Finding points on the ground with the value ofFinding points on the ground with the value of
the required contourthe required contour
Indirect methodIndirect method
Random spot heightsRandom spot heights
Grid of spot heightsGrid of spot heights
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Productions of contoursProductions of contours
(indirect method)(indirect method)
From random spot heights
From a grid of spot heights
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For next practicalFor next practical
Determine the crossDetermine the cross--section and longsection and long--
section for a road, with distance of 100msection for a road, with distance of 100m
Contouring using the Grid and LevellingContouring using the Grid and Levellingmethodmethod
Use the rise/fall or HC method for dataUse the rise/fall or HC method for data
calculationcalculation