EvaluationofHorizontalCurveSuperelevation
Submittedto:
Submittedby: Dr.JitenShah
AnimeshRathi (171010012001) CourseInstructor
Abstract
AsheeshKumar (171010012002)
AyushJai (171010012003) AyushKumar (171010012004)
PranathiPabbati (171010012008)
Riding comfortably and safely through horizontal curves in roadways should be provided by superelevation.Duringthemaintenanceofroadthereisachancethatsuperelevationgetsaltered. Thus,assessingaroad'scrossslopealongcurvesisofgreatimportance.Inthissurvey,horizontal curvesuperelevationwasmeasurednearAnupam Cinema.Itwas chosenbecauseit was nearto ourcollegeandthesitewaswithpropercurvaturewithpropertraffic.Basedonsurveyresultsand analysis, it is concluded that the curvature was designed as per the guidelines of the IRC with radiusofcurvatureof358m,designspeedof45km/hr.andthesuper-elevation3.7%whichwas acceptable. The road also had the widening of 4.25 m. In this case, the assessment of the superelevationshouldbedoneinaregulartimeintervalsoastoreducefatalaccidentsthatoccur duetoincorrectsuperelevationatthecurvatureoftheroad.
1. Introduction
1.1General
Providingcomfortandsafetyareimportantparametersinhorizontalcurves.Thebalance ofthevehiclewhilepassingthroughacurveissecuredbysuperelevation.Superelevation is directly dependent upon how the pavement is constructed. Lack of attention to road construction or inappropriate implementation of asphalt overlay during the maintenance periodresultsinreducedcomfortandsafetyofthecurves.
There are several methods for collecting cross slope data, but surveying techniques to collect data, accuracy, cost, speed of collection, and safety considerations are varied. Conventional survey techniques use manual methods to collect coordinate points. Surveyors use levels, rods, and electronic devices for site measurement. The point and elevation data are extremely accurate; however, the time required for data collection coupledwithreducedsafetyandrestrictedtrafficoperationsmakesthisapproachinfeasible forlarge-scaleprojectdatabases.
Surveytechniquesinconcertwithhand-heldGPSequipmentcanprovideaccurateresults, buthavedisadvantagessimilartothoseofthemanualmethod.Locatingsurveyequipment in a static vehicle permits data collection with improved safety. The vehicle is typically positioned on the shoulder of roadway, and with the aid of an electronic data collector, disto-meter, notebook computer, and GPS unit, accurate results can be obtained for the pavementcrosssection.However,therequiredequipmentiscostly,andthevehiclecannot beinmotionduringdatacollection
a. Superelevation: Bankingofaroadwayalongahorizontalcurvesomotoristscan safely and comfortably maneuver the curve at reasonable speeds. A steeper superelevation rate is required as speeds increase or horizontal curves become tighter
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b. Design Speed: It is a selected speed used to determine the various geometric features of theroadway. Theassumed design speed should be a logicalonewith respectto thetopography,anticipatedoperating speed,theadjacentlanduse, and thefunctionalclassificationofthehighway.
c. Camber:Itisthetransverseslopeprovidedtotheroadsurfaceforthedrainageof rainwaterforthebetterperformanceoftheroad.
d. SideFriction:Thefrictionforcebetweenavehicle’stiresandthepavementwhich preventsthevehiclefromslidingofftheroadway.
e. AxisofRotation:Thepointonthecrosssectionaboutwhichtheroadwayisrotated toattainthedesiredsuperelevation.
f. SuperelevationRate(e):Thecrossslopeofthepavementatfullsuperelevation.
g. SuperelevationRunoffLength(L):Thelengthrequiredtochangethecrossslope from0%tothefullsuperelevationrate.
h. Tangent RunoutLength (x): Thelengthrequiredtochangethecrossslopefrom 0%tothenormalcrossslope.
i. Relative Gradient (G): Theslopeoftheedgeofpavementrelativetotheaxisof rotation.
j. Width(w):Thedistancefromtheaxisofrotationtotheoutsideedgeofthetraveled way.
k. Carriage Way: Itisthewidthoftheroadwhichisusedbythetrafficformoving onit.Itisgenerallycentralportionofthetotallandwidthandispavedandsurfaced withbituminousconcreteforservicetotheroadusers.
2. ObjectivesandScopeoftheStudy
ObjectiveofstudyingandprovidingSuperelevationistoovercomethefollowing:
i. Effect of centrifugal force acting on the moving vehicle to pull out the same outward on a horizontalcurve.
ii. Helpafast-movingvehicletonegotiatecurvedpathwithoutoverturningandskidding.
iii. Ensuresafetyofthefast-movingtraffic.
iv. Preventdamagingeffectontheroadsurfaceduetoimproperdistributionofload.
3.BackgroundoftheStudy
TheareaofoursurveywasnearAnupamCinemaasthislocationwasneartoourcollegeandthe sitewaswithpropercurvatureaswecanseefromthefigurewithoutanytypeofintersection.We collectedthedatai.e.speedofvehiclesinthemorninghourasitwillgivethehighestspeedof runningvehiclesbecauseofverylighttrafficwithrespecttothepeaktraffic.Asourtopicisthe designofsuperelevation,toconsiderthisweneeddesignspeedsoweareintendedtotakethe optimumspeed.
Figure1.StudyArea
Figure2.StudyArea
Figure3.RoadSideConditions
4.Methodology
Thespeedgunwasusedtomeasurethespeedofrunningvehicles.Tomeasurethewidthofthe carrywageweusedthemeasuringtapes.Atthesite,theexitingcamberandsuperelevationwere alsomeasured(ReferAnnexureI).Tomeasurethese,staffandthelaserlightwereused.Thedata collectedwasofmorninghours(6:40AMto7:35AM).
ClassInterval (speedkm/hr.) Mid-Point Frequency
%Relative Frequency %Cumulative Frequency
15-19 17 5 3.185 3.185
20-24 22 19 12.102 15.287 25-29 27 40 25.477 40.764 30-34 32 43 27.388 68.152 35-39 37 26 16.561 84.713 40-44 42 12 7.643 92.356 45-49 47 8 5.095 97.451 50-54 52 2 1.273 98.724 55-59 57 2 1.273 99.997
Sum 157
Thegraphscorrespondingtothedatacollectedandinterpretedareasfollows:
Figure6.FrequencyCurve
Fromthisplotbetweenfrequencyandspeed,wegetthenormaldistribution,justlikeabellshape curve.
Figure7.CumulativeFrequencyCurve
TheS-curveisplottedbetween%cumulativefrequencyandspeedofvehicles.Fromthegraph weinferthatthedesignspeedi.e.95percentilespeedis=45km/hr.
