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Journal of Multidisciplinary Engineering Science and Technology (JMEST)ISSN: 2458-9403Vol. 4 Issue 6, June - 2017Geometric Design of a Highway Using AutocadCivil 3dS.A. RajiSnr Lect.: Dept. ofCivil Engineering,University of IlorinSaraji12000@gmail.comA. ZavaPG Std. Dept. of CivilEngineering,University of Ilorinaperzava@gmail.comAbstract - Roadway geometry design involvessuch tasks as creating the road alignment andplotting the alignment profile using bearings orcoordinates (easting and northing), stations andelevations of points along the proposed route;calculation of sight distances, radii of horizontalcurves, and lengths of vertical curves;computation of earthwork quantities, andnumerous other analyses and calculations aimedat finding the optimum alignment while satisfyingdesign standards and constraints. Whenperformed manually, geometric design is verycumbersome,time-consumingandhighlysusceptible to very costly errors. Current trendsare geared towards the use of computerprograms for roadway geometry design. Theprograms offer amazing precision and save lotsof time and effort. This paper presents acomplete geometric design of a typical highwayusing AutoCAD Civil 3D software. The aim of theproject was to demonstrate how roadwaygeometric design can be performed in a veryshort time with much ease and precision. Theroad design procedure using AutoCAD Civil 3Dhas been presented. Manual geometric design ofthe same road was also performed, the results ofwhich was compared favourably with that ofAutoCAD Civil 3D.Keywords—Geometric Design; AutoCADCivil 3D.I. INTRODUCTIONHighways are expected to guarantee users’ comfortand safety, to permit efficient traffic operation, and atthe same time attract the least possible cost inconstruction and maintenance. Highways are alsoexpected to cause minimum damage to theenvironment and be aesthetically pleasing in theirfinished form. Geometric design is the meansthrough which these demands are met. As theNigerian Federal Ministry of Works (FMW) HighwayManual [1] puts it, “geometric design focuses on thespecific measures that provide for efficient andappropriate operation of the road, as well as providefor all the specific details that make roads safe es surrounding the road”.K. JirgbaPG Std. Dept. of CivilEngineering,University of Ilorinjirgbakavnen@yahoo.comA.B. OsunkunlePG Std. Dept. of CivilEngineering,University of Ilorinraji.azizat@yahoo.comGeometric design of roads can be subdivided intothree main parts: horizontal alignment, verticalalignment and cross section, which when combinedprovide a three-dimensional layout for a highway [2,3].Horizontal alignment of a highway defines its locationand orientation in plan-view. It comprises threegeometric elements, including tangents (straightsections), circular curves and transition spiralsbetween tangents and curves [2]The vertical alignment (or roadway profile) is thelongitudinal section of the road, comprising suchgeometric elements as crest and sag curves, and thegradients (straight grade lines) connecting them [1, 2]The highway cross section shows the position andnumber of vehicle and bicycle lanes and sidewalksalong with their cross slopes; shoulders, drainageditches, etc.Highway geometry elements are expected to beselected, sized and positioned in a way that satisfiessuch design criteria as sight distance, vehiclestability, driver comfort, drainage, economy, andaesthetics. The design process involves somedrafting and a number of analyses and calculations.The tasks which are usually performed by the designengineer include: creating the road alignment andplotting the road profile using coordinates (orbearings), stations and elevations; calculation of sightdistances, radii of horizontal curves, and lengths ofvertical curves; computation of earthwork quantities,and numerous other analyses and calculations aimedat finding the optimum alignment while satisfyingdesign standards and constraints.Traditionally, these tasks are performed manuallyusing drawing tools and mathematical techniques.When performed manually, geometric design is verycumbersome, time-consuming and highly susceptibleto very costly errors [4, 5] The traditional approach isalso based mainly on a two-dimensional (2-D)analysis which does not guarantee a satisfactorydesign, reports Yesser et al. [6]www.jmest.orgJMESTN423522317415

Journal of Multidisciplinary Engineering Science and Technology (JMEST)ISSN: 2458-9403Vol. 4 Issue 6, June - 2017Current trends are geared towards the use of verysophisticated computer programs for roadwaygeometry design that offer amazing precision andsave lots of time and effort. Autodesk [7] summarizesthe importance of specialized road design softwaresaying the tools help civil engineering professionalsworking on transportation projects to: explorepreliminary design options and optimize projectperformance; determine optimal horizontal andvertical roadway geometry that are constrained bydesign criteria; engineer roadway geometry in thecontext of the existing environment more efficientlyand effectively. The tools also enable engineers towork with a more realistic model of what truly existsat the project site thereby affording engineers theopportunity to consider safety requirements earlier inproject development. As Ananya and Sahimol [4] putit, these computer applications can produce amazingvisual graphics that enable the design engineer toview the road on screen from the perspective of thedriver. They [4] further state that “without the use ofthree-dimensional modeling, highway planningexperiences a significant difficulty. Cut and fillcalculation tends to consume a significant amount oftime By using the object-oriented approach, theprocess of cut and fill calculation can be performedautomatically and in an accurate manner”.There are ongoing efforts to complete thedevelopment of campus road network of theUniversity of Ilorin, located in southwestern Nigeriantown of Ilorin. One of the links in the road networkthat has been selected for development is the oneleading to students’ hostels from the University busstop. This paper presents a complete geometricdesign of this road using AutoCAD Civil 3D software.The aim is to demonstrate how roadway geometricdesign can be performed in a very short time withmuch ease and precision so as to encourage civilengineering practitioners in the developing world toembrace the use of road design software. To providea basis for comparison, manual design of thegeometry of the same road was also performed.II. AUTODESK AUTOCAD CIVIL 3DAutoCAD Civil 3D is a civil engineering design anddocumentation tool developed by Autodesk.AutoCAD Civil 3D software supports BuildingInformation Modeling (that is, digital representation ofthe physical and functional characteristics of afacility). It is used for modeling, analysis and designof a variety of civil infrastructure project types,including roads and highways, land development,rail, airports, and water. AutoCAD Civil 3D helps civilinfrastructure professionals improve project delivery,maintain more consistent data and processes, andrespond faster to project changes, all within thefamiliar AutoCAD environment [8]Autodesk [7] lists the features of AutoCAD Civil 3Das follows:i.ii.iii.iv.v.BIM tools for civil engineering design:AutoCAD Civil 3D supports BuildingInformation Modeling (BIM) and helps reducethe time it takes to design, analyze, andimplement changes.Efficient civil design: AutoCAD Civil 3Dperforms faster design iterations with anintelligent, 3D model-based application thatdynamically updates related civil designelements when changes are made.Itstreamlines time-consuming tasks forcorridor design, parcel design, and pressureand gravity network design.It improves civil drafting and documentation.Connecting design and documentation helpsboost productivity and deliver higher-qualitydesigns and construction documentation.Changes to design elements are captured indocumentation, minimizing manual updates.GPS surveying tools for faster processing.GPS surveying and data collection tools inAutoCAD Civil 3D can help you update yourprocesses for improved project delivery.Integrated storm water management andgeospatial analysis. AutoCAD Civil 3D helpsthe designer to improve project delivery andmake more informed decisions usingvisualization, simulation, and water analysisintegrated with the design process for stormwater management, geospatial analysis, andmodel analysis.III. DESIGN METHODOLOGYA. Survey Data CollectionThe existing ground surface data are required fordesigning the geometry of highways. The surveyinformation of the proposed route was obtained fromthe firm handling the development of the road. Thesurvey information included Easting, Northing andelevations of points along the proposed route.B. Design CriteriaThe following design criteria based on the NigerianFederal Ministry of Works Manual [1] were assignedto the horizontal geometry of the center line and alsoto the profile and cross section of the roadway:i.Design speed 60 km/hii.Superelevation rate 4%iii.Friction factor 0.14iv.Minimum Stopping Sight Distance 130 mv.Minimum Passing Sight Distance 540 mvi.Maximum grade 7%vii.Minimum K (rate of vertical curvature) for sagcurves 30viii.Minimum K (rate of vertical curvature) forcrest curves 26.ix.Roadway width 12.8 mx.Carriageway width 7.3 mxi.Shoulder width 2.75 mC. rgJMESTN423522317416