| Disadur dari Centre of Transportation Research and Education, Iowa State University, CE353 Lecture William W. Hay defines excellence in engineering as an economic combination of traffic, distance, curvature, rise and fall, and gradient. The concepts described as related to the location process apply equally to new construction, realignment, and major rehabilitation. This is particularly important given the maturity of the rail and highway transport systems (e.g., few new rail lines are being constructed today). LocationGeneral Steps in the Planning and Design Process Establish needEstablish/define basic featuresTerminiGeneral locationSize or classLevel of serviceIdentify and compare preliminary alternative alignmentsChoose preferred preliminary alignmentFinal design (including Horizontal/vertical alignment, dimensions/slopes, standards, quantities and types)Location influences cost and other impacts (environmental, socio-economic, operational, etc.)Factors Topography/terrainManmade developmentOperating speedsUse (freight or passenger train traffic)TonnageType of rolling stockPhysical featuresGround CoverWeatherWater CourseWater TableSoil ConditionsLocation of Resources (for contruction and market)Location of IndustryTownsHighwaysRailroadsMountain PassesRiver Crossing SitesTraffic CentersPopulation CentersControlling factors that depend upon terrain Level terrainRight of way costLand useBridgesExisting roads, rail, power linesSubgrade conditionAvailability of borrowRolling terrain Grade and curvature considered carefullyDepth of cut, height of fillDrainage structuresNumber of bridgesMountainous terrain Grade controls (maximum grade criteria)Preliminary Location Begin with aerial photogrammetry or a topographical mapClick here for an example aerial photo for a location we will design for in lab this semester, near Berwick IowaClick here for a closeup of the existing rail line through BerwickClick here for terraserver aerial photography of the worldClick here for an example USGS DRG (digital raster graphic) with topo mapA good scale is 200 (1″ = 200′) – same as 1:2400 (error ~4′)Contours at this scale are usually provided at 2′ to 5’intervalsConsiderations:Grade rules operating costs. It determines the number of trains required to haul a specific amount of traffic. Ruling grade determines operating speed, number of locomotives needed and tonnage (number of cars) that can be accommodated ina single train. Alternatively, the tonnage rating for a specific line gives the maximum tonnage that can be hauled in a single train, given that the train may have to stop along its route (see lecture on motive power)Follow the terrain where possibleConnect long tangents with long curvesDon’t mix long, small curves with short, sharp curvesConsider grades and curves and satisfy criteria (balance)Directness is not very important in rail design for operating costs, but may be very important for ROW costs in relatively level terrain.Crossings – minimizeImpacts (environmental, social)If federal funds involved or interstate, must do an EIS (Environmental Impact Statement)covering …Environmental ImpactAdverse Impact During ImplementationPresentation of AlternativesShort Term vs. Long Term AffectsIrretrievable Resources NeededAn example of one environmental issue related to rail operations is noise impact Click here to see what the CN Railroad has to say about the issue The following images illustrate some constraints to the alignment process:topographical mapProposed AlignmentNatural Barriers (water courses, wetlands, archeological)Manmade Barriers – roadsManmade Barriers – structuresManmade other: sensitive land usesCriteria listed in Table 12-1Final Design Use 100 scale maps (1:1200, others 1:1000 or 1:500)Set horizontal and vertical controlsCalculate tangents, curve lengths, superelevation transition, …Try to balance cut (waste) and fill (borrow)Hauls should be downhill and shortPlace crests in cuts and sags in fillsUse long tangents and long curves, short tangents with sharp curvesProvide for DrainageConsider operational impact of designMax grade of 1 degree if possible, 2-2.5 in mountainous areas possible (see lectures on motive power and resistive forces to determine power requirements.)Economic Analysis For a profitable line, choose the line with the highest p … To account for time value of money, and to put costs and expenses into the same units, must use an anualized cost… For a subsidized line, do a benefit/cost analysis, and choose the one with the highest B/C … Can also use present worth … To compute present value of building the line, compute present value of components individually or use a weighted average of anticipated useful life …40 yrs. for structures50-100 yrs. for ROW20-30 yrs. for rolling stock“Maafkan saya yang hina telah buta, tidak melihat gunung Thay Shan yang tinggi telah berdiri di depan mata.” (Kam Hong Tie dan saya dihadapan teman-teman) |
| Terakhir diperbaharui ( Selasa, 05 Agustus 2008 ) |
Pemilihan Lokasi Jalan Rel
In Technical Reference On 06 January 2020
