Factors

• Topography/terrain
• Manmade development
• Operating speeds
• Use (freight or passenger train traffic)
• Tonnage
• Type of rolling stock
• Physical features
• Ground Cover
• Weather
• Water Course
• Water Table
• Soil Conditions
• Location of Resources (for contruction and market)
• Location of Industry
• Towns
• Highways
• Railroads
• Mountain Passes
• River Crossing Sites
• Traffic Centers
• Population Centers

Controlling factors that depend upon terrain

• Level terrain
  • Right of way cost
  • Land use
  • Bridges
  • Existing roads, rail, power lines
  • Subgrade condition
  • Availability of borrow
• Rolling terrain
  • Grade and curvature considered carefully
  • Depth of cut, height of fill
  • Drainage structures
  • Number of bridges
• Mountainous terrain
  • Grade controls (maximum grade criteria)

Preliminary Location

• Begin with aerial photogrammetry or a topographical map
  Click here for an example aerial photo for a location we will design for in lab this semester, near Berwick Iowa

  Click here for a closeup of the existing rail line through Berwick

  Click here for terraserver aerial photography of the world

  Click here for an example USGS DRG (digital raster graphic) with topo map

  A good scale is 200 (1" = 200') - same as 1:2400 (error ~4')

  Contours at this scale are usually provided at 2' to 5'intervals

  Considerations:

  • 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 possible
  • Connect long tangents with long curves
  • Don't mix long, small curves with short, sharp curves
  • Consider 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 - minimize
  • Impacts (environmental, social)
  • If federal funds involved or interstate, must do an EIS (Environmental Impact Statement)covering ...
    Environmental Impact
    Adverse Impact During Implementation
    Presentation of Alternatives
    Short Term vs. Long Term Affects
    Irretrievable Resources Needed
  • An 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 map

  Proposed Alignment

  Natural Barriers (water courses, wetlands, archeological)

  Manmade Barriers - roads

  Manmade Barriers - structures

  Manmade other: sensitive land uses

  Criteria listed in Table 12-1

Final Design

• Use 100 scale maps (1:1200, others 1:1000 or 1:500)
• Set horizontal and vertical controls
• Calculate tangents, curve lengths, superelevation transition, ...
• Try to balance cut (waste) and fill (borrow)
• Hauls should be downhill and short
• Place crests in cuts and sags in fills
• Use long tangents and long curves, short tangents with sharp curves
• Provide for Drainage
• Consider operational impact of design
• Max 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

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 structures
• 50-100 yrs. for ROW
• 20-30 yrs. for rolling stock