Railway Alignment Design and Geometry

[Pages:35]Railway Alignment Design and Geometry

Pasi Lautala, Michigan Tech University Tyler Dick, HDR, Inc.

Topics ?Horizontal and Vertical geometry

?Clearances ?Turnout design ?Structures and loading

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REES Module #6 - Railway Alignment Design and Geometry 1

Railroad vs. Highway ? Passenger Vehicles

Top speed (mph) Weight (tons) Power to weight ratio (hp/ton) Length (ft) # of passengers Propulsion method

Passenger Car 65+ 1.4 150

Light rail vehicle 65 53.5 9.3

15 5 Gasoline engine

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92 (articulated) 160 Electric (or dieselelectric)

REES Module #6 - Railway Alignment Design and Geometry 2

Railroad vs. Highway ? Freight

Top speed (mph) Weight (tons) Power to weight ratio (hp/ton) Length (ft) # of power units # of trailing units Propulsion method

Semi-trailer Truck 55+ 40 12.5

Freight (Unit) Train 40+ 18,000 0.73

65 1 1 Diesel engine

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7,000 1-4 Up to 125 Diesel-electric

REES Module #6 - Railway Alignment Design and Geometry 3

Horizontal Geometry ? Degree of Curve

? Arc (Roadway and LRT)

? Angle measured along the length of a section of curve subtended by a 100' arc

100'

? Chord (Railroad)

? Angle measured along the length of a section of curve subtended by a 100' chord

100'

D R

D R

D/360 = 100/2(pi)R ? 1-deg curve, R= 5729.58' ? 7-deg curve, R=818.51'

R = 50/sin(D/2) ? 1-deg curve, R=5729.65' ? 7-deg curve, R=819.02'

REES Module #6 - Railway Alignment Design and Geometry 4

Curve length difference

Watch out for LONG and SHARP curves

REES Module #6 - Railway Alignment Design and Geometry 5

Horizontal Geometry ? Curves

Criteria Typical values

Highway - Design speed

Freeway: - 60 mph, R=1,340, D=4.28 - 70 mph, R=2,050, D=2.79

Railroad

-Design speed -Allowable superelevation

Main lines: -High speed: R > 5,729, D2,865, D1,433, D764, D ................
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