[This is a draft page]

I’ll collect here all my posts on track geometry and try to arrange them in a logical order … but it will take some time.

1. General elements
   • Track definitions and simplifications
     • Track centreline. Differences between the centerline radius and the rail radii. Versine convention.
     • Why a right hand curve is positive?
   • Track Quality Index. Evaluation of the track quality
     • Track defect
     • Track Quality Index
     • Inherent Track Geometry Standard Deviation
     • Rolling Standard Deviation. Inherent Rolling Standard Deviation.

     

   • Tolerances. Errors. 1+1=1!
   • The limits of track alignment design parameters. Safety and comfort parameters. EN 13803-1 Definitions.
   • Track design drawings
     • Horizontal arrangement
     • Vertical profile
     • Cross sections

2. Track alignment theory
   • Vehicle running through a curve
   • Cant parameters
     • Cant Deficiency. Cant Excess
     • Rates of change of cant and cant deficiency
     • Cant and cant deficiency diagrams.
     • Horizontal and Vertical Jerk
     • Ways of applying the cant
   • Transition curves
   • Principles of track rectification and realignment
     • Versine definition
     • Types of versines
     • Curvature and versine diagrams

 

3. Horizontal alignment
   • Horizontal curves and cant design
   • How is the cant measures? 
     • Cant and cant deficiency. Where 11.82 is coming from?
     • Cant transition
     • Designing a sudden change in curvature. Virtual transition
   • Transition curves
     • Clothoid. The Clothoid geometry. The Clothoid shift
     • Cubic Parabolas
     • Non-linear transitions parameters
     • Bloss transition
     • Cosinusoidal transition – the Japanese transition. The Cosinusoidal transition parameters used on California High-Speed Rail

• Bi-quadratic transition
• Sinusoidal transition
• Hasslinger transition – the Viennese curve

4. Vertical alignment
   • Vertical curve
   • The limits of vertical acceleration
   • Vertical parabolic curve
   • Vertical circular curve
   • Transitioned vertical curves
   • Vertical alignment design principles

 

5. Particular design topics
   • Green field design principles
     • Null earthworks axis
     • Geometrisation. Primary alignment. Final alignment.
     • Refining the design alignment
   • Reverse curve design. Cant over the reverse curve
     • Linear transition
     • Non-linear transition
   • Virtual transition design examples. TRK 2049 justification.
   • Chainage creep
   • Platform clearances
   • Relative position of adjacent tracks
   • Maglev guideway alignment design

6. Rectification and realignment methods
   • The versine formula
   • Versine (Hallade) surveying. Checking the versine survey precision.
   • Types of versines
   • Rectification. Realignment
   • Hallade realignment method
   • Direction angle method
   • Other realignment methods. Cassan