(Quickly but nostalgically written, remembering the good old days when Taylor was not yet known as the name of a beautiful singer but as the laborious math trick used to solve rather painful Mathematical Analysis problems …) The deflection angle (θ) of the Bloss transition is: The rectangular equations (x and y) of the curve are…
For the track realignment methods (Hallade or similar) the existing alignment is surveyed by measuring the outer rail offsets (versines) to overlapping chords. One such setup is drawn below: A’, B’, C’ are points on the outer rail of the track and for point B’ the versine B’D’ = vB ex is measured to the chord A’C’. We…
A field measurement of any kind is never exact and intrinsically contains errors (NJDoT Survey Manual – 2014). For track topographical measurements some of these errors are known and eliminated by applying appropriate corrections and compensations. Even after all known errors are eliminated however, a site measurement will still be in error by some unknown value. To minimise the…
There are three types of versines used for the track realignment and rectification methods (Radu, 2003): Measured (existing) versine – the versine measured with a real chord on the outer rail of the real existing track. This is the result of the versine (Hallade) survey and based on it are computed the track offsets (slues…
The running of the trains over the railway track is inducing vertical and lateral forces that, in time, are affecting the track alignment, changing incrementally the installed track and causing track irregularities. On curved track this deterioration process is more significant due to the additional effect of the lateral (centrifugal) acceleration. When the irregularities become…
The measurement and analysis of track geometry is carried out regularly by all the railway infrastructure administrators in order to obtain data from which the track quality is established and the maintenance can be scheduled (Cope – 1993). Historically, the use of track inspection cars can be traced back to the early 1920’s in France…
This is the presentation I gave to the Glasgow Section of the Permanent Way Institution: Track Quality Measurement and Inherent Design Standard Deviation Later note: Some fundamental things stated in this presentation need to be revised.
When designing multiple line alignments – in railway stations or plain line sections – there will be a creep of the alignment stationing due to the length difference between the alignments. This stationing (or chainage) creep becomes relevant when adjacent alignments have to be kept at the same level or with a well-defined elevation difference.…
Track measurement The importance of knowing the track geometric quality arose in the middle of 20th century, when European infrastructure managers developed their own track recording vehicles allowing a continuous measurement of track geometry and based on this, their own track geometry quality evaluation standards (EN 13848-6). Periodic track measurement is required to evaluate the…
Maglev is a transport system that uses the magnetic levitation to move vehicles without contact to the guideway. The system uses magnetic forces for levitation, propulsion and guidance of the vehicle, thereby making practically negligible the friction forces and allowing very high speeds. The technological evolution is making this transportation system competitive and gaining consideration as a…
A railway track blog 