La voie ferrée

When it comes to Railway track engineering literature, there are a few books we can consider “classic”. Even old, some very old, these books still have significant railway engineering value and can be always a good reference both for young and inexperienced engineers as for the ones that already have robust railway track experience and…

How is the cant measured?

The good old times Since the early beginnings of the railway, the track engineers were aware of the centrifugal forces influence to the train riding when passing through a curved section of track. To compensate this influence, the track was inclined laterally by creating a positive level difference between the outer and inner rails of a…

Why a right hand curve is positive?

In transportation engineering there is the following signage convention  for curves in horizontal alignment design: a right hand curve is considered positive a left hand curve is considered negative This convention is considered relative to the stationing direction of that alignment. This signage convention is established in the following way (see the figure above):

Virtual Transition

This is an animation showing how a PWay Track Horizontal Alignment Virtual Transition is defined by the trajectory of the vehicle centre, when is passing over a railway track section with a sudden change in curvature: The nature of this curve is presented in this post: THE VIRTUAL TRANSITION CURVATURE VARIATION. More details about this principle…

Cant and Cant Deficiency. Where is the 11.82 coming from?

A railway vehicle moving along a circular curve is subjected to an inertial centrifugal acceleration (ac), directly proportional with its speed and in reverse proportion with the curve radius. This lateral acceleration is perceived by the passengers as an uncomfortable sensation and, above a certain limit, endangers the lateral stability of the running vehicle. In…

The Virtual Transition curvature variation

(A prelude to a proper article about the Virtual Transition) Motto: Measured, weighed and divided. Principle of Virtual Transition  The Principle of Virtual Transition is used in Permanent Way alignment design to establish when a transition curve in not needed and design a sudden change in curvature. The principle is defined in sheet B.3.4 of…

Numeri Regunt FerroVia

The track geometry is governed by numbers and all the time we are using them to design and check our work. The geometry of the non-linear transition curves is also governed by important numbers, useful to know in the alignment design when these transitions are used: – Bloss – Cosine (and its close approximation: the…

Bloss like a boss

(a prelude to a proper design guidance) Non-linear transitions and their use in alignment design  In alignment design the transition curves are used to provide a smooth variation of the centrifugal acceleration between alignment segments of different curvature. When needed, the cant transition is applied, in direct relation with the curvature variation of the transition…