INTRODUCTION In transportation infrastructure design the route is defined based on its axis (centreline) – the alignment model. This simplified abstract model is designed in such a way to clearly define the principle course of the infrastructure project. For most of the transportation means the infrastructure alignment design is split into two main two-dimensional complex…
An anecdote: Track geometry exam, somewhere at a Civil Engineering University. One of the exam subjects is realignment methods and types of versines. This important subject was covered during the track course hours but also in four seminars and in a realignment project homework – so it was supposed to be an easy one … After checking the…
The theory of vertical movement. The parabolic projectile motion An object thrown in the air, near the earth’s surface, moves along a parabolic path under the action of gravity only. The only force of significance that acts on the object is gravity, which acts downward to cause a downward acceleration. Because of the object’s inertia, no external horizontal force is needed…
Another classic book it sure is “British Railway Track Design, Construction and Maintenance”, edited by Geoffrey H Cope and having around 40 contributors for writing the 30 chapters of this essential track compendium. Its last six edition was published in 1993 by The Permanent Way Institution. Presenting the essential principles but also the British specifics…
The slides of the presentation I gave in November at the West of England section meeting of the Permanent Way Institution: The main topics presented: – Cant parameters definition. The origin of the 11.82 (UK) cant constant. Ways of applying cant. – Track geometry recording. Track Quality Standard deviation. Inherent standard deviation. Quality bands…
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…
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):
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…
The track buckling happens in hot weather because of a multitude of factors but it is massively influenced by the track longitudinal and lateral resistances. Both these resistances have three levels of action: Figure 1. The three levels of track lateral and longitudinal resistance – between rail and fastening – at this level all the modern fastenings are behaving…
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…
