Cant deficiency converted in percentage of g

As demonstrated in a previous post here: https://pwayblog.com/2015/10/29/11-82_cant-deficiency-un-compensated-acceleration-pway/ , the cant deficiency is the conventional representation of the uncompensated lateral acceleration. And since cant deficiency is an acceleration, we can easily represent it as a percentage of g, the gravitational acceleration. The formula that relates the cant deficiency D to un-compensated lateral acceleration is: The…

Is the surveyed cant the actual cant?

One of the instruments used to survey the track is the rail shoe – an L shaped device placed horizontally on the rail head, that touches laterally the running edge at 14mm below its horizontal arm – see figure 1. The horizontal placement of the shoe is checked using a spirit level. There might be…

Versine artefacts?

Motto: If you can’t explain it simply, you don’t understand it well enough. (Easy for you to say…) Einstein Well, hello again, dear reader! Before moving on from the TGSD Calculator allow me to explain what it measures, without any reference to waves and filters, without frustration or passive-aggressiveness (is that an actual word?) ,…

What is the TGSD Calculator?

This post follows up from the Faith of TGSD Calculator. Before my four year too late discussion with David Marriott I wrongly believed that the TGSD Calculator computes a special kind of uncompensated accelerations that appear only at the points where any design element changes to another and turns those into a wave-like shape that…

The Faith of TGSD Calculator

Motto: “I am not the Messiah!”,  Brian [Later edit: I wrote this during the pandemic, not in a very happy state of mind, nostalgic about good old and normal times, and dreaming of white whales. It is a personal opinion and, to a degree, an expression of powerless frustration. Don’t take it too seriously!] For…

Thermal forces and broken rails

Rail steel has a considerably higher carbon content (0.7-0.8%), and hence is more brittle than mild steel. A variety of stress concentrating defects in rails, combined with the alternating loads from the passage of traffic, can produce slowly propagating fatigue crack. When this crack attains a critical size it causes an almost instantaneous brittle fracture…

CWR stress transition zone

(prelude to a new PWI Journal article) A stress transition zone is any section of continuous welded rails (CWR) where the thermal force is variable, the longitudinal resistance (p) is active and rail movement occurs due to rail temperature variations. The most common (and well known) location of the stress transition zone is at the…

The rectangular coordinates of the Bloss transition

(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…

A day in the life of a jointed track

ΔG = αLΔT°. Free expansion For a free thermal expansion jointed track the rails expand and contract freely and the track components do not provide any resistance to oppose this rail length variation. The joint gap varies linearly relative to the rail temperature. The figure below presents the joint gap variation for a jointed track formed…