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…
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?) ,…
The location of the stress transition zone is not only limited to the extremities of a continuous welded rail (CWR) track, the case presented in a previous article – CWR stress transition zone. A stress transition zone may also be present between two fixed zones, inside the CWR. These internal stress transition zones are shorter…
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…
(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…
(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…
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…
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 railway track blog 