# Where’s the point?

All the railway networks have design rules for marking the limit from which it is safe to stable a vehicle on a line, without the risk of obstructing the train passage on the other line of an S&C (turnout or whatever other arrangement). In the UK this limit comes in a pair – Fouling Point…

# What’s the degree of curvature?

… or – How to convert a curve into an angle? In the track design handbook we have a too complex formula that refers to “degree of curvature”. Before discussing about the equivalent gradient, let’s see first what this is – what is the degree of curvature? This measure is used in United States in…

# Which is better – S&C or plain line?

Thank you for visiting this page. I would really appreciate if you could spare a minute and answer the few questions below. I’ll publish the responses with a few comments as soon as enough answers are collected. If you don’t see the form below, please go to this link: Which is better – S&C or…

# 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…

# Vehicle rollover speed

The Santiago de Compostela derailment occurred on 24 July 2013, when a high-speed train, travelling from Madrid to Ferrol (north-west of Spain) derailed at high speed on a 400 m radius curve, at Angrois, in Santiago de Compostela. Around 140 people were injured and 79 died. Data from the train’s black box revealed that before the start of the curve the train was travelling at…

# 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…