snippet – Lateral resistance before and after tamping

Things you find on Spark. In 1972, RTC conducted a series of tests to evaluate the effect on tamping on the track lateral resistance. Their results, published in 1973, have been referenced in numerous other research documents, including the ERRI D202 Reports – the committee that produced UIC Leaflet 720R “Laying and Maintenance of CWR…

snippet – Track realignment using involutes

Hallade was not alone. His method of track alignment rectification is by far the most used and known but there are quite few other methods for rectification and even proper realignment. One of these methods used a strange curve called involute (or evolvent). It was first described in this book from 1927. Die Absteckung von…

When is the cant negative in LandXML?

Motto: “I don’t see the code anymore. All I see is blonde, brunette, redhead, negative, adverse.” Cypher Disclaimer: This is not a design guidance. Don’t believe everything you read online. LandXML? LandXML is a non-proprietary data standard on the Extensible Markup Language (XML) format, developed for engineering data exchange. A LandXML file can contain civil and survey…

The other Bernoulli boy and his lemniscate

When I hear the name Bernoulli I think about some funny high school experiments of spraying coloured water on paper but also about an infinite loop curve the Roads Professor tormented us in Uni. I would have bet both things were discovered by the same Bernoulli. But no. The more known one, D. Bernoulli, the…

Hallade’s broken clothoid

I mentioned in a previous article, The Cubic Parabola – a complicated simplification, that the curvature diagram of the Cubic Parabola increases linearly up to a peak point and then drops down. Only that first section of the parabolic curve can be used as an alignment transition. The curvature diagram of the Clothoid is however…

Pi is never 3.14 in engineering

One alignment design homework I had for my students was to calculate the installation coordinates for a simple alignment. This was a long time ago, before Excel was a thing. We were using scientific calculators back then; a lot of typing. One of the submissions puzzled me. All the coordinates were almost correct. The length…