Tag Archives: geometrics

Parameters (3) vehicle type

So far I have discussed the concept of fundamental parameters in highway geometric design (for example, here) and the fundamental parameter “road type“. This post covers the fundamental parameter “vehicle type“. Vehicle type relates directly to design vehicles – the … Continue reading

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Simplification of standards (2)

Suppose someone does manage to list the features which influence- or are influenced by – a geometric parameter (see previous post here). This information by itself is not enough to allow anyone to simplify things. We would also need to … Continue reading

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Road geometric design – control lines

A control line is an imaginary line along a design for a new road. For example, (Ref. 2133)  says that “The horizontal and vertical elements of a road are described in terms of control lines. Control lines are lines mathematically … Continue reading

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Words which are out of date (1) carriageway

Road engineers don’t really know what they are talking about – at least, not when they use words inconsistently, or where the meaning starts to fade away. Take for example the word “carriageway”. Definitions are not consistent, and what some … Continue reading

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New road classification / 4 : a two-dimensional geometrics classification

The previous post in this series gave an example of a two-dimensional classification for roads, and asked: What would be the features suitable for use in a 2-dimensional code for the geometry of roads? The same post argued that when … Continue reading

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New road classification / 3 – two-dimensional classification

The many terms used for road types and classes can give rise to minsunderstandings. This can be due to the use of different language, or inconsistent terms within one language. It could well be a good idea if road engineers … Continue reading

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New road classification / 2 – English is not enough

In an earlier post I suggested that there is a confusion of languages in the world (one estimate puts the number at around 6,700). I also said that, in trying to make sense of terms on road classification: “Since English … Continue reading

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Basic formula for calculating horizontal radius

There are various, equally correct, methods to calculate horizontal radius. The first relates radius to speed, surface friction and superelevation. A second considers the physical limitations of a long vehicle negotiating a tight bend. This is more appropriate for low … Continue reading

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