One basic aspect of highway engineering concerns the development of geometric design standards – of features such as side friction factor, horizontal radius, maximum gradient and so on. Here we can argue that there are four types of engineer.
Practicing engineers who are busy designing roads and do not have time to question whether the the values they use (for side friction etc) actually make sense. Here see the article written by Charles Marohn in 2010 (link) where he says for example “a book of standards to an engineer is better than a bible to a priest“.
Engineers who work on developing and updating standards and guidelines but mainly source their information from earlier standards, either from their own or from other countries. For one possible example of this see my earlier blog post here.
Researchers who carry out complex and detailed studies on aspects of highway engineering, but whose research reports are either incomprehensible to ordinary engineers or which are little related to immediate problems in the real world.
Engineers who ask pragmatic questions such as “What’s going on here?” or “Does this make sense?”. Two examples of pragmatic engineers are the Australian, Ray Brindle, and the Ezra Hauer of Canada. For example, on road classification, Mr. Brindle said
“Road classification is a means to an end, not an end in itself. Successfully allocating agreed labels to each element in the road system involves so much effort and controversy that it is pointless and best avoided unless the labels are going to have some application.” (ref. 334*)
Ezra Hauer , in a very readable paper (ref. 765, 1999) argued that “roads designed to standards are neither safe nor appropriately safe”, and said (for example) that
“(if) the design speed has no clear relationship to either the speed limit or the speed expected to be exceeded by only a very small proportion of drivers, it is entirely unclear what it represents or why it ought to be relevant to curve design.”
It would be good if more engineers were prepared to speak clearly and publicly about fundamental aspects of the design concepts.
*ref. 334, quoting Brindle, 1989, ‘Road Hierarchy and Functional Classification’
334 – ICSM, “Assessing the feasibility of a national road classification” Australia, 2006
765 – Hauer, Ezra, “Safety in geometric design standards”, Toronto, Canada; 1999