Superceded standards

road standardsImage: Trail originally constructed by the Inca in Peru; now part of the Inca trail to Machu Picchu (Bcasterline at English Wikipedia)

It could be argued that, when a road geometric design standard has been superceded, it is should be thrown away – after all, it is out-of-date.

In fact, these old design standards have a much longer useful life. For example, suppose someone completes a 10 km section of new road just before a new standard is introduced. No-one is going to dig up the road section and build it again, so – as far as this piece of road and its owners are concerned – the old standard will continue to apply. And if another section of the road is built to the new standard, its  designers will want to check the old and new standards to make sure there is sensible consistency in design over the whole road corridor. There may also be a case here for keeping records of old standards in terms of the law and liab ility .

Design standards usually evolve through gradual rather than dramatic change, and it can be interesting to track back through the changes – something which you can only do if you have a copy of the old standards.

And over the longer time-scale – say a thousand years or so – historians as well as engineers might be interested in checking out superceded design standards. Certainly it would be interesting to look through a copy of the “Inka road design manual” or Caesar’s “Roman streetscape standard” (if he ever found time to write one).

So maybe research on standards should take a two-dimensional approach – that is, to include standards from other parts of the world besides your own, and to cover other time periods besides your own.

If you have copies of out-of-date road geometric design standards for your country, I would be interested in adding them to a library of road design standards.


  1. As a matter of fact the National Museum of the American Indian currently has an Exhibition on “The Great Inka Road: Engineering an Empire” (see here), with an interesting related website.

About roadnotes

Robert Bartlett is an international consultant with over 30 years of professional experience as a highway and traffic engineer with leading companies and organisations in several countries, including Germany, China (Hong Kong), Qatar and the UK. Specialised in urban studies, transport and the use of GIS, research has included new ideas on subjects such as the study of social justice using GIS, the dimensions of vehicles, and comparative geometrics (highways and transport).
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