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 could decide what the details are which they are trying to summarise, and then use simple codes for each detail The codes would be at least independent of any language.
In fact, codes are already to be found in several different road design manuals….
Examples of 1-dimensional codes:
The following figure is part of table 3 from the 2012 Russian road design standards (ref. 1823)
And from the Polish standard (ref. 376)
And from a Saudi Arabian document on roads (ref. 967) comes this excerpt of a table:
An example of 2-dimensional codes
However maybe a 1-dimensional code system is not enough. After all, in geometric design terms we could argue that roads are two-dimensional objects – they exist only in length and width. (A road would be a 3-dimensional object if we included a feature for depth, such as “location of utilities”).
We can find an example of a 2-dimensional code for roads in a recent German document on road planning and design (ref. 1615). This table combines a code for the importance of a connecting link (Y axis), and a code for the category group of the link (X axis).
What would be the features suitable for use in a 2-dimensional code for the geometry of roads?
376 – Poland , excerpt from a document on road design from a regulation of the Ministry of transport and maritime affairs, March 1999
967 – Saudi Arabia , دليل التصميم الهندسي للطرق (engineering design manual for roads), MOMRA downloaded 2015
1615 – Germany, RAA Richtlinien für die Anlage von Autobahnen; FGSV 2008
1823 – Russia, АВТОМОБИЛЬНЫЕ ДОРОГИ (Autromobile roads), СНиП 2.05.02-85; 2012