In an earlier post (here) I argued that there are in effect only two types of road. For example I said that:
“It might be possible to simplify things if we argue that there are two main groups of “roads” which could be called “highways” and “streets”. The key difference between the two groups is this – the first group is used for movement, the second is not”.
I quoted some published sources which seem to make this argument.
However,looking through the collection of national road design standards / manuals from some 40 countries I get the impression that other engineers might argue for three types of road:
- regional roads (my “highways”)
- urban roads (my “streets”)
- rural roads (these could perhaps be described as low speed, low volume roads used both for movement and for access)
I could live with this – particularly as it begins to appear that geometric design parameters such as stopping sight distance vary depending whether a road is regional or rural (although I am not yet sure why this should be).
However we could also add a fourth type of road: special roads, such as Montenegro’s panoramic routes and lifeline roads, or Lancashire County Council (UK)’s quiet lanes and greenways. This would give the following types of road:
Even 4 classes is still a reasonably low number when comparing highway geometrics.