Super two
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- This article is about a two-lane road built to high but not freeway standards. For the topic of two-lane freeways, see two-lane freeway.
A super two, super two-lane highway or wide two lane is a two-lane surface road built to high standards, typically including partial control of access, occasional passing lanes and hard shoulders. It is often built for eventual conversion to freeway or at least divided highway status once traffic volumes rise.
[edit] Wide two lane
In the Republic of Ireland, the term wide two lane is used by the National Roads Authority in the planning of routes using such a road type [1]. In policy documents, the designation WS2 is used [2]. Wide two lane roads are common on national roads; both on less important but medium capacity routes, and on more important routes not yet upgraded to dual carriageway or motorway. Wide two lane roads in the Republic generally have hard shoulders and are undivided single carriageway. Grade separation of junctions has been used on some schemes, for example the N20 bypassing Croom. Most wide two lane roads are wide enough that one can overtake without crossing the centre line, if a vehicle in front pulls into the hard shoulder (the carriageway including hard shoulders is 15-17 metres wide [3]). Many future national road schemes in the Republic will use 2+1 roads [1], as opposed to wide two lane which is considered to better suit lower capacities than that catered for by 2+1 [4]. Wide two lane, if finished to particularly high quality, with grade separated interchanges, has been shown to lead to a false sense of security (from the apparently high speed road) and more dangerous driving (due to the carriageways not being separated) [5].
[edit] References
- ^ a b National Roads Authority - Major National Road Schemes in Planning
- ^ Definition of the WS2 designation by the NRA: Interim Advice Note on Road Link Design for 2+1 roads (PDF 4.7MB), page 0/2
- ^ National Roads Authority: Interim Advice Note on Road Link Design for 2+1 roads, page 1/1
- ^ National Roads Authority: Interim Advice Note on Road Link Design for 2+1 roads, page 9/1
- ^ National Roads Authority: Interim Advice Note on Road Link Design for 2+1 roads, page 7/11
