# When should I divide a simple way into dual carriageway or divided road?

 5 1 I'm mapping some ways in town which in places have physical and marked barriers between carriageways plus turning lanes, and multiple forward lanes. In other places they're simple roads with one lane in either direction and just a dotted line separating oncoming traffic. I realise there's a need to keep things simple, but there's also a need to map complex lanes and barriers accurately. At what point should one decide to map a partly-dualled carriageway using two ways rather than one? I'm trying to apply some vague criteria to keep my mapping from descending into a pit of insane detail, and I've discussed it on the local mailing list and in IRC without much in the way of resolution. Does: A simple way should be divided if: The division between carriageways must either: be physical - you can't drive over it sensibly - or consist of diagonal hatched lines with smaller physical traffic islands at both ends The division must be more than 20 metres in length. Divisions are continued through junction areas in their middles, but that distance probably shouldn't be counted towards 2. seem sound, or does it err on the side of too much dividedness? If the latter, where should the cutoff lie? This question is marked "community wiki". asked 31 May '11, 21:05 Andrew Chadwick 1.1k●7●17●21 accept rate: 25% I'd just point out that there is a difference, in the UK at least, between different types of "diagonal hatched lines" - if they are bordered by a broken line you are free to enter the area when safe to do so, but when they are bordered by solid lines you aren't. Usually has more influence on overtaking than much else though. (01 Jun '11, 08:43) Andy Allan 1 @andy-allan Yep, this is in the UK. Hopefully insisting on some kind of physical barrier in addition will help make the distinction more obvious and verifiable. Probably we shouldn't count just wedges of lane divider marking on their own. Perhaps another criterion is to ask "can a U-turn (normally) be made here?" (01 Jun '11, 09:32) Andrew Chadwick There's a section on this funny old wiki page: Editing Standards and Conventions ...on the topic. Doesn't answer you question though. Maybe you could lay down some guidelines there, if your ideas are accepted. (06 Jun '11, 12:33) Harry Wood In the UK, a dual carriageway must have a physical barrier between the two directions of traffic. The "consist of diagonal hatched lines" is insufficient to make it a DC. This is important because the N speed limit on a DC is 70mph (versus 60mph). Using as one's defence for traveling at 65mph (when NSL is in force) that "there are hatched lines" is unlikely to work ! (27 Jul '11, 11:43) mwbg

 3 I've always mapped using a physical barrier = multiple ways.. ta Chris answered 05 Jun '11, 23:31 c2r 413●2●6●11 accept rate: 18%
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question asked: 31 May '11, 21:05

question was seen: 6,059 times

last updated: 27 Jul '11, 11:43