The technical term is a drop lane. This might later intersect with a roundabout, join with another motorway or primary road etc. Between junctions, a single way for each direction is commonplace. At junctions, there are ways for the through lanes and for traffic exiting and entering the motorway.
For example, on a 3-lane motorway with 3 lanes going in one direction and no junction anywhere near, the way would typically be placed along the centre of lane 2. However, when lane 1 is designated as a drop lane, what was being mapped as 1 way needs to split into 2 ways. The question is where ? There are various anticipatory changes in road markings well ahead of the physical separation of the asphalt, together with blue and white signs, some of which precede the first of the changes in road markings. In the case described above, my convention is to pick the start of the shorter dashes between the drop lane (1) and the through lanes (2 and 3). From then onwards, the way for the through lanes is mapped along the longer dashes dividing lanes 2 and 3, while the way for the drop lane is mapped along the centre of lane 1. Others do it differently. See "https://www.gov.uk/government/publications/traffic-signs-manual"; from where you can download "Traffic signs manual chapter 5 road markings (2019)" which is a PDF. Page 82 contains figure 7.7 and text documenting drop lane road markings.
_______________________________________________ Talk-GB mailing list [email protected] https://lists.openstreetmap.org/listinfo/talk-gb
