al_t (2015-01-05 14:32:11+00:00): The Cumberland Basin is a very complex set of junctions, ramps, flyovers and underpasses. My aim is to improve this section of the map for road navigation. Ultimately this should have lane data ( http://wiki.openstreetmap.org/wiki/Lanes ), but that is a lot of work.

The  changes I made here were to clarify the basic east/west direction of the A4 along the Floating Harbour at this section. As a broad approach the A4 heads North/South along the Avon Gorge then East/West along the Floating Harbour. The complexity in the area of this changeset is the one way system in a square shape and the junction with the A3029. So the West to East flow of the A4 is Hotwell Road, not sure Dowry Parade is correct, that needs surveying. The East to West flow is Hotwell Road, Rownham Mead, Merchants Road, Cumberland Basic Road and then rejoins Hotwell Road.

A *_link tag is described as "slip roads/ramps and "channelized" (physically separated) at-grade turning lanes connecting the through carriageways/through lanes of highways to other roadways of all types" ( http://wiki.openstreetmap.org/wiki/Link_%28highway%29 ). 

So on to the details of my changes. Working East to West. To the East at the top, just outside of this changeset, are two curved joining roads. These are lanes that allow a road user to change the direction they travel along the A4. They are single lane and give way to oncoming traffic. To me this clearly fits the definition of a link road. I changed this in an earlier changeset, but I hope it gives the idea of where I am coming from.

The North segment of Merchants road is a single lane that allows traffic to change from the West to East flow of A4 along Hotwell Road to the East West flow of the A4. After travelling along this section it seemed worth changing this to link road to clarify the main flow of the A4. It is also now the same status as Faraday Road, in the South West section of that square, which is a similar single lane joining road.

Humphry Davy Way gives way where it joins the A3029 (Cabot Way/Brunel Way). It is a two lane ramp up to the trunk road where traffic has to give way at the top. The main flow of traffic is from North to South along the A4 and then Cabot Way is joined by getting in the correct lane. There are no give ways along the main flow and the traffic lights only operate for the swing bridge as far as I know. This is why I classified Humphry Davy Way as a link road, because it gives way when joining the main flow. It is a two lane ramp that comes off the A4 to join the A3029 by giving way at the top of the ramp.

Finally, not in this change set, but also relevant to the discussion is Bennett Way. The A3029 (Brunel Way) is dual carriageway and when travelling along here South to North the two carriageways continue on to Bristol Gate and then joins the A4 at traffic lights. All of that section, including Bristol Gate is dual carriageway.  Bennett Way is a single lane ramp down to then join the A4. There is no feeder lane from Brunel Way, it is a left turn from the dual carriageway to the single lane ramp. By classifying this as a link road it makes it clearer for navigation that the road user is looking for a smaller road turning off the dual carriageway. Continuing along the dual carriageway would mean joining the wrong flow of the A4.

I hope this clarifies my aim and that you agree the changes I made help to map the traffic flows of this complex junction better.