I'm talking basically about the UK here but I know of similar examples in the States and Australia and I assume the same rules can be applied world wide.
There are a large number of structures currently mapped that require prior knowledge to establish their existence and previous usage. Railways, canals, buildings and even ancient track-ways. Some of those routes are protected so that new work has to maintain the viability of the original. Some are currently used as leisure routes again to maintain the possibility at some time in the future the original use can be restored, and some railways and canals HAVE been restored since OSM started mapping them. So 'abandoned' may not be the right tag, but neither is 'dismantled'. They both have a legitimate value though if only for the appreciative user. These structures/objects should be protected on the map as they often are in law. Now we come to those situations where an existing object has been replaced by a new one. One where substantial detail exists on the map currently but which OVER A PERIOD OF TIME evolves from one structure to another. There is an outline beyond which nothing changes and elements within that may be protected much as already described. We can ignore the work until it's completed, or because of the period of time that work takes we can map the changes as they happen so routing software is aware of the current situation. http://www.openstreetmap.org/#map=16/52.3790/-1.4692 is a perfect example, where a small roundabout has evolved into a much larger one, but the new through route is still being excavated. The problem with this is while it is a good approximation of how work is progressing, many of the original roads have been deleted and replaced and all the history relating to them lost. Because 'it's easier to delete and start again' is encouraged rather than 'preserve the history of development' where someone HAS already spent the time doing that in the past so much is being lost! Nothing changed on the ground in 2012 so why was the A46 deleted? The work over three years has been carried out by using the pre-2012 roads and while the work has evolved beyond that now, the historic record WAS more accurate. All I am asking is that people respect the work that has already been done, and that THE SYSTEM makes sure that the historic record is not destroyed because it is easier just to delete something and redraw it. Going back through the history now and finding the original Tollbar Roundabout history is now a lot of work, but equally, the current roads are not an accurate reflection of what is on the ground. Phase 4 is due to come into effect now, with the new bridges in use and that can probably improved with actual GPS tracks once the new routes are open, but the date of that changeover should be recoded as the old routes are removed and the new ones upgraded from 'construction' ... the date the data is actually changed is academic, but the prep work with a future start date is what SHOULD happen, just as the underpass route should become available in June next year. -- Lester Caine - G8HFL ----------------------------- Contact - http://lsces.co.uk/wiki/?page=contact L.S.Caine Electronic Services - http://lsces.co.uk EnquirySolve - http://enquirysolve.com/ Model Engineers Digital Workshop - http://medw.co.uk Rainbow Digital Media - http://rainbowdigitalmedia.co.uk _______________________________________________ talk mailing list [email protected] https://lists.openstreetmap.org/listinfo/talk
