Andrew Chadwick's Diary

Recent diary entries

After several months of sitting on my backside about this, I've decided to try and rehabilitate these two offending little tags. They look so simple in theory, don't they? You just add


to something to mark as it disused, and you're done, right? Wrong, because it generates inconsistencies and internal contradictions in the data if you tag a disused pub, say, like the wiki docs used to recommend:


Oops. Logically, something can't be both currently used as a pub and currently disused. Additionally, software written without knowledge of the magic "disused=yes" or any of the many other weird and wonderful tags that share the same pattern. Which means that routing engines may route people to disused objects, and disused objects render on the map. This calls for a better approach, a backwards-compatible one: namespaces and better docs to the rescue. For ages now, folks on IRC and mappers generally have been doing something like


to prevent software that has no reason to understand new magic tagging from doing the wrong thing. I've just written it up at

with some thoughts about naming and and when a building stops being a building. It's looking good to me, anyway.

In general, tag-semantically, if you're proposing a tag like this which completely breaks the meaning of other tags or keys, you probably shouldn't. But if you want to, please consider a pattern like this to prevent bad data from happening.

Cotswold Village A Day

Posted by Andrew Chadwick on 14 June 2010 in English.

The northern reaches of the Cotswolds are lovely and picturesque, but they're sorely under-mapped in OSM. To address this, I've decided to try and complete one each day for a few days this month using OS StreetView data and ITO's wonderful OS Locator layer. Primary focus will be the major waterways, roads completeness and expanding the POI coverage in the area. So one village a day, along with anything else important in the bbox given me by JOSM's "area near" downloader tab.

Today's C.V.a.D. is South Newington, with nearby Milcombe as a bonus village. The River Swere extends W to E through this area, but I've left the more minor streams and field drains alone this time.

Doing armchair mapping this way requires two passes: the first to get the basic shape right using OS StreetView (and correlating with NPE for further information), and a second pass a day or so after to correct street name extents and add ones OSSV misses using OS Locator.

(I know - armchair mapping sucks. I'm currently walking the Cross Cotswold Pathway from Banbury to bath over several Sundays this summer, so I at least get a bit of first-hand verification of the work I do on this. In particular I find that ways I'd previously recorded as "track" are frequently far better represented as service ways: so that now tends to be my interpretation of the grey/borderless OSSV ways)

Location: South Newington, Cherwell District, Oxfordshire, England, United Kingdom

It's not ideally signposted by any means, but interpreting it as having two alternate routes around the Railway Centre seems plausible to me. Looks like the "main" signposted route is the long loop to the South, past Didcot Parkway station. However, if you can handle riding North for 50 metres and sharing a road with some lorries, you'll discover some (older?) - branded blue sticker-signs, mostly without numbers, that lead you via a much shorter route over a footbridge. Handy shortcut, not obvious on the ground, so I've added it to the route.

In other news, getting face pebbledashed repeatedly by clouds of tiny yet dense and impactful flies reminds me how little I like off-road cycle routes.

Location: Southmead Industrial Estate, Didcot, South Oxfordshire, Oxfordshire, England, United Kingdom

Nearly finished reviewing and checking Cyclox's suggested routes for Oxford. Just some bits that are (rather conveniently) near work to finish up and we're set. It's generally not a bad secondary network, though I'll be making a few suggestions about, ahem, more legal alternatives to some bits of it now that I've actually found those alternatives :)

I've been adding surface values, litness, legal way designations, and funky bike barriers to the suggested routes. The routes are currently done as lcn=yes on the way itself, though I may redo that as a relation since I've been tripping over Oxford's rather pointless yet numbered official lcn scheme as I've been going around.

Location: Cumnor, Vale of White Horse, Oxfordshire, England, United Kingdom

Mapping complexes

Posted by Andrew Chadwick on 16 December 2008 in English.

Out mapping today: I failed at getting the Christmas shopping done and ended up wandering around St. Ebbes and the Castle complex instead, tidying up shapes and getting more detail and landuse areas in. Osm2Go is wonderful for the data-gathering part of this. I still feel the need to tweak and fiddle afterwards in JOSM so good traces are still necessary for me, but hand-held mapping tools allow lots of good mapping of things you (I) might otherwise miss to be done right there on the ground.

Count of members of the public asking me for directions: 1.

Location: St Thomas', City Centre, Oxford, Oxfordshire, England, OX1 1JH, United Kingdom

Central Oxford routing

Posted by Andrew Chadwick on 22 October 2008 in English.

Scouted most of the 20 MPH zone in the centre of the city this evening, fixing the bus gate location and permitted traffic and doing a lot of s/^car=/motorcar=/g. So now applications like YOURS shouldn't route your car through the camera enforcement bit. Hopefully that link'll update nicely with the next planet.osm pull. Saved copy for comparison later on.

There's still no way of saying "PSVs only down this road, but bicycles and *only* bicycles may also use it between t1 and t2".

Location: Westgate, City Centre, Oxford, Oxfordshire, England, United Kingdom

It's this coming weekend. This is my first one organised, but people are signing up, which frankly astounds me as I hardly know anyone within the project yet. Still need to do the cake slices, but so far so good.

Location: Abingdon on Thames, Abingdon, Vale of White Horse, Oxfordshire, England, United Kingdom

Cyclox & OpenStreetMap

Posted by Andrew Chadwick on 10 October 2008 in English.

The Oxford portion of OSM might well be getting some mapping help from the fine members of the local cycling campaign group Cyclox. Back in late September I was contacted out of the blue by the University's Sustainable Transport Officer who is working with Cyclox to help improve (upon) the county council's old, rather unhelpful cycle map of the city. To quote: "I think something based upon OSM and the OpenCycleMap is the way to go".

This is awesome news because Cyclox are a decidedly enthusiastic and committed group, because the association will raise the profiles of both groups, and because there's the possibility of some involvement from the university (who want useful maps of good bike routes taking in colleges, departments, and noting parking in those places). There might be some nice printed maps based on OSM data coming out of this.

It's early days yet, but feedback from an informal meetup over lunch and a committee meeting I've attended seems positive. Next step is a little presentation at their AGM, and then I think a series of little workshops and mapping mini-parties to get people up-to-speed with our processes and out improving the map. I dare say there'll be further meetings working on the details of what Cyclox need and what the University needs. Now I just need to learn Mapnik and figure out a custom rendering to show off how easy it is to subset and snapshot the OSM data nicely to meet those needs.

Location: Headington Hill, Headington, Oxford, Oxfordshire, England, OX3 0DR, United Kingdom

For all the roads there at least. The new Zycast SG-949-USB receiver (SiRf-III) I'm using is the business compared to the one in my N810 - though I carry both when I'm out tracing.

Onto Cuddesdon and Garsington for the bank holiday weekend, lunch at the Bat and Ball (NOM, and IIRC they do wifi too). Then maybe some more bits of poor, dragon-infested Abingdon during the week.

Location: Wheatley, South Oxfordshire, Oxfordshire, England, United Kingdom

Dean Court / Botley, Oxford

Posted by Andrew Chadwick on 29 June 2008 in English.

Finally got the chance to do the Dean Court end of town some justice; named and added several roads, tweaked and detailed. The St Thomas / Osney area was missing a few pubs and other things on the way up so I've either fixed those or queued them up on OpenStreetBugs for a future visit.

Location: Cumnor, Vale of White Horse, Oxfordshire, England, United Kingdom

Oxford meetup

Posted by Andrew Chadwick on 2 June 2008 in English.

I seem to be trying to organise a weekend meetup in the Oxford (UK) area. Anyone out there interested?

Right now the plans are not much more than "Find a pub → with wifi → ... → profit!", but I'm sure we can come up with something better than that, perhaps make it a mini mapping session. If nothing else, it'll be nice to put faces to the IRC/wiki nicks.

The Jericho Tavern has been mentioned, and is supposed to be quite a nice place these days. 5th or the 19th of July, perhaps?

Location: Jericho, Oxford, Oxfordshire, England, United Kingdom

Night hospital'er

Posted by Andrew Chadwick on 31 May 2008 in English.

Begun detailing the Warneford Churchill hospital area that sits just outside my office last night. building:type=Complex, no kidding, but the N/S layout of the site and JOSM's extrude stuff makes it easier. I'm deliberately restricting myself to only naming buildings which have some relevance to the general public or to visiting academics.

How to map subdivisions like wards in buildings with more than one use? We need some way of mapping (important) building entrances too.

Location: Headington Hill, Headington, Oxford, Oxfordshire, England, OX3 0DR, United Kingdom

Day out in Wallingford with the family, who are visiting Oxford this week. I've improved the map of the town's mediaeval centre a bit - hope I've got the one-way system right - and found some unmapped tracts of land on the way there and back.

- Previously unmapped restricted byway between Drayton St Leonard and Chiselhampton. highway=byway sounds quaint. Renders oddly in Osmarender.

- Two new villages: Newington and Warborough.

- Innumerable churches and pubs.

- Connected the River Thame using OAM and NPE data. Not sure about the direction of flow though.

Location: Wallingford, South Oxfordshire, Oxfordshire, England, United Kingdom

Derailed, damn

Posted by Andrew Chadwick on 14 March 2008 in English.

Having systematic plans for a half-hour lightning mapping session and then finding streets and alleys and dense little time-consuming conservation areas in areas you just meant to de-maplint sucks. Finding C. S. Lewis's grave after a hint from a passer-by and being able to evangelise a bit about OSM helps make up for that, though.

Location: Headington Quarry, Headington, Oxford, Oxfordshire, England, United Kingdom

Small-scale Oxford

Posted by Andrew Chadwick on 12 March 2008 in English.

Circuitous route to the sandwich shop this lunchtime via Headington Quarry - not an area I'm familiar with - and finding all sorts of hidden footpaths, parklets, allotments, and the usual small-scale stuff. Oddities: one tiny Assemblies of God[1] chapel about the size of a small shoebox.

[1] The Jimmy Swaggart lot, unless that's some other sub-cult^Wsect.

Location: Headington, Oxford, Oxfordshire, England, United Kingdom

More detailing of the land North of Headington way this lunchtime, after filling in the maze of pedestrian access around The Croft over the middle of this week (difficult, but rewarding: high walls, trees, and sunken footpaths make my n810's GPS unhappy, so multiple passes are sometimes necessary). I now want to capture the modern extent of the ancient Cuckoo Lane running down to Marston Lane and the new Centre for Islamic Studies . As ever, has history, photos and out of copyright (-looking) maps:

Location: Headington Hill, Headington, Oxford, Oxfordshire, England, OX3 0DR, United Kingdom