Researching this meant spending a memorable day with some great OpenStreetMap volunteers on the Isle of Wight, in the early days of what has become a massive wikimap.
It’s a wet Saturday afternoon in Yarmouth on the Isle of Wight. Damian Steer walks into Tennyson Close, a quiet suburban street, passing a handmade sign reading “Private Road – No Parking – Access Only”. He is carrying a £90 Gekko 201 global positioning system (GPS) tracker the size of a small mobile phone. It’s waterproof – a useful property, given the steady drizzle.
On reaching the end of Tennyson Close, I ask Steer for the time and write “3.35” on a scribbled map in an increasingly damp notebook. Meanwhile, Steer notices that although we are north of the A3054 – which he had already traced using the Gekko – it insists that we are south of it.
Steer is taking part in an attempt to map the Isle of Wight’s roads in one weekend for OpenStreetMap.org, a website that helps create maps free for anyone to use for any purpose (See http://tinyurl.com/ny84m). If Ordnance Survey and other national agencies will not make their data freely available, then OpenStreetMap, developed over the past two years, will re-collect it from scratch.
The weekend drew around 40 people. By Monday, OpenStreetMap’s founder Steve Coast estimated that more than 90% of the island’s roads had been recorded. When asked if volunteers used OS maps, Coast says: “No. It’s a taboo.” Someone who did pull out an OS map was told to put it away immediately.
Instead, Coast distributed older, out-of-copyright maps to aid navigation. OS maps are covered by Crown copyright, which lasts 50 years from the end of the year of publication, so the 1940s OS New Popular Edition, which covers all of England and Wales at a scale of one inch to the mile (1:63,360), is free to use.
Along with other historical editions, the New Popular Edition is freely available online through the Great Britain Historical GIS project (www.visionofbritain.org.uk/maps/) using digital photographs taken by the British Library. Dr Humphrey Southall, reader in geography at the University of Portsmouth and director of the project, says that much of the series is still usable: “Most of the parish boundaries existed 100 years ago,” he says, and in many rural areas, the 1940s maps are still pretty accurate: “There are large areas of the country which are like that, but most people don’t live in them,” he notes.
OpenStreetMap is re-scanning the New Popular maps at a higher resolution than the British Library did, so volunteers can trace the likes of railways and old roads into the system: images of paper maps are not the same thing as digital maps, which – for example – store roads as lines.
But OS has all material up to date, so wouldn’t it be better to campaign for OS to open up its data rather than rebuild it? “Freeing certain scales of data would be good, but the best way to make it happen [is] to go and do it,” replies Coast. “There’s no reason for OS to [free the data] because it has a monopoly. There’s no economic incentive – until we produce one.”
OS’s chief technology officer Ed Parsons has raised the possibility of allowing access to data for non-commercial purposes (Ordnance Survey challenged to open up, Guardian Technology, March 23, http://tinyurl.com/qeko6). Coast says that would be welcome, but would still bar, for example, a company putting a location map on its website.
And he adds that OpenStreetMap can do a superior job, for example by avoiding the deliberate inaccuracies made by professional cartographers to catch those abusing their copyright. These include the non-existent “trap street” Lye Close, which according to Bristol’s A-Z is a tiny cul-de-sac off Canynge Square in Clifton.
Norman Dennison, director of Geographers’ A-Z Map Company, confirms that Lye Close is a lie, which will now be removed. “The idea is to put something on the map to protect copyright,” he says. “We try to put it in an area or a part of a road which would not be misleading to the ordinary person in the street. They have been put in out-of-the-way places.”
OS says it uses “stylistic fingerprinting” to track unauthorised use, such as the position of tree symbols within an area of forest. It does not insert fake roads, kinks in rivers, buildings or exaggerate curves in roads. “We never put in false detail,” says a spokesperson.
Dennison says that Geographers’ A-Z, which publishes more than 300 UK street-maps, supplements data from OS with material from the Post Office, local authorities, members of the public and its own researchers, who use GPS in a similar way to OpenStreetMap’s volunteers. “The difficulty is keeping them up to date,” Dennison says of OpenStreetMap; his firm adds around 2,000 streets to its London A-Z each year.
“We make an average of 5,000 changes to our large-scale data every day,” said an OS spokesperson. “It’s not about mapping the Isle of Wight once – it’s about continuing to map it … It is expensive to collect detailed, accurate information on the ever-changing world to the level of detail our customers require.”
However, Coast argues that most people do not require a high level of accuracy: once an area is mapped, local people will maintain it. Nationally, he reckons OpenStreetMap could have a complete road map in about five years. Urban areas will be completed first, but “that is where most people want a map”, he says.
OpenStreetMap’s aim is to produce maps such as that for Weybridge (http://tinyurl.com/rcd8u) where someone using the name 80n has turned GPS tracings and research into a fairly detailed map of the town. Next weekend OpenStreetMap will attempt to map the centre of Manchester, with the aim of producing a free-to-use map of venues for the city’s Futuresonic 2006 arts festival in July. “They can’t get it from OS without spending vast amounts of money,” says Coast.
The “Mapchester” event is getting space and support from Manchester Digital Development Agency, a public-sector organisation. “We very much endorse it,” says Dave Carter, its head. “We see it as a map version of open source. It might not work, but … we’re funded to promote innovative research and development, which is why we’re supporting this.”
· See the campaign blog at www.freeourdata.org.uk
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