1. Technical look at the new FixMyStreet maps

    This post explains how various aspects of the new FixMyStreet maps work, including how we supply our own OS StreetView tile server and how the maps work without JavaScript.

    Progressive enhancement

    During our work on FiksGataMi (the Norwegian version of FixMyStreet) with NUUG, we factored out the map code (for the Perlmongers among you, it’s now using Module::Pluggable to pick the required map) as FiksGataMi was going to be using OpenStreetMap, and we had plans to improve our own mapping too. Moving to OpenLayers rather than continuing to use our own slippy map JavaScript dating from 2006 was an obvious decision for FiksGataMi (and then FixMyStreet), but FixMyStreet maps have always been usable without JavaScript, utilising the ancient HTML technology of image maps to provide the same functionality, and we wanted to maintain that level of universality with OpenLayers. Thankfully, this isn’t hard to do – simply outputting the relevant tiles and pins as part of the HTML, allowing latitude/longitude/zoom to be passed as query parameters, and a bit of maths to convert image map tile clicks to the actual latitude/longitude selected. So if you’re on a slow connection, or for whatever reason don’t get the OpenLayers JavaScript in some way, the maps on FixMyStreet should still work fine. I’m not really aware of many people who use OpenLayers that do this (or indeed any JavaScript mapping API), and I hope to encourage more to do so by this example.

    Zooming

    We investigated many different maps, and as I wrote in my previous blog post, we decided upon a combination of OS StreetView and Bing Maps’ OS layer as the best solution for the site. The specific OpenLayers code for this (which you can see in map-bing-ol.js is not complicated (as long as you don’t leave in superfluous commas breaking the site in IE6!) – overriding the getURL function and returning appropriate tile URLs based upon the zoom level. OpenLayers 2.11 (due out soon) will make using Bing tiles even easier, with its own seamless handling of them, as opposed to my slight bodge with regard to attribution (I’m displaying all the relevant copyright statements, rather than just the one for the appropriate location and zoom level which the new OpenLayers will do for you). I also had to tweak bits of the OpenLayers map initialisation so that I could restrict the zoom levels of the reporting map, something which again I believe is made easier in 2.11.

    OpenStreetMap

    Having pluggable maps makes it easy to change them if necessary – and it also means that for those who wish to use it, we can provide an OpenStreetMap version of FixMyStreet. This works by noticing the hostname and overriding the map class being asked for; everything necessary to the map handling is contained within the module, so the rest of the site can just carry on without realising anything is different.

    OS StreetView tile server

    Things started to get a bit tricky when it came to being ready for production. In development, I had been using http://os.openstreetmap.org/ (a service hosted on OpenStreetMap’s development server) as my StreetView tile server, but I did not feel that I could use it for the live site – OpenStreetMap rightly make no reliability claims for it, it has a few rendering issues, and we would probably be having quite a bit of traffic which was not really fair to pass on to the service. I wanted my own version that I had control over, but then had a sinking feeling that I’d have to wait a month for something to process all the OS TIFF files (each one a 5km square) into millions and millions of PNG tiles. But after many diversions and dead ends, and with thanks to a variety of helpful web pages and people (Andrew Larcombe’s guide [dead link removed] to his similar install was helpful), I came up with the following working on-demand set-up, with no pre-seeding necessary, which I’m documenting in case it might be useful to someone else.

    Requests come in to our tile server at tilma.mysociety.org, in standard OSM/Google tile URL format (e.g. http://tilma.mysociety.org/sv/16/32422/21504.png. Apache passes them on to TileCache, which is set up to cache as GoogleDisk (ie. in the same format as the URLs) and to pass on queries as WMS internally to MapServer using this layer:

    [sv]
    type=WMS
    url=path/to/mapserv.fcgi?map=os.map&
    layers=streetview
    tms_type=google
    spherical_mercator=true

    MapServer is set up with a Shapefile (generated by gdaltindex) pointing at the OS source TIFF and TFW files, meaning it can map tile requests to the relevant bits of the TIFF files quickly and return the correct tile (view MapServer’s configuration* – our tileserver is so old, this is still in CVS). The OUTPUTFORMAT section at the top is to make sure the tiles returned are anti-aliased (at one point, I thought I had a choice between waiting for tiles to be prerendered anti-aliased, or going live with working but jaggedy tiles – thankfully I persevered until it all worked 🙂 ).

    Other benefits of OpenLayers

    As you drag the map around, you want the pins to update – the original OpenLayers code I wrote used the Markers layer to display the pins, which has the benefit of being simple, but doesn’t fit in with the more advanced OpenLayers concepts. Once this was switched to a Vector layer, it now has access to the BBOX strategy, which just needs a URL that can take in a bounding box and return the relevant data. I created a subclass of OpenLayers.Format.JSON, so that the server can return data for the left hand text columns, as well as the relevant pins for the map itself.

    Lastly, using OpenLayers made adding KML overlays for wards trivial and made those pages of the site much nicer. The code for displaying an area from MaPit is as follows:

        if ( fixmystreet.area ) {
            var area = new OpenLayers.Layer.Vector("KML", {
                strategies: [ new OpenLayers.Strategy.Fixed() ],
                protocol: new OpenLayers.Protocol.HTTP({
                    url: "/mapit/area/" + fixmystreet.area + ".kml?simplify_tolerance=0.0001",
                    format: new OpenLayers.Format.KML()
                })
            });
            fixmystreet.map.addLayer(area);
            area.events.register('loadend', null, function(a,b,c) {
                var bounds = area.getDataExtent();
                if (bounds) { fixmystreet.map.zoomToExtent( bounds ); }
            });
        }

    Note that also shows a new feature of MaPit – being able to ask for a simplified KML file, which will be smaller and quicker (though of course less accurate) than the full boundary.

     

    *Broken link removed, Nov 2014

  2. Helping voters in the devolved elections

    As well as council elections and the referendum, the Scottish Parliament, Welsh Assembly, and Northern Ireland Assembly are holding elections this May. In Scotland and Northern Ireland, there are accompanying boundary changes, meaning this year you might be voting in a different constituency from last time.

    To help people, as we’ve again had a few requests, our service from the 2010 general election is back, at http://www.theyworkforyou.com/boundaries/, just for the Scottish Parliament and Northern Ireland Assembly. Our generic lookup service MaPit also provides programmatic access to these results (technical footnote).

    Alongside this service, we have refreshed our Scotland and Northern Ireland front pages, to slightly better display and access the wide array of information TheyWorkForYou holds for those devolved legislatures.

    Sadly the Scottish Parliament changed the format of their Official Report in mid January and we haven’t been able to parse the debates from then until its dissolution this March – hopefully we’ll be able to fix that at some point, and apologies for the inconvenience in the meantime.

    There don’t appear to be any central official lists of candidates in these elections. Amnesty.org.uk has a PDF of all candidates in Northern Ireland; David Boothroyd has a list of Scottish Parliament candidates. CAMRA appears to have lists for both Scotland and Wales. Those were simply found while searching for candidate lists, we obviously hold no position on those organisations 🙂

    Technical footnote: To look up the new Scottish Parliament boundaries using MaPit, provide a URL query parameter of “generation=15” to the postcode lookup call. The Northern Ireland Assembly boundaries are aligning with the Parliamentary boundaries, so you can just perform a normal lookup and use the “WMC” result for the new boundary.

  3. New features on MaPit

    We’ve added a variety of new features to our postcode and point administrative area database, MaPit, in the past month – new data (Super Output Areas and Crown dependency postcodes), new functionality (more geographic functions, council shortcuts, and JSONP callback), and most interestingly for most people, a way of browsing all the data on the site.

    • Firstly, we have some new geographic functions to join touches – overlaps, covered, covers, and coverlaps. These do as you would expect, enabling you to see the areas that overlap, cover, or are covered by a particular area, optionally restricted to particular types of area. ‘coverlaps’ returns the areas either overlapped or covered by a chosen area – this might be useful for questions such as “Tell me all the Parliamentary constituencies fully or partly within the boundary of Manchester City Council” (three of those are entirely covered by the council, and two overlap another council, Salford or Trafford).
    • As you can see from that link, nearly everything on MaPit now has an HTML representation – just stick “.html” on the end of a JSON URI to see it. This makes it very easy to explore the data contained within MaPit, linking areas together and letting you view any area on Google Maps (e.g. Rutland Council on a map). It also means every postcode has a page.
    • From a discussion on our mailing list started by Paul Waring, we discovered that the NSPD – already used by us for Northern Ireland postcodes – also contains Crown dependency postcodes (the Channel Islands and the Isle of Man) – no location information is included, but it does mean that given something that looks like a Crown dependency postcode, we can now at least tell you if it’s a valid postcode or not for those areas.
    • Next, we now have all Lower and Middle Super Output Areas in the system; thanks go to our volunteer Anna for getting the CD and writing the import script. These are provided by ONS for small area statistics after the 2001 census, and it’s great that you can now trivially look up the SOA for a postcode, or see what SOAs are within a particular ward. Two areas are in MaPit for each LSOA and MSOA – one has a less accurate boundary than the other for quicker plotting, and we thought we might as well just load it all in. The licences on the CD (Conditions of supply of SOA boundaries and Ordnance Survey Output Area Licence) talk about a click-use licence, and a not very sraightforward OS licence covering only those SOAs that might share part of a boundary with Boundary-Line (whichever ones those are), but ONS now use the Open Government Licence, Boundary-Line is included in OS OpenData, various councils have published their SOAs as open data (e.g. Warwickshire), and these areas should be publicly available under the same licences.
    • As the UK has a variety of different types of council, depending on where exactly you are, the postcode lookup now includes a shortcuts dictionary in its result, with two keys, “council” and “ward”. In one-tier areas, the values will simply by the IDs of that postcode’s council and ward (whether it’s a Metropolitan district, Unitary authority, London borough, or whatever); in two-tier areas, the values will again be dictionaries with keys “district” and “council”, pointing at the respective IDs. This should hopefully make lookups of councils easier.
    • Lastly, to enable use directly on other sites with JavaScript, MaPit now sends out an “Access-Control-Allow-Origin: *” header, and allows you to specify a JSON callback with a callback parameter (e.g. put “?callback=foo” at the end of your query to have the JSON results wrapped in a call to the foo() function). JSONP calls will always return a 200 response, to enable the JavaScript to access the contents – look for the “error” key to see if something went wrong.

    Phew! I hope you find this a useful resource for getting at administrative geographic data; please do let us know of any uses you make of the site.

  4. Mapping points and postcodes to areas

    I’m very pleased to announce that mySociety’s upgraded point and postcode lookup service, MaPit, is public and available to all. It can tell you about administrative areas, such as councils, Welsh Assembly constituencies, or civil parishes, by various different lookups including name, point, or postcode. It has a number of features not available elsewhere as far as I know, including:

    • Full Northern Ireland coverage – we found a free and open dataset from the Office of National Statistics, called NSPD Open, available for a £200 data supply charge. We’ve paid that and uploaded it to our data mirror under the terms of the licence, so you don’t have to pay – if you feel like contributing to the charity that runs mySociety to cover our costs in this, please donate! 🙂
    • Actual boundaries – for any specific area, you can get the co-ordinates of the boundary in either KML, JSON, or WKT – be warned, some can be rather big!
    • Point lookup – given a point, in any geometry PostGIS knows about, it can tell you about all the areas containing that point, from parish and ward up to European electoral region.
    • History – large scale boundary changes will be stored as new areas; as of now, this means the site contains the Westminster constituency boundaries from both before and after the 2010 general election, queryable just like current areas.

    If you wish to use our service commercially or are considering high-volume usage, please get in touch to discuss options; the data and source code are available under their respective licences from the site. I hope this service may prove useful – we will slowly be migrating our own sites to use this service (FixMyStreet has already been done and already seems a bit nippier), so it should hopefully be quite reliable.

    Thanks must go to the bodies releasing this open data that we can build upon and provide these useful services, and everyone involved in working towards the release of the data. Thanks also to everyone behind GeoDjango and PostGIS, making working with polygons and shapefiles a much nicer experience than it was back in 2004.

  5. Political parties don’t know where the boundaries are

    In my last blog post, I explained the new service TheyWorkForYou offers to show you what constituency you will be in at the next general election. Now I’m going to show you why you shouldn’t use anything else.

    The defintions of the boundaries for the forthcoming constituencies in England were originally published in The Parliamentary Constituencies (England) Order 2007 (SI 2007/1681), based on ward boundaries as they were on 12th April 2005. However, due to some local government changes since that date, The Parliamentary Constituencies (England) (Amendment) Order 2009 (SI 2009/698) was published changing the boundaries for four constituencies – Daventry, South Northamptonshire, Wells, and Somerton & Frome – to be based on the new council wards as they were on 3rd May 2007.

    The forthcoming constituencies in Northern Ireland were defined in The Parliamentary Constituencies (Northern Ireland) Order 2008 (SI 2008/1486). In this, Derryaghy ward was split between two constituencies – Belfast West is given “that part of Derryaghy ward lying to the north of the Derryaghy and Lagmore townland boundary.”

    All of which means that other sites that try to tell you what constituency you will be in at the election invariably get it wrong.

    Both Labour and the Conservatives say that BA6 8NJ is in Wells at the next election, when it will be in Somerton & Frome. Both say that NN12 8NF will be in Daventry, when it will be in South Northamptonshire. I assume that both sites are using boundary data predating the Amendment Order from March 2009. The Conservatives also say that BT17 0XD will be in Lagan Valley when it will be in Belfast West; Labour simply say “Northern Ireland” for any Northern Irish postcode you provide.

    The Liberal Democrats site currently returns no results for any postcode, which I assume is a bug 🙂

    The current boundary between Belfast West and Lagan Valley.

    The /current/ boundary between Belfast West and Lagan Valley. (Image produced from the Ordnance Survey electionmap service. Image reproduced with permission of Ordnance Survey and Land and Property Services)

    The official election-maps.co.uk service (from where TheyWorkForYou gets its boundary maps) returns the correct results for BA6 8NJ and NN12 8NF, but doesn’t have future boundaries for Northern Ireland. It’s not clear that it doesn’t, as searching for Lagan Valley with “future boundaries” selected returns a result, but that result is the current boundary. This can be seen from the picture on the right – as is clear from the quote I gave above, everything within Derryaghy ward north of the Lagmore/Derryaghy boundary will be in Belfast West at the next election. Plus the site doesn’t work without JavaScript.

    TheyWorkForYou’s “constituency at the next election” service gives BA6 8NJ in Somerton & Frome, NN12 8NF in South Northamptonshire, and BT17 0XD in Belfast West. There is enough confusion with the changes to boundaries for everywhere except Scotland, that it is somewhat frustrating to have it compounded by sites giving incorrect information. The lack of any official service also doesn’t help.

  6. Constituency boundaries at the next election

    Constituency boundaries are changing at the next general election in England, Wales, and Northern Ireland. After some amount of fiddling (I’ll go into technical details in another post, but it wasn’t as easy as just importing some shapefiles), as a slightly early Christmas present, TheyWorkForYou now has a section where you can enter your postcode to find out what constituency you are currently in, and what constituency you will be voting in at the election, along with maps of before and after:

    http://www.theyworkforyou.com/boundaries/

    This service is also available through the TheyWorkForYou API. This is a facility we have been asked for frequently, more so as we approach the forthcoming election; the large amount of boundary changes have led to confusion from our users and elsewhere, so this will hopefully prove useful.

    One site that will need the boundaries before the election is DemocracyClub – join to help make this coming election the most transparent ever!

    Side effects of the above process include updated council boundaries, so those councils on WriteToThem that we’ve had switched off since May due to lack of boundary data are now back; a more up-to-date postcode dataset; and the beginnings of parish council support (as in they’re now in the database, but the front-end doesn’t know what to do with them yet).

    I hope you all have a happy Christmas and New Year.

  7. Parliamentary boundary changes

    Parliamentary boundary changes appear to be a source of confusion to many people and organisations. The facts are quite simple – parliamentary boundary changes, proposed by the various Boundary Commissions, do not take effect until the next general election. Until then, your MP remains whoever they have been, no matter what literature you may get through your letter box, or what anyone may tell you.

    As one example, take Birmingham City Council. Their page on constituencies and wards correctly states that Birmingham is divided into eleven parliamentary constituencies, but then goes on to list only ten – they are listing the new constituencies which do not yet exist, as Birmingham is losing one constituency at the next election. It appears that they have organised themselves along the new boundaries in advance – which is fine, but this doesn’t affect current Parliamentary representation, and so they should explain this clearly, as otherwise members of the public get confused (and blame us for giving them the “wrong” MP, when we haven’t done so). As you can see from the maps above (which highlight Birmingham, Hall Green), the constituencies will be changing their boundaries quite a bit, and we have had reports of people receiving letters from candidates in the next election who are MPs of different neighbouring constituencies, simply referring to themselves as an MP, which is a great source of confusion.

    An inhabitant of St Josephs Avenue, Birmingham (behind the Royal Orthopaedic Hospital), which is currently within the Selly Oak parliamentary constituency (red), and the Northfield ward of Birmingham City Council (green), would, on looking at Birmingham City Council’s website, assume they’re in a parliamentary constituency called Northfield. Northfield is currently the constituency to the west of Selly Oak; at the next election, its boundary with Selly Oak will change to the blue line, at which point St Josephs Avenue will be in the Northfield constituency. But not until then.

    Map of Streatham constituency at next election

    As another example (chosen purely as it has come up in user support), the Labour candidate’s website for Streatham had a page about the constituency – obviously you would expect a candidate to be talking about the future constituency, but would it hurt to add some explanation that Streatham is currently a slightly different shape?

    Boundaries of different things are all independent – if a ward boundary moves due to some local issue, the corresponding Parliamentary boundary does not necessarily change with it (probably not, in fact). So when Birmingham changed its ward boundaries back in 2003, they became out of sync with the Parliamentary constituencies. From the next election, things will be more in sync as the new Parliamentary boundaries are based on more recent ward boundaries, but this will again separate over time. All we can do is always clearly explain the current situation, and ask that others do the same.

  8. April Fools’ Day Council changes

    They could perhaps have picked a better day, as it was quite serious – at the stroke of midnight on the 1st of April, 37 district councils and 7 county councils in England ceased to exist, replaced by 9 new unitary authorities. This means people in Durham, Northumberland, Cornwall, Shropshire, Wiltshire, Chesire, and Bedfordshire only have one principal local authority to deal with now. The Wikipedia article on the changes has more information on the background to this change.

    Obviously this meant some work for WriteToThem and FixMyStreet, both of which require up-to-date local council information. Our database of voting areas, MaPit, has “generations”, so we can keep old areas around for various historical purposes. So firstly, I created a new generation and updated all the areas that weren’t affected to the new generation. Next, six of the new unitary authorities (all the counties except Cheshire and Bedfordshire, plus Bedford) share their boundaries and wards with the coterminous councils they’re replacing, so for them it was a simple matter of updating those councils to be unitary authorities.

    That left Bedfordshire and Cheshire. I created areas for the three new councils (Cheshire West and Chester, Cheshire East, and Central Bedfordshire), and transferred across the relevant wards from the old county councils – basically a manual process of working out the list of correct ward IDs.

    WriteToThem was now dealt with, but FixMyStreet needed a little more work. The councils that no longer existed had understandably disappeared from the all reports table, so I had to modify the function that fetches the list of councils to optionally return historical areas so they could be included. And lastly, FixMyStreet needs a way of mapping a point on a map to the relevant council. For this, it needs to know the area covered by a council, which was missing for the new authorities I’d manually created. Thankfully, each of the three new authorities are made up of the areas of either 2 or 3 district councils (e.g. Cheshire East is the area covered by Congleton, Macclesfield, and Crewe and Nantwich), so I just had to write a script that stuck those areas together to create the area of the new council. It all seems to work, and I’m sure our users will be in touch if it doesn’t 🙂

    So goodbye to Alnwick, Bedfordshire, Berwick-upon-Tweed, Blyth Valley, Bridgnorth, Caradon, Carrick, Castle Morpeth, Cheshire, Chester, Chester-le-Street, Congleton, Crewe and Nantwich, Derwentside, Durham City, Easington, Ellesmere Port and Neston, Kennet, Kerrier, Macclesfield, Mid Bedfordshire, North Cornwall, North Shropshire, North Wiltshire, Oswestry, Penwith, Restormel, Salisbury (which is getting a new town council), Sedgefield, Shrewsbury and Atcham, South Bedfordshire, South Shropshire, Teesdale, Tynedale, Vale Royal, Wansbeck, Wear Valley, and West Wiltshire. RIP.

  9. Postcode and boundary refresh

    We updated our boundary and postcode database at the start of the week (apart from two wards in Scotland that I misspelled and updated on Tuesday, sorry), so hopefully everyone in the country can contact their representatives at WriteToThem or have their postcode recognised on HearFromYourMP or TheyWorkForYou. This applies especially to a small number of councils, such as Bradford, for which the boundaries had completely changed at their last election and which we were unable to get working until now – apologies for the inconvenience.

    Related to this, and for interest, on 1st April, a number of councils are being abolished as their county councils become unitary authorities. The district councils within Durham, Northumberland, Cornwall, Wiltshire, Shropshire, and Cheshire/Chester all disappear – Cheshire becomes two unitary authorities called Cheshire West and Chester, and Cheshire East. Lastly, Bedford borough council becomes a unitary authority, and Central Bedfordshire council covers the area previously covered by Mid Bedfordshire and South Bedfordshire.

    Parliamentary boundaries in England and Northern Ireland are changing, but these do not take effect until the next general election – until then, your constituency and MP remains the same.

  10. Postcodes on TheyWorkForYou

    If you enter your postcode on TheyWorkForYou and it’s Scottish or Northern Irish, you’re now presented with your MSPs and MLAs as well as your MP, which makes sense given the site covers their Parliament and Assembly respectively. 🙂 You also get an extra tab in the navigation linking through to Your MSPs or MLAs. In order to do this, I needed a quick way of determining if a postcode was Northern Irish or Scottish. Northern Ireland was easy, as all postcodes there begin with BT. I assumed Scotland was also easy, which turned out to be true apart from the TD postcode area that straddled the border like a mail-sorting Niagara Falls. After some very dull investigation, I eventually worked out that e.g. most of TD15 is in England, but (amongst others) TD15 1X* is in Scotland, except for TD15 1XX which is apparently back in England. The final result was the postcode_is_scottish() function in postcode.inc, which (hopefully) correctly determines if a given postcode is Scottish or not – perhaps someone else will find it useful.