The state of Welsh-language mapping

We worked with Transport for Wales to investigate Welsh language mapping, geolocation and route finding. This is what we found.

Mapping in Welsh

Transport for Wales asked us to undertake a piece of research for them. They wanted to know how they could build online mapping applications that treated Welsh and English language equally.

We’ve been thinking about these issues for several years and we maintain a Welsh language map of Wales at This, however, was a real opportunity to think about these questions from an organisation providing public transport services across Wales. We’ve produced a report for Transport for Wales which has a lot of detail in it and is very focused on their specific circumstances. This post is an opportunity to take a step back and think about some of the key things we have learned.

Digital mapping is really commodified… in English

If you want to spin up a transport application with slick background mapping, geo-location, route finding and lots of points of interest there are many robust options available. For many uses digital mapping applications can be rapidly assembled, at least in part, by stitching together commercial services that provide data on demand (for a fee).

For those of us on the team who remember when they had to drive to a mini-Computer in Cardiff to do some fairly simple GIS tasks this is really impressive. When you want those results in Welsh it suddenly becomes much harder.

Google Maps does not support Welsh… but…

Google Maps does not officially support Welsh.
This means that if you are a developer wanting to create an online mapping application using the Google Maps APIs you can’t ask for the data to be provided to you in Welsh. That should rule it out for most uses by public bodies in Wales. But… Google Maps does use Welsh in interesting ways. It seems to perform on-the fly translation. For example: it knows that Prifysgol is the same as University and so if you search for Prifysgol… it will offer you universities not just in Wales but across the World. We searched for a pub called the Black Horse and were offered the Ceffyl Du. This is quite clever.

If you use Google Maps on your phone with your locality set to Cymraeg you will see Welsh place names on the map, including in England. But without official support there are real limits to where it should be used.

Bing surfaces a lot more Welsh than we had realised

Bing Maps is Microsoft’s mapping platform. I’m sure they wouldn’t like to be de-scribed this way but I think most of us would say they are “Microsoft’s version of Google Maps”.

Unlike Google Maps, Bing Maps does officially support Welsh. As a casual user of the Bing maps website you might not notice this but as a developer you can amend your API calls to request responses in Welsh. Overall a developer can surface a great deal of Welsh in services from Bing maps. At most zoom levels roads will have bilingual names (rather than the Welsh name or the English name) and there are some odd gaps.

If you have very simple requirements for displaying points on a background map of Wales that won’t be dominated by English-language names Bing Maps is certainly worth a look at.

We feel that most public bodies could probably go beyond what Bing offers however.

Ordnance Survey could do better

Public bodies in Wales can use Ordnance Survey data under the Public Sector Geospatial Agreement. Ordnance Survey data is of extremely high quality and they offer a range of data downloads and APIs to support public bodies in their work.

But the way OS handles Welsh could be much improved.

OS publishes tiles: essentially electronic versions of the OS maps we are familiar with from walking trips. These include Welsh and English language names but OS policy means that English language names are more likely to appear than Welsh language names. It is not possible to request tiles that show only Welsh language names or where Welsh language names are more likely to appear than English language names.

OS also provides other datasets. Some of these contain the Welsh and English language names for features but we found that often the way that the data is labelled in the datasets made it difficult to identify what was the Welsh language name and what was the English language name.

Some of these are data quality issues, others are policy issues. Hopefully public bodies in Wales are working with OS to see improvements in these areas.

The “official” name

In many cases there isn’t an obvious, official source of the English language name and Welsh language name for a place, for a stream, a forest or an area.

This makes it hard to measure how good the coverage of a map is. There simply isn’t a “correct” dataset to compare it to. In many ways this is one of the strengths of the Welsh language, it truly is a living language and things are called what people using the language call them.

That said, computers need rules, and as we use maps on computers more and more the need for some rules around Welsh language names grows.

Our Welsh language map is based on the community edited OpenStreetMap and Wikidata databases. Our researches suggest that these datasets are likely to remain part of the mix in terms of naming places and features until, at least, commercial competitors catch-up. We really encourage people to contribute to these datasets.


At the time of writing:

  • It is very straightforward to build web mapping applications in English.
  • It isn’t at all straightforward to build web mapping applications in Welsh. It is possible to build them in Welsh though.
  • We’d like to encourage public bodies and other organisations serving the people of Wales to look into how they can build bilingual mapping applications. The more organisations working on this problem the more solutions will be developed.

We will carry on working on this area and we would love to hear from others with questions or ideas about welsh language and bilingual mapping.

We’d like to thank Transport for Wales for commissioning this work and for allowing us to share this summary of things we found as a result of this project.


(Cymraeg) Enwau Cymraeg am adeiladau Gradd I o Fôn i Fynwy – eich cyfraniad plîs!

This entry is only available in Welsh.


Put your organisation on the map : FREE workshop

Putting your organisation on the map for FREE!


Welsh Government is sponsoring a Welsh map to promote events in Wales.

As we move towards 2022, find out how to put your events on the map for free.

Join our mapping expert Ben Proctor of Herefordshire 3rd sector organisation Data Orchard & David Wyn of at 11am this Wednesday 1st December on Zoom

as they explain how the WG’s @MapioCymru could help you promote your events on an embeddable map for your website at no cost to you.


Decolonising Welsh mapping: uncovering Wikidata’s place names in Welsh

Recently Mapio Cymru as a project has been working with the National Library of Wales to uncover the place names in Welsh that are in Wikidata, and improve them.

Now there are hundreds of names from Wikidata on the map along with the names from OpenStreetMap (OSM).

Here’s Jason Evans from the library to elaborate on the work and its importance:


Combining Wikidata with OSM allows us to build on the work of Mapio Cymru which has been developing a map of Wales using only Welsh language data held in the OSM database. By aligning and combining this with Wikidata the map can begin to grow further, offering more information to users through the medium of Welsh.

And this is important. Many places in Wales, be they towns, villages, hills or beaches have two names, or sometimes more. The names in Welsh are almost always the original place names, ancient in origin and steeped in history. These names are usually descriptive or refer to long lost saints, chieftains or fortresses. The English versions of place names are sometimes meaningless mutations of the Welsh originals or names imposed by medieval invaders or Victorian ‘modernisers’. Even today historic properties are renamed in English by their new owners and Welsh names are dropped from websites and maps in favour of English alternatives deemed to be ‘more easy to pronounce’.

This project aims to decolonise mapping in Wales, not by erasing English place names from the record but giving users the option to view and explore a modern map of Wales solely through the medium of Welsh – a service that didn’t really exist until the launch of Mapio Cymru.

So the first challenge with this project is actually to encourage communities to contribute their local Welsh place names to OSM or Wikidata so that they can be included in the map, and this is done through a series of discussions, workshops and editing events. […]

Read the whole article on the National Library’s blog.


What’s wrong with what3words? A video

The always pre-revenue what3words company has been buying up advertisement slots again, and there’s been some pretty unquestioning – might I say gushing – press coverage lately too.

I found this very interesting video which lists several of the serious weaknesses of the company and system.

A particularly big no-no for the Mapio Cymru team is the lack of open licensing of the data and software, mentioned in the video – and as a result the lack of peer review of the system.

The confusion inherent in converting from one language system to another is a cause for concern too.

See also: Rescuers question what3words’ use in emergencies (BBC)

Guides Events

VIDEO: Gweithdy Mapio Cymru, Eisteddfod AmGen 2021

This post is a video recording of our event Gweithdy Mapio Cymru held at Eisteddfod AmGen 2021.

The video is entirely through the medium of Welsh.

In the video we discuss:

Diolch o galon i Eisteddfod AmGen a’r Lle Hanes am y croeso, ac wrth gwrs i bawb a gymerodd rhan yn y gweithdy!


Come to Gweithdy Mapio Cymru, Y Lle Hanes, Eisteddfod AmGen 2021

UPDATE: Here’s the video of the event.

This is an introduction to the Mapio Cymru project which is creating a map of Wales with place names in Welsh.

During the session there will be opportunities to play with the map, find names and locations, and contribute information to the next generation of Welsh map apps.

The work is relevant to education, leisure, employment, heritage and community – and history.

The organisers will describe how the project takes advantage of open and freely-licensed web resources such as OpenStreetMap and Wikipedia / Wikidata, and what you can do to get involved.

No prior experience or understanding is required, just curiosity!

This Zoom workshop has been organised by the Mapio Cymru project in association with Y Lle Hanes.

dydd Iau 5ed Awst 2021
3PM tan 4PM
On Zoom

Please note that this event at Eisteddfod AmGen 2021 will be held through the medium of Welsh. Please see the post in Welsh for further details.


Still mapping!

Our team has been working continuously on improving the number of Welsh place names that appear online since our inception in 2017 as partt of the Welsh Government’s Welsh Government #Cymraeg2050 project, and we are now very happy to announce that we’ll be working with the National Library of Wales this year on new aspects of the work.

The National Library has a great experience of crowdsourcing projects, and between now and April 2022 we hope to attract quite a crowd to a number of aspects of the work:

hold Wikidata-OSM Cymru events all over Wales –

e.g. school sessions (come into contact if you want to invite us over!) and collect audio clips of local names

As well as crowdsourcing the project, we will also use Wikidata to store and share Welsh language information. Wikidata is a sister project for Wikipedia, and we will take advantage of the wealth of Welsh data already in this huge dataset to improve the map in terms of the core data that we have at our fingertips. In addition to using the existing Wikidata we intend to add between 5,000 and 10,000 new data records with Welsh labels, for things like hills, mountains, lakes and public services and ensure that these are displayed on our Welsh map on OSM.  Menter Iaith Mon will lead on a series of events in schools to improve the content of Wicipedia Cymraeg for their local places and spaces.

By making links between Wici and OSM projects we can help build a Welsh map rich in data and more ways for users to explore that data in Welsh.

We hope that this project will provide a framework for developers and organisations who want to build digital mapping services in the Welsh language.

In addition, by the end of this year’s project, we will move ‘back to the future’ and to the blue sky thinking of the popular SatNav concept that attracted a great deal of attention during our first year…and we’ll ask

what kind of additional steps are needed for an external company to add Welsh to the languages supported by SatNav?

Mapio Cymru, like OpenStreetMap itself, is a community project where people from different parts of the country co-operate via the ‘parent’ site ; which in turn feeds a lot of data to our Welsh-language map so if you’ve developed a taste for changing the world and would like to know more our work on any other aspect of the work of adding to the Welsh names that exist online – that therefore protects our history and culture and indeed our legacy – then please do get in touch 

use #mapioCymru on social media, or email


Mapio Cymru now loads faster. Here’s what we did to speed up the server

We are building an open public map of Wales with all the names in Welsh. Because of recent work, the map will load much faster for you now.

Here’s what we did to improve the map loading speed.

When you load the map, what you’re seeing is a grid of tiles. Each is a square image file, like this:

Here’s a small bit of Tyddewi / St David’s at zoom level 17.

A JavaScript library called Leaflet manages your navigation around the map (panning and zooming). The main point is, it’s ultimately made up of images.

These tile images are rendered from the underlying map data in OpenStreetMap, which is stored as points, ways, and relations. As well as the data, the OpenStreetMap software stack developed by the project is also freely licensed.

The most time consuming part of showing an up-to-date map to a user is converting the data into images. This tends to be done when the user loads the map: the images are generated and served, and also stored in a cache on the server.

If the map were completely finished and final then that would help. We could make sure the server has the tile images all rendered and stored, and serve them every time. But that’s not an option for the whole map for a couple of reasons.

At the moment the Mapio Cymru map is updated automatically once every night when most people in Wales are asleep, and server capacity tends to be higher. These updates are necessary because geographical map features and names change often, whenever somebody makes an edit to OpenStreetMap. This is often an improvement to the map, e.g. somebody adding a name to a feature. The open data elements are constantly being revised, making it a bit like a Wikipedia of maps. The edit can also be a response to something changing in the physical world, e.g. a café changing its name or perhaps a lovely new railway station.

Therefore we can’t preserve the map in aspic, it’s changing all the time.

It turns out there’s another snag to the idea of pre-rendering and storing the whole map to speed up loading. There is a different set of image tiles at each zoom level. For the furthest zoom levels it is possible to store all the tile images. But for closer zoom levels, the total number of tiles grows exponentially. Pretty soon we need a vast amount of time and storage space, much more than we have.

For example all of Wales at zoom level 17 took a little over seven hours to render overnight. That’s too much.

Can we pre-render and store some selected tiles, and then render any others on demand? It turns out that we can. The challenge is to figure out what to pre-render for maximum speed advantage, given the constraints of time and storage.

What are the map areas of ‘interest’ or ‘relevance’, and how do we codify this more precisely?

Initially we had a hypothesis that for the map sparsely populated areas would be less frequently visited than densely populated areas. One method would be to pre-render areas above a certain population density threshold.

I then realised that there was another solution much more ready to go, and even better. We could refer to aggregated browser requests for tiles to see which parts of our map were visited most. This allows us to look at the historical popularity of areas right down to individual tile level. This was data we already had, lying in the server logs.

Here’s a heat map produced by Ben Proctor.

Heat map for one year of visits at all zoom levels

The popular areas do seem to correspond to population density. There may also be a relationship with the number and/or percentage of Welsh speakers in different areas, which is available from Census data.

I’ve instructed the server to pre-render these tiles and store them. We have chosen these areas:

Zoom levels 3 to 16 are now entirely pre-rendered.

Zoom levels 17 and 18 are now partially pre-rendered.

Now the server automatically pre-renders these areas every night, immediately after importing the up-to-date data.

The difference was very noticeable when I loaded the site before and after the change. Beforehand I’d been a bit embarrassed about the huge blank areas and the apparent freeze-ups of the map, while the server wheezed along. I am not experiencing that anymore – at least for now!

On average, tiles are loading in 40% of the time when pre-rendered. That’s a dramatic improvement, although the degree of speed-up is highly dependent on how many users are accessing the server at once.

Even tiles that are not pre-rendered are loading faster because there is usually more capacity on the server.

Incidentally the smooth running of the server also depends on choosing the right settings and configuration. (We briefly considered nginx as an alternative to Apache but it appears not to have an equivalent of the mod_tile module.)

As we gain more interest and users for the map I expect to have to visit this again. Your contributions to project costs are always useful.


Fun with Wales’ map data: a tutorial using Overpass queries and OpenStreetmap

Map: places in Wales that have ‘llan’ in their names

Would you like to get castles, rivers, post boxes, or cycleways in Wales from a map?

How about investigating place names in Welsh in your local area?

How about getting other features in Wales and further afield, as open data from a map?

This blog post will show you how to get open data from OpenStreetMap, with a particular emphasis on Welsh-language data.

It is intended as a fun introduction, not as a comprehensive reference guide. No previous experience is necessary.

We will be passing queries to the Overpass API, and it’s easy to get started. The queries can be run from your web browser in Overpass Turbo, which is one seriously cool app. Other than that your curiosity is the only prerequisite!

Introductory concepts

Feel free to skip this section if you want to head to the practical bit straightaway.

OpenStreetMap is a global map which has been built by thousands of people. It uses a wiki-like approach to mapping – anybody can edit and re-use the content. Because it’s all open data, you can use it however you want in your own learning, work, and leisure.

There is a huge amount of Welsh-language data in OpenStreetMap.

It’s independent of proprietary mapping providers, allowing you freedom to work with the data in your own projects.

The underlying code is also freedom-respecting software and open source. As the Mapio Cymru project we have built a showcase map which shows Welsh-language names for features including places, roads, rivers, and so on.

How to run an Overpass query

The quickest way to try Overpass queries is to visit the Overpass Turbo website.

The screen will be divided into an editor panel and a map/data viewer panel. Now do this:

  1. Write (or paste!) a query into the editor.
  2. Click the Run button.
  3. The results are shown in the data viewer.
  4. Within the data viewer you can select Map tab or the Data tab.

You’ll be following these same steps every time you run a query.

Towns query

Here is a simple query you can use. First drag the map and zoom until it shows an area you want to investigate, e.g. a part of Wales. Then follow the above steps using this query.


Bingo, you should now see towns plotted on the map area you’ve selected. Congratulations on accomplishing your first Overpass query!

The data

Select the Data tab in the data viewer to see the data. It will be in the default format, which is XML.

Here’s a portion of the XML data you’ll see for the results of the above query, for two towns:

<node id="8997358" lat="51.5912466" lon="-2.7517629">
  <tag k="name" v="Caldicot"/>
  <tag k="name:cy" v="Cil-y-coed"/>
  <tag k="place" v="town"/>
  <tag k="population" v="11200"/>
  <tag k="postal_code" v="NP26 4"/>
  <tag k="wikidata" v="Q722585"/>
  <tag k="wikipedia" v="en:Caldicot, Monmouthshire"/>

<node id="21413062" lat="51.8591257" lon="-4.3115907">
  <tag k="is_in" v="Wales"/>
  <tag k="name" v="Carmarthen"/>
  <tag k="name:br" v="Caerfyrddin"/>
  <tag k="name:cy" v="Caerfyrddin"/>
  <tag k="name:en" v="Carmarthen"/>
  <tag k="name:ja" v="カーマーゼン"/>
  <tag k="name:la" v="Moridunum"/>
  <tag k="name:ru" v="Кармартен"/>
  <tag k="place" v="town"/>
  <tag k="population" v="14185"/>
  <tag k="population:date" v="2011"/>
  <tag k="source" v="NPE"/>
  <tag k="source:population" v="Census"/>
  <tag k="wikidata" v="Q835835"/>

As you can see, the name:cy tag has the town’s name in Welsh. There are equivalent tags for other languages. There’s also a tag called name without a language code, here’s the definition of the name key.

In general name:cy will provide the name in Welsh for anything on the map – if it’s been submitted.

The other data in the examples above should be fairly self-explanatory, and include latitude and longitude, Wikidata item identifier, and other things.

Note that OpenStreetMap is always a work in progress. You’ll see pretty good data for many queries although some others will display gaps. (You can edit/add place names on the map, and other features and their tags.)

Change your Overpass Turbo map to Mapio Cymru

Within Overpass Turbo your underlying map will probably be the main OpenStreetMap. This is OK but it won’t always display all names in Welsh.

You can change it to the Mapio Cymru map server, like this:

  1. Select Settings menu
  2. Select Map
  3. In the Tile-Server box put: //{z}/{x}/{y}.png

Please note that when you click on map pins any links will still go to the main OpenStreetMap.

Farms, cities, and other places

You can take the query above and modify it:


Spot the difference between this query and the one above. Alternatively use one of the possible key values for place. For example you can use “village”, “city”, “island” and so on.

Your bounding box

In general:

  • If your query refers to a bbox (bounding box) the query will run on the visible map, the portion of the map you’ve selected.
  • You can also reduce the width of the map: drag its edge to reduce its size, and increase the size of the editor.
  • If your query has a lot of results, there may be too much data to plot on the Overpass Turbo map in your browser. Try zooming in to reduce the size of the bounding box.

Towns in Wales only

No matter how much you move the bounding box it’s not possible to get all of Wales, and Wales only. Our query needs to change.

This time, click the Wizard button and type ‘towns in Wales’ then click Build Query. When I ran it it suggested ‘town in Wales’ then gave the following query, and yours will be similar or the same.

This has been generated by the overpass-turbo wizard.
The original search was:
“town in wales”
// fetch area “wales” to search in
// gather results
  // query part for: “town”
// print results
out body;
out skel qt;

Where possible the Wizard will take the English you type and give a query in Overpass query language. As far as I know the Wizard is only available in English at the moment.

searchArea above is a variable containing our geocode area for Wales. It is set for the life of the query. We don’t have to call it searchArea, we can call it almost anything – as long as there’s no clash with other reserved terms.

The above query contains comments which have no effect on the query. There are two styles:

/* comment within slash star delimiters */

// comment between double slash and end of line

Llan place names

As well as Llanelwy this will return Rhosllannerchrugog in the results – and so on. It’s a case-insensitive search.

out center;

This is a narrower search for Llan with a capital L.

out center;

Here’s a search that includes the tags name a name:cy for a comprehensive map which includes places which currently lack a name:cy tag and names like Llanandras (Presteigne) and Llanllieni (Leominster) (diolch/thanks for your replies via Twitter!).


This will give all places in Wales with Llan in the name. It gives data only – in Overpass Turbo the map tab will be blank. You can use the CSV results data in a project, e.g. in a spreadsheet.

[out:csv("name:cy", "name", ::lat, ::lon, "place", ::id; true; ",")][timeout:50];

You could modify one of the above for ‘Aber’, ‘Caer’, ‘Tre’ and so on.

Castles in any area

Now try this query.

// gather results
  // query part for: “castle”
// print results
out body;
out skel qt;

This is OK but how about all the castles in Wales only? Use this:

// gather results
  // query part for: “castle”
// print results
out body;
out skel qt;

Here are some others to try. In each case you should edit the three statements above to cover all nodes, ways and relations in the search. Let’s look up the definitions of those in a jiffy…




"amenity"="bicycle parking"


"amenity"="bus station"

The last one will identify, among others, the National Express coach station in Cardiff – currently the only bus station in the city.

Elements of OpenStreetMap

There are millions of possible Overpass queries.

You can play around with basic queries without having a comprehensive understanding of OpenStreetMap. The wizard may help.

Sooner or later though you might want more context to help you write that special query for your own interest. This portion from the documentation on elements has some vital definitions will help:

Elements are the basic components of OpenStreetMap’s conceptual data model of the physical world. They consist of

  • nodes (defining points in space),
  • ways (defining linear features and area boundaries), and
  • relations (which are sometimes used to explain how other elements work together).

All of the above can have one or more associated tags (which describe the meaning of a particular element).

If you want to see some examples of nodes, use this query.

In Overpass Turbo this will only work for small bounding boxes, because the amounts of data are relatively large.

Show the Wales Coastal Path

This is a simple query that only shows one relation – the northern part of the Wales Coastal Path.


This shows the entire Wales Coastal Path. (Because this is stored as a relation of relations, the query uses a ‘recurse down relations’ operator >> to display the relations, ways, and nodes within the overall relation. Here’s more info on the recurse down relations operator.)


Hiking routes

Taken from the Overpass API examples. You probably need to zoom into a bounding box.


{ color:green; fill-color:green; }

relation[network=lwn] way
{ color:blue; fill-color:cyan; }

relation[network=iwn] way
{ color:red; fill-color:red; }

relation[network=nwn] way
{ color:green; fill-color:green; }

relation[network=rwn] way
{ color:yellow; fill-color:yellow; }


Rectangular buildings in Wales that are taller than they are wide

This one’s adapted from the examples.

// Find rectangular buildings that are taller then they are wide
  // Compare the height to the average length of a side
    count_members() < 6 && is_closed() &&
    number(t["height"]) > length() / 4);
  // Assume a floor is 3 m tall
    count_members() < 6 && is_closed() &&
    number(t["building:levels"]) * 3 > length() / 4);

// Print results
out body;
out skel qt;

What’s next? Edit the map

If you notice any deficiencies in the data then you can edit the map. Welcome to the open data mapping community!

Overpass can be used deliberately to look for opportunities to improve the map.

Overpass Turbo in Welsh?

Overpass Turbo’s interface is available in a few languages but it doesn’t offer Welsh as an interface language yet. If you’d like to contribute to the translation head to its Transifex project.

Write your own queries

Start with the Overpass Turbo examples and Overpass API examples provided by the OSM community.

You can even delve into the user manual for Overpass.

Using Python instead of Overpass Turbo

If you can use Python you can run Overpass queries in your code using this simple wrapper instead of the Overpass Turbo web interface. Write an app and wow us!

Alternatively check out these other methods of querying Overpass via code.

In any case Overpass Turbo is handy for perfecting your queries.