mapping

The OSM iD editor, used for editing the map

The map data for Trailmap's best maps for finding trails and navigating on them (the "MTB map", for example) comes from the OpenStreetMap community map (OSM) database, which has been "drawn" (= mapped) by enthusiasts as voluntary work. Although a map made by volunteers doesn't sound like something to take very seriously, OSM has become so comprehensive and accurate that it has spread very widely into use across all sorts of online services — and while it has a strong direct competitor in Google Maps when it comes to street maps, in trail maps it has no serious global competitor at all. In Finland the alternative is the NLS topographic maps, but in most areas the trails drawn on them are both out of date and poor at covering the trail network compared with OSM's trails (there's an example of the differences in this post).

The OSM database is open and equally available to everyone — to commercial services such as Strava, Garmin, Suunto or Komoot, and to free services like Trailmap alike. This is a significant advantage over some other community-based services: the Trailforks trail map, popular in Sweden too, is also based on trails mapped by users as voluntary work, but the Trailforks database is only available to that service, and the work done by users is therefore only of use to the Trailforks company.

The OSM community has plenty of very productive enthusiasts who have spent a long time learning the finer points of mapping, and thanks to their work the map has comprehensive coverage of the road network, waterways, buildings and other "backbone elements". The map isn't finished yet, though, and there's a need to find new mappers to fill it in, especially when it comes to smaller details such as trails.

Every single carefully made addition or refinement to the map is valuable. There's strength in numbers, and many small contributions add up to something big. So becoming a mapper isn't something you need to think of as a big question, or as committing to something that takes a lot of time before it's any use. In practice what it takes is a session of an hour or two to get to grips with the basics of mapping, after which adding new trails or refining the details of existing ones takes just a few minutes, even done right after a ride.

The video below shows an example of using a GPX track opened from Strava, from a ride done earlier, to help add a new trail to OSM — and done at normal speed it takes just under a couple of minutes. Very little effort when done right after a ride, while the technicality of the trails you rode is still fresh in your mind. I've made a habit of checking right after a ride whether I rode any trails that are still missing from OSM or unclassified, if I have even the slightest suspicion that might be the case.

Adding a new trail via the Trailmap service with the OSM iD editor

OSM is a big thing, and its general documentation and guidance isn't the easiest. For trail mapping, though, you only need to learn a small part of mapping and OSM. This post and the guides linked to it aim specifically at covering the know-how needed for trail mapping, so that a new mapper doesn't have to dive deep into the depths of the OSM Wiki.

OpenStreetMap basics

OSM is, to simplify slightly, a substantial database describing all the map elements shown on OSM-based maps. OSM-based maps can look very different from each other: the OSM standard map, which is the default on the openstreetmap.org site, and Trailmap's "MTB map" look very different indeed. Both are based on the same OSM database data, but use a different map style. A map style describes which of the database's map elements are shown on the map, and how they're drawn on it. The particular feature of the MTB map is that it emphasises trails and shows their technicality (= how rideable they are on a mountain bike) in illustrative colours.

The map elements of the OSM database are points (node), lines (way) and areas (a way that forms a closed loop). Each element can be given tags describing it, of which there are typically a few mandatory ones, a few very useful ones, and then endless optional ones. With these tags you can define, for example, that a line drawn on the map is a cycle path with an asphalt surface and a width of 3 metres — or, using other tags, that it's a 1.5-metre-wide trail whose difficulty on a mountain bike is very easy, meaning you can also ride it smoothly on a cyclocross bike with narrower tyres.

In practice, adding a new trail to the OSM database is done by drawing the new trail in one of OSM's alternative map editors, which are like a drawing program. The easiest of these is OSM's iD editor, which is the default option. Drawing is usually supported by a GPS track (in GPX file format) recorded on one or more earlier rides. The GPS track helps you draw the trail in the right place on the map. As well as drawing it, you describe the trail's properties and so on with tags. Finally you save the new trail, and about a day later it appears on Trailmap's maps for everyone to see.

Why doesn't the trail I just drew show up in Trailmap?

Trailmap fetches a new OSM database at night, containing all the OSM database edits made by 21:00 the previous day, and draws a new map from it in the morning, available in the service by about 07:30. The new trail will show up then (unless the browser cache problem takes a bite out of you).

So if the new trail you drew doesn't show up even the next day, the reason may be the browser cache. You can turn it off temporarily — in Chrome, for example, Menu --> View --> Developer --> Developer Tools, and in the list at the top of the panel that opens on the right-hand side of the browser window, Network --> Disable cache. Then zooming in and out on the map a few times at a leisurely pace usually gets the browser to show the new trail.

Another way to solve the cache problem is to use two different browsers: first browse the area where the new trail is in, say, Firefox or Safari. If the trail doesn't show, wait half a minute and then look at the same area in another browser, such as Chrome. This solution works most of the time, because in the meantime — after the first viewing — the Trailmap server has time to update the new map tiles, which are then available to the second browser. And that second browser's cache shouldn't have old map tiles either, if it hasn't been used to look at that area in the last day.

Detailed instructions for getting started

The following post continues from the above and gives step-by-step instructions on how to get started with mapping and what to take into account when mapping — read it here >.

Once you're up and running, what you'll need most is a checklist of how trails are described ("tags") in the OSM database. There are instructions for that in table form here >.

From a trail runner's point of view, trails look a little different than they do to mountain bikers — more on the differences here >.