Editing Standards and Conventions

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The following are some Standards and Conventions for editing the maps. For basic information on how to edit, see Editing

Tagging

You can assign "tags" ("keys" and "values") to any point (node), street (way) and area (closed ways). You can find a list of suggested tags on the Map Features page. It is recommended that you take a good look at that page and familiarise yourself with the tags which are most widely accepted and recognised by most tools/renderers. Note though that any keys and values are valid and may be employed in OpenStreetMap, and the Map Features page is subject to change, with proposals being voted upon.

The Good practice page has a number of points concerning tagging.

Roads

A physical road, street,footpath etc is initially drawn as a series of nodes connected by ways. Nodes are grouped together to form ways. The way should then be tagged with a highway tag and a name.

Visually all ways appear the same in most of the OSM editors, however, when rendered they will be displayed in different colours and widths based on the tag values entered.

Street Names

In the name tag, enter the full name as it appears on the street name signs. Use mixed case with the first letter of each word capitalised (for example, Church Street, not Church street). Do not abbreviate words. There is currently no table of standard abbreviations (St. could be Street or it could be Saint) and it has been decided that this is a rendering issue. i.e. the underlying data should have the full street name. This will allow a renderer to introduce abbreviations as necessary.

Watch out for apostrophes. The same rule applies. If the street sign has an apostrophy, the OSM data should have an apostrophy. There is no obvious consistency; the London Underground station Barons Court is adjacent to Earl's Court, one with an apostrophe, one without.

Also see Bilingual street names

Roads without names

Sometimes a road does not have a name (in the real world) That's fairly rare, but it sometimes happens. In this case, enter the highway tag, but not the name tag.

Often a road has a name, but you don't know what it is. This might be because you didn't write it down while you were out surveying. Maybe you used a camera but the picture came out blurry. Or maybe you are skethcing over Yahoo! Imagery. These kinds of roads should be drawn in as untagged ways as per the guidelines on Yahoo! Aerial Imagery#How to sketch? ...however not everyone follows this, and "sketched" roads are often given a highway tag.

One way streets

If traffic can only travel down a road oneway then it is important to draw the way in the direction of travel and then add a "oneway=yes" tag.

Dual carriageways A dual carriageway (or separated highway) should be drawn as two separate ways. The general rule is that if it is not possible to turn across the street at any junction then it should be drawn as two paths. If there are limited turning points then these should be explicitly marked as a link between the two carriageways. Nodes should be aligned in pairs along the two carriageways, so the ways run in parallel. Each carriageway should be created as a separate way.

Wrong

Right. Nodes aligned in pairs.

Roundabouts

Roundabouts are discussed in detail on Mapping/Features/Roundabout.

Junctions

All road junctions should be drawn as a node with connecting paths. It is incorrect to add a node that appears to be on a path but is actually not connected. While this might look right, it will not define a valid path from one road to the other.

Bridges

A bridge is drawn as a seperate way. This is one of many situations where a road is no longer represented as a single way, but as several ways arranged end-to-end, each with different tagging. The editors provide an easy way to split a way at a given node, for this purpose.

The highway and name tag should be applied to throughout. The short way representing the bridge should additionally be tagged with bridge=yes and layer=1. See Key:bridge for details.

Tagging Areas

On some occasions the feature you wish to tag is not represented by a line (as is the case of a road, river, rail line etc), but by an area. For instance a wooded area, a park, or a lake are all Map_features which are areas.

The current method of tagging an area, is to do one of the following:

Note 1: Do not add e.g. landuse=retail to an already existing way, make a new way instead.

• Create a way which represents the outline of the required area. Annotate this way with the required tagging from the Map_features page, such as natural=water (for a lake), landuse=forest (for a forest), or leisure=park (for a park), etc.

Accuracy

Accuracy is important. The GPS system provides fixes that can be accurate to 1-10m which is more than good enough for this project. Do bear in mind, however, that a road can be several metres wide and a GPS fix could have been made anywhere in the road or even on the pavement. For many purposes accuracy to a few metres is plenty good enough. What is equally important however is topological accuracy. Do two roads intersect at the some point (a crossroads) or is the intersection offset? This detail may only be a matter of a few metres, but can be the difference between driving instructions that might say at the crossroads go straight ahead or at the junction turn left and then after 10 metres, turn right.

When tracing roads - particularly winding, rural ones - you should add enough points to make each curve look like a curve. Don't just put one or two points per bend. Remember, you are drawing a map, not just a routing diagram.

How not to do it

The above is an example of a very roughly-traced rural road. Drawing roads like this isn't helpful. When someone comes along to do it properly, they will most likely delete your way and start again from scratch, as it's quicker to draw a new road than to add lots of points into an existing way.

How to do it

This is the same road - but this will look much better on the map, and gives the map user a better sense of the curves of the road.

Dates

Dates should be in ISO 8601 format, i.e. YYYY-MM-DD. Where a numeric day of week is necessary, Monday=1, Sunday=0 or 7.

Other crap

• Intersections and interchanges - how much detail
• Accuracy. How do you judge and or indicate the accuracy? How accurate is good enough? Is a rough approximation better than nothing (i.e. inaccurate roads get refined the way wikipedia articles do).
• Is it constructive/helpful to mark a road that you know is roughly in the right place but don't have any supporting GPS data?
• Landmarks, footpaths, etc?
• How do you indicate that one road passes over or under another?
• If a road is made up of several/many ways, how often should it be labelled with its name? eg M25 - once between each junction? Once on each carriageway (M25 Clockwise, M25 Anti-clockwise)?

Topology

• Is correct topology more or less important than accurate location?
• If a road is a dual carriageway it should be shown as two lines
• If a road has a small traffic island (eg at the approach to a large roundabout) should this be represented as a triangle or not? How big should it be before it should be drawn?
• Should mini-roundabouts (comprising of just white paint on the road) be drawn as a roundabout?

No. Mapping/Features/Roundabout entry has information on how to tag mini-roundabouts Avantman42

• Where a side road connects to a main road should there be a node with three lines connected to it or should the main road be a continuous unbroken line and the side road just ending at but not connected to a node that is part of the main road?

The side road should be connected to a node on the main road. See the Junctions section above Avantman42

• If a road can be clearly made out from the aerial photo, but there are also a few GPS tracks, which should be considered to be the more accurate?

The GPS tracks. Landsat, aerial photos, etc, can be some distance out Avantman42

• Should roads be drawn based solely on the aerial photo if there are no GPS track points?

Yes, but mark them with a source tag Avantman42

• How should (long) tunnels where no GPS is available be drawn?

In some GPS (for the cars for example), the GPS has one or several gyroscopes so that it is able to know the position. FredB 18:04, 18 Jul 2006 (BST)

WARNING: OpenStreetMap is highly addictive For some people the process of mapping on OpenStreetMap is highly addictive. Take frequent breaks, there is a lot to be done.