Key:bridge

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bridge

Description: A bridge is an artificial construction that spans a road, railway, waterway or other feature and carries a road, railway or other feature. Google definition User discussion

Group: Properties

Element: help

Implies:

Tagwatch: help Europe France Germany Italy Netherlands Spain Turkey Great-Britain

Contents 1 Summary 2 How to Map 3 Complex Bridges 4 Combining with Key:layer 5 Rendering 6 See also

Summary

A bridge is an artificial construction that spans a road, railway, waterway or other feature and carries a road, railway or other feature.

There is a single "bridge=<type>" tag:

bridge=yes

bridge=aqueduct

bridge=viaduct

bridge=swing

bridge=...

which includes various bridge and bridge-like structures like viaducts and aqueducts.

In other words, all bridge-like structures are values of the bridge tag. This is acceptable on nodes and ways, although most instances are on short-ish ways.

How to Map

The way of a street or of a railway has to be split in three parts: the way before the bridge, the bridge itself, the way after the bridge.

1. Mark the beginning of the bridge (abutment) by a node.
   In JOSM split the line by key P.
2. Mark also the end of the bridge by a node.
   In JOSM split the line by key P.
3. Now select the way representing the bridge.
4. Add the attributes by bridge=yes.

Example for a primary road:

highway=primary 
+ ref=*
+ bridge=yes
+ name=name of the bridge

Other useful tags:

maxweight=# - max load

maxspeed=# - speed limit

height=# - height over ground

length=# - length

If the bridge ends in a junction, you'll need a small non-bridge way between bridge and junction (see image).

Complex Bridges

For the description of complex bridges, where two or more bridges cross each other, we use Key:layer:

highway=motorway - the ground level
+ layer=0

highway=motorway - the first bridge from ground level
+ bridge=yes
+ layer=1

highway=motorway - the upper bridge
+ bridge=yes 
+ layer=2

There are five layer-degrees upwards (1 to 5), and five downwards (-1 bis -5).

For ascending/descending chutes we dont use a layer.

When there are several bridges close together it is sometimes acceptable not to tag them as bridges, but to tag the single road below as going through a tunnel.

Combining with Key:layer

Tag layer=* is used to separate things that are physically on different levels. The tag bridge=* does not imply anything about layers, so if your bridge crosses any feature on layer=0 (the default if not present), you should consider adding a layer=1 (or higher).

We don't tag for renderers, which means not to use layer=* for features that are not on separate levels.

Rendering

In Osmarender (version 4) bridges are drawn with a black outline ending in angled little stubs. The road is drawn on top as usual depending on its type. Mapnik uses a black outline for bridges.

See also

• Key:name - Name of bridge or road through the bridge
• Key:layer - specify the layering of your ways in special cases.
• Key:tunnel - as opposite for the bridge.
• Approved features/bridge - discussion and voting for extension of values
• Relations/Proposed/Bridges_and_Tunnels - group multiple bridge elements with a relation