                                OpenStreetMap Tagging
                                =====================

   The different tags that are used by the router software are described
   below.


Node Tags
---------

   The only node tags that are used are the id, latitude and longitude of
   the node. The id tag is required to associate the node with the ways
   and the position tags are not tags in the normal sense.


Way Tags
--------

   The tags from the ways in the data are the ones that provide most of
   the information. The id tag is used only so that the segments can be
   associated with a way.


The highway Tag

   The most important tag that is used from a way is the highway tag. This
   defines the type of highway that the way represents. Any way that does
   not have a highway tag is discarded.

   There are more highway types defined than are used by the router. The
   subset that the router uses are:
     * motorway
     * trunk
     * primary
     * secondary
     * tertiary
     * unclassified
     * residential
     * service
     * track
     * cycleway
     * path (1)
     * steps (2)

   Note 1: This has changed in version 1.3 of Routino - the bridleway and
   footway types have been included within the path highway type. This
   change is to reduce confusion over multiple highway types that are
   likely to be physically indistinguishable.
   Note 2: This has changed in version 1.3 of Routino - the steps type has
   been separated from the footway type.

   The other highway types are assumed to be equivalent to one of the
   types listed above according to the table below.

   Highway type  Equivalent type
   bridleway     path
   byway         track
   footway       path
   living_street residential
   minor         unclassified
   pedestrian    path
   road          unclassified
   services      service
   unsurfaced    track
   unpaved       track
   walkway       path


The access Tag

   The access tag is used to specify the default access restrictions on
   the way.

   If the access tag is set to one of the values true, yes, 1, permissive,
   designated or destination then the normal default access permissions
   apply. If the access tag is set to any other value then the default
   setting for the way is set to no types of transport.

   The default value of the access permissions depend on the type of
   highway. The default assumptions are as shown in the table below.

     Highway    foot horse  wheelchair bicycle moped motorbike motorcar goods hgv psv
   motorway     no   no     no         no      no    yes       yes      yes   yes yes
   trunk        no   no     no         yes     yes   yes       yes      yes   yes yes
   primary      yes  yes    yes        yes     yes   yes       yes      yes   yes yes
   secondary    yes  yes    yes        yes     yes   yes       yes      yes   yes yes
   tertiary     yes  yes    yes        yes     yes   yes       yes      yes   yes yes
   unclassified yes  yes    yes        yes     yes   yes       yes      yes   yes yes
   residential  yes  yes    yes        yes     yes   yes       yes      yes   yes yes
   service      yes  yes    yes        yes     yes   yes       yes      yes   yes yes
   track        yes  yes    yes        yes     no    no        no       no    no  no
   cycleway     yes  no     yes        yes     no    no        no       no    no  no
   path         yes  yes(1) yes        yes(1)  no    no        no       no    no  no
   steps        yes  no     yes        no      no    no        no       no    no  no

   Note 1: A path allows bicycle or horse access by default only if
   actually labelled as a "bridleway".
   Note 2: A wheelchair is allowed anywhere that foot access is allowed
   unless the wheelchair is explicity disallowed.

   In addition to the access tag there is also one tag for each of the
   different modes of transport: foot, horse, bicycle, wheelchair, moped,
   motorbike, motorcar, goods, hgv and psv. If one of these tags is
   present and the value is set to one of true, yes, 1, permissive,
   designated or destination then that particular transport type is
   allowed (even if the generic access tag says that it is not). If the
   tag is present but not one of the values above then it is assumed that
   the particular form of transport is forbidden. A tag named vehicle
   means any of the above transport types that have wheels (except
   wheelchair) and motor_vehicle is any vehicle except a bicycle.

   For example a highway that has the tags: highway=service,
   service=driveway, access=private, foot=designated is a private driveway
   that has a public footpath running along it (not uncommon in the UK).


The bridge Tag

   The bridge tag is used to identify whether a highway is a bridge and
   therefore set one of the available properties.


The designation Tag

   The designation tag is used as an alternative method of identifying the
   legal right of way on a path. The values recognised are bridleway,
   byway and footpath which equate to the following permissions:

   Designation tag             Equivalent access permissions
   bridleway       foot=designated, horse=designated, bicycle=designated
   byway           foot=designated, horse=designated, bicycle=designated
   footpath        foot=designated


The name Tag

   The name tag is used to provide the label for the highway when printing
   the results.


The ref Tag

   The ref tag is used to provide the label for the highway when printing
   the results.


The junction Tag

   The junction tag is used to check if a highway is (part of) a
   roundabout. This tag is used for information to label the highway if no
   other name is provided.

   In addition to providing the label for the highway the presence of the
   junction=roundabout tag also implies the highway is oneway.


The lanes Tag

   The lanes tag is used to identify whether a highway has multiple lanes
   for traffic or not (the number of lanes is not important in this case,
   only whether it is more than one) this sets one of the highway
   properties.

   In the absence of a lanes tag only the motorway highway type is assumed
   to have multiple lanes.


The surface Tag

   The surface tag is used to identify whether a highway is paved or not,
   this is one of the available highway properties.

   In the absence of a surface tag the following highway types are assumed
   to be paved: motorway, trunk, primary, secondary, tertiary,
   unclassified, residential, service or cycleway.

   If there is a surface tag then the highway is assumed to be unpaved
   unless the tag value matches one of the following: paved, asphalt or
   concrete.

   Support for the obsolete paved tag is also provided and the highway is
   paved if this is set to one of true, yes or 1.


The oneway Tag

   The oneway tag is used to specify that traffic is only allowed to
   travel in one direction. When tagging it is important to make sure that
   the direction that traffic is allowed follows the order of the nodes in
   the way.

   One additional assumption is that if a highway is a motorway then it
   implies that the highway is also oneway.


The maxspeed Tag

   The maxspeed tag is used to specify the maximum speed limit on the
   highway; this is always measured in km/hr in OpenStreetMap data. If the
   tag value contains "mph" or the tag name is actually maxspeed:mph then
   it is assumed to be a value in those units and converted to km/hr.


The maxweight Tag

   The maxweight tag is used to specify the maximum weight of any traffic
   on the way. In other words this must be set to the heaviest weight
   allowed on the way (for example a bridge) in tonnes.


The maxheight Tag

   The maxheight tag is used to specify the maximum height of any traffic
   on the way. In other words this must be set to the lowest height of
   anything above the way (like a bridge) in metres. If the tag value
   contains a measurement in feet or feet and inches then attempts are
   made to convert this to metres.


The maxwidth Tag

   The maxwidth tag is used to specify the maximum width of any traffic on
   the way. This must be set to the minimum width of the contraints at the
   wayside in metres. If the tag value contains a measurement in feet or
   feet and inches then attempts are made to convert this to metres.


The maxlength Tag

   The maxlength tag is used to specify the maximum length of any traffic
   on the way (usually from a traffic sign) in metres. If the tag value
   contains a measurement in feet or feet and inches then attempts are
   made to convert this to metres.


The tunnel Tag

   The tunnel tag is used to identify whether a highway is a tunnel and
   therefore set one of the available properties.


Relation Tags

   Currently no relation tags are used.


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Copyright 2008,2009,2010 Andrew M. Bishop.
