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 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 * path * bridleway * cycleway * footway 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 byway track living_street residential minor unclassified pedestrian footway road unclassified services service steps footway unsurfaced track unpaved track walkway footway CAPTION: Aliasing of equivalent highway types The second important thing that can be taken from the highway tag is the type of tansport that is allowed to use the highway. The list can be modified depending on other tags, but the default assumptions are as shown in the table below. Highway foot bicycle horse motorbike motorcar goods hgv psv motorway no no no yes yes yes yes yes trunk yes no no yes yes yes yes yes primary yes yes yes yes yes yes yes yes secondary yes yes yes yes yes yes yes yes tertiary yes yes yes yes yes yes yes yes unclassified yes yes yes yes yes yes yes yes residential yes yes yes yes yes yes yes yes service yes yes yes yes yes yes yes yes track yes yes yes no no no no no path yes yes yes no no no no no bridleway yes yes yes no no no no no cycleway yes yes no no no no no no footway yes no no no no no no no CAPTION: Default assumption about allowed transport on different highway types The type of highway and the method of transport chosen for routing together define a default maximum speed limit. One additional assumption is that a motorway implies that the highway is also oneway. 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 or designated then the normal access permissions above 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. In addition to the access tag there is also one tag for each of the different modes of transport: foot, bicycle, horse, 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 or designated 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 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 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 only 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 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. 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. Relation Tags Currently no relation tags are used. -------- Copyright 2008,2009 Andrew M. Bishop.