Km4City Urban Graph Representation

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Starting from the OSM data and the KM4City Ontology (http://www.disit.org/km4city/schema), the Graph is created. In this document some details are described.

A road network is a directed graph composed by arcs that meet at some nodes, corresponding to road junctions. The urban roads’ characteristics are stored in the OpenStreetMap database, for example:

Each road admits an initial node and an end node in order to determine the corresponding directed arc in the graph. In the following we consider an example.

 

Road 1 (labelled with OS00030031299SR, in OSM: https://www.openstreetmap.org/way/30031299):

 Road 2 (labelled with OS00026943048SR):

 Road 3 (labelled with OS00205385722SR):

 Road 4 (labelled with OS00509328804SR):

Listing the previous road-segments with their initial (nodeA, see the following table) and end node (nodeB, see the following table), the related road junction J (labelled with OS00330684306NO) is implicitly determined by means of the corresponding incoming and outcoming road-segments. In particular, the incoming road-segments in the road junction J are the road-segments having J as their end node, while the outcoming road-segments in the road junction J are the road-segments having J as their initial node (road details can be found in roadDetails.xlsx file coming from the ingestion process).

nodeA

segment

length

road

nodeB

OS01344583128NO

OS00030031299RE/4

4

OS00030031299SR

OS00330684306NO

OS00295213650NO

OS00026943048RE/5

8

OS00026943048SR

OS00330684306NO

OS00330684306NO

OS00205385722RE/0

29

OS00205385722SR

OS04985765666NO

OS00330684306NO

OS00509328804RE/0

3

OS00509328804SR

OS05200009916NO

 

Road Junction node (labelled with OS00330684306NO):

Moreover, further relations can be considered at the given junction (for example, representing the related turn restriction https://wiki.openstreetmap.org/wiki/Relation:restriction). In the example, no_right_turn restriction from road-segment labelled with 26943048 to road-segment labelled with 205385772 is considered.   

 

node

from

to

restriction

OS00330684306NO

OS00026943048RE/5

OS00205385722RE/0

no_right_turn

  

Mapping KM4city - OSM

The following aspects are at the basis of the street path description:

  • roads type (motorway, trunk, primary, secondary, tertiary, unclassified, residential, service),
  • number of roads lanes,
  • maximum flux permitted in the roads
  • turn restrictions
  • restricted traffic zone
  • speed limit
  • roads access restriction
  • bidirectional traffic roads
  • presence of designated lanes for public transport

 

In the following table it is possible to find the relation of these aspects with the Open Street Map Model

KM4City - Traffic model

OSM Model

Relevance

road type (motorway, trunk, primary, secondary, tertiary, unclassified, residential, service)

https://wiki.openstreetmap.org/wiki/Key:highway

 

high

roads lanes (number)

https://wiki.openstreetmap.org/wiki/Key:lanes

high

presence of designated lanes for public transport

 

https://wiki.openstreetmap.org/wiki/Key:lanes

public service vehicles (PSV)

(eg: Bus lanes, )

medium

maximum flux permitted in the roads

 

 

low (it is deduced by the traffic flow model from the road lanes)

turn restrictions

 

https://wiki.openstreetmap.org/wiki/Relation:restriction

high

restricted traffic zone

 

Ask to municipality (shape fiel or path)

high

speed limit

 

https://wiki.openstreetmap.org/wiki/Speed_limits

high

roads access restriction

 

https://wiki.openstreetmap.org/wiki/Key:access

High, if the restrictions are present in the roads (only for pedestrian, only for bikes, etc.)

bidirectional traffic roads

 

https://wiki.openstreetmap.org/wiki/Key:oneway

high (if the street is open in only one direction)

 

 

Crossing Roads in Km4city Knowledge Base

                                     
                                       

nodeA

g1

segment

length

dir

road

nodeB

g2

nALat

nALong

nBLat

nBLong

type

elemType

total_lanes

designated_lanes

forward_lanes

designated_forward_lanes

backward_lanes

designated_backward_lanes

OS01344583128NO

POINT(11.271626472473 43.763538360596)

OS00030031299RE/4

4

tratto stradale aperto nella direzione positiva (da giunzione NOD_INI a giunzione NOD_FIN)

OS00030031299SR

OS00330684306NO

POINT(11.271666526794 43.763565063477)

43,763538

11,27162647

43,76356506

11,27166653

primary

di tronco carreggiata

2

OS00295213650NO

POINT(11.271677017212 43.763496398926)

OS00026943048RE/5

8

tratto stradale aperto nella direzione positiva (da giunzione NOD_INI a giunzione NOD_FIN)

OS00026943048SR

OS00330684306NO

POINT(11.271666526794 43.763565063477)

43,763496

11,27167702

43,76356506

11,27166653

primary

di tronco carreggiata

2

OS00330684306NO

POINT(11.271666526794 43.763565063477)

OS00205385722RE/0

29

tratto stradale aperto nella direzione positiva (da giunzione NOD_INI a giunzione NOD_FIN)

OS00205385722SR

OS04985765666NO

POINT(11.27202129364 43.76354598999)

43,763565

11,27166653

43,76354599

11,27202129

tertiary

di tronco carreggiata

1

OS00330684306NO

POINT(11.271666526794 43.763565063477)

OS00509328804RE/0

3

tratto stradale aperto nella direzione positiva (da giunzione NOD_INI a giunzione NOD_FIN)

OS00509328804SR

OS05200009916NO

POINT(11.271676063538 43.763584136963)

43,763565

11,27166653

43,76358414

11,27167606

primary

di tronco carreggiata

2

Mapping in KM4City ontology (http://www.disit.org/km4city/schema)

Columns (referred to the previous table )

Km4City Ontology/KB

nodeA

dct:identifier of km4c:Node

g1

geo:geometry of km4c:Node

segment

dct:identifier of km4c:RoadElement

length

km4c:length of km4c:RoadElement

dir

km4c:trafficDir of km4c:RoadElement

road

dct:identifier of km4c:Road

nodeB

dct:identifier of km4c:Node

g2

geo:geometry of km4c:Node

nALat

geo:lat of km4c:Node

nALong

geo:long of km4c:Node

nBLat

geo:lat of km4c:Node

nBLong

geo:long of km4c:Node

type

km4c:highwayType of km4c:RoadElement

elemType

km4c:elementType of km4c:RoadElement

total_lanes

km4c:RoadElement -- km4c:lanes --> km4c:Lanes -- km4c:lanesCount --> km4c:LanesCount -- sum values on km4c:* properties, each of which takes its name to a type of vehicle or user category (e.g. km4c:taxy, km4c:emergency, km4c:psv, …, and km4c:undesignated for those lanes that can be traversed by any vehicle/user category) --> total_lanes 

designated_lanes

See the mapping for total_lanes, but exclude the value of km4c:undesignated from the count

forward_lanes

km4c:RoadElement -- km4c:lanes --> km4c:Lanes -- discard km4c:Lane resources that have km4c:direction set to something other than "forward"  --> km4c:Lanes of your interest  -- km4c:lanesCount --> km4c:LanesCount -- sum values on km4c:* properties, each of which takes its name to a type of vehicle or user category (e.g. km4c:taxy, km4c:emergency, km4c:psv, …, and km4c:undesignated for those lanes that can be traversed by any vehicle/user category) --> total_lanes 

designated_forward_lanes

See the mapping for forward_lanes, and also exclude the value of km4c:undesignated from the count

backward_lanes

km4c:RoadElement -- km4c:lanes --> km4c:Lanes -- discard km4c:Lane resources that have km4c:direction set to something other than "backward"  --> km4c:Lanes of your interest  -- km4c:lanesCount --> km4c:LanesCount -- sum values on km4c:* properties, each of which takes its name to a type of vehicle or user category (e.g. km4c:taxy, km4c:emergency, km4c:psv, …, and km4c:undesignated for those lanes that can be traversed by any vehicle/user category) --> total_lanes 

designated_backward_lanes

See the mapping for backward_lanes, and also exclude the value of km4c:undesignated from the count

 

Relations of interest

km4c:Road resources are linked to segments of road (each represented through a km4c:RoadElement resource) through the km4c:containsElement property

each km4c:RoadElement resource is linked to the km4c:Node resource that represents the point where the road element starts, through the km4c:startsAtNode property

each km4c:RoadElement resource is linked to the km4c:Node resource that represents the point where the road element ends, through the km4c:endsAtNode property

 

Namespaces of interest:

Prefix

Namespace

km4c

http://www.disit.org/km4city/schema#

dct

http://purl.org/dc/terms/

geo

http://www.w3.org/2003/01/geo/wgs84_pos#