Exit Info

This article or section may contain out-of-date information: Usage differs in newer Proposed features/Destination details, User:Minh Nguyen/destination:street, etc.
If you know about the current state of affairs, please help keep everyone informed by updating this information. (Discussion)

motorway_link tagging best practice

There are two methods to assign exit sign information into OpenStreetMap:

The collective node and way method - the exit sign information is stored on both nodes and ways
The node only method - all of the exit sign information is stored on a node

The preferred approach is the collective node and way method for the following technical reasons:

It can handle complex interchanges, as where a motorway_link and its associated reference number can split multiple times (such as 3A-B-C)
It handles turnoffs different from a country's standard without requiring tagging exceptions (e.g. a 'left' exit in right side driving countries), meaning it is easier for data consumers to be programmed for it
Associating the exit sign information with the *_link way clarifies route guidance
Data consumers Telenav and OsmAnd(+) both issue route guidance using node-and-way, and do not support node-only tags. A tool exists for OSRM installations to convert node-only tagging to node-and-way tagging.

node-and-way method

The exit sign information is stored on both nodes and ways as follows:

Node
key	value
highway	motorway_junction
ref	<junction/exit number> OR
noref	yes (if no reference number exists)
name	<Rarely used. Name of the indicated exit/interchange itself, not the exit's destination. Use destination tags for that, below.>

Way
key	value
highway	*_link
oneway	yes
destination	<toward location>
destination:ref (proposed)	<branch route number>
destination:ref:to (proposed)	<toward route number>
destination:street (proposed)	<branch road name>
destination:street:to (proposed)	<toward road name>
junction:ref	<junction/exit number> Best practice is to always use this tag on the link way.*
maxspeed:advisory	<safe exit speed> (Optional: populate when there is an advisory speed posted on ramp)
destination:symbol (proposed)	<motorist services> (Optional: populate when there are motorist services located at exit)

* junction:ref is recommended on all outbound junction points from a motorway, and should have the same value of ref=* on the node. While a node provides user-readable indicators of an exit's reference as indicated, junction:ref gracefully handles routing edge cases unambiguously, such as:

'left' exits in right-side-driving countries (and vice-versa)
Nodes where multiple exit references fork away from the same node

node-only method

All of the exit sign information is stored on the node where a link splits from the motorway as follows:

Node
key	value
highway	motorway_junction
ref	<junction/exit number>
name	<exit name>
exit_to	<branch route number/road name> and/or <toward route number/road name> and/or <toward location>

This method was popularized in the U.S. but is no longer recommended. This method is less structured than the node-and-way method and requires routers to rewrite exit_to as destination.

Definitions

Node
Node Term	Explanation
<junction/exit number>	The junction/exit number from the exit sign. Examples: 236, 11A, 51A-B
<exit name>	The exit name form the exit sign - this is not typical for most exits. Example from Pennsylvania Turnpike in the US: Gettysburg Pike

Way
Way Term	Explanation
<toward location>	The location(typically a city) that the exit/ramp/slip road will head toward
<branch route number>	The route number that the exit/ramp/slip road will branch onto
<toward route number>	The route number that the exit/ramp/slip road will head toward
<branch road name>	The road name that the exit/ramp/slip road will branch onto
<toward road name>	The road name that the exit/ramp/slip road will head toward
<junction/exit number>	Populate when a exit/ramp/slip road splits at a common node and has different junction/exit numbers Example: 51A (the node <junction/exit number> will have 51A-B)
<safe exit speed>	Populate when a exit/ramp/slip road has an advisory speed sign
<motorist services>	Populate when the exit/ramp/slip road has access to services motorist need

Examples

Canada

Québec

Node
key	value
highway	motorway_junction
ref	143

Way
key	value
highway	motorway_link
oneway	yes
destination	Saint-Valérien-de-Milton
destination:ref	211 Sud
junction:ref	143
maxspeed:advisory	45

United States

A/B split

The above exit sign information shall be added to OpenStreetMap as follows:

Node
key	value
highway	motorway_junction
ref	51A;51B

Southbound Way
key	value
highway	motorway_link
oneway	yes
destination	Carlisle;Lewistown
destination:ref	I 81 South;US 322 West
junction:ref	51A

Northbound Way
key	value
highway	motorway_link
oneway	yes
destination	Hazleton;Allentown
destination:ref	I 81 North
destination:ref:to	I 78
junction:ref	51B

Simple road name

This article or section may contain out-of-date information: Does not match usage in Exit_Info#Road_name below, with conflicting definition between User:Minh Nguyen/destination:street and Proposed features/Destination details.
If you know about the current state of affairs, please help keep everyone informed by updating this information. (Discussion)

The above exit sign information shall be added to OpenStreetMap as follows:

Way
key	value
highway	motorway_link
oneway	yes
destination:street	Derry Street

Road name

This article or section may contain out-of-date information: Contradictory usage between two directions.
If you know about the current state of affairs, please help keep everyone informed by updating this information. (Discussion)

The above exit sign information shall be added to OpenStreetMap as follows:

Node
key	value
highway	motorway_junction
ref	7B

Northbound Way
key	value
highway	motorway_link
oneway	yes
destination	Baltimore
destination:ref	MD 295 North
destination:street	Baltimore-Washington Parkway
junction:ref	7B
maxspeed:advisory	25 mph

At the next exit, tag:

Next exit node
key	value
highway	motorway_junction
ref	6

Next northbound way
key	value
highway	motorway_link
oneway	yes
destination	Linthicum
destination:ref	MD 170
destination:street	Camp Meade Road
junction:ref	6

Exit name

Exit names are usually found on toll roads. On guide signs, exit names look similar to road names. The above exit sign information shall be added to OpenStreetMap as follows:

Node
key	value
highway	motorway_junction
ref	236
name	Gettysburg Pike

Way
key	value
highway	motorway_link
oneway	yes
destination	Gettysburg;Harrisburg
destination:ref	US 15
maxspeed:advisory	25 mph
destination:symbol	hospital
junction:ref	236

Shared direction

This exit for northbound U.S. 67 and northbound U.S. 167 displays "North" only once, but destination:ref=* should contain "North" twice:

Node
key	value
highway	motorway_junction
ref	155

Way
key	value
highway	motorway_link
oneway	yes
destination	Jacksonville;Little Rock Air Force Base
destination:ref	US 67 North;US 167 North
junction:ref	155

Shared exit

This exit serves both eastbound and westbound State Route 4:

Node
key	value
highway	motorway_junction
ref	53

Way
key	value
highway	motorway_link
oneway	yes
destination	Pittsburg;Antioch;Martinez;Hercules
destination:lanes	Pittsburg;Antioch\|Martinez;Hercules
destination:ref	CA 4 East;CA 4 West
destination:ref:lanes	CA 4 East\|CA 4 West
junction:ref	53

A short distance later, the exit splits:

Subsequent node
key	value
highway	motorway_junction
noref	yes

Subsequent eastbound way
key	value
highway	motorway_link
oneway	yes
destination	Pittsburg;Antioch
destination:ref	CA 4 East

Subsequent westbound way
key	value
highway	motorway_link
oneway	yes
destination	Martinez;Hercules
destination:ref	CA 4 West

Unnumbered exit

This exit has no visible number signage. Unnumbered exits are common on controlled-access U.S. routes and state highways in many parts of the U.S., as well as on Interstate freeways in California.

Node
key	value
highway	motorway_junction
noref	yes
unsigned_ref	445B

Way
key	value
highway	motorway_link
oneway	yes
destination	Mill Valley;Stinson Beach
destination:ref	CA 1
junction:unsigned_ref	445B

Freeway entrance

destination=* can also be tagged on an on-ramp – a highway=motorway_link way leading to a motorway:

Way
key	value
highway	motorway_link
oneway	yes
destination	Pocatello
destination:ref	I 15 North

Issues

U.S. issues

Off-ramp/on-ramp way split

When adding interchange information to ways - please review the relationship of the interchange sign information and the connected ways. Sometimes a way will need to be split between an off ramp and an on ramp. Here is an example of when interchange information was added to a way that was both an off ramp and an on ramp:

Thus, leading to the following invalid on ramp directions:

The above way was split - here is the updated off ramp way:

Here is the updated on ramp with the proper interchange information ( destination and destination:ref):

The on ramp instruction will now be: Turn left to take the I 99 North/US 220 North ramp toward Tyrone.

This article is issued from Openstreetmap. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.