Proposed features/Motorway indication

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Motorway indication
Status: Abandoned (inactive)
Proposed by: Vid the Kid
Tagging: motorway=yes(/substandard/no)
Applies to: ways
Definition: Tagging for lesser roads which are physically motorways, but whose functional roles indicate different highway=* choices
Rendered as: Just like highway=motorway but with slightly lighter colors
Drafted on: 2010-07-13
RFC start: 2010-07-14
Vote start: *
Vote end: *

Proposal

As an alternative to highway=motorway, roads which have the physical characteristics of a freeway/motorway can be tagged motorway=yes in addition to some other highway=*. This is particularly useful for roads that aren't very long or serve fairly minor purposes, but physically are motorways. Highways that are a part of some official network of motorways (Such as the UK's M roads, Quebec's Autoroutes, and the Interstates in the US) should continue to be tagged highway=motorway and be unaffected by this proposal.

Additionally, motorway=substandard can indicate that a road is a motorway, but is older and has many geometric deficiencies that would not be present in a modern design.

Finally, motorway=no can indicate that a road, tagged highway=motorway for reasons of official designation, is not physically a motorway. (This combination should be limited to exceptionally rare cases.)

Note that this proposal may affect what highway=* value is used in some cases, and an enhancement to rendering is recommended. Changes to tagging per this proposal which may be made before the renderer is updated may result in a few cases of maps that "look wrong", but are still usable. Therefore, I consider this proposal to be partially backwards-compatible. Practical implementation of the proposal may be gradual.

Rationale

There seems to be a prevailing philosophy, expressed on this wiki and in the OpenStreetMap data, that highway=* should indicate a roadway's role in the greater highway network, and that a road's physical characteristics should be expressed in other tags. Considering motorway nature to be a physical characteristic, I propose this new tag. Along with Proposed features/Expressway indication, this separation of form and function can be made complete.

Examples

highway!=motorway + motorway=yes

Note, the exact selection of highway=* values here are debatable and mostly irrelevant to this proposal.

  • Short motorway sections of routes that generally aren't motorways:
  • Airport access roads:
    • Port Columbus International Airport's main entrance road (International Gateway) consists of a short freeway spur from I-670 and an expressway-grade loop; the freeway portion could be tagged highway=secondary+motorway=yes.
    • Dayton International Airport's main entrance road consists of a short freeway spur from I-70 and a surface loop; the freeway portion could be tagged highway=secondary+motorway=yes.
  • Vestigial motorway spurs that have been superseded by newer motorways:
  • Possibly, any non-Interstate freeway in the US could be demoted from highway=motorway (to what, depends on the situation) and have motorway=yes added. Whether to do so would fall under the jurisdiction of US guidelines for the highway=* tag, but with this proposal, the option to distinguish Interstates from non-Interstate freeways exists. Similar distinctions can be made for other motorway-network systems in other countries.

motorway=substandard

  • Portions of Business I-40 and Business I-85 in Winston-Salem and Greensboro, North Carolina. (There's a reason NCDOT re-routed those...)
  • Autostrada A3 in Italy.

highway=motorway + motorway=no

Interstate 180 in Cheyenne, Wyoming is actually an expressway and not a freeway. But since it is officially an Interstate, highway=motorway+motorway=no might make sense. Maybe even expressway=yes...

Implied tags

highway=motorway implies motorway=yes.

motorway=yes and motorway=substandard imply:

Useful combinations

Applies to

  • ways (roads, also tagged highway=*)

Rendering

Roads tagged with motorway=yes or motorway=substandard, in combination with highway=trunk, highway=primary, highway=secondary, or highway=tertiary, should be rendered very similar to highway=motorway but with lighter shades of blue for the core and casing. These roads should be visible (or not visible) at the same zoom levels as if they did not have a motorway=* tag. The combination highway=motorway+motorway=yes should be rendered exactly like ordinary highway=motorway.

Rendering of motorway=substandard could be done a few different ways:

  • Treat it like motorway=yes for rendering purposes.
  • Treat it like motorway=yes for the basic line, but overlay some kind of dashed or dotted line over the core in some non-clashing color.
  • Same as motorway=yes, but with a thinner line (somewhere between standard highway=motorway and highway=motorway_link).
  • Same as motorway=yes, but with a thinner core and thicker casing, so the total width is the same.
  • Draw a line with the same core and casing widths as highway=motorway, but in much less saturated shades of blue. The colors used may or may not vary based on whether highway=motorway or not.

Rendering of the combination highway=motorway+motorway=no could be:

  • Identical to highway=trunk (ideally, including casing color variation according to expressway=yes if present).
  • Open to more suggestions...

Illustrations of these possibilities may come at a later time.

Routing

Routing applications should take note of motorway=yes and motorway=substandard, as well as highway=motorway without motorway=no (and possibly expressway=yes). Generated routes should probably not start or end directly on roads tagged this way, though in some cases this may be desired. Certainly, when determining the nearest-point-on-road to a geocoded address, roads with these tags are to be excluded from the search. (Buildings located next to a motorway or expressway are typically not accessed directly from that motorway or expressway.)

Comments

Please use the discussion page for comments.

Tagging

Tag Description Notes Photo
highway=* The functional role played by the road in the greater highway system. Don't omit this; motorway=* is meaningless without it.
motorway=yes The road is a freeway/motorway. Implied by highway=motorway. None yet.jpg
motorway=substandard The road is a substandard freeway/motorway. None yet.jpg
motorway=no The road is not a freeway/motorway. It might be an expressway (expressway=yes) or a conventional road. Implied by highway=* other than motorway. None yet.jpg

See Also

Voting

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