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Should a *_link road be the same 'rank' as the most important road involved in the junction?
Or should it try to indicate the type of road that it leads to?

For example, if a trunk road has a one-way slip road off onto a primary road, then should that road be tagged as a "trunk_link", as it is a link from a trunk (and trunk road rules may still apply); or should it be a "primary_link", as it is a link to a primary road?

And should the link be marked with the ref of the road that it leads to, or just left blank?

asked 19 Jul '10, 11:30

GrahamS's gravatar image

accept rate: 28%

You should use the link type which reflects the set of rules that apply to that road. If the link is under motorway rules, use highway=motorway_link; if it's under trunk road rules (for your country) use highway=trunk_link, and so on. This is where the meaning in *_link highway types comes from.

If there's no explicit designation for a link road, you can deduce the rules in place from clues like where the speed limit changes, any roadside markings, or any other roadsigns (such as No Stopping) signs. It may not always be the designation for the higher of the two roads it connects.

The ref=* should be omitted unless the link road itself has a route reference.

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answered 19 Jul '10, 14:22

Jonathan%20Bennett's gravatar image

Jonathan Ben...
accept rate: 18%

edited 22 Sep '10, 23:43

Thanks. Indicating the rules of the road makes sense to me. I guess the remaining vagueness is where the rules don't change. i.e. In the UK there is no real difference between a trunk and primary (as used by OSM) so I think in that situation we may have to fall back on what looks the best.

(19 Jul '10, 20:44) GrahamS

The link should always be tagged with the "higher" link road class. So a connection between a motorway and a trunks gets motorway_link etc. The reason is not only that it looks better, it also reflects reality in that the "higher" the road class the more restrictions regarding the type of traffic there usually are. And on and off ramps must obviously have the same kind of restrictions as the main road. There are no bicycles allowed on the motorway on-ramp because it leads to a motorway that doesn't allow bicycles.

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answered 19 Jul '10, 14:46

Jochen%20Topf's gravatar image

Jochen Topf
accept rate: 31%

The rule has always been to use the highest classification - so a link road between a motorway and any other sort of road is motorway_link, a link road between a trunk road and anything that isn't a motorway is trunk_link and so on.

I don't normally apply a ref or name to a link road, but some people do.

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answered 19 Jul '10, 14:35

TomH's gravatar image

TomH ♦♦
accept rate: 20%


There's no consensus on whether to use the higher or lower classification. I personally use the higher if it's a complicated interchange but the lower if it's a simple intersection bypass. Other people always use the lower or the higher. Since the type of link (other than motorway_link, which comes with restrictions) has no real-world meaning, the only consideration is how it looks when rendered, and different people have different preferences.

In my opinion and experience, links should not be tagged with refs unless they actually carry a route. There's no benefit in adding the ref and the potential exists for confusion. But some countries may have a different default (I think Germany does include a ref; I'm not sure how they treat a link that splits for multiple roads).

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answered 19 Jul '10, 11:52

NE2's gravatar image

accept rate: 9%

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question asked: 19 Jul '10, 11:30

question was seen: 9,664 times

last updated: 22 Sep '10, 23:43

NOTICE: is no longer in use from 1st March 2024. Please use the OpenStreetMap Community Forum