Kerb Heights - When "Lowered" becomes "Raised"

[UW_Amy_Bordenave (Amy Bordenave)]

Central Question: At what height does a curb (kerb) go from being a kerb=lowered to a kerb=raised?

“Height” here refers to the “lip height” - the difference in elevation between the last point on the roadway and the first point on the curb, not the difference in elevation between the last point on the roadway and first point on the top landing or sidewalk.

Proposed Wiki Edit: On Key:kerb, in the table in the Values section, change “Typical height” for lowered from ~3 cm → ≲3 cm (or ⪅3 cm, or whatever best conveys “Less than or equal to approximately three centimeters or one inch”)

Previous Discussions

1. OSM Forum: How do I tag normal-height kerbs?
2. OSM Wiki: Talk:Key:kerb
3. OSM Wiki: Proposal:kerb=regular
4. OSM World Discord: “What happened to kerb=regular?”

Resources

1. (ADA) United States Access Board “Guide to the ADA Accessibility Standards” Chapter 4, section “Transition to Street”

5. (PROWAG) United States Access Board “Public Right-of-Way Accessibility Guidelines” Chapter R3, section “Changes in Level”

Changes in level of ¼ inch (6.4 mm) maximum shall be permitted to be vertical. Changes in level between ¼ inch (6.4 mm) and ½ inch (13 mm) shall be beveled with a slope not steeper than 1:2 (50.0%). Changes in level greater than ½ inch (13 mm) up to 6 inches shall have a 1:12 (8.3%) maximum slope.

[UW_Amy_Bordenave (Amy Bordenave)]

@A35K shared the following images (self-annotated screenshots from Apple Look Around) in the recent OSM World Discord discussion which serve as helpful examples:

---

@LordGarySugar shared a UK perspective:

some thought should be given to change the focus of ‘raised’ description [on the Wiki] away from specifically bus stops […] many average height kerbs at the edge of roads (sometimes where a footway might join a road not at a crossing) actually should be included in this raised category

[A35K]

I agree with LordGarySugar´s perspective, the Wiki page makes it sound like kerb=raised is for the raised kerbs at bus stops and not the regular (less-)raised kerbs, it should be worded differently.

[0235]

For me, My point of view comes from a pedestrian and crossing point of view, where they are a navigational aid, more than an “edge of the carriageway barrier”. Most of my tagging for Kerbs also comes from street complete, Which handles raised and lowered kerbs a bit better (though also has a fake “a little bit higher” answer). This has likely swayed my influence a bit for not having the same confusion.

Any Kerb that intentionally deviates from the height of the surrounding kerb down to meet the height of the surrounding area (and also gets very close) should be “lowered”. I think that 3cm is still too tall. Would it hurt if i wheeled my suitcase over it?

I find “flush” and “no” quite well defined.

However, I do agree with some of the confusion around “Raised”. Where I live, Kerbs do not raise up at bus stops, they don’t even have tactile paving. The height of the Kerbs are pretty standard, even many places with pedestrian crossings with no lowered section. This means the standard is just “raised”. I can understand the confusion around Bus Stops, or areas of easy access for level boarding on trams.

Think of a 2 floor mansion vs a 2 floor cottage. The thing that really makes a difference is a specific height tag… but like cottages and mansions, people don’t like you poking around with a tape measure. And kerbs for roads can be dangerous.

Though raised Kerbs on bus stops etc. is implied as assistance rather than an obstacle for people with mobility issues. There doesn’t seem to be an industry term for these though. Bus Stop Kerb, Access Kerb, Boarding Kerb…

I think what i mean to say is, I have little to no input, and it is a shame the “regular” Kerb never really took off and got approval, and that the “bus stop” kerb was forced into the “Kassel kerb”, Which I have also never seen, and ignores trams, taxis, trams, which might have sections with extra height.

[dieterdreist (Martin Koppenhöfer)]

I believe we should have more classes for higher kerbs. Currently the upper end is raised kerb for everything above 3cm.

Regular kerbs are around 10-15cm and there are also higher kerbs like 20-25cm which better protect pedestrians from vehicles. I am not a wheelchair user myself but I expect that there is still a huge difference between a kerb of 4 or 6cm and one of 14 or even 25cm, and it is worth storing this information, today, they would all be “raised”.

[0235]

Apparently about 2 million kerbs are mapped, most lowered, and only 3% have a height tag associated with them.

I think being able to highlight these different types of Kerbs will let people focus more on exact measurements later.

Kerb mapping seems to be on a sharp rise in the past few years, mainly focused around crossings.

[Kovoschiz]

How I interpret it, the “raised” is relative for wheelchair= , compared to =lowered being traversable. =regular / =normal / etc doesn’t work universally as it depends on the region, and can even change along time.
There’s ~100 kerb*=high that I prefer for such higher kerbs. It would further be more specific to have eg =low_floor vs =high_floor to clearly show some are designed for buses.

[Nadjita]

@UW_Amy_Bordenave

Central Question: At what height does a curb (kerb) go from being a kerb=lowered to a kerb=raised?

For me, lowered means “lower than the regular kerb used here”, and raised is the actual “regular kerb”. It’s not about an absolute height. Of course, some roads have only lowered kerbs, that doesn’t make them regular. I would argue that the most important reason for having lowered kerbs is that cars and wheelchairs could traverse them without (major) problems, while “raised” kerbs would be impossible for a wheelchair user.

@Kovoschiz

It would further be more specific to have eg =low_floor vs =high_floor to clearly show some are designed for buses.

I’m not a native speaker, but aren’t these called “high access” / “low access” kerbs? Our city sometimes uses high access kerbs to prevent people from parking on the pavement, because they are significantly higher. There’s also “Kassel kerbs” which are what we tag with kerb:approach_aid=yes.

The one thing I’m also missing is the full height kerb with diagonal cut. Cars can go over it, even though it has full height. It’s horrible to use on a bike, which is, why I think it should be neither lowered, not raised.

[ManuelB701 (Manuel B.)]

The way kerb=* is used right now is that it tells you the kerb’s shape alongside the relative height (consider the existence of kerb=rolled which doesn’t tell you much about the kerb height). kerb=raised is therefore an edgy stone, a step, while kerb=lowered might be a kerb cut or a kerb which is traversable with smaller wheels (may or may not be slightly sloped)

Thus, we’d ideally measure it out exactly and use (kerb:)height but this certainly isn’t possible because not everyone has a ruler, measure tape or something.