Proposal:Incline:across
| Tag for lateral inclination | |
|---|---|
| Proposal status: | Draft (under way) |
| Proposed by: | species |
| Tagging: | incline:across=x % |
| Applies to: | |
| Definition: | specifies lateral inclination of a way |
| Statistics: | |
| Draft started: | 2014-06-08 |
| RFC start: | * |
| Vote start: | * |
| Vote end: | * |
Across Incline
similar to incline=*, the proposed key incline:across describes lateral inclination, see Cross Slope on Wikipedia.
Cross slope is crucial for wheelchair routing, as (especially electric) wheelchairs are prone to slip sidewards if the lateral incline is greater than 2.5%.
The key “incline:across“ has be chosen to be in line with the incline=*-tag.
incline:across=* is already in use by some wheelchair-routing projects, like Namo in Germany and Access2Life in Austria.
Usage
On ways
Split the way at the ends of the lateral inclined section and add a tag incline:across=value% on the way with values as given below. The value should be given for the practical maximum lateral incline on the steep section (i.e., the maximum lateral incline that a vehicle/primary user could achieve), and not for the average incline between the nodes.
Most occurences of this tag are on highway=footway, footway=sidewalk where a user wants to inform wheelchair users of the risk of slipping sidewards.
On nodes
The use of this tag has limited (if any) usage, as nodes do not have a direction.
Values
The incline is most commonly given as percentage values (postfixed with a percent sign, %), e.g. incline:across=7%. Degree-values should only be used where they are common (postfixed with a degree sign, °), e.g. incline:across=10°.
Positive values indicate movement downwards to the right side, looking in the direction of the way and negative values indicate movement downwards to the left side, looking in the direction of the way (similar to natural=cliff)
Relationship between percent and degree values
A percentage value gives, when multiplied by the horizontal distance travelled, the corresponding vertical distance. That is, a value of 2% (the compulsory lateral inclination for a sidewalk to allow the water to drain) would indicate a 2 cm vertical gain on the width of 1 m.
Note that a 10° incline is not the same as a 10% incline. A 10° incline is actually a 17.63% incline, and a 10% incline is actually a 5.71° incline. Values can be converted as follows:
<incline in %> = tan(<incline in °>) * 100
<incline in °> = arctan(<incline in %> / 100)
Rendering
- JOSM: in Style “Wheelchair Routing Attributes” - this is shown as a colored slope symbol across a way
See Also
- incline=*