# 2022 10 Use OSM to detect new cycleways

###### tags: `archive`

## 1. Get a current and a reference OSM snapshot

### Example of extraction of one municipallity
- Halle, 2020-01-01: http://overpass-turbo.eu/s/1n0i
- All of Flanders: similar but https://help.openstreetmap.org/questions/41137/overpass-turbo-without-map-rendering, something like this http://overpass-turbo.eu/s/1n0l (though it seems to require too much memory)

### Extraction of Belgium and selection of timestaps
- GeoFabrik download server: https://osm-internal.download.geofabrik.de/europe/belgium.html
- Filter with Osmium to extract specific timestamps. Blog post: https://pavie.info/2020/08/12/complete-full-history-osm/

## 2. Extract cycleways in the two datasets

References for tags:
- https://wiki.openstreetmap.org/wiki/Key:cycleway
- https://wiki.openstreetmap.org/wiki/Bicycle
- https://wiki.openstreetmap.org/wiki/Category:Cycleways

## Tags to be used

We make one categorie 'bicycle path', because considering and counting multiple categories could lead to count fluctuations due to tags changes.

We focus on:
* Cycle path part of the road (lane/track)
* Free cycle path
* Cycle streets

Difficult cases:
* Roads meant for cyclists
* Towpaths (jaagpaden): often tagged as cycleway, but not always

We think we shouldn't count:
* Fietssuggestiestroken (cycleway=shared_lane of sharrow)
* Shared buslanes
* Service roads (often parking roads)
* Woonerf, autoluwe weg

Note:
Some roads can "flip" from highway=cycleway to other road types.
* There is no tag on a road to say it is a cycle highway. It's possible to add the info from the cycle highway relations. We suggest NOT to do this, since these roads don't necessarilly have cycling infrastructure.
* Special category: [towpaths](https://wiki.openstreetmap.org/wiki/NL:Jaagpad)
* Paths that look like a cyclepath but lack signage. Usually they are marked with a C3 + exception fo bicycles (and mopeds). Sometimes there's an exception for residents/local traffic. [This is an extreme example](https://www.mapillary.com/app/?pKey=923788774856558), [tagging here](https://www.openstreetmap.org/way/558768856).
* Many roads belonging to the above categories are mapped as highway=path or highway=service or highway=track or highway=unclassified. But they could easily change to highway=cycleway. These are hard to exclude, unless you do geometric filtering of "only cycleways along roads" ([see below](https://hackmd.io/zzqBeXMOQ_GYH__ov5hfJw?both#Exclude-free-laying-cycleways-to-only-include-cycle-infrastructure-next-to-roads))

## Decided

| tag | note | weight |
| -- | -- | -- |
highway=cycleway | afzonderlijk fietspad | 2 (except if oneway=yes or -1, then 1)
cycleway | lane, track, opposite_lane | 2
cycleway:left | lane, track, opposite_lane | 1 (except if cycleway:left:oneway=no)
cycleway:right | lane, track, opposite_lane | 1 (except if cycleway:right:oneway=no)
cycleway:both | lane, track, opposite_lane | 1 (except if cycleway:right:oneway=no)

## To be validated

| tag | note | weight |
| -- | -- | -- |
highway=path + bicycle=yes/designated | "fietspad/fietsweg" in de volksmond, maar geen "officieel fietspad" | 2 (except if oneway=yes or -1, then 1)
highway=pedestrian + bicycle=yes/designated | voetgangersstraat waar je mag fietsen (maar dat kan eventueel overruled worden door bicycle:conditonal=no op bepaalde uren) | 2 (if oneway=yes or -1 and there is no bicycle:oneway=no; then 1)
highway=track + tracktype=grade1 + traffic_sign=F99c (en varianten) | sommige veldwegen zijn zeer fietsvriendelijk. Niet alles met dit bord heeft highway=track | 2 (if oneway=yes or -1 and there is no bicycle:oneway=no; then 1)
cyclestreet=yes | fietsstraat | 2 (if oneway=yes or -1 and there is no bicycle:oneway=no; then 1)
highway=service | heel wat jaagpaden | 2 (if oneway=yes or -1 and there is no bicycle:oneway=no; then 1)

## 3. Calculate the length by municipality in both snapshots

Tel de lengtes op van alle straten
* lengte 1 keer tellen
* eenrichtingsfietspad
* eenrichting weg, zonder uitzondering voor fietsen
* lengte 2 keer tellen
* fietspaden aan beide kanten:
* cycleway
* of zowel cycleway:right & *:right & *:both
* fietsstraten

Mind the assignment to municipality:
- Segments might extend beyond borders, so clipping is required
- Roads might follow the municipal border. Small changes in geometry can move a road entirely to one or the other municipality
- Prepare a reference layer of municipality borders to clip per municipality

# Optional follow up:

## Exclude free-laying cycleways to only include cycle infrastructure next to roads

The problem:
- `highway=*` + `cycleway=track` BETEKENT HETZELFDE als `highway=cycleway`. Maar dit heeft weinig impact op totale afstand. Te detecteren met tags als cycleway=separate of bicycle=use_sidepath . Dit heeft WEINIG impact op totale lengte, dus dit kunnen we negeren. Maar het heeft wél een impact als je de "fietspaden bij een weg" afzonderlijk wilt bekijken. Eigenlijk heb je ene ruimtelijke analyse nodig om highway=cycleway die "horen bij een autoweg" afzonderlijk te behandelen

Possible solution: use buffers to check if there is a road nearby.

## Make a visual inspection tool

- Plot both snapshots
- Compute their difference using buffer and difference algorithms, and plot the differences

# Tools

Open source tools could include osmnx or pyrosm

# Similar methods found elsewhere

https://ecfbrussel-my.sharepoint.com/:w:/g/personal/e_denneman_ecf_com/EWReUiGetMZPuMI_l6JrVRsBsu_F1WR7BAdqINEkxNZsSw?rtime=jRzBmlW22kg
We are asking them for their source code for this project.