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5. Get OSM data

Source: vignettes/osm.Rmd
osm.Rmd

Introduction

OpenStreetMaps (OSM) is an important data source for transit analysis, due to its rich, open, and detailed geographic data. GTFShift includes some methods that allow to access its information directly.

Download bus lanes

Dedicated bus lanes can improve bus transit operation. Understanding their spatial distribution is important to study operation dynamics. osm_bus_lanes allows to obtain the bus lanes network on OpenStreetMaps for a given area.

aml = sf::st_read("https://github.com/U-Shift/MQAT/raw/refs/heads/main/geo/MUNICIPIOSgeo.gpkg", quiet = TRUE)
lisboa = aml |> dplyr::filter(Concelho == "Lisboa") |> sf::st_bbox()

bus_lanes = GTFShift::osm_bus_lanes(lisboa) |> select(osm_id)
mapview::mapview(bus_lanes, layer.name = "Bus lanes")

Get centerlines for OSM road network

Performing an aggregated analysis for the spatial distribution of the route frequencies might be easier if the routes are projected over a simplified road network (refer to vignette(“analyse”) for more details).

GTFShift::osm_centerlines() allows to generate this simplification by creating the centerlines for the road network exported from OpenStreetMaps, using Python neatnet package.

Original network 

library(osmdata)

road_osm = opq("Arroios, Lisboa, Portugal") |>
    add_osm_feature(key = "highway", value = c("motorway", "trunk", "primary", "secondary", "tertiary", "residential", "unclassified", "living_street")) |>
    add_osm_feature(key = "area", value = "!yes") |>
    osmdata_sf() |>
    osm_poly2line()

road_osm = road_osm$osm_lines
mapview::mapview(road_osm)

Simplified network 

centerlines = GTFShift::osm_centerlines(place="Arroios, Lisboa, Portugal")
#> Using Python: /usr/bin/python3.12
#> Creating virtual environment '~/.virtualenvs/r-reticulate' ...
#> Done!
#> Installing packages: pip, wheel, setuptools
#> Installing packages: numpy
#> Virtual environment '~/.virtualenvs/r-reticulate' successfully created.
#> Using virtual environment '/home/runner/.virtualenvs/r-reticulate' ...
mapview::mapview(centerlines)

Get OSM bus routes

OpenStreetMaps defines bus routes as a relation of ways (usually roads) and nodes (stops and platforms). GTFShift provides methods to use them in the GTFS analysis.

For demonstration purposes, the next snippets will use the Lisbon urban bus network.

# Get GTFS from library GTFS database for Portugal
data = read.csv(system.file("extdata", "gtfs_sources_pt.csv", package = "GTFShift"))
gtfs_id = "lisboa"
gtfs = GTFShift::load_feed(data$URL[data$ID == gtfs_id], create_transfers=FALSE)

# Build OSM query
library(osmdata)
q = opq("Lisbon")  |>
  add_osm_feature(key = "route", value = c("bus", "tram")) |>
  add_osm_feature(key = "network", value = "Carris", key_exact = TRUE)

Matching GTFS ids

GTFS routes shapes and OSM bus routes are linked through OSM gtfs:* keys. GTFShift::osm_shapes_to_routes() and GTFShift::osm_trips_to_routes() allow to query OSM for the routes matching the feed trips, given, respectively, their shape or trip id.

# Subset feed for some routes only, for demonstration purposes
gtfs_794 = GTFShift::filter_by_route_name(gtfs, list("794"))

# Match shapes geometry
shapes_geometry_osm = GTFShift::osm_shapes_to_routes(gtfs_794, q)

shapes_geometry_osm
#> Simple feature collection with 2 features and 2 fields
#> Geometry type: MULTILINESTRING
#> Dimension:     XY
#> Bounding box:  xmin: -9.133896 ymin: 38.70714 xmax: -9.099827 ymax: 38.76858
#> Geodetic CRS:  WGS 84
#> # A tibble: 2 × 3
#>   shape_id       osm_id                                                 geometry
#>   <chr>          <chr>                                     <MULTILINESTRING [°]>
#> 1 115_0_ASC_shp  15470713 ((-9.13309 38.70745, -9.133067 38.70747), (-9.133067 …
#> 2 115_0_DESC_shp 15470712 ((-9.099841 38.76819, -9.09986 38.76797, -9.099882 38…

GTFS shapes 

shapes_sf = tidytransit::shapes_as_sf(gtfs_794$shapes)
mapview::mapview(shapes_sf, zcol = "shape_id", legend = TRUE, layer.name="GTFS shapes")

OSM routes 

mapview::mapview(shapes_geometry_osm, zcol = "shape_id", legend = TRUE, layer.name="OSM routes")

Matching shapes geometry

Despite existing, OSM gtfs:* keys are not widely used. In July 2025, only 3.1% of relations tagged as route=bus had the gtfs:shape_id key set (9 784 of 312 049).

To overcome this issue, GTFShift::osm_shapes_match_routes() performs the association between the OSM bus routes and the GTFS shapes considering, for each route, the start and end points and total length.

GTFShift provides a test script that runs this method for several cities around the world at dev/test_osm_shapes_match_routes_local.R.

# Subset feed for some routes only, for demonstration purposes
gtfs_subset = GTFShift::filter_by_route_name(gtfs, list("736", "750", "15E", "65B"))

# Match shapes geometry
shapes_match_routes = GTFShift::osm_shapes_match_routes(gtfs_subset, q)
#> > Found 14 GTFS shapes and 229 stops
#> > Found 300 OSM route relations and 4900 bus stops/platforms
#> > Associated 14 shapes (100.00% of 14 total) of 8 routes (100.00% of 8 total) with OSM routes, with a mean distance of 25.68 meters for points, 32.32 meters for route length and a mean difference of 0.43 stops
#> > Of those, 14 shapes (100.00% of 14 matched) have a distance difference below 1000 meters, a points difference below 500 meters

summary(shapes_match_routes)
#>    route_id           shape_id            osm_id          distance_diff   
#>  Length:14          Length:14          Length:14          Min.   : 5.099  
#>  Class :character   Class :character   Class :character   1st Qu.:20.775  
#>  Mode  :character   Mode  :character   Mode  :character   Median :30.866  
#>                                                           Mean   :32.319  
#>                                                           3rd Qu.:40.804  
#>                                                           Max.   :72.802  
#>   points_diff       stops_diff     route_short_name   route_long_name   
#>  Min.   : 7.965   Min.   :0.0000   Length:14          Length:14         
#>  1st Qu.:13.605   1st Qu.:0.0000   Class :character   Class :character  
#>  Median :22.481   Median :0.0000   Mode  :character   Mode  :character  
#>  Mean   :25.683   Mean   :0.4286                                        
#>  3rd Qu.:37.835   3rd Qu.:1.0000                                        
#>  Max.   :49.602   Max.   :1.0000                                        
#>             geometry 
#>  MULTILINESTRING:14  
#>  epsg:4326      : 0  
#>  +proj=long...  : 0  
#>                      
#>                      
#> 

# Visualize results
shapes_match_routes$map_name = paste(
  shapes_match_routes$route_short_name,
  " | ",
  shapes_match_routes$shape_id, 
  " | ", 
  shapes_match_routes$osm_id
)
mapview::mapview(shapes_match_routes, zcol = "map_name", legend = TRUE, layer.name="route_short_name | shape_id | osm_id")

Updating OSM routes with shape_id

The association between OSM route relations id and the GTFS shapes_id returned by GTFShift::osm_shapes_match_routes() can be used to update OpenStreetMaps data. Refer to Extra. Update OSM data for more details.

Validating OSM routes

The warning logs displayed by GTFShift::osm_shapes_match_routes() can be used to validate the OSM routes, identifying shapes without a match, or even OSM existing routes that violate OSM integrity rules, such as having stops in the wrong order.