detailed_itineraries: Detailed itineraries between origin-destination pairs

In r5r: Rapid Realistic Routing with 'R5'

Detailed itineraries between origin-destination pairs

Description

Returns detailed trip information between origin-destination pairs. The output includes the waiting and moving time in each trip leg, as well as some info such as the distance traveled, the routes used and the geometry of each leg. Please note that this function was originally conceptualized as a trip planning functionality, similar to other commercial and non-commercial APIs and apps (e.g. Moovit, Google's Directions API, OpenTripPlanning's PlannerResource API). Thus, it consumes much more time and memory than the other (more analytical) routing functions included in the package.

Usage

detailed_itineraries(
  r5r_core,
  origins,
  destinations,
  mode = "WALK",
  mode_egress = "WALK",
  departure_datetime = Sys.time(),
  time_window = 10L,
  suboptimal_minutes = 0L,
  fare_structure = NULL,
  max_fare = Inf,
  max_walk_time = Inf,
  max_bike_time = Inf,
  max_car_time = Inf,
  max_trip_duration = 120L,
  walk_speed = 3.6,
  bike_speed = 12,
  max_rides = 3,
  max_lts = 2,
  shortest_path = TRUE,
  all_to_all = FALSE,
  n_threads = Inf,
  verbose = FALSE,
  progress = FALSE,
  drop_geometry = FALSE,
  output_dir = NULL
)

Arguments

r5r_core	An object to connect with the R5 routing engine, created with setup_r5().
origins, destinations	Either a ⁠POINT sf⁠ object with WGS84 CRS, or a data.frame containing the columns id, lon and lat.
mode	A character vector. The transport modes allowed for access, transfer and vehicle legs of the trips. Defaults to WALK. Please see details for other options.
mode_egress	A character vector. The transport mode used after egress from the last public transport. It can be either WALK, BICYCLE or CAR. Defaults to WALK. Ignored when public transport is not used.
departure_datetime	A POSIXct object. Please note that the departure time only influences public transport legs. When working with public transport networks, please check the calendar.txt within your GTFS feeds for valid dates. Please see details for further information on how datetimes are parsed.
time_window	An integer. The time window in minutes for which r5r will calculate multiple itineraries departing each minute. Defaults to 10 minutes. If the same sequence of routes appear in different minutes of the time window, only the fastest of them will be kept in the output. This happens because the result is not aggregated by percentile, as opposed to other routing functions in the package. Because of that, the output may contain trips departing after the specified departure_datetime, but still within the time window. Please read the time window vignette for more details on how this argument affects the results of each routing function: vignette("time_window", package = "r5r").
suboptimal_minutes	A number. The difference in minutes that each non-optimal RAPTOR branch can have from the optimal branch without being disregarded by the routing algorithm. If, for example, users set suboptimal_minutes = 10, the routing algorithm will consider sub-optimal routes that arrive up to 10 minutes after the arrival of the optimal one. This argument emulates the real-life behaviour that makes people want to take a path that is technically not optimal in terms of travel time, for example, for some practical reasons (e.g. mode preference, safety, etc). In practice, the higher this value, the more itineraries will be returned in the final result.
fare_structure	A fare structure object, following the convention set in setup_fare_structure(). This object describes how transit fares should be calculated. Please see the fare structure vignette to understand how this object is structured: vignette("fare_structure", package = "r5r").
max_fare	A number. The maximum value that trips can cost when calculating the fastest journey between each origin and destination pair.
max_walk_time	An integer. The maximum walking time (in minutes) to access and egress the transit network, to make transfers within the network or to complete walk-only trips. Defaults to no restrictions (numeric value of Inf), as long as max_trip_duration is respected. When routing transit trips, the max time is considered separately for each leg (e.g. if you set max_walk_time to 15, you could get trips with an up to 15 minutes walk leg to reach transit and another up to 15 minutes walk leg to reach the destination after leaving transit. In walk-only trips, whenever max_walk_time differs from max_trip_duration, the lowest value is considered.
max_bike_time	An integer. The maximum cycling time (in minutes) to access and egress the transit network, to make transfers within the network or to complete bicycle-only trips. Defaults to no restrictions (numeric value of Inf), as long as max_trip_duration is respected. When routing transit trips, the max time is considered separately for each leg (e.g. if you set max_bike_time to 15, you could get trips with an up to 15 minutes cycle leg to reach transit and another up to 15 minutes cycle leg to reach the destination after leaving transit. In bicycle-only trips, whenever max_bike_time differs from max_trip_duration, the lowest value is considered.
max_car_time	An integer. The maximum driving time (in minutes) to access and egress the transit network. Defaults to no restrictions, as long as max_trip_duration is respected. The max time is considered separately for each leg (e.g. if you set max_car_time to 15 minutes, you could potentially drive up to 15 minutes to reach transit, and up to another 15 minutes to reach the destination after leaving transit). Defaults to Inf, no limit.
max_trip_duration	An integer. The maximum trip duration in minutes. Defaults to 120 minutes (2 hours).
walk_speed	A numeric. Average walk speed in km/h. Defaults to 3.6 km/h.
bike_speed	A numeric. Average cycling speed in km/h. Defaults to 12 km/h.
max_rides	An integer. The maximum number of public transport rides allowed in the same trip. Defaults to 3.
max_lts	An integer between 1 and 4. The maximum level of traffic stress that cyclists will tolerate. A value of 1 means cyclists will only travel through the quietest streets, while a value of 4 indicates cyclists can travel through any road. Defaults to 2. Please see details for more information.
shortest_path	A logical. Whether the function should only return the fastest itinerary between each origin and destination pair (the default) or multiple alternatives.
all_to_all	A logical. Whether to query routes between the 1st origin to the 1st destination, then the 2nd origin to the 2nd destination, and so on (FALSE, the default) or to query routes between all origins to all destinations (TRUE).
n_threads	An integer. The number of threads to use when running the router in parallel. Defaults to use all available threads (Inf).
verbose	A logical. Whether to show R5 informative messages when running the function. Defaults to FALSE (please note that in such case R5 error messages are still shown). Setting verbose to TRUE shows detailed output, which can be useful for debugging issues not caught by r5r.
progress	A logical. Whether to show a progress counter when running the router. Defaults to FALSE. Only works when verbose is set to FALSE, so the progress counter does not interfere with R5's output messages. Setting progress to TRUE may impose a small penalty for computation efficiency, because the progress counter must be synchronized among all active threads.
drop_geometry	A logical. Whether the output should include the geometry of each trip leg or not. The default value of FALSE keeps the geometry column in the result.
output_dir	Either NULL or a path to an existing directory. When not NULL (the default), the function will write one .csv file with the results for each origin in the specified directory. In such case, the function returns the path specified in this parameter. This parameter is particularly useful when running on memory-constrained settings because writing the results directly to disk prevents r5r from loading them to RAM memory.

Value

When drop_geometry is FALSE, the function outputs a ⁠LINESTRING sf⁠ with detailed information on the itineraries between the specified origins and destinations. When TRUE, the output is a data.table. All distances are in meters and travel times are in minutes. If output_dir is not NULL, the function returns the path specified in that parameter, in which the .csv files containing the results are saved.

Transport modes

R5 allows for multiple combinations of transport modes. The options include:

• Transit modes: TRAM, SUBWAY, RAIL, BUS, FERRY, CABLE_CAR, GONDOLA, FUNICULAR. The option TRANSIT automatically considers all public transport modes available.

• Non transit modes: WALK, BICYCLE, CAR, BICYCLE_RENT, CAR_PARK.

Level of Traffic Stress (LTS)

When cycling is enabled in R5 (by passing the value BIKE to either mode or mode_egress), setting max_lts will allow cycling only on streets with a given level of danger/stress. Setting max_lts to 1, for example, will allow cycling only on separated bicycle infrastructure or low-traffic streets and routing will revert to walking when traversing any links with LTS exceeding 1. Setting max_lts to 3 will allow cycling on links with LTS 1, 2 or 3. Routing also reverts to walking if the street segment is tagged as non-bikable in OSM (e.g. a staircase), independently of the specified max LTS.

The default methodology for assigning LTS values to network edges is based on commonly tagged attributes of OSM ways. See more info about LTS in the original documentation of R5 from Conveyal at https://docs.conveyal.com/learn-more/traffic-stress. In summary:

• LTS 1: Tolerable for children. This includes low-speed, low-volume streets, as well as those with separated bicycle facilities (such as parking-protected lanes or cycle tracks).

• LTS 2: Tolerable for the mainstream adult population. This includes streets where cyclists have dedicated lanes and only have to interact with traffic at formal crossing.

• LTS 3: Tolerable for "enthused and confident" cyclists. This includes streets which may involve close proximity to moderate- or high-speed vehicular traffic.

• LTS 4: Tolerable only for "strong and fearless" cyclists. This includes streets where cyclists are required to mix with moderate- to high-speed vehicular traffic.

For advanced users, you can provide custom LTS values by adding a tag ⁠<key = "lts">⁠ to the osm.pbf file.

Datetime parsing

r5r ignores the timezone attribute of datetime objects when parsing dates and times, using the study area's timezone instead. For example, let's say you are running some calculations using Rio de Janeiro, Brazil, as your study area. The datetime as.POSIXct("13-05-2019 14:00:00", format = "%d-%m-%Y %H:%M:%S") will be parsed as May 13th, 2019, 14:00h in Rio's local time, as expected. But as.POSIXct("13-05-2019 14:00:00", format = "%d-%m-%Y %H:%M:%S", tz = "Europe/Paris") will also be parsed as the exact same date and time in Rio's local time, perhaps surprisingly, ignoring the timezone attribute.

Routing algorithm

The detailed_itineraries() and pareto_frontier() functions use an R5-specific extension to the McRAPTOR routing algorithm. The implementation used in detailed_itineraries() allows the router to find paths that are optimal and less than optimal in terms of travel time, with some heuristics around multiple access modes, riding the same patterns, etc. The specific extension to McRAPTOR to do suboptimal path routing is not documented yet, but a detailed description of base McRAPTOR can be found in Delling et al (2015). The implementation used in pareto_frontier(), on the other hand, returns only the fastest trip within a given monetary cutoff, ignoring slower trips that cost the same. A detailed discussion on the algorithm can be found in Conway and Stewart (2019).

• Delling, D., Pajor, T., & Werneck, R. F. (2015). Round-based public transit routing. Transportation Science, 49(3), 591-604. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1287/trsc.2014.0534")}

• Conway, M. W., & Stewart, A. F. (2019). Getting Charlie off the MTA: a multiobjective optimization method to account for cost constraints in public transit accessibility metrics. International Journal of Geographical Information Science, 33(9), 1759-1787. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1080/13658816.2019.1605075")}

See Also

Other routing: expanded_travel_time_matrix(), pareto_frontier(), travel_time_matrix()

Examples

library(r5r)

# build transport network
data_path <- system.file("extdata/poa", package = "r5r")
r5r_core <- setup_r5(data_path)

# load origin/destination points
points <- read.csv(file.path(data_path, "poa_points_of_interest.csv"))

# inputs
departure_datetime <- as.POSIXct(
  "13-05-2019 14:00:00",
  format = "%d-%m-%Y %H:%M:%S"
)

det <- detailed_itineraries(
  r5r_core,
  origins = points[10,],
  destinations = points[12,],
  mode = c("WALK", "TRANSIT"),
  departure_datetime = departure_datetime,
  max_trip_duration = 60
)
head(det)

stop_r5(r5r_core)

r5r documentation built on May 29, 2024, 7:30 a.m.