In this project we propose a robust public transport route planner based for Zurich Area in Switzerland. Given a desired arrival time, the route planner computes the fastest route between departure and arrival stops within a provided confidence tolerance expressed as interquartiles.
A 7-min presentation of the project and a description of our approach and results can be found at the following link.
The project is accomplished by:
- Raphael Attias: @raphaelattias (Statistics)
- Riccardo Cadei: @riccardocadei (Algorithm)
- Mateo Chapatte: @ChapatteMateo (Front-end developer)
- Guillaume Parchet: @Ingloryon (Data Engineer)
Imagine you are a regular user of the public transport system, and you are checking the operator's schedule to meet your friends for a class reunion. The choices are:
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You could leave in 10mins, and arrive with enough time to spare for gossips before the reunion starts.
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You could leave now on a different route and arrive just in time for the reunion.
Undoubtedly, if this is the only information available, most of us will opt for option 1.
If we now tell you that option 1 carries a fifty percent chance of missing a connection and be late for the reunion. Whereas, option 2 is almost guaranteed to take you there on time. Would you still consider option 1?
Probably not. However, most public transport applications will insist on the first option. This is because they are programmed to plan routes that offer the shortest travel times, without considering the risk factors.
In this project we propose our robust public transport route planner to improve on that, using the SBB dataset (See next section: Dataset Description).
Given a desired arrival time, the route planner computes the fastest route between departure and arrival stops within a provided confidence tolerance expressed as interquartiles. For instance, "what route from A to B is the fastest at least Q% of the time if I want to arrive at B before instant T". Note that confidence is a measure of a route being feasible within the travel time computed by the algorithm.
The output of the algorithm is a list of routes between A and B and their confidence levels. The routes are sorted from latest (fastest) to earliest (longest) departure time at A, they must all arrive at B before T with a confidence level greater than or equal to Q. It is also possible to visualize the routes on a map with straight lines connecting all the stops traversed by the route.
In order to answer this question we had to:
- Model the public transport infrastructure for the route planning algorithm.
- Build a predictive model using the historical arrival/departure time data, and optionally other sources of data.
- Implement a robust route planning algorithm using this predictive model.
- Test and validate the results.
- Implement a simple Jupyter-based visualization to demonstrate the method (alternative: using Jupyter dashboard such as Voilà or ipywidgets).
Solving this problem accurately can be very difficult, then we fixed the following simplifying assumptions:
- We only consider journeys at reasonable hours of the day, and on a typical business day.
- We allow short (total max 500m "As the Crows Flies") walking distances for transfers between two stops, and assume a walking speed of 50m/1min on a straight line, regardless of obstacles, human-built or natural, such as building, highways, rivers, or lakes.
- We only consider journeys that start and end on known station coordinates (train station, bus stops, etc.), never from a random location. However, walking from the departure stop to a nearby stop is allowed.
- We only consider departure and arrival stops in a 15km radius of Zürich's train station,
Zürich HB (8503000), (lat, lon) =(47.378177, 8.540192). - We only consider stops in the 15km radius that are reachable from Zürich HB. If needed stops may be reached via transfers through other stops outside the 15km area.
- Once a route is computed, a traveller is expected to follow the planned routes to the end, or until it fails (i.e. miss a connection). We haven't addressed the case where travellers are able to defer their decisions and adapt their journey "en route", as more information becomes available. This would require us to consider all alternative routes (contingency plans) in the computation of the uncertainty levels, which is more difficult to implement.
- We assumed that the timetables remain unchanged throughout the 2018 - 2020 period (i.e. schedule of May 13-17, 2019).
- (Optional) Rederive the different datasets used from raw sources:
- Run the instructions in the notebook
PrepareTablesHDFS.ipynb. This will create the required tables on your personnal HDFS space (on icc cluster). - Run the cells in part I of the main notebook
ZurichJourneyPlanning.ipynb. This will re-create the different pickles and dataframes used for the main CSA algorithm and the delays derivation.
If you have not built the HDFS tables and run part I, you can replace in cell 2 of ZurichJourneyPlanning.ipynb your personal username by 'parchet' (who should already have all the tables correctly setup).
- Find the Zurich area jounrney that fits you best !
- Run part 2 of
ZurichJourneyPlanning.ipynbthat determines the different delays CDF aggregated by mean of transport and time of the day - Run part 3 to define all necessary functions for the extended CSA algorithm
- Finally in part 4 you can play with the vizual interface to interactively find your journey based on maximal arrival time, confidence interval and locations.
- (Optional) In the last part you can find a showcase of how our algorithm compares to sereval SBB trips
Figure 1. Example of journey display
For this project we used the data published on the Open Data Platform Mobility Switzerland.
We used the SBB data limited around the Zurich area, focusing only on stops within 15km of the Zurich main train station.
The 2018 to 2020 data is available as a Hive table in ORC format on our HDFS system, under /data/sbb/orc/istdaten.
The full description of the data is available in the opentransportdata.swiss data istdaten cookbooks.
BETRIEBSTAG: date of the tripFAHRT_BEZEICHNER: identifies the tripBETREIBER_ABK,BETREIBER_NAME: operator (name will contain the full name, e.g. Schweizerische Bundesbahnen for SBB)PRODUCT_ID: type of transport, e.g. train, busLINIEN_ID: for trains, this is the train numberLINIEN_TEXT,VERKEHRSMITTEL_TEXT: for trains, the service type (IC, IR, RE, etc.)ZUSATZFAHRT_TF: boolean, true if this is an additional trip (not part of the regular schedule)FAELLT_AUS_TF: boolean, true if this trip failed (cancelled or not completed)HALTESTELLEN_NAME: name of the stopANKUNFTSZEIT: arrival time at the stop according to scheduleAN_PROGNOSE: actual arrival time (whenAN_PROGNOSE_STATUSisGESCHAETZT)AN_PROGNOSE_STATUS: look only at lines when this isGESCHAETZT. This indicates thatAN_PROGNOSEis the measured time of arrival.ABFAHRTSZEIT: departure time at the stop according to scheduleAB_PROGNOSE: actual departure time (whenAN_PROGNOSE_STATUSisGESCHAETZT)AB_PROGNOSE_STATUS: look only at lines when this isGESCHAETZT. This indicates thatAB_PROGNOSEis the measured time of arrival.DURCHFAHRT_TF: boolean, true if the transport does not stop there
Each line of the file represents a stop and contains arrival and departure times. When the stop is the start or end of a journey, the corresponding columns will be empty (ANKUNFTSZEIT/ABFAHRTSZEIT).
In some cases, the actual times were not measured so the AN_PROGNOSE_STATUS/AB_PROGNOSE_STATUS will be empty or set to PROGNOSE and AN_PROGNOSE/AB_PROGNOSE will be empty.
We have copied the timetable to HDFS.
Here the timetables for the years 2018, 2019 and 2020. The timetables are updated weekly.
Only GTFS format has been copied on HDFS, the full description of which is available in the opentransportdata.swiss data timetable cookbooks.
We provide also a summary description of the files below. The most relevant files are marked by (+):
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stops.txt(+):
STOP_ID: unique identifier (PK) of the stopSTOP_NAME: long name of the stopSTOP_LAT: stop latitude (WGS84)STOP_LON: stop longitudeLOCATION_TYPE:PARENT_STATION: if the stop is one of many collocated at a same location, such as platforms at a train station
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stop_times.txt(+):
TRIP_ID: identifier (FK) of the trip, unique for the day - e.g. 1.TA.1-100-j19-1.1.HARRIVAL_TIME: scheduled (local) time of arrival at the stop (same as DEPARTURE_TIME if this is the start of the journey)DEPARTURE_TIME: scheduled (local) time of departure at the stopSTOP_ID: stop (station) identifier (FK), from stops.txtSTOP_SEQUENCE: sequence number of the stop on this trip id, starting at 1.PICKUP_TYPE:DROP_OFF_TYPE:
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trips.txt:
ROUTE_ID: identifier (FK) for the route. A route is a sequence of stops. It is time independent.SERVICE_ID: identifier (FK) of a group of trips in the calendar, and for managing exceptions (e.g. holidays, etc).TRIP_ID: is one instance (PK) of a vehicle journey on a given route - the same route can have many trips at regular intervals; a trip may skip some of the route stops.TRIP_HEADSIGN: displayed to passengers, most of the time this is the (short) name of the last stop.TRIP_SHORT_NAME: internal identifier for the trip_headsign (note TRIP_HEADSIGN and TRIP_SHORT_NAME are only unique for an agency)DIRECTION_ID: if the route is bidirectional, this field indicates the direction of the trip on the route.
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calendar.txt:
SERVICE_ID: identifier (PK) of a group of trips sharing a same calendar and calendar exception pattern.MONDAY..SUNDAY: 0 or 1 for each day of the week, indicating occurence of the service on that day.START_DATE: start date when weekly service id pattern is validEND_DATE: end date after which weekly service id pattern is no longer valid
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routes.txt:
ROUTE_ID: identifier for the route (PK)AGENCY_ID: identifier of the operator (FK)ROUTE_SHORT_NAME: the short name of the route, usually a line numberROUTE_LONG_NAME: (empty)ROUTE_DESC: Bus, Zub, Tram, etc.ROUTE_TYPE:
Note: PK=Primary Key (unique), FK=Foreign Key (refers to a Primary Key in another table)
The other files are:
- calendar-dates.txt contains exceptions to the weekly patterns expressed in calendar.txt.
- agency.txt has the details of the operators
- transfers.txt contains the transfer times between stops or platforms.
Figure 1. better illustrates the above concepts relating stops, routes, trips and stop times on a real example (route 11-3-A-j19-1, direction 0)
Figure 1. Relation between stops, routes, trips and stop times. The vertical axis represents the stops along the route in the direction of travel. The horizontal axis represents the time of day on a non-linear scale. Solid lines connecting the stops correspond to trips. A trip is one instances of a vehicle journey on the route. Trips on same route do not need to mark all the stops on the route, resulting in trips having different stop lists for the same route.
Consolidated list of stop locations in ORC format under /data/sbb/orc/geostops. The schema of this table is the same as for the stops.txt format described earlier.
Finally, additional stops data in BFKOORD_GEO. This list is older and not as complete as the stops data from the GTFS timetables. Nevertheless, it has the altitude information of the stops, which is not available from the timetable files, in case you need that.
It has the schema:
STATIONID: identifier of the station/stopLONGITUDE: longitude (WGS84)LATITUDE: latitude (WGS84)HEIGHT: altitude (meters) of the stopREMARK: long name of the stop
- "Connection Scan Algorithm", Julian Dibbelt, Thomas Pajor, Ben Strasser, Dorothea Wagner, 17-Mar-2017
- "Intriguingly Simple and Fast Transit Routing", Julian Dibbelt, Thomas Pajor, Ben Strasser, Dorothea Wagner, Jun-2013 - page 43-54