Deducing Mode and Purpose from GPS Data

1. Deducing Mode and Purpose from GPS Data Peter Stopher, Jun Zhang and Eoin Clifford Institute of Transport and Logistics Studies The University of Sydney and Camden FitzGerald Parson Brinkerhoff, Sydney April 2007

2. Introduction • Increasing use of and interest in GPS devices to measure travel • Used primarily to validate standard diary surveys • Also used in Australia to evaluate VTBC interventions • Recent developments have produced small and lightweight personal devices that are very sensitive Deducing Mode and Purpose from GPS Data -- Case Studies

3. Introduction • GPS collects accurate data on: • Location at each instant • Time at each instant • Speed of movement at each instant • Heading • Data quality measures • Data can be collected as often as every second or as long as desired Deducing Mode and Purpose from GPS Data -- Case Studies

4. Introduction • For transport planning applications: • Logging devices are all that is required • Transmission in real time is not advantageous and may be expensive • 4-8 Mb of on-board memory will collect second-by-second data for 1-3 months Deducing Mode and Purpose from GPS Data -- Case Studies

5. Introduction • To substitute for conventional surveys, additional data are needed: • Mode of travel • Purpose of travel • GPS cannot collect these • With certain supplemental data, these can be determined Deducing Mode and Purpose from GPS Data -- Case Studies

6. Mode and Purpose Identification

7. Supplemental Data Requirements • For mode: • GIS of the street network • GIS of all public transport routes (including rail and subway lines) • For purpose: • Locations used frequently by household members • A GIS of the land use at the parcel level Deducing Mode and Purpose from GPS Data -- Case Studies

8. Frequently Visited Locations • Our surveys collect: • Address of each workplace for each household member • Address of each educational establishment attended by a household member • Two most frequently-used grocery stores • Home address is known already • These locations are all then geocoded Deducing Mode and Purpose from GPS Data -- Case Studies

9. Preliminary Steps • Assumes that the data have been subdivided into trips • We define a trip end as occurring whenever the device is stationary for more than 120 seconds • Visual inspection is also used to cross-check and correct some trip ends • About 5 percent of identified trip ends are just traffic stops • About 5 percent of actual trip ends are shorter than 120 seconds and not identified by software Deducing Mode and Purpose from GPS Data -- Case Studies

10. Mode Identification

11. Mode Identification • Proceeds in a hierarchical process: • Identify walk trips first – based on maximum speed • Identify rail, ferry, and other off-network modes next – determined by location of path • Identify bus trips next – based on maximum speed and acceleration and beginning and ending on a bus route Deducing Mode and Purpose from GPS Data -- Case Studies

12. Mode Identification • Identify bicycle trips next – household must have bicycles available • If bicycle is available: • Check maximum speed and acceleration • Check that trip origin is home or is a location to which bicycle has already been used • If all of these are acceptable, then trip is allocated to bicycle Deducing Mode and Purpose from GPS Data -- Case Studies

13. Mode Identification • Remaining trips should be car • Check maximum speed and acceleration • Check that travel remains on the roadway network • If these check out, then trip is car, probably driver • Check to see if origin is home or car was used previously to reach the origin • If not, and car is still identified, classify as car passenger Deducing Mode and Purpose from GPS Data -- Case Studies

14. Trip Purpose

15. Trip Purpose • Examine trip end locations and check against frequently-used locations • Following purposes should be evident: • Home-based work • Home-based school • Some home-based shop • Non-home-based work • Non-home-based school • Non-home-based shop (some) Deducing Mode and Purpose from GPS Data -- Case Studies

16. Trip List (n) * search radius: 200 meters End Points (n+1) Private Level Home Address Work Address Education Address Shopping Address … Link Match (Geocoded) To Private Level Destination Trip Purpose Explanation Public Level Shopping Centre Education Institutes Commercial Places Residence Area … Link Match (Geocoded) To Public Level Destinations (>1) To Public Level Destination (Best) FAIL Trip Purpose Deducing Mode and Purpose from GPS Data -- Case Studies

17. Trip Purpose • 30 percent of trips are usually home-based work/school • 13 percent of trips are home-based shop • About 5-10 percent of trips are non-home-based work, school or shop • About 70 percent of trips are home-based • This process identifies about 50 percent of trip purposes completely • About 35 percent will have either origin or destination purpose identified Deducing Mode and Purpose from GPS Data -- Case Studies

18. Trip Purpose • Remaining trips are examined with respect to: • Duration of stop • Frequency of visits in GPS period • Nature of land use at the trip ends • These provide further identification of about 35-40 percent of other trip end purposes Deducing Mode and Purpose from GPS Data -- Case Studies

19. Trip Purpose • Problems are: • Multi-use parcels • Shopping centres – people may • Use personal services • Eat a meal • Shop • Visit medical facilities • If the purposes are to be split to HBW, HBSchool, HBOther, and NHB – no problem Deducing Mode and Purpose from GPS Data -- Case Studies

20. Example • The following slides provide an example of the processing steps • GPS data are collected by having respondents carry GPS devices with them for a period of time • Devices are retruned to us and the data are downloaded Deducing Mode and Purpose from GPS Data -- Case Studies

21. Data File from GPS Device V,07/03/2006,12:58:49,138.509622,-34.843843,500,78,3,3,8.3 V,07/03/2006,12:58:51,138.509650,-34.843825,500,77,3,3,8.3 V,07/03/2006,12:58:53,138.509686,-34.843809,500,65,2,3,8.3 V,07/03/2006,12:58:55,138.509714,-34.843786,500,66,3,3,8.3 V,07/03/2006,12:58:57,138.509732,-34.843779,500,68,2,3,8.3 A,07/03/2006,12:59:00,138.509741,-34.843580,500,26,8,4,11.6 A,07/03/2006,12:59:02,138.509778,-34.843454,500,34,3,4,11.6 A,07/03/2006,12:59:04,138.509805,-34.843373,500,53,3,4,11.6 A,07/03/2006,12:59:06,138.509824,-34.843316,500,53,3,4,11.5 A,07/03/2006,12:59:08,138.509833,-34.843252,500,28,4,4,11.5 A,07/03/2006,12:59:11,138.509879,-34.843183,500,30,2,4,11.5 A,07/03/2006,12:59:14,138.509943,-34.843149,500,38,2,4,11.4 A,07/03/2006,12:59:16,138.509970,-34.843126,500,56,4,4,11.4 A,07/03/2006,12:59:18,138.510016,-34.843098,499,63,4,4,11.4 A,07/03/2006,12:59:20,138.510007,-34.843115,499,72,3,4,11.4 A,07/03/2006,12:59:22,138.510007,-34.843115,499,77,4,4,11.3 A,07/03/2006,12:59:25,138.509970,-34.843149,498,82,2,4,11.3 A,07/03/2006,12:59:30,138.509961,-34.843172,498,84,2,4,11.3 A,07/03/2006,12:59:32,138.509989,-34.843176,497,86,2,4,11.2 A,07/03/2006,12:59:34,138.509970,-34.843188,497,89,2,4,11.2 A,07/03/2006,12:59:37,138.509961,-34.843199,496,93,2,4,11.2 A,07/03/2006,12:59:39,138.509970,-34.843202,496,75,3,4,11.1 A,07/03/2006,12:59:41,138.509961,-34.843206,495,73,3,4,11.1 A,07/03/2006,12:59:45,138.509925,-34.843222,494,76,2,4,11.1 A,07/03/2006,12:59:54,138.509833,-34.843337,492,95,2,4,11.0 A,07/03/2006,12:59:57,138.509824,-34.843373,491,107,2,4,11.0 A,07/03/2006,12:59:59,138.509833,-34.843390,491,110,2,4,10.9 A,07/03/2006,13:00:01,138.509870,-34.843390,490,109,2,4,10.9 • Data are stored as binary in the device • Data are downloaded and converted to .csv file using software • Information is stored with filename which includes deployment information • Gives us information on position, time, heading, speed etc for each data point Deducing Mode and Purpose from GPS Data -- Case Studies

22. GPS Data Processing Procedure Pre-processing Trip Identification Mode Detection Purpose Detection GPS Data Trip Identification General Mode Detect Household Addresses List Deployment Information Trip Validation Public Transport Network Public Places List Convert Format Trip Manual Checking Trip List GPS Record Validation Position Matching & Purpose Detect Public Mode Detect Base Map Trip Map Final Trip List Deducing Mode and Purpose from GPS Data -- Case Studies

23. Data Prior to Editing Deducing Mode and Purpose from GPS Data -- Case Studies

24. Post Editing Deducing Mode and Purpose from GPS Data -- Case Studies

25. With Mode Added Deducing Mode and Purpose from GPS Data -- Case Studies

26. With Purpose Added Deducing Mode and Purpose from GPS Data -- Case Studies

27. Conclusions • Both mode and purpose can be identified from GPS records • Requires supplemental data such as GIS layers • Requires supplemental questions on: • Bicycle availability • Addresses of frequently-used locations • All other information is available from the GPS record Deducing Mode and Purpose from GPS Data -- Case Studies

28. Questions ? • Please use the Microphone. Deducing Mode and Purpose from GPS Data -- Case Studies