Evaluating GPS Technology for Household Surveys
This study presented at the 15th TRB Conference on Transportation Planning Applications evaluated the use of GPS technology for household surveys by NCTCOG. The research focused on understanding the effectiveness and accuracy of GPS technologies through the demonstration of GPS Logger, Smart Phone App, and Cell Phone Triangulation. Participants were involved in data collection using these technologies passively and completing travel diaries. The study steps included participant recruitment, data collection, processing of travel diary and technology data, comparison of technology locations with travel diary locations, and investigation of non-matches. A Habitual Locations form was designed to record key locations visited often. Overall, the research aimed to enhance the understanding of implementing technologies in surveys.
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Evaluating GPS Technology Used for Household Surveys 15th TRB Conference on Transportation Planning Applications Atlantic City, NJ May 18, 2015 Kathy Yu, Arash Mirzaei, Behruz Paschai North Central Texas Council of Governments (NCTCOG)
Background NCTCOG was interested in understanding how technologies could be used in household surveys and what was known about the GPS technologies. Before we use technologies in a survey, it is important to know the methods fully including accuracy, and strengths/weaknesses. 15th TRB Conference on Transportation Planning Applications 2 May 18, 2015
Study Design Three Technologies Demonstrated GPS Logger Smart Phone App Cell Phone Triangulation Each technology was required to work passively. Data collection of all technologies would be conducted simultaneously. 15th TRB Conference on Transportation Planning Applications 3 May 18, 2015
Study Design Participants were divided into 3 waves. During the data collection, participant was asked to do the following: - Complete a week long data collection period. - Carry 1, 2, or 3 technologies during the week. - Complete a travel diary for the first 24 hours. 15th TRB Conference on Transportation Planning Applications 4 May 18, 2015
Study Steps 1. NCTCOG recruits participants. 2. Consultants conduct data collection. 3. NCTCOG processes travel diary while Consultants process technology data. 4. NCTCOG compares technology locations with travel diary locations. 5. NCTCOG investigates non-matches. 15th TRB Conference on Transportation Planning Applications 5 May 18, 2015
Habitual Locations Form The consultants and NCTCOG designed a Habitual Locations form which records: - Home Location - Primary and Secondary Workplace Locations - School Location - Up to 3 Additional Locations Visited Most Often. Other Information Requested: - Preferred Survey Dates - Preferred Technologies - Mobile Phone Model, O/S, Carrier. 15th TRB Conference on Transportation Planning Applications 6 May 18, 2015
Habitual Locations Form Excerpt 15th TRB Conference on Transportation Planning Applications 7 May 18, 2015
Travel Diary Form The Consultants and NCTCOG designed a Travel Diary to record the following: - Place Name/Address at 3 a.m. - Successive Locations - Place Name and Address - Arrival and Departure Time - Mode of Access - Activity at Location 15th TRB Conference on Transportation Planning Applications 8 May 18, 2015
Travel Diary Form Excerpt 15th TRB Conference on Transportation Planning Applications 9 May 18, 2015
Participant Details Gender Male Female Percent 45% 55% NCTCOG Status COG Employee Other Percent 58% 42% Home State Texas Other Percent 88% 12% 15th TRB Conference on Transportation Planning Applications 10 May 18, 2015
Technology Usage Breakdown Technology Used Logger Only Smart Phone App Only Triangulation Only Triangulation Only Logger and Smart Phone App Logger and Triangulation Smart Phone App and Triangulation Smart Phone App and Triangulation All Technologies TOTAL Technology Used Logger Only Smart Phone App Only Smart Phone App Only Triangulation Only Logger and Smart Phone App Logger and Triangulation Technology Used Logger Only Count Count Count Pct. Pct. Pct. 25 12 7 7 16 19 12 12 58 149 25 12 12 25 17% 8% 5% 5% 11% 13% 8% 8% 39% 100% 17% 8% 8% 5% 11% 13% 17% 7 16 19 TOTAL TOTAL 149 149 100% 100% 15th TRB Conference on Transportation Planning Applications 11 May 18, 2015
Wave Breakdown # Logger Users # Smart Phone App Users # Triangulation Users Total Users Wave May 15 35 27 23 44 June 5 42 35 34 53 June 21 41 36 39 52 TOTAL 118 98 96 149 15th TRB Conference on Transportation Planning Applications 12 May 18, 2015
Participants with Data To Compare GPS Logger Logger Logger Logger GPS GPS GPS Smart Phone Smart Phone Smart Phone Smart Phone App App App App Triangulation Triangulation Triangulation Triangulation Registered Participants Registered Participants Did not return a travel diary diary Had no GPS data for travel day travel day # Participants with Data to Compare % Registered Participants with Data to Compare Registered Participants Did not return a travel Did not return a travel diary Had no GPS data for Registered Participants 118 118 118 118 98 98 98 98 96 96 96 96 12 12 12 21 21 21 17 17 17 21 21 19 19 5 5 85 58 74 72% 59% 77 % 15th TRB Conference on Transportation Planning Applications 13 May 18, 2015
Location Match Results A match was defined as the technology matching the diary location within 15 min. and 0.25 miles. GPS Logger Logger Logger Logger GPS GPS GPS Smart Phone App Phone App Phone App Phone App Smart Smart Smart Triangulation Triangulation Triangulation Triangulation # Travel Diary Location Records # Technology Location Records # Diary Matches # Diary Matches # Travel Diary Location Records # Technology Location Records # Diary Matches % Match against % Match against % Match against # Travel Diary Location Records # Technology Location Records # Travel Diary Location Records # Technology Location Records # Diary Matches % Match against Total Total Total Total 585 585 585 398 398 520 566 476 476 476 566 566 328 328 261 261 484 84 81% 81% 81% 66% 66% 16% 15th TRB Conference on Transportation Planning Applications 14 May 18, 2015
Person Match Results Considering only the people with at least one location match with the corresponding technology. GPS Logger Smart Phone App Triangulation % People-50% diary match 94% 78% 27% % People-75% diary match 79% 50% 8% % People-100% diary match 48% 24% 5% 15th TRB Conference on Transportation Planning Applications 15 May 18, 2015
Unmatched Travel Diary Records For the GPS Logger and Smart Phone App: NCTCOG reviewed the technology stops and raw data during the time of a missed travel diary record. NCTCOG tried to determine a reason for each missed stop, and notice any patterns or common issues. NCTCOG did not have any details about algorithms used by consultants. 15th TRB Conference on Transportation Planning Applications 16 May 18, 2015
Analyze Non-Match: Logger Non-Match Reason Match Made Match Made No logger data existed for all/part of corresponding trip. all/part of corresponding trip. Short or Rolling Stops (2-3 min)* min)* Possible Diary Issue Other TOTAL Non-Match Reason Match Made Non-Match Reason Non-Match Reason Match Made No logger data existed for No logger data existed for all/part of corresponding trip. Short or Rolling Stops (2-3 # Records # Records # Records # Records % Records % Records % Records % Records 476 476 476 476 81% 81% 81% 81% 62 62 62 11% 11% 11% 34 34 9 6% 6% <2% <1% 4 TOTAL TOTAL TOTAL 585 585 585 585 100% 100% 100% 100% * 24% of Short Trips corresponded to Habitual Locations. 15th TRB Conference on Transportation Planning Applications 17 May 18, 2015
Analyze Non-Match: Smartphone Non-Match Reason Match made Match made No Smartphone Data existed for all/part of corresponding trip all/part of corresponding trip all/part of corresponding trip Non-Match Reason Non-Match Reason Match made No Smartphone Data existed for No Smartphone Data existed for Non-Match Reason Match made # Records % Records # Records % Records # Records % Records # Records % Records 261 261 261 261 66% 66% 66% 66% 89 89 89 22% 22% 22% Short or Rolling Stops (2-3 min)* Stop Not Identified, but Raw Short or Rolling Stops (2-3 min)* Short or Rolling Stops (2-3 min)* Stop Not Identified, but Raw Data shows at location Data shows at location Possible Diary Issue Other 14 14 14 4% 4% 4% 20 20 6 8 5% 5% <2% 2% TOTAL TOTAL TOTAL TOTAL 398 398 398 398 100% 100% 100% 100% * 29% of Short Trips corresponded to Habitual Locations. 15th TRB Conference on Transportation Planning Applications 18 May 18, 2015
Unmatched Technology Records Did the technology capture stops that the user made but did not record in the diary? NCTCOG looked at longitude/latitude of unmatched technology records to determine: if it was a valid location is it a reasonable stop given the rest of the user s travel diary stops. 15th TRB Conference on Transportation Planning Applications 19 May 18, 2015
Unmatched Logger Records Number of Records Records Records Number % of New Records Found Found Found % of New Number of of % of New Records Records Classification Classification Classification New Valid Location New Diary Match (user did not specify location well) Match to Street/Intersection Duplicate of Existing Diary 32 35% 2 2% Match to Street/Intersection Duplicate of Existing Diary Record Record 28 28 31% 31% 10 10 11% 11% Miscellaneous Miscellaneous 19 19 21% 21% Total Unmatched Logger Total Unmatched Logger Total Unmatched Logger May 18, 2015 Locations Locations Locations 91 91 91 100% 100% 100% 15th TRB Conference on Transportation Planning Applications 20
Unmatched Smartphone Records Number of New Records Records Records Number of Number of New New % of New Records Found Found Found % of New % of New Records Records Classification Classification Classification New Valid Location Duplicate of Existing Diary 17 24% Duplicate of Existing Diary Record Record 16 16 23% 23% Match to Street/Intersection Created New Location from Match to Street/Intersection Created New Location from inconsistent points inconsistent points 9 9 13% 13% 9 9 13% 13% Miscellaneous Miscellaneous 19 19 27% 27% Total Unmatched Total Unmatched Total Unmatched May 18, 2015 Smartphone Locations Smartphone Locations Smartphone Locations 70 70 70 100.00% 100.00% 100.00% 15th TRB Conference on Transportation Planning Applications 21
Feedback Questionnaire After participating in the survey, a feedback questionnaire was sent to all participants, which contained 17 questions. Allowed consultants to get feedback on use of their technology. 95 people responded. 15th TRB Conference on Transportation Planning Applications 22 May 18, 2015
Feedback Future Survey Format If asked to participate in a household travel survey in the future, I would be willing to use (check all that apply): Answer Option % Selected Travel Diary 51% GPS Logger 72% Smartphone App 53% Triangulation 57% 15th TRB Conference on Transportation Planning Applications 23 May 18, 2015
Feedback Diary or Technology What is your preference for using a paper travel diary and using a GPS/location- based technology? % Respondents I prefer using GPS technology ONLY Paper travel diary AND GPS technology TOGETHER Paper travel diary ONLY No preference TOTAL 69% 14% 5% 12% 100% 15th TRB Conference on Transportation Planning Applications 24 May 18, 2015
Observations Travel Diary times and locations were subject to user error. Almost 2/3rd of the diary trip ends are habitual locations that were asked before the diary survey. Contractors algorithms were fairly successful in differentiating signals from real end points of trips. 15th TRB Conference on Transportation Planning Applications 25 May 18, 2015
Improvement Areas Short trip stops are hard to capture. Habitual Locations may be useful. For logger and smartphone app, many missed locations were due to the lack of recorded data. Further testing can be done on teaching people to use technology correctly to minimize user error. 15th TRB Conference on Transportation Planning Applications 26 May 18, 2015
Conclusions Continued refinement of algorithms can improve results. The feedback survey showed 83% preferred using technology in a future survey. Only 5% preferred travel diary only. Technology methods may not be appropriate for all survey participants. 15th TRB Conference on Transportation Planning Applications 27 May 18, 2015
Contact Information Kathy Yu Arash Mirzaei amirzaei@nctcog.org Behruz Paschai bpaschai@nctcog.org kyu@nctcog.org 15th TRB Conference on Transportation Planning Applications 28 May 18, 2015
