Comparison of Cell, GPS, and Bluetooth Derived Travel Data

Results from the 2014 Tyler, Texas Study

Texas A&M Big Data Workshop

February 13, 2015

Ed HardByron Chigoy

Praprut Songchitruksa, Ph.D, P.E.Steve Farnsworth

Darrell Borchardt, P.E.

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Comparison of O-D Data by TechnologyOrigin-Destination (O-D)

Technology Comparison Cellular GPS Data

Stream Bluetooth

Data Unit cell ‘sighting’ GPS ping MAC address

Type of Travel Collected movements /flows trips traces trips between device readers

Data Saturation/Penetration good poor fair

Positional Accuracy 150–500 meters 5–30 meters 100 meters

Sample Frequency minutes , hours seconds , minutes seconds

Continuous Data Stream? no yes yes

Is it Big Data? yes sometimes no

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Study Area and Overview

• Tyler MPO, Smith County, Texas

• Conducted Spring 2014

• Focused on: – external trips, E-E, E-I/I-E– average weekday trips

• Trial external O-D travel survey using cell, GPS, Bluetooth (BT)

Tyler

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Data Collection/Capture Time Periods

Bluetooth - 2 weeks, April 1-April 14

Cell - 4 weeks, March 21-April 24

GPS - 3 months, February 24 – May 9

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Study Area Zones and Capture Areas

• 420 MPO zones aggregated to 307 cell capture zones

• 18 Exterior cell data capture areas created

• 10 mile GPS buffer area utilized

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Bluetooth Detection and E-E Matching

• Over 170,000 BT observations during study period– 24,500 ave. weekday E-E matches – 4,000 per ave. weekday matches with time constraints

• BT detection ranged from 4% to 11%

• Matches expanded to counts

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Cell DataProcessing, Analyses

• 198,000 unique resident devices; 17% residential sampling rate

• Ave. of 180 device sightings per day

• Removed trips that did not cross study boundary

• For E-E: developed trip matrix, counts by station, percent resident vs non-residents by station

• For E-I/I-E: developed matrix, trip length frequency distributions (TLFD)

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GPS DataProcessing, Analyses

• Raw GPS data processed to develop O-D trips

• Analysis incorporated anonymization

• O-D datasets developed for freight, cars, and apps

• Developed E-E, E-I/I-E trips and count totals by station

• Same E-E time constraints for GPS as used for Bluetooth

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External-to-External ResultsAll Vehicles

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E-E Results

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E-I/I-E Results – Total TripsSaturation/Distribution across Internal TAZs

Max Value = 13,500

Max Value = 4,900Max Value =

3,500

GPS Data2004 Survey Data Cell Data

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E-I/I-E Trip LengthAll Stations – All Vehicles

K-S Test p-value << 0.01

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ConclusionsHighly Summarized

• O-D methods/technologies still evolving

• Combination of technologies providers best approach for external data (currently)

• Bluetooth remains E-E benchmark, for time being

• Cell data better suited for larger studies areas

• Third party GPS appears to be viable option – especially as sample sizes increase– more trials needed

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For more Information:

Ed Harde-hard@tamu.edu (979)845-8539

Byron Chigoyb-chigoy@ttimail.tamu.edu (512)407-1156

Praprut Songchitruksa, Ph.D., P.E.praprut@tamu.edu (979)862-3559

Steve Farnsworths-farnsworth44@tamu.edu(979)862-4927

Questions?

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Acknowledgments and Special Thanks!

• Bill Knowles• Janie Temple• Charlie Hall

• Bill King• Vijay Sivaraman

• Rick Schuman• Andrew Davies