Cover - TRB Travel Survey Methods Committee _ABJ40_ by xiaocuisanmin


									  UK National Travel Survey
     GPS Feasibility Study
GPS Equipment Review / Pretest

                   Michelle Lee, GISP
                    Jean Wolf, PhD

                     GeoStats LP
                     Atlanta, GA

                     TRB Conference
                      January 2010
Background of Feasibility Study

National Centre for Social Research (NatCen) is contracted by the
Department for Transport (DfT) to conduct the UK National Travel Survey
    n Continuous survey (~ 8000-10,000 households each year)
    n One week diary, with short walk trips reported day 7 only

The DfT has been interested in the possibility of using GPS in their NTS and
asked NatCen to perform a feasibility study

The feasibility study was conducted in 2008-2009 and included:
    n Technology assessment of commercially available GPS data loggers
    n A pretest of the best devices by NatCen and the DfT
    n A pilot study of 100 households using the selected device in tandem with the
    one week travel diary to compare GPS detected and diary reported trips
Task One: Technology Assessment

Task One: Identify portable (i.e., wearable) GPS data logging devices
   commercially available in January 2008 and assess the suitability of
   these devices based on the project requirements, which included:

    n Form factor, size and weight – the device should be relatively
    unobtrusive or else respondents may be reluctant to carry them around
    n Battery life – the battery should support data collection for at least
    one day of travel activity without recharging to avoid data loss
    n Ease of recharging
    n Memory capacity – the memory must be capable of storing the data
    for the full period
    n Cost – including any additional costs for chargers, cases etc.
    n Ease of Use
    n Ease of device configuration data download
    n Required data elements captured – latitude, longitude, time, date,
    and speed
    n Data quality – output data should be of high quality with regard to
    coverage area and horizontal positional accuracy
GPS Requirements

After an extensive internet and vendor-based search, GeoStats
identified 32 wearable GPS logging devices available on the market.
During the initial evaluation, all GPS data logging devices found
whose specifications did not meet a minimum memory capacity,
battery life, and the ability to download data via a USB connection
were eliminated. Consequently, this elimination process resulted in the
selection and purchase of nine devices for further evaluation.

    n Atmel BTT08 Data Logger
    n   EverMore BT-900
    n   GiSTEQ PhotoTrackr
    n   GlobalSat DG-100 Data Logger
    n   i-Blue 747 Data Logger
    n   i-Blue 821 Slim Trip Recorder
    n   Pharos Trips & Pics with GPS
    n   Qstarz BT-Q1000P
    n   Wintec WBT-201 Data Logger
Test Plan Overview
To evaluate the performance and suitability of the nine devices selected, GeoStats
defined twelve tests broken into three test phases. At the end of each phase, some
devices were eliminated based on that phase’s results. Those devices remaining
after a given phase of testing were then tested in the next phase.

Phase 1
     TEST ONE:               Document data fields captured by each GPS device
     TEST TWO:               Evaluate ease of use, form factor, and durability
     Eliminate any devices that should not be further tested
Phase 2
     TEST THREE:             Evaluate cold start acquisition time
     TEST FOUR:              Compare GPS traces versus accuracy of road network
     TEST FIVE:              Compare GPS traces between different manufacturers
     TEST SIX:               Compare GPS traces between the same manufacturers (when possible)
     TEST SEVEN:             Evaluate GPS performance in urban canyon environment
     Eliminate any devices that should not be further tested
Phase 3
     TEST EIGHT: Test battery life
     TEST NINE:  Test memory capacity
     TEST TEN:    Test volatile or non-volatile memory
     TEST ELEVEN: Check vibrations sensor effectiveness – if applicable
     TEST TWELVE: Check speed screen accuracy

     Select top three devices for DfT / NatCen pretest
Testing Route
Results: Selected Devices for Pretest

GeoStats recommended that the Atmel BTT08, the GlobalSat DG-100 and
iBlue 747 continue into the pretest phase of the study

    n The Atmel and GlobalSat have been successfully deployed in
    numerous wearable GPS studies with reported success.

    n When properly configured, the point capacity, battery life and positional
    accuracy of all three devices exceeded the requirements for the UK NTS
    GPS Feasibility Study.

    n It was believed that each device met the form factor requirement for
    this study. Remaining concerns:
          n Atmel: voice feature could cause participants to not carry that
          device, flashing lights could also be deterent from use
          n iBlue 747: the “LOG” / “NAV” switch on the iBlue 747 could result
          in accidental data loss
          n GlobalSat: slightly larger size could be an issue
Pretest Overview

 n   The top three GPS devices identified in the Task One Technology
     Assessment were the Atmel BTT08, the GlobalSat DG-100 and the
     iBlue 747.

 n   The testing was completed in two rounds with the first round
     conducted in a similar manner to a typical household travel survey,
     and the second conducted with some head to head tests.

 n   Employee volunteers from the DfT and NatCen carried the devices
     and fill out a simple travel diary including mode of transport.

 n   Overall there were 31 GPS files collected during the pretest and
     compared to the reported travel diary data.
Pretest Results Overview

 n   Atmel – Technology / Data Processing
      n  Performed well with recommended settings
      n  Software issues with configuration
      n  Vibration sensor helpful for point reduction
      n  ‘Wavy’ traces on some files
 n   Atmel – Form Factor
      n  Small Size / Lanyard versus Clip
      n  Audible Voice Feature
      n  Flashing Lights

 n   GlobalSat – Technology / Data Processing
      n  Performed well, easy to configure
      n  Data easily processed
 n   GlobalSat – Form Factor
      n  Heavier and larger than the Atmel or iBlue

 n   iBlue – Technology / Data Processing
       n  Unable to hold speed screen configuration setting
 n   iBlue – Form Factor
       n  Switch on side (power / log / navigation) easy to move
Thank You

n   NatCen and DfT
n   New Technology Subcommittee

Study Report to be released by DfT this winter

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