Evaluation and Safety Benefits of Using Cell Phone Probe Data in Georgia

1
Evaluation and Safety Benefits of Using Cell
Phone Probe Data in Georgia

• Presented by
• Ronald Boodhoo, MSc, MBA
• Alvin Shultz, MSPH

2
Introduction

• State and Federal agencies commonly use crash
  data to identify problems, develop
  countermeasures and evaluate those
  countermeasures.
• Georgia has recently developed a probe-based
  system to provide traffic data along portions of
  the metro Atlanta highway system.
• GDOTs probe-based system has the potential to
  provide a robust data source for various highway
  safety applications.

3
Georgia System Background

• Fiber Communications along GA 400 were disabled
  due to a disruption in communications.
• GDOT needed to collect and report travel times,
  local speeds, and incident alerts.
• Deployment of a replacement fiber backbone would
  have taken at least two years.

4
Georgia System Background Cont.

• A cellular probe-based system was installed on a
  12-mile stretch of GA 400 from Abernathy Road to
  Old Milton Parkway.
• Data is integrated with GDOTs central control
  system.
• Data is delivered to the public through 3
  channels
• Provided through the 511 traveler information
  system
• Displayed on Dynamic Message Signs
• Displayed on the Georgia NaviGAtor website

5
GA 400 Project cont.
6
System Configuration

• Data extraction and analysis system is located at
  the cellular facility.
• Standard probes are installed.
• Signaling data on the cellular network passively
  monitored.
• There is no need to modify the network or the
  handset.
• Only anonymous data is extracted from the probe.

Base Station Controllers
Antennas

One way
Agilent Probe
Anonymous data
Cellular switch
Cellints Pattern Matching Server
Only travel time data
Firewall
Central Traffic Server
Application Server
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Cell Probe vs. VDS Data
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Enhancements to Safety Analytics

• Potential areas for impact provided by
  probe-based systems
• Speed Enforcement
• Vehicle-Miles-Traveled-Estimation
• Safety Countermeasure Evaluation

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Safety Analytics - Speed

• Current efforts to determine where speed is a
  problem via crash data is problematic since
• Associating speeding with a crash is usually left
  to the subjective judgment of the responding
  officer.
• Time lag before crash data makes it into a system
  for analysis.
• Locations characterized by high speeds may be
  potentially dangerous and overlooked due to, for
  example, lower traffic volumes.

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Safety Analytics VMT Estimation

• Current methodologies for estimating VMT do not
  attempt to measure
• Corridor-specific VMT
• Time-specific VMT
• The Georgia probe system was not designed for the
  purpose of estimating VMT it is nonetheless a
  future application.

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Safety Analytics - Evaluation

• Probe data would allow one to enhance evaluation
  through
• Transparency of speed countermeasures in terms of
  changes in actual speeds.
• Timeliness of corresponding changes in speed due
  to the implementation of the specific
  countermeasure.
• Other examples include
• Technologies such as red light cameras where the
  confounding effect of changes in traffic volumes
  could be incorporated into the analysis.
• EMS outcomes where crash notification and
  location are factors.

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Challenges to Implementation

• There are many challenges in deploying and
  evaluating a cellular probe-based traffic data
  collection system, including
• Technical (Differentiating stopped traffic and
  parked vehicles, unreliability of speed estimates
  at extreme values, etc.)
• Legal (Data privacy and confidentiality, etc.)
• Institutional (Developing cooperative
  agreements, public sector technology adoption,
  etc.)

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Conclusions

• There is no statistical difference (p0.1)
  between speeds measured by Georgias probe-based
  and point detection systems at speeds between 20
  and 70 mph.
• To achieve technological maturity - Technical
  Limitations, privacy, and market penetration
  issues must be addressed.
• Probe-based systems are an untapped resource in
  the highway safety realm and have the potential
  for providing more cost-effective, timely,
  accurate, sensitive, and flexible information.

November 16, 2008