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Susan R. Dickey Somak Datta Gupta James A. Misener David Nelson ITSA Annual Meeting TS10 - PowerPoint PPT Presentation

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Roadside Equipment Architectures for DSRC-enabled Applications Using Traffic Signal Phase and Timing Information. Susan R. Dickey Somak Datta Gupta James A. Misener David Nelson ITSA Annual Meeting TS10 May 4, 2010. Agenda. PATH Experience Partitioning SPAT Uses Local Global

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Roadside Equipment Architectures for DSRC-enabled Applications Using Traffic Signal Phase and Timing Information

Susan R. Dickey

Somak Datta Gupta

James A. Misener

David Nelson

ITSA Annual Meeting


May 4, 2010


  • PATH Experience

  • Partitioning SPAT


    • Local

    • Global

    • Use Cases

  • Alternate Configurations

  • Last Words: Generalized Approach

California path spat experience
California PATHSPAT Experience

PATH experience in sending SPAT since 2003…

  • Close relationship with Caltrans, both the Division of Research and Innovation and the local District 4, gives practical perspectice

  • Richmond Field Station Smart Intersectio

    • different traffic signal controller types

    • variety of communications technologies, wired and wireless

  • California Vehicle Infrastructure Integration (VII) Testbed,

  • DSRC SPAT demonstrations

    • Turner Fairbank Highway Research Center in 2003

    • ITS World Congresses in 2005 and 2008


California path smart intersection 2004 present
California PATH Smart Intersection (2004-present)

  • Initially WiFi was used to deliver in-vehicle warnings and enable SV/POV/RSE communication for driver behavior research.

  • Kapsch-TraffiCom IEEE 1609 capable MCNU has been installed

  • Savari MobiWAVE and ITRI radios have also been installed.

Vii california test bed 2005 to present
VII California Test Bed (2005 to Present)

  • 60 miles right of way

  • Denso and Kapsch RSE

  • Test bed applications:

    • Traveler information using 511

    • Electronic payment and toll collection

    • Ramp metering

    • Cooperative Intersection Collision Avoidance

    • Curve Over-Speed warning

    • HA-NDGPS

    • Vehicle information and diagnostics

  • Public agency and auto industry partners.

Path signal phase software history


AB3418 (TSP Project, 2002)

Sniffer (Page Mill, 2006)


NTCIP serial (Turner Fairbank, 2003; RFS, 2004)

AB3418 (ECR/Fifth, 2007)

Econolite ASC/3-2100

NTCIP ethernet (World Congress, 2005)

PATH Signal Phase Software: History

Signal phase count down and broadcast software modular design




Data Server

Signal Phase Count-Down and Broadcast Software: Modular Design

Phase Countdown

Message Broadcast

Broadcast devices and formats can be changed, with no impact to other modules

Any signal information source may be used, with no change to other modules

Path atcp 2070 controller
PATH ATCP 2070 Controller

  • A “Traffic Control PC”, utilizing ATC 2070 hardware

  • Open architecture and open source software

  • Layer (modular) construction

    • Field I/O layer provides a interface for traditional input (loop, pedestrian push button) and output (traffic signal bulbs and pedestrian signs)

    • Communications layer provides interface for advanced input (IntelliDrive, TSA request) and output (SPAT)

    • Control layer (open source)

  • Better adaptability to advances in technology

  • Ensures interoperability within systems

  • A platform and environment

    • Test new technology

    • Conduct repeatable experiments

Current use
Current Use

  • Controls traffic lights at Richmond Field Station test intersection

  • Used by FHWA TFHRC SBIR Contractor

  • Supports

    • Fixed-time control

    • TSP (green truncation and extension)

    • CICAS-TSA all-red extension

    • CICAS-SLTA driver behavior experimental study

    • Real-time performance monitoring

New work with spat
New Work with SPAT

  • FHWA Exploratory Advanced Research Proposal (Advanced Traffic Signal Control Algorithms): Caltrans, PATH, BMW

    • Base idea: Use vehicles as probes

    • Can use DSRC or other (3G, 4G) wireless communications between intersections

    • Use and fuse field elements (discrete detectors) where available

    • Uses modern control theory

  • State Pooled Fund Study: Investigating the Potential Benefits of Broadcasted SPAT Data under IntelliDrive

Local and current spat information
Local and Current SPAT Information

Traffic Signal Violation Warning

Signal Violation Warning

Traffic Signal Adaptation

Left Turn Gap Assistance

Since global information is not required, these could be implemented incrementally where most needed

Since advanced count-down prediction is not required, could be implemented with conflict monitor or current sniffer without advanced traffic signal controller.


Local only spat sent i2v
Local, only SPAT, sent I2V

Traffic Signal Violation


Heavy Vehicle Traffic

Signal Advisory

Particularly suited for implementation by the traffic signal controller with the addition of only a simple DSRC unit, since additional dynamic information from other sensors or global sources is not required.


Global information bidirectional communication
Global Information, Bidirectional Communication

SPAT-Aware Navigation

Dynamic Transit Arrival Time Prediction

Transit Signal Priority

SPAT-Aware Green Acceleration

Particularly suited for initial implementation using traffic signal information already being sent to traffic management centers, and possibly 4G communications, if the latencies are found to be tolerable. As more cars become enabled for these applications, the latencies may grow and require DSRC implementation.


Spat rse functional modules and data flow
SPAT RSE Functional Modules and Data Flow

Traffic Signal Info Source

Radio Unit

Signal Info

SPAT Constructor


Message Formatter


Intersection Timing Specification

Intersection Geographical Information

  • Traffic Signal Info Source could be, e.g., current sniffer, conflict monitor or 170 enhanced serial interface.

  • SPAT Constructor creates SPAT, including countdown, in internal format using best available information from traffic signal.

  • Message Formatter uses geographical information to place SPAT information in correct bytes to match geographical information (GID), as well as formatting GID

  • Radio Unit takes formatted messages and broadcasts using desired frequency and protocol


Spat rse hardware architectures
SPAT RSE Hardware Architectures

2008 ITSA World Congress New York City

Traffic Signal Info Source

SPAT Constructor

Message Formatter

Peek Traffic Signal Controller

Radio Unit



Richmond field station rse
Richmond Field Station RSE

Current Sniffer

Digital I/O



SPAT Constructor

Message Formatter

Radio Unit




EDI Conflict Monitor




A variety of traffic signal sources have been tested.

Vii california testbed rse
VII California Testbed RSE

El Camino Real/Page Mill Road,

Palo Alto

SPAT Constructor

Message Formatter

Radio Unit

Digital I/O

Current Sniffer



Denso WRM



Steps to deploying individual spat rse
Steps to Deploying Individual SPAT RSE

Top level activities (some in parallel)

Testing for radio and computer system performance and reliability

Testing of interface to traffic signal controllers for enhanced SPAT information

Development of J2735-compatible SPAT format and associated GID

Vehicle reception of new SPAT format

On-site installation of RSE

On-site installation of controller interface

Calibration of accurate Map/GID (for each intersection, requires vehicle testing)

On-site broadcast of enhanced SPAT/Map (GID)




Jim Misener

California PATH Program, University of California, Berkeley

[email protected]