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Traffic Detection Systems. CEE 320 Anne Goodchild. Outline. What are traffic detectors? Traffic detector importance Detector types Use Example. What Are Traffic Detectors?. Devices that are used for detecting vehicles, bicycles, and pedestrians. Traffic Detection Systems Structure.

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Traffic detection systems l.jpg

Traffic Detection Systems

CEE 320Anne Goodchild


Outline l.jpg
Outline

  • What are traffic detectors?

  • Traffic detector importance

  • Detector types

  • Use Example


What are traffic detectors l.jpg
What Are Traffic Detectors?

Devices that are used for detecting vehicles, bicycles, and pedestrians


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Traffic Detection Systems Structure

Detector

Processor/Controller

Storage


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Applications

  • Monitor conditions

    • Reduce congestion

  • Control operations

    • Signal timing

    • Variable speed limits

  • Understand system for strategic planning

    • Infrastructure development

    • Improved management




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Why Is Traffic Detection Important?

Actuated Signal Control



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Why Is Traffic Detection Important?

Dynamic Traffic Assignment


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ATIS

Why Is Traffic Detection Important?

!

!

E-Message Sign

Control Center

Quality Data


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Traffic Detector Types

  • Inductive loops

  • Video

  • Microwave

  • Infrared

  • Acoustic

  • Radar

  • Magnetic

  • Radio frequency

  • Global positioning system (GPS)

Use various waves and fields, frequencies, passive or active, mobile or fixed infrastructure


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Share of Detector Types at new ATMS Sites

Environment, cost, application


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Popular Traffic Detector Types

Inductive loops

Video Image Processors (VIPs)


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Popular Traffic Detector Types

Remote Traffic Microwave Sensor (RTMS)

Photos and picture from Electronic Integrated Systems, Inc.


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RTMS

  • Multi-zone traffic detector with few occlusion problems

  • Unaffected by weather and light

  • Low-power microwave signal

  • Volume, Occupancy, Average Speed and Classification by length


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Popular Traffic Detector Types

Magnetic Sensors

Infrared Sensors


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Popular Traffic Detector Types

Radio Frequency Tag


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Popular Traffic Detector Types

ASIM TT 298: Doppler RADAR, ultrasonic, passive infrared.

Volume, classification, speed, occupancy, queue detection, wrong-way


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Popular Traffic Detector Types

ASIM TT 298: Doppler RADAR, ultrasonic, passive infrared.


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Popular Traffic Detector Types

Intersection Control

Traffic Data Acquisition

= infrared (counting)

= ultrasonic (vehicle height)

= microwave doppler radar (speed)


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Popular Traffic Detector Types

GPS-Based Tracking Systems


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Inductance Loop Detectors

  • Most popular

Photos from Never

Fail Loop Systems, Inc.



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Inductance Loop Detectors

Loop inductance decreases when a car is on top of it.

Inductance

T = ton

0

ton

T = toff

toff

Time


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Inductance

High

low

Tn

tn1

tn2

tn3

Tn+1

Time

Inductance Loop Detectors

  • Single loops can measure:

    • Occupancy (O): % of time loop is occupied per interval

    • Volume (N): vehicles per interval

Single loop measurements?



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Field Component

Traffic Control Cabinet

Pull Box

Lead-In Cable

Loop wires

DEUs

Inductance Loop Detectors



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Dual Loop Detector

  • Formed by two consecutive single loop detectors placed a short distance apart

ldist

lloop


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Dual Loop Detectors

  • Dual loop measurements

ldist

lloop

T = t2

T = t1

oti = on-time for loop detector i

Measured vehicle lengths are used to classify vehicles into different categories, such as long and short.


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Only 20 sec aggregated data are available from TSMC

TSMC

queried

20 sec data

(e.g. 0:00:00 3, 0.98

0:00:20 2, 0.65)

measured data

per 20 sec.

real time

measurements

Loops

Station

cabinet

User

Inductance Loop Detectors


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Can We Get Speed from a Single Loop?

  • Perhaps…

EVL ~ vehicle length + detector length


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Can We Get Speed from a Single Loop?

  • Using typical traffic data

100 converts percent to decimal




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Video Image Processors

Much more promising for pedestrian detection.



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Ramp Meter Schematic

Diagram from ITS Decision website




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Primary References

  • Cosgrove, C. and Cutchin, C. (2003). ITS Decision. Website hosted by the California Center for Innovative Transportation at the University of California and Berkeley and Caltrans. http://www.calccit.org/itsdecision

  • Wang, Y. (2004). CEE 599F, Advanced Traffic Detection Systems Course Pak. Civil and Environmental Engineering, University of Washington.


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