June 2006 ITE District 6 Annual Meeting June 26 2006 1 Evaluation of Single-Loop Detector...

June 2006 ITE District 6 Annual MeetingJune 26 2006 1

Evaluation of Single-Loop Detector Vehicle-Classification Algorithms using an Archived Data User Service System

Benjamin Auffray,Kristin A. Tufte, Zachary Horowitz, Spicer Matthews,Robert L. Bertini Portland State University

June 2006, ITE District 6 Annual Meeting


Presentation outline

• Introduction• Project Background• Data Collection• Results• Conclusions• Next Steps• Acknowledgements


Why collect freight data?

• Economic importance

• Lack of knowledge of freight transportation system operation

• Safety and security

• Positive affects on overall transportation system


Project background

Basic idea: Record freeway traffic in order to compare truck counting methods

3 methods:

1) Manual

2) Autoscope “speed” and “count” detectors

3) Nihan-Wang algorithm (UW)


Data sources• PORTAL

• Portland area traffic data archive• Collects volume & occupancy data at 20 second intervals

• ODOT surveillance CCTV network• About 80 cameras on local highways• Recorded to DVD• Used for both manual counts and Autoscope

• Autoscope• Recorded video data processed using RackVision and accompanying software


Site selection

4 locations in Portland, OR

I-5 SB at Marine Dr.I-84 WB at Sandy Blvd/37th

I-5 NB at Lower Boones Fy.OR-217 at SW Hall Blvd

10 days over 4 weeks

Traffic recorded primarilyFrom noon to 5 pm


Data organization and processing• Manual count data sorted by:

• Lane• Vehicle type (short / long / combined)

• Cumulative and oblique plots• Histogram of Autoscope speed detector data used for length determination in some cases

-80

-60

-40

-20

0

20

40

11:40 11:55 12:10 12:25 12:40

Time

N(L

ow

er

Bo

on

es

Fe

rry,

t)

Manual count

Autoscope speed detector

PORTAL-Wang


Graphical plots

Cumulative count of all vehicles

Oblique graph of allvehicles plotted usinga scaling factor

Oblique graph of shortvehicles using a scaling factor


Comparison data

Total Count

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

0 200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000

Predicted Values

Man

ual

Co

un

t

Autoscope

Autoscope Speed

Portal-Wang

Series4

Comparison of total count mechanisms to ground truth

Truck Count Percent Difference

-50%

-25%

0%

25%

50%

75%

100%

125%

150%

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

Hour

Per

cen

t D

iffe

ren

ce

Autoscope SpeedPortal-Wang

=4.4%=6.7%=44.1%, =41.6%

Truck count percent difference


Comparison dataSpeed Relation to All Count Error

-10%

-8%

-6%

-4%

-2%

0%

2%

4%

6%

8%

10%

40 45 50 55 60 65

Measured Speed

Per

cen

t D

iffe

ren

ce

Autoscope

Portal Wang

Note: two outliers removed.

Measured average speed relation to all count error

Comparison by site


Conclusions• Nihan-Wang estimations

• Unusually large error for some speeds and counts• Detector issues such as loop sensitivities• Incorrect or missing data

• Autoscope• Difficulties in calibration and data processing• Returned some favorable results compared to ground truth• ODOT surveillance camera system not ideal for Autoscope

• Manual counts still produce best data


Next steps• Additional data collection

• Detector fidelity is key• Different sites may produce better data• Vehicle classification by type

• Further statistical testing• PORTAL data calibration will improve Nihan-Wang algorithm implementation results• Travel time estimation for freight vehicles• Permanent, automated freight vehicle counting• Ramp meter speed trap installations


Acknowledgements• ODOT TMOC Staff

• Dr. Robert Bertini • PORTAL Team:

• Dr. Kristin Tufte• Spicer Matthews

• Zachary Horowitz


References[1] Y. Wang and N. Nihan. Dynamic estimation of freeway large truck volume based on single-loop measurements. CD-Rom for the 80th Annual Meeting of TRB, paper 01-2853, TRB, National Research Council, Washington D.C., 2001. [2] Kwon, Jaimyoung. Joint Estimation of the Traffic Speed and Mean Vehicle Length From Single-Loop Detector Data. CD-Rom for the 82nd Annual Meeting of TRB, National Research Council, Washington, D.C. 2003. [3] Kwon, Jaimyoung; Varaiya, P. P.; Skabardonis, Alexander. ESTIMATION OF TRUCK TRAFFIC VOLUME FROM SINGLE LOOP DETECTOR USING LANE-TO-LANE SPEED CORRELATION. CD-Rom for the 82nd Annual Meeting of TRB, National Research Council, Washington, D.C. 2003. [4] Nihan, NL; Wang, Y; Zhang, XP. EVALUATION OF DUAL-LOOP DATA ACCURACY USING VIDEO GROUND TRUTH DATA. TransNow, Transportation Northwest, Washington Univ, Civil Engineering Dept, 2002. [5] Y. Wang and N. Nihan. Can Single-Loop Detectors Do the Work of Dual-Loop Detectors? ASCE Journal of Transportation Engineering, 129(2), 169-176, 2003 [6] National ITS ADUS Addendum [7] S. Turner. Guidelines for Developing ITS Data Archiving Systems. Report 2127-3. FHWA, U.S. Department of Transportation, Texas Department of Transportation and Texas Transportation Institute, 2001. [8] Y. Wang and N. Nihan. A Robust Method of Filtering Single-Loop Data for Improved Speed Estimation. CD-Rom for the 81st Annual Meeting of TRB, paper 02-3843, TRB, National Research Council, Washington, D.C. 2002. [9] P. Athol. Interdependence of Certain Operation Characteristics within a Moving Traffic Stream. Highway Research Record 72, 58-87.


Questions and Comments

June 2006 ITE District 6 Annual Meeting June 26 2006 1 Evaluation of Single-Loop Detector...

Documents

Transcript of June 2006 ITE District 6 Annual Meeting June 26 2006 1 Evaluation of Single-Loop Detector...