january 23, 2006transportation research board 85 th annual meeting using ground truth geospatial...

January 23, 2006Transportation Research Board 85th Annual Meeting

Using Ground Truth Geospatial Data to Validate Advanced Traveler Information Systems Freeway Travel Time Messages

Transportation Research Board Annual Meeting, January 23, 2006

Christopher M. MonsereDepartment of Civil & Environmental EngineeringPortland State University

Aaron BreakstoneSchool of Urban Studies & Planning Portland State University

Robert L. Bertini Department of Civil & Environmental EngineeringPortland State University

Dean DeeterCastle Rock Consultants

Galen McGillOregon Department of Transportation


Outline

• Introduction

• Study Area

• Archived Data

• Data Collection

• Data Analysis

• Conclusions

• Next Steps


Project Goal

• Evaluation of Oregon Department of Transportation (ODOT)’s travel time estimating and reporting capabilities


Real-time Travel Time Estimates

• FHWA policy• Variety of technologies

– Inductive loop detectors– Microwave radar– Automatic vehicle tag matching– Video detection– License plate matching– Cell phone matching

• Past research– General accuracy in free-flow conditions– Recurring congestion & incidents more challenging


Portland ATMS• Freeway surveillance

– 485 inductive loop detectors (approximately 175 stations)

Dual loop Mainline lanes Upstream of on-ramps

– 135 ramp meters– 98 CCTV

• ATIS– www.TripCheck.com

Real-time speed map Static CCTV images

– 18 dynamic message signs (DMS) 3 display travel times


Outline

• Introduction

• Study Area

• Archived Data

• Data Collection

• Data Analysis

• Conclusions

• Next Steps


Study Area

• 15 directional freeway links– I-5 (6)– I-205 (3) – I-84 (2)– US-26 (2)– OR-217 (2)

Downtown Portland


Travel Time Calculation

Influence

Area 4 Travel Time 4

Travel Time 1Influence

Area 1


Area 3


Area 2

Link Travel Time

(TT1 + TT2 + TT3 + TT4)

Downtown Portland


Outline

• Introduction

• Study Area

• Archived Data

• Data Collection

• Data Analysis

• Conclusions

• Next Steps


PORTAL• National ITS

Architecture ADUS• Funded by NSF• Direct fiber-optic

connection between ODOT and PSU

• 20-second data– Occupancy– Volume– Speed

• Customized travel time area – Conforms to TMOC

www.portal.its.pdx.edu

(Portland Regional Transportation Archive Listing)


Outline

• Introduction

• Study Area

• Archived Data

• Data Collection

• Data Analysis

• Conclusions

• Next Steps


Experimental Design• Analysis of estimates

– Plan logical routes– Determine variability

• Data collection plan– 5-10 runs required for

most links– 4 routes designed– Transitional periods

targeted– Groups with 5-7 minute

headways– Standard probe vehicle

instructions

217 Southbound: US26 Interchange to I-5 Interchange [Link 9]

0

10

20

30

40

50

60

0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00

Time

Tra

ve

l T

ime

s

Cu

mu

lativ

e T

rav

el T

ime


Data Collection• Hardware

– Palm handheld computers

– Magellan GPS devices

• Software– ITS-GPS

Available at www.its.pdx.edu

• Individual runs and groups of probe vehicles

• Variety of traffic conditions– 45 percent congested

– 2 notable incidents


Data Collection• 87 probe vehicle runs• 904 minutes (~15 hours) of collection time• 516 miles of data• 12 drivers• 7 days (Wed – Fri)

date time elapsed latitude longitude dist mi vel mi/h2005.04.08 16:17:12 3 45.50830 -122.66865 0.036 43.0982005.04.08 16:17:15 3 45.50865 -122.66806 0.037 44.9632005.04.08 16:17:18 3 45.50902 -122.66749 0.038 45.1932005.04.08 16:17:21 3 45.50944 -122.66705 0.036 43.2472005.04.08 16:17:24 3 45.50995 -122.66680 0.037 44.7582005.04.08 16:17:27 3 45.51050 -122.66676 0.038 45.7102005.04.08 16:17:30 3 45.51106 -122.66690 0.039 47.1882005.04.08 16:17:33 3 45.51161 -122.66719 0.041 48.6672005.04.08 16:17:36 3 45.51222 -122.66750 0.045 53.7452005.04.08 16:17:39 3 45.51289 -122.66770 0.047 56.8142005.04.08 16:17:42 3 45.51360 -122.66776 0.049 59.034


Outline

• Introduction

• Study Area

• Archived Data

• Data Collection

• Data Analysis

• Conclusions

• Next Steps


Probe Vehicle Data• Individual runs

downloaded – “run” = several links

+ extraneous data

• Unique ID for each GPS record

• Runs plotted on freeway network

– Links color-coded

• Pertinent data segments extracted

last point on Link 9

last point on Link 2

first point on Link 3


Matching Estimates• Nearest 20-second interval

– e.g. 9:15:34 9:15:20

• Aggregation– Averages more realistic to operation of system

Average of nearest interval and 1 minute prior Average of nearest interval and 3 minutes prior


Probe vs. Estimated Travel Times

0

5

10

15

20

25

30

35

0 5 10 15 20 25 30 35

Observed Probe Vehicle Travel Tim e

Est

imat

ed T

rave

l Tim

e

Average of previous 3 minutes


-100%

-80%

-60%

-40%

-20%

0%

20%

40%

60%

80%

100%

2 3 4 5 6 7 8 9 10 12 13 14 16 17

Link Num ber

Per

cen

t E

rro

rResults


Outline

• Introduction

• Study Area

• Archived Data

• Data Collection

• Data Analysis

• Conclusions

• Next Steps


Conclusions • Estimates reasonably accurate given current

system configuration– Many within 20% of probe times– Less so under congested conditions– Incidents produced highest error

• Averaging improves accuracy• Detector density and location critical


303.5

304.0

304.5

305.0

305.5

306.0

306.5

307.0

307.5

308.0

8:06:00 8:08:00 8:10:00 8:12:00 8:14:00 8:16:00

Time

Mile

po

st

Run 7292.3

293.3

294.3

295.3

296.3

297.3

298.3

299.3

300.3

8:05:00 8:10:00 8:15:00 8:20:00 8:25:00 8:30:00

Time

Mile

po

stConclusions

• Detector density and location criticalEstimated Travel Time: ~25.5 minutes

Probe Travel Time: ~14.5 minutes

68.9

69.4

69.9

70.4

70.9

71.4

71.9

72.4

72.9

8:17:00 8:18:30 8:20:00 8:21:30 8:23:00 8:24:30 8:26:00 8:27:30

Time

Mile

po

st

Probe

Projection

Influence Area Limit

Probe Travel Time: ~11 minutes

Estimated Travel Time: ~9.5 minutes


0.3

1.1

1.9

2.7

3.5

4.3

5.1

5.9

6.7

8:18:00 8:23:00 8:28:00 8:33:00 8:38:00 8:43:00 8:48:00 8:53:00 8:58:00

Time

Mile

po

st

69.7

70.2

70.7

71.2

71.7

72.2

72.7

73.2

73.7

16:26:00 16:28:00 16:30:00 16:32:00 16:34:00 16:36:00 16:38:00 16:40:00 16:42:00

Time

Mile

po

st

Conclusions• Incidents difficult to capture


Outline

• Introduction

• Study Area

• Archived Data

• Data Collection

• Data Analysis

• Conclusions

• Next Steps


Next Steps

• More data– Targeted conditions– Fill gaps

Incidents Software/hardware issues

– Up-to-date

• Different algorithms– Historical data– Other detectors


Acknowledgements

• ODOT– Stacy Shetler– Dennis Mitchell– Jack Marchant

– Hau Hagedorn

• Student Drivers

• PSU Department of Civil and Environmental Engineering

january 23, 2006transportation research board 85 th annual meeting using ground truth geospatial...

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