evaluation of effectiveness of automated workzone information systems
DESCRIPTION
Evaluation of Effectiveness of Automated Workzone Information Systems. Lianyu Chu CCIT, University of California Berkeley Hee-Kyung Kim, Yonshik Chung, Will Recker University of California Irvine. OUTLINE. Introduction Framework and Operation of CHIPS Safety Effects Diversion Effects - PowerPoint PPT PresentationTRANSCRIPT
1University of California
IrvineUniversity of California
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IrvineUniversity of California
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Evaluation of Effectiveness of Automated Workzone Information Systems
Lianyu Chu CCIT, University of California Berkeley
Hee-Kyung Kim, Yonshik Chung, Will ReckerUniversity of California Irvine
2University of California
IrvineUniversity of California
IrvineUniversity of California
IrvineUniversity of California
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OUTLINE
• Introduction• Framework and Operation of CHIPS• Safety Effects• Diversion Effects • Driver Survey• Conclusion
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IrvineUniversity of California
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Background
ITS AWIS Central ControllerTraffic SensorsChangeable Message Signs
provide traffic information to travelers potentially:
-> increase safety-> improve the efficiency of traffic system
Benefits
work zones have become one of source of traffic congestion
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IrvineUniversity of California
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IrvineUniversity of California
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Background
Example of AWIS ADAPTIR CHIPS Smart Zone TIPS
Evaluation studies Most studies: system functionality and reliability Few studies: effectiveness of AWISs
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Objectives & approach
Evaluation of CHIPS Developed by ASTI Deployed in southern California
focus: effectiveness Safety effects Diversion effects Drivers’ acceptance
Approach: before and after study
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• Introduction• Framework and Operation of CHIPS
System Structure Study Area System Setup
• Safety Effects• Diversion Effects • Driver Survey• Conclusion
OUTLINE
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IrvineUniversity of California
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System Structure
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Study Area
Site Location City of Santa Clarita, 20 miles north
of Los Angeles, on freeway I-5 I-5: 4-lane freeway with the closure
of one lane on the median side Construction zone: 1.5 miles long Parallel route: the Old Road
System Configuration - 3 RTMSs - 5 PCMSs - 3 CCTV cameras
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System Setup
ScenarioQueue Detector CMS Combo Message
RTMS-1 RTMS-2 RTMS-3 PCMS-1 PCMS-2 PCMS-3 PCMS-4 PCMS-5
SBS01 F F F CMB01 CMB01 CMB01
SBS02 T F F CMB02 CMB03 CMB05
SBS03 T T F CMB06 CMB07 CMB03 CMB10
SBS04 T T T CMB06 CMB07 CMB08 CMB09 CMB11
T = Queue being detected, F = No queue being detected
Scenario SBS04: all three RTMSs have congestion, the following messages are shown on PCMSs:
CMB06 : SOUTH 5/TRAFFIC/JAMMED, AUTOS/USE NEXT/EXIT CMB07 : JAMMED/TO MAGIC/MOUNTAIN, EXPECT/10 MIN/DELAY CMB08 : JAMMED/TO MAGIC/MOUNTAIN, EXPECT/15 MIN/DELAY CMB09 : TRAFFIC JAMMED TO MAGIC MTN, AVOID DELAY USE NEXT EXIT CMB11: SOUTH 5 ALTERNAT ROUTE, AUTOS USE NEXT 2 EXITS
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IrvineUniversity of California
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• Introduction• Framework and Operation of CHIPS• Safety Effects
Data Collection Traffic Throughput Travel Speed
• Diversion Effects • Driver Survey• Conclusion
OUTLINE
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Data Collection
Collection locations RTMS-1: 0.15 mile before construction RTMS-2: 1.19 miles before construction
Collection time Before scenario : Aug. 17th, 2003 After scenario : Sep. 1st , 2003
Collection Methods Jamar DB-100 counters and Bushnell Speed Guns
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Traffic Volume Variance
Total Lane 1 Lane 2 Lane 3 Lane 4
RTMS-1 BeforeAfter
11.66.5
11.66.5
15.76.3
3.44.5
7.87.6
RTMS-2 BeforeAfter
37.431.2
4.44.2
2.84.6
3.94.3
1.82.4
11.66.5
15.76.3
44.925.4
Difference between before and after values is significant (90% confidence level)
With the grouped traffic data, the difference of variance was significant at RTMS-1, which means that the variance of the after scenario was statistically smaller than that of the before scenario With lane-based traffic data, the significant differences of variances were found for lane 1 and lane 2 at RTMS-1
Variance of traffic volume based on 1-min data
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Speed Mean and Variance
# of Samples
Sample Mean
Standard Deviation
Sample Variance
RTMS-1BeforeAfter
979970
29.930.6
8.97.1
80.050.2
RTMS-2BeforeAfter
1,186993
21.221.0
5.73.7
32.413.5
RTMS-1 RTMS-2
80.050.232.413.5
Difference between before and after values is significant (90% confidence level)
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• Introduction• Framework and Operation of CHIPS• Safety Effects• Diversion Effects
Data Collection Calculation of Diversion Diversion Estimation Travel Time Analysis
• Driver Survey• Conclusion
OUTLINE
Lake HughesOff-ramp
Hasley CanyonOff-ramp
SR-126
I-5Old Road
Rye CanyonOff-ramp
Magic MountainOn-ramp
ValenciaOn-ramp
Old Road I-5
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Data Collection
Collection Methods I-5 mainline traffic volume : PeMS database Off-ramp traffic volume : Tube counter
Collection Periods Before scenario : May 13th ~ May 18th,2003 May 18th
After scenario : Independence Holiday weekend (June 30th ~ July 7th, 2003) July 6th
Labor Holiday weekend (Aug. 30th ~ Sep. 2nd, 2003) Sep. 1st
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Calculation of Diversion
Proportion-based method
P = Voff
V
V
Voff
I-5 S
Old road
= Pa - Pb =Voff
a
VaVoff
b
Vb
Vd = Va
Proportion
Diversion rate
Diversion traffic volume
a : after scenariob : before scenario
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Diversion Estimation
Hasley Canyon off-ramp traffic proportions
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Diversion Estimation
Estimation of diversion traffic volume
Based on Caltran’s traffic report regarding Maximum DelayOn July 6th 15:30 ~ 17:30On Sep. 1st 17:30 ~ 20:00
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Travel Time Analysis
Comparison of travel times- July 6th ,2003 by GPS-based probe vehicles survey
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Driver Survey
Method : Postcard-based survey Location : Lake Hughes and Hasley Canyon off-
ramp Date : 1:40~4:30 PM, Sunday, July 6th , 2003 Response rate : 25% (100/400)
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Driver Survey
Did the traffic signs influence route choice? Yes : 78% of people who saw the PCMS message
Why did you get off the I-5 south? 73% : avoid traffic 22% : buy gas and foods 5% : arrived at destination
Did you find these signs useful? (check all that apply) 70% : useful for providing information 63% : useful for taking alternative routes 53% : useful for avoiding delay 48% : useful for reducing anxiety 9% : NOT useful
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Conclusion
Three aspects of effectiveness studies were conducted, including traffic diversion, safety effects, and responses from travelers
The results of these studies showed that: Obvious diversion were observed on two evaluation
dates, July 6th and September1st Based on the study of the effects of traffic flow, the
driving environment after the use of CHIPS seemed safer
Positive responses about the system were obtained based on driver surveys.
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Conclusion
• The safety has been enhanced– Stable traffic condition (speed and volume
variance)• Network performance improved
– 12% of diversion was observed– Alternative was still faster than mainline
• Driver response– 70% of drivers expressed the system to be useful
• Direct quantification was not made, but found positive effectiveness of the system.