1 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

2 OUTLINE Introduction Framework and Operation of CHIPS Safety Effects Diversion Effects Driver Survey Conclusion

3 Background ITS  AWIS Central Controller Traffic Sensors Changeable 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

4 Background Example of AWIS  ADAPTIR  CHIPS  Smart Zone  TIPS Evaluation studies  Most studies: system functionality and reliability  Few studies: effectiveness of AWISs

5 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

6 Introduction Framework and Operation of CHIPS  System Structure  Study Area  System Setup Safety Effects Diversion Effects Driver Survey Conclusion OUTLINE

7 System Structure

8 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

9 System Setup Scenario Queue DetectorCMS Combo Message RTMS-1RTMS-2RTMS-3PCMS-1PCMS-2PCMS-3PCMS-4 PCMS-5 SBS01FFFCMB01 SBS02TFFCMB02CMB03CMB05 SBS03TTFCMB06CMB07CMB03CMB10 SBS04TTTCMB06CMB07CMB08CMB09CMB11 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

10 Introduction Framework and Operation of CHIPS Safety Effects  Data Collection  Traffic Throughput  Travel Speed Diversion Effects Driver Survey Conclusion OUTLINE

11 Data Collection Collection locations  RTMS-1: 0.15 mile before construction  RTMS-2: 1.19 miles before construction Collection time  Before scenario : Aug. 17 th, 2003  After scenario : Sep. 1 st, 2003 Collection Methods  Jamar DB-100 counters and Bushnell Speed Guns

12 Traffic Volume Variance TotalLane 1Lane 2Lane 3Lane 4 RTMS-1 Before After RTMS-2 Before After 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

13 Speed Mean and Variance # of Samples Sample Mean Standard Deviation Sample Variance RTMS-1 Before After RTMS-2 Before After 1, RTMS-1RTMS Difference between before and after values is significant (90% confidence level)

14 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 Hughes Off-ramp Hasley Canyon Off-ramp SR-126 I-5 Old Road Rye Canyon Off-ramp Magic Mountain On-ramp Valencia On-ramp Old Road I-5

15 Data Collection Collection Methods  I-5 mainline traffic volume : PeMS database  Off-ramp traffic volume : Tube counter Collection Periods  Before scenario : May 13 th ~ May 18 th,2003  May 18 th  After scenario : Independence Holiday weekend (June 30 th ~ July 7 th, 2003)  July 6 th Labor Holiday weekend (Aug. 30 th ~ Sep. 2 nd, 2003)  Sep. 1 st

16 Calculation of Diversion Proportion-based method P = V off V V I-5 S Old road  = P a - P b = V off a VaVa V off b VbVb V d =  V a  Proportion  Diversion rate  Diversion traffic volume a : after scenario b : before scenario

17 Diversion Estimation Hasley Canyon off-ramp traffic proportions

18 Diversion Estimation Estimation of diversion traffic volume Based on Caltran’s traffic report regarding Maximum Delay On July 6 th  15:30 ~ 17:30 On Sep. 1 st  17:30 ~ 20:00

19 Travel Time Analysis Comparison of travel times - July 6 th,2003 by GPS-based probe vehicles survey

20 Driver Survey  Method : Postcard-based survey  Location : Lake Hughes and Hasley Canyon off-ramp  Date : 1:40~4:30 PM, Sunday, July 6 th, 2003  Response rate : 25% (100/400)

21 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

22 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 6 th and September1 st  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.

23 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.