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Probabilistic Analysis of a Large-Scale Urban Traffic Sensor Data Set Jon Hutchins, Alexander Ihler, and Padhraic Smyth Department of Computer Science.

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Presentation on theme: "Probabilistic Analysis of a Large-Scale Urban Traffic Sensor Data Set Jon Hutchins, Alexander Ihler, and Padhraic Smyth Department of Computer Science."— Presentation transcript:

1 Probabilistic Analysis of a Large-Scale Urban Traffic Sensor Data Set Jon Hutchins, Alexander Ihler, and Padhraic Smyth Department of Computer Science University of California, Irvine

2 People Counter – Optical Sensor Car Counter – Loop Detector Human Activity Sensors Pe MS

3 Outline Modeling human count data Scale-Up challenges Fault-tolerant model Urban Analysis

4 Outline Modeling human count data Scale-Up challenges Fault-tolerant model Urban Analysis

5 Outline Modeling human count data Scale-Up challenges Fault-tolerant model Urban Analysis

6 Outline Modeling human count data Scale-Up challenges Fault-tolerant model Urban Analysis

7 Time Series of Cumulative Counts TimeCar Count 10:0022 10:0526 10:1026 10:1519 10:2031 10:2528 10:3025

8 One Week of Freeway Observations car count

9 One Week of Freeway Observations car count

10 One Week of Freeway Observations car count

11 Sensor location car count One Week of Freeway Observations

12 Original Model hiddenobserved Observed Count

13 Original Model hiddenobserved Observed Count Normal Count Poisson Rate λ(t)

14 Original Model hiddenobserved Observed Count Normal Count Poisson Rate λ(t) Event State Event Count

15 Original Model hiddenobserved Observed Count Normal Count Poisson Rate λ(t) Event State Event Count OBSERVED COUNT NORMAL COUNT (UNOBSERVED) EVENT COUNT (UNOBSERVED) Time-varying Poisson Markov with Poisson counts

16 Original Model hiddenobserved Observed Count Normal Count Poisson Rate λ(t) Event State Event Count OBSERVED COUNT NORMAL COUNT (UNOBSERVED) EVENT COUNT (UNOBSERVED) Time-varying Poisson Markov with Poisson counts Markov Modulated Poisson Process (MMPP) e.g., see Scott (1998)

17 Time t+1 Event State Observed Count Observed Count Observed Count Event Count Event Count Event Count Poisson Rate λ(t) Normal Count Normal Count Normal Count Poisson Rate λ(t) Poisson Rate λ(t) Time t-1Time t Inference over Time hidden observed

18 Learning and Inference Bayesian Framework –Gibbs sampling to approximate parameters and hidden variables –Forward-backward algorithm –Complexity Linear in the number of time slices For Details see Ihler, Hutchins, Smyth ACM TKDD (Dec 2007)

19 Original Model

20 Urban Scale-Up Sensor LocationsMap of study area 1716 sensors + 7 months = over 100 million measurements

21 Urban Scale-Up Difficult Sensors to Analyze see Bickel et al. Statistical Science (2007)

22 Urban Scale-Up – Original Model Event FractionNumber of Sensors 0 to 10%912 10 to 20%386 20 to 50%265 50 to 100%153

23 Event FractionNumber of Sensors 0 to 10%912 10 to 20%386 20 to 50%265 50 to 100%153 car count p(E) Urban Scale-Up – Original Model

24 Urban Scale-Up - Challenges Event FractionNumber of Sensors 0 to 10%912 10 to 20%386 20 to 50%265 50 to 100%153 car count p(E)

25 Urban Scale-Up - Challenges Event FractionNumber of Sensors 0 to 10%912 10 to 20%386 20 to 50%265 50 to 100%153

26 Urban Scale-Up - Challenges Event FractionNumber of Sensors 0 to 10%912 10 to 20%386 20 to 50%265 50 to 100%153

27 Urban Scale-Up - Challenges Event FractionNumber of Sensors 0 to 10%912 10 to 20%386 20 to 50%265 50 to 100%153

28 Event FractionNumber of Sensors 0 to 10%912 10 to 20%386 20 to 50%265 50 to 100%153 Periods of clear periodic behavior missed by our model Long periods of sensor failure

29 Time t+1 Event State Observed Count Observed Count Observed Count Event Count Event Count Event Count Poisson Rate λ(t) Normal Count Normal Count Normal Count hidden observed Poisson Rate λ(t) Poisson Rate λ(t) Time t-1Time t Original Model Fault State Fault-Tolerant Model

30 Event FractionOriginal Model Number of Sensors Fault-Tolerant Model Number of Sensors 0 to 10%9601285 10 to 20%375242 20 to 50%244117 50 to 100%13772 Fault-Tolerant Model

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32 Large-Scale Urban Study Event FractionFault-Tolerant Model Number of Sensors 0 to 10%1285 10 to 20%242 20 to 50%117 50 to 100%72

33 Large-Scale Urban Study Event FractionFault-Tolerant Model Number of Sensors 0 to 10%1285 10 to 20%242 20 to 50%117 50 to 100%72

34 Unusual activity detection as a function of day of week and time of day

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37 16:30 Spatial Event

38 16:30 16:40 16:55 17:05 17:20 17:25 17:50 18:05 18:20

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42 Model prediction of normal flow Raw flow measurements

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45 Model prediction of normal flow Raw flow measurements

46 Conclusions Extended our earlier work to add a fault-tolerant component Our new model automatically learned normal and anomalous behavior for over 1700 sensors and 100 million measurements This approach has made possible analysis of a large- scale urban traffic sensor data set that was previously considered beyond analysis


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