Presentation is loading. Please wait.

Presentation is loading. Please wait.

Status Report: Evaluation of Private Sector Data in Minneapolis Shawn Turner 979-845-8829 Texas Transportation.

Similar presentations


Presentation on theme: "Status Report: Evaluation of Private Sector Data in Minneapolis Shawn Turner 979-845-8829 Texas Transportation."— Presentation transcript:

1 Status Report: Evaluation of Private Sector Data in Minneapolis Shawn Turner Texas Transportation Institute Mobility Measurement Pooled Fund Study Baltimore, July 22, 2008

2 Average Speed Data Provided by Inrix 15-minute average speeds for each day of the week – from Jan 2006 through Feb 2008 (26 months) – Location – Day-of-week/time (672 bins) – Average speed – Number of data samples 60-minute average speeds for each day of the week and month of the year - from Jan 2006 through Feb 2008 (26 months) – Location – Day-of-week/time (168 bins) for 26 months – Average speed – Number of data samples 2

3 Reliability Statistics Provided by Inrix 15-minute by day-of-week statistics from speed distribution – Location – Day-of-week/time – Average speed – Speed percentiles: 10, 15, 25, 50, 85 – Failure rate – frequency of time below 30, 50, 60 mph 3

4 Other Data Provided by Inrix Location referencing tables – The decoder ring for locations – TMC: Traffic Message Channel, a location referencing method (de facto standard) that started in Europe and is popular among traffic information and navigation/map database companies 4

5 Analysis Steps Translate TMC linear referencing Aggregate data to longer road segments Visual checks of basic traffic patterns/trends Compare data with other sources – MnDOT freeway fixed-point detectors (I-494) – MnDOT manual floating car signal timing runs Sample size analysis (Confidential) Merge with HPMS/other DOT databases (TBD) Calculate performance measures (TBD) 5

6 Case Study Corridors 6 MN 65 US 61 US 10/US 61 MN 7 MN 55 US 169 US 10/US 169 CO HWY 14 I-494 HWY 13

7 Example Segmentation: MN 7 7

8 8

9 9

10 10

11 11

12 Comparison with MnDOT Fixed- Point Detectors along I-494 Not apples-apples comparison Fixed vs. mobile point speed measurement Population vs. GPS probe sample 12

13 13

14 14

15 15

16 16

17 Comparison with MnDOT Test Vehicle Runs (Signal Retiming) Still not apples-apples comparison Segment level – not link-by-link Specific days vs. monthly average 17

18 3 Comparison Corridors MN 7 MN 65 MN 55 18

19 19

20 20

21 21

22 22

23 23

24 24

25 25

26 26

27 27

28 28

29 29

30 30

31 31

32 32

33 Preliminary Findings-1 Samples (actual numbers confidential) – More than you get from special studies, but spread over numerous days – Current probes are mostly fleet, but vehicle mix will evolve to include consumer vehicles – Samples have increased 2-3X since 2006 – Samples most dense during workday, few during overnight or weekends (but overnight/weekend not critical for congestion analysis) 33

34 Preliminary Findings-2 Average Speeds – Visual checks show reasonable data during workday hours – Inrix speeds consistently slower than MnDOT freeway detectors Vehicle bias – Inrix mostly commercial vehicles Speed measurement – Mn/DOT has fixed locations – Inrix speeds in range of arterial travel time runs – Larger month-to-month variation on arterial streets than freeways 34

35 Conclusions Applications – Segment level, maybe link (not intersection) – Historical average speeds Hourly values on quarterly or maybe monthly 15-minute values on at least annual basis – Reliability statistics Have not yet analyzed Inrix failure statistics Instinct says we need more samples to represent day- to-day variation 35

36 Conclusions Possible Applications – Identifying most congested routes or segments for further study and improvement – Ranking or prioritizing routes for funding based on average congestion levels – Monitoring and identifying routes with the highest increase in average congestion levels (on monthly or annual basis) – Using as a general indicator in before-after studies of mobility improvements – Developing performance measures on an aggregate basis. 36

37 Recommendations Proceed with more in-depth pilot/feasibility efforts – produce prototype reports – Have only taken preliminary look – Still some work needed before we get performance measures – Private sector data will improve over time 37

38 Implications for Future There will be a private sector market for historical speeds/travel times – How can DOTs take advantage of this? – How to integrate data and address VMT? Different data sources – Each measurement technique has bias/error (until we have GPS probes everywhere) – Use caution in combining/comparing data from different measurement techniques – Adjusting for method bias? 38


Download ppt "Status Report: Evaluation of Private Sector Data in Minneapolis Shawn Turner 979-845-8829 Texas Transportation."

Similar presentations


Ads by Google