Status Report: Evaluation of Private Sector Data in Minneapolis Shawn Turner [email protected]@tamu.edu, 979-845-8829 Texas Transportation

Status Report:Evaluation of Private Sector Data

in MinneapolisShawn Turner

[email protected], 979-845-8829Texas Transportation Institute

Mobility Measurement Pooled Fund StudyBaltimore, July 22, 2008

mailto:[email protected]

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

“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

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

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

Case Study Corridors

6

MN 65

US 61

US 10/US 61MN 7

MN 55

US 169

US 10/US 169

CO HWY 14

I-494

HWY 13

Example Segmentation: MN 7

7

0

10

20

30

40

50

60

70

12 AM 2 AM 4 AM 6 AM 8 AM 10 AM 12 PM 2 PM 4 PM 6 PM 8 PM 10 PM

Ave

rage

Corr

idor Spee

d (

mph)

Time of Average Weekday

US 169 NB: HWY 130 to HWY 610

Posted speed limit is 55 mph

15-Minute Average Weekday Speeds, Jan 2006 through Feb 2008

8

0

10

20

30

40

50

60

70


Ave

rage

Corr

idor Spee

d (

mph)


US 169 SB: HWY 610 to HWY 130


15-Minute Average Weekday Speeds, Jan 2006 through Feb 2008

9

0

10

20

30

40

50

60

70


Ave

rage

Corr

idor Spee

d (

mph)


US 169 NB: HWY 130 to HWY 610

2007 - 1

2007 - 2

2007 - 3

2007 - 4

2007 - 5

2007 - 6

2007 - 7

2007 - 8

2007 - 9

2007 - 10

2007 - 11

2007 - 12

Hourly Average Weekday Speeds by Month in 2007

Postedspeed limit is 55 mph

10

0

10

20

30

40

50

60

70


Ave

rage

Corr

idor Spee

d (

mph)


US 169 SB: HWY 610 to HWY 130

2007 - 1

2007 - 2

2007 - 3

2007 - 4

2007 - 5

2007 - 6

2007 - 7

2007 - 8

2007 - 9

2007 - 10

2007 - 11

2007 - 12

Hourly Average Weekday Speeds by Month in 2007

Postedspeed limit is 55 mph

11

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

0

10

20

30

40

50

60

70


Avera

ge S

peed (

mph)


Comparison of Average Weekday Speeds along I-494(15-Minute Intervals, Jan 2006 through Feb 2008)

MnDOT Detectors Inrix Probes Mean Absolute Difference 13

0

100

200

300

400

500

600

-50 -40 -30 -20 -10 0 10 20 30 40 50

Fre

quency

Difference (MnDOT - Inrix)

Distribution of Average Speed Differences along I-494(15-Minute Intervals, Jan 2006 through Feb 2008)

Inrix speeds faster than MnDOT speeds Inrix speeds slower than MnDOT speeds

14

0

10

20

30

40

50

60

70


Avera

ge S

peed (

mph)


Comparison of Average Weekday Speeds along I-494(60-Minute Intervals, Jan-Feb 2008)

MnDOT Detectors Inrix Probes Mean Absolute Difference 15

0

20

40

60

80

100

120

-50 -40 -30 -20 -10 0 10 20 30 40 50

Fre

quency

Difference (MnDOT - Inrix)

Distribution of Average Speed Differences along I-494(60-Minute Intervals, Jan-Feb 2008)

Inrix speeds faster than MnDOT speeds Inrix speeds slower than MnDOT speeds

16

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

3 Comparison Corridors

MN 7MN 65

MN 55

18

19

0

10

20

30

40

50

60

70


Avera

ge S

peed (

mph)


Comparison of Average Weekday Speeds along TH 55 EB

Hourly Average Weekday Speeds by Month in May 2007


Inrix Monthly Average

MnDOT Average

20

0

10

20

30

40

50

60

70


Avera

ge S

peed (

mph)


Comparison of Average Weekday Speeds along TH 55 WB

Hourly Average Weekday Speeds by Month in May 2007


Inrix Monthly Average

MnDOT Average

21

0

10

20

30

40

50

60

70


Avera

ge S

peed (

mph)


Comparison of Average Weekday Speeds along MN 65 NB

Hourly Average Weekday Speeds

MnDOT Average(Aug-Sep2003)

Inrix Average(Aug-Sep2006,2007)

22

0

10

20

30

40

50

60

70


Avera

ge S

peed (

mph)


Comparison of Average Weekday Speeds along MN 65 SB

Hourly Average Weekday Speeds

MnDOT Average(Aug-Sep2003)

Inrix Average(Aug-Sep2006,2007)

27

0

50

100

150

200

250

300

12 AM 2 AM 4 AM 6 AM 8 AM 10 AM12 PM 2 PM 4 PM 6 PM 8 PM 10 PM

Num

ber of Speed D

ata

Sam

ple

s


Total Number of 15-Minute Samples in 26 MonthsAveraged across all links (both directions) on each corridor

US 10/US 169

I-494

HWY 13

US 169

MN 65

US 10/US 61

HWY 14

HWY 55

MN 7

US 61

28

0

10

20

30

40

50

60

70

80

90

100


Num

ber of Speed D

ata

Sam

ple

s


Total Number of 15-Minute Samples in 26 MonthsAveraged across all corridors for each day of the week

Sunday Monday Tuesday Wednesday Thursday Friday Saturday

29

0

2

4

6

8

10

12

14

16


Num

ber of Speed D

ata

Sam

ple

s


Total Number of 60-Minute Samples in January 2006Averaged across all links (both directions) on each corridor

US 10/US 169

HWY 13

US 169

MN 65

I-494

HWY 14

HWY 55

MN 7

US 61

30

0

2

4

6

8

10

12

14

16


Num

ber of Speed D

ata

Sam

ple

s


Total Number of 60-Minute Samples in January 2008Averaged across all links (both directions) for each day of the week

US 10/US 169

HWY 13

I-494

US 10/US 61

MN 65

HWY 14

MN 7

HWY 55

US 169

US 61

31

0

2

4

6

8

10

12

14

16


Num

ber of Speed D

ata

Sam

ple

s


Total Number of 60-Minute Samples in January 2006Averaged across all links (both directions) on each corridor


32

0

1

2

3

4

5

6

7


Num

ber of Speed D

ata

Sam

ple

s


Total Number of 60-Minute Samples in January 2008Averaged across all links (both directions) for each day of the week


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

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 freeways34

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

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

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

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

Documents

Status Report: Evaluation of Private Sector Data in Minneapolis Shawn Turner [email protected]@tamu.edu, 979-845-8829 Texas Transportation