Travel Time Reliability Evaluation of Recurring and Nonrecurring Congestion

Midwest Travel Model Users Group July 19, 2016

Reliability - Travel Times

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Measuring Reliability • Travel Time Data

– INRIX, Bluetooth, TICAS, etc. – Not an average!

• Nonrecurring elements – Weather – Crashes – Roadwork – Events

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Reliability– Surface Plot

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Previous SHRP 2 Work

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Reliability – CDF Curves

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0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

10 20 30 40 50 60Travel Time (minutes)

None

Weather

Event

Crash

Incident

Roadwork

Other*

*Other includes combinations of categories

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Reliability Thermometers

Existing Future

Days/Month Days/Month

Congestion Threshold

2x Free Flow Travel Time

Congestion Threshold 2x Free Flow Travel Time

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Performance Measures

Travel Time Index Travel Time Index is the ratio of the average observed travel time divided by the average free-flow travel time. Buffer Index The buffer index is the proportion of extra time (or time cushion) that most travelers add to their average travel time when planning trips to ensure on-time arrival. Planning Time Index Planning Time Index is the factor applied to the free-flow time needed to ensure on-time arrival 95% of the time. It differs from the buffer index since it includes recurring delay as well as unexpected delay.

Planning Time Failure / On-Time Measures Planning Time Failure / On-Time Measures describe the percentage of trips with travel times within a certain factor of the median travel time. Common thresholds include 1.1* Median Travel Time or 1.25* Median Travel Time. Other formulations of these measures denote the percentage of trips with average speeds below a specified threshold, for example 50 mph, 45 mph, or 30 mph.

80th Percentile Travel Time Index 80th Percentile Travel Time Index is the 80th percentile travel time divided by the free flow travel time. It represents another threshold of impacted traffic flow condition.

Misery Index Misery Index is the average of the highest five percent of travel times divided by the free flow travel time. Often referred as the 97.5% travel time index.

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𝑇𝑇𝑇𝑇𝑇𝑇 =𝑇𝑇𝑇𝑇𝑂𝑂𝑂𝑂𝑂𝑂𝑂𝑂𝑂𝑂𝑂𝑂𝑂𝑂𝑂𝑂𝑇𝑇𝑇𝑇𝐹𝐹𝑂𝑂𝑂𝑂𝑂𝑂𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹

𝐵𝐵𝑇𝑇 =𝑇𝑇𝑇𝑇95% − 𝑇𝑇𝑇𝑇𝑀𝑀𝑂𝑂𝑀𝑀𝑀𝑀

𝑇𝑇𝑇𝑇𝑀𝑀𝑂𝑂𝑀𝑀𝑀𝑀

𝑃𝑃𝑇𝑇𝑇𝑇 =𝑇𝑇𝑇𝑇95%

𝑇𝑇𝑇𝑇𝐹𝐹𝑂𝑂𝑂𝑂𝑂𝑂𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹

𝑇𝑇𝑇𝑇𝑇𝑇80% =𝑇𝑇𝑇𝑇80%

𝑇𝑇𝑇𝑇𝐹𝐹𝑂𝑂𝑂𝑂𝑂𝑂𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹

𝑀𝑀𝑇𝑇 =𝑇𝑇𝑇𝑇97.5%

𝑇𝑇𝑇𝑇𝐹𝐹𝑂𝑂𝑂𝑂𝑂𝑂𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹

Previous SHRP 2 Work

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0

5

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45

50

0

50

100

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2006 2007 2008 2009 2010 2011 2012

Volu

me

(100

0 AD

T)

Dela

y (1

000

hour

s) None

Weather

Event

Crash

Incident

Roadwork

Other

Volume

Previous SHRP 2 Work

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• Approximately 800 directional miles – Freeways -- 4 and 6 lanes – Rural two-lane highways – Urban arterials

• 3 years of Travel Time Data – 1 to 5 min. intervals

• ATR Continuous Volume Data

• Sites with highest combined volumes and crashes received priority

• 90% used for model development 10% used to verify and calibrate

WisDOT Reliability

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Travel Time Equations

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0

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70

0 1000 2000 3000 4000 5000 6000 7000 8000

Spee

d (m

ph)

Demand (pce/hr)

Freeway Corridor with 65 mph FFS

Normal Conditions

Snow Conditions

Crash

Incident

Crash + Snow

Incident + Snow

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Snow Frequencies

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0%

5%

10%

15%

20%

25%

Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec

Aver

age

Freq

uenc

y

Snow – Northwest Region

Snow

• Average Frequencies developed for each month by weather region

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Crash Risk Distribution

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y = 1.7689e0.0007x R² = 0.9146

0

5

10

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25

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35

0 500 1000 1500 2000 2500 3000 3500 4000 4500

Cras

h O

bser

vatio

ns p

er 1

000

Volu

me

Occ

urre

nces

Volume

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Predictive Reliability Example

0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

6.0%

7.0%

8.0%

0

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0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000

VMT

Dist

ribut

ion

Spee

d (m

ph)

Demand (vph)

2040 No Build VMT

2040 Build VMT

4-Lane Speed

6-Lane Speed

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I-35W Managed Lane

• 8 segments in study area • Travel time and volume data

– Year 2014 (every day)

– 15-minute intervals

• Non-recurring conditions data – MnCMAT crash data

– NOAA weather data

1

2

Project Area Study Area

Reliability Segments

3

5

6

7

8

4

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Project Alternatives

No Build HOV / MnPASS Gen Purpose

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Southbound – 2040 No Build

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Southbound – 2040 GP

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Southbound – 2040 MnPASS

MnPASS Lane

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Southbound Reliability – AM Peak

2040 GP 2040 MnPASS (GP Lanes)

2040 MnPASS (MnPASS Lane)

2040 HOV (GP Lanes)

2040 HOV (HOV Lane)

North of Lexington Ave to Mississippi River Days/Month Days/Month Days/Month Days/Month Days/Month

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Northbound Reliability – PM Peak

2040 GP 2040 MnPASS (GP Lane)

2040 MnPASS (MnPASS Lane)

2040 HOV (GP Lanes)

2040 HOV (HOV Lane)

Mississippi River to North of Lexington Ave Days/Month Days/Month Days/Month Days/Month Days/Month

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-

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

Add General Purpose Add MnPASS Add HOV

Peak

Per

iod

Pers

on T

rips

Reliability by Person Trips - Peak Period/Peak Direction

4.0 x Free Flow

3.5 x Free Flow

3.0 x Free Flow

2.5 x Free Flow

2.0 x Free Flow

1.5 x Free Flow

Free Flow

Managed Lane

Reliability Comparison

12,000

21,000

18,000

Increase reliability by 9,000 trips

Additional 4,000 people throughput

Travel Times

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I-494/TH 62 Congestion Relief

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TH 169 Mobility Study

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NB

PTI Delay (hr) RR Weather

RR Crash

RR PTI Delay (hr) RR Weather

RR Crash

RR

1.33 44 92% 77% 33% 3.42 446 41% 19% 16%

2.30 78 89% 75% 67% 2.20 136 76% 51% 8%

2.06 162 66% 51% 50% 0.97 2 100% 99% N/A

1.40 60 91% 81% 70% 1.30 39 95% 87% 50%

Excelsior

Old Shakopee

CR 69 Notes: Tuesday – Thursday only

Planning Time Index (PTI) = 𝑇𝑇𝑇𝑇95%𝑇𝑇𝑇𝑇𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹

Delay is the average total delay (for all vehicles) for the peak period in hours Reliability Rating (RR) = 𝑇𝑇𝑂𝑂𝑇𝑇𝑇𝑇𝑂𝑂𝑇𝑇𝑇𝑇<1.25∗𝐹𝐹𝐹𝐹𝑇𝑇𝑇𝑇

𝑇𝑇𝑂𝑂𝑇𝑇𝑇𝑇𝑂𝑂𝑡𝑡𝐹𝐹𝑡𝑡𝑡𝑡𝐹𝐹

N/A = Insufficient Data

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Previous Applications

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Scott County Congestion

Performance Measures

AM Peak

Reliability/ Congestion Map

Data Source: NPMRDS

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Reliability Resources Upcoming Activities • Minnesota Reliability Outreach (Fall 2015)

Online Resources • SHRP 2 Website

– Publications, Tools, and Webinars • Travel Time Reliability Reference Manual

– Online Wikibook by Michael Janson 7/19/2016 27

Contact: Paul Morris pmorris@srfconsulting.com

763-475-0010

Questions? Thank you!

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