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Beyond Gee-Whiz Statistics: Beyond Gee-Whiz Statistics: Guiding Transportation Investments Guiding Transportation Investments with Transportation System with Transportation System Performance Measures Performance Measures presented by presented by Richard Margiotta, Principal Richard Margiotta, Principal Cambridge Systematics, Inc. Cambridge Systematics, Inc. November 6, 2003 November 6, 2003

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Page 1: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

Beyond Gee-Whiz Statistics:Beyond Gee-Whiz Statistics:

Guiding Transportation Investments Guiding Transportation Investments with Transportation System with Transportation System Performance MeasuresPerformance Measures

presented bypresented by

Richard Margiotta, PrincipalRichard Margiotta, PrincipalCambridge Systematics, Inc.Cambridge Systematics, Inc.

November 6, 2003November 6, 2003

Page 2: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

Presentation OverviewPresentation Overview

Why Bother With Performance Measures?Why Bother With Performance Measures?

Where We’ve BeenWhere We’ve Been

Advances in Metrics and DataAdvances in Metrics and Data

Opportunities for Performance Measures to Guide Opportunities for Performance Measures to Guide Investment -- Focus on Operations investmentsInvestment -- Focus on Operations investments

Page 3: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

Congestion Performance: Why Bother?Congestion Performance: Why Bother?

Sound Business PracticeSound Business Practice

• Private sector has embraced performance measures as a Private sector has embraced performance measures as a way to:way to:

- Better serve customersBetter serve customers

- Assess return on investmentAssess return on investment

• ““Know where you are before you decide where to go”Know where you are before you decide where to go”

Use of Performance Measures Becoming More Widespread and Use of Performance Measures Becoming More Widespread and Accepted as Best PracticeAccepted as Best Practice

• Well established in pavement and bridge managementWell established in pavement and bridge management

• Service-oriented measures increasingly being used in State Service-oriented measures increasingly being used in State and MPO Long Range Plansand MPO Long Range Plans

Page 4: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

Why Bother? (cont.)Why Bother? (cont.)

AccountabilityAccountability

• Broader customer base for performance measuresBroader customer base for performance measures

• Decision-makers and public becoming increasingly more Decision-makers and public becoming increasingly more interested in “how are we doing?”interested in “how are we doing?”

Becoming easier to do with new technologiesBecoming easier to do with new technologies

Challenges: Challenges:

• How to apply concepts worked out in private sector and How to apply concepts worked out in private sector and transportation planning to real-time Operationstransportation planning to real-time Operations

• Moving beyond simple reporting of trendsMoving beyond simple reporting of trends

Page 5: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

Where We’ve BeenWhere We’ve Been

Performance measures have always been used to some degree Performance measures have always been used to some degree in transportation planning, but at a simplified scale…in transportation planning, but at a simplified scale…

• V/C, travel time/delay studiesV/C, travel time/delay studies

… … But suffer from data problemsBut suffer from data problems

• Indirect measurement (traffic volumes as a surrogate)Indirect measurement (traffic volumes as a surrogate)

• Travel demand forecasting modelsTravel demand forecasting models

• Small samples, infrequent surveysSmall samples, infrequent surveys

Page 6: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

ADVANCES IN DATA AND METRICSADVANCES IN DATA AND METRICS

Page 7: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

What Are We Measuring?What Are We Measuring?

Congestion Congestion

• What happens on facilitiesWhat happens on facilities

MobilityMobility

• What happens to users -- how they experience the What happens to users -- how they experience the transportation system (trips)transportation system (trips)

AccessibilityAccessibility

• Interaction of transportation system and activities Interaction of transportation system and activities (opportunities)(opportunities)

Congestion and Mobility can use similar metricsCongestion and Mobility can use similar metrics

Page 8: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

Metrics for Performance MonitoringMetrics for Performance Monitoring

System performance tracked at the level of the user (trip) System performance tracked at the level of the user (trip) and facility (corridor)and facility (corridor)

Understandable to professionals and publicUnderstandable to professionals and public

Multiple metrics to capture full rangeMultiple metrics to capture full range

Existing data and methods, preferably through continuous Existing data and methods, preferably through continuous monitoring monitoring

Integration with other transportation functionsIntegration with other transportation functions

Page 9: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

Travel Time(route segments or trips)

Performance Measures

average travelspeed (mph)

travel time(min)

travel rate(min/mile)

indices•travel rate index•traffic temperature•congestion severity

delay (min)• per vehicle• per person• per VMT• per driver

roadway characteristicsideal travel conditionsvolumes

probe vehicles instrumented cars ITS roadway equipment

Special Studies

short-termtraffic counts

forecastingmodels

transformation

ContinuousSpecial StudiesContinuous

spot speeds

models

volumes Post-processors(IDAS)

Indirect Measurement/ModelingDirect Measurement

absolute measures

relative measures

Page 10: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

Performance Measures Should Encompass Performance Measures Should Encompass Multiple DimensionsMultiple Dimensions

DISTANCEDISTANCE

SOURCESOURCE

DailyDaily

Late NightLate Night

P.M. PeakP.M. Peak

Mid-DayMid-Day

A.M. PeakA.M. Peak

Early A.M.Early A.M.

IncidentsIncidents

Work ZoneWork Zone

BottleneckBottleneck

WeatherWeather

DemandDemand

Special EventsSpecial Events

TCD’sTCD’s

Segm

ent

Segm

ent

TripTrip

Corridor

Corridor

Areaw

ide

Areaw

ide

DailyDailyHistoriesHistories

DetectionDetection

TIMETIME

TrendsTrends

Page 11: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

Recommended Measures: BasicRecommended Measures: Basic

Travel Rate Index (TRI)Travel Rate Index (TRI)

ratio of:ratio of: travel rate in peaktravel rate in peakideal travel rateideal travel rate

Delay per DriverDelay per Driver

Percent of Congested Travel Percent of Congested Travel

• %VMT where speeds < 45 mph (fwy)%VMT where speeds < 45 mph (fwy)

Page 12: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

Travel Time Reliability: DefinitionTravel Time Reliability: Definition

Measured by how travel time of a trip varies from one time period Measured by how travel time of a trip varies from one time period to anotherto another

• In other words, reliability is measured as the variability of travel In other words, reliability is measured as the variability of travel timestimes

• ““How long will my trip take today compared to the same trip at How long will my trip take today compared to the same trip at the same time on any average day?”the same time on any average day?”

OROR

• Ability of travelers to predict travel time for a trip and to arrive Ability of travelers to predict travel time for a trip and to arrive at destination within an “on-time window”at destination within an “on-time window”

Variability caused by the “Seven Sources” of congestionVariability caused by the “Seven Sources” of congestion

Page 13: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

Categories of Reliability MeasuresCategories of Reliability Measures

There are three categories of reliability There are three categories of reliability measuresmeasures

• StatisticalStatistical

• Buffer timeBuffer time

• ““Tardy arrival”Tardy arrival”

Page 14: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

Travel Time Distribution and Travel Time Distribution and Reliability MeasuresReliability Measures

FrequencyFrequency

Buffer TimeBuffer Time Tardy TripsTardy Trips

Mean Travel TimeMean Travel Time

On-Time PerformanceOn-Time Performance

Statistical MeasuresStatistical Measures

Page 15: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

Buffer IndexBuffer Index

Weighted average of . . .Weighted average of . . .

The extra time needed to arrive on timeThe extra time needed to arrive on time

Seems to resonate with practitionersSeems to resonate with practitioners

95th %Travel Rate

Average Travel Rate

Average Travel Rate

Page 16: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

Measuring ReliabilityMeasuring Reliability

Field measurementField measurement

• Requires many samples or, ideally, continuous measurementRequires many samples or, ideally, continuous measurement

• Roadway performance versus trip performanceRoadway performance versus trip performance

- Different technologies and measurement scaleDifferent technologies and measurement scale

• Hard to separate out Hard to separate out ““root causesroot causes”” due to complex interactions due to complex interactions

- Requires combination of travel time and Requires combination of travel time and ““eventevent”” data data

Modeling methodsModeling methods

• Tend to regress to average conditionsTend to regress to average conditions

• May be useful in decomposing reliability into sourcesMay be useful in decomposing reliability into sources

Page 17: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

Intermediate or Surrogate Performance MetricsIntermediate or Surrogate Performance Metrics

Examples:Examples:

• Incident duration and “timeline”Incident duration and “timeline”

• Clearance time for snowy roadsClearance time for snowy roads

Easier to developEasier to develop

More understandable to professionMore understandable to profession

BUTBUT

Don’t get to the bottom-line as effectively as travel time Don’t get to the bottom-line as effectively as travel time measuresmeasures

Page 18: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

The “Family Tree” of Performance MeasuresThe “Family Tree” of Performance Measures

ClearanceClearanceClearanceClearance

Total Total DelayDelay

ReliabilityReliability(Variability)(Variability)

““Nonrecurring”Nonrecurring”DelayDelay

AgencyAgencyResponseResponse

ororEvent-Event-

RelatedRelated

ThroughputThroughput

IncidentIncident

Total DurationTotal Duration

DetectionDetection ResponseResponse

Work ZoneWork Zone

Total DurationTotal Duration

During PeakDuring Peak

Weather Weather

TotalTotalDurationDuration

ResponseResponse

““Recurring”Recurring”DelayDelay

(Bottleneck)(Bottleneck)

UserUserImpactsImpacts

Page 19: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

Data Issues Associated With Detailed Data Issues Associated With Detailed Performance MeasuresPerformance Measures

Secondary Use of Operations a tremendous data source, BUT…Secondary Use of Operations a tremendous data source, BUT…

Limited primarily to freeways in major urban areasLimited primarily to freeways in major urban areas

Archiving and data quality are problematicArchiving and data quality are problematic

Measurement limited to facility performance or “corridor-trips”Measurement limited to facility performance or “corridor-trips”

Comparability of measures calculated from continuous Comparability of measures calculated from continuous Operations data vs. “traditional” or “synthetic” methodsOperations data vs. “traditional” or “synthetic” methods

Page 20: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

OPPORTUNITIES TO GUIDE INVESTMENTOPPORTUNITIES TO GUIDE INVESTMENT

Page 21: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

Performance Measures Can Be Applied At Performance Measures Can Be Applied At Several Levels of InterestSeveral Levels of Interest

Real-Time OperationsReal-Time Operations

• What is happening now; expected to happen shortlyWhat is happening now; expected to happen shortly

• How do we respond to travel/system conditions; what How do we respond to travel/system conditions; what strategies do we implement?strategies do we implement?

- Incident response, traveler information (esp. advanced Incident response, traveler information (esp. advanced guidance)guidance)

Operations PlanningOperations Planning

• What we expect to happen next week/next monthWhat we expect to happen next week/next month

• How can we adjust our strategies to be more responsiveHow can we adjust our strategies to be more responsive

- New coordination plans, pre-deployment, routing plansNew coordination plans, pre-deployment, routing plans

Page 22: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

Performance Measures Can Be Applied At Performance Measures Can Be Applied At Several Levels of InterestSeveral Levels of Interest

Short-Term Planning and Programming - 1-5 years (TIP, ITS Short-Term Planning and Programming - 1-5 years (TIP, ITS Deployment Plans and Architectures)Deployment Plans and Architectures)

Long-Term Planning - 5-20 years (Long-Range Plans)Long-Term Planning - 5-20 years (Long-Range Plans)

Expected impacts on the “family” of performance measures can Expected impacts on the “family” of performance measures can help in deciding priorities and trade-offshelp in deciding priorities and trade-offs

• Models need to be sensitive to performance measures, Models need to be sensitive to performance measures, especially reliability and the “Seven Sources” especially reliability and the “Seven Sources”

Page 23: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

Measuring Reliability Measuring Reliability (continued)(continued) Atlanta, GeorgiaAtlanta, Georgia TrTI/Buffer Index by Time-of-DayTrTI/Buffer Index by Time-of-Day

0.000.00

0.200.20

0.400.40

0.600.60

0.800.80

1.001.00

1.201.20

1.401.40

0:000:00 2:002:00 4:004:00 6:006:00 8:008:00 10:0010:00 12:0012:00 14:0014:00 16:0016:00 18:0018:00 20:0020:00 22:0022:00 0:000:00

Time of Day (Average Weekdays Only)Time of Day (Average Weekdays Only)

Index Value or Index Value or Congested Travel (1.0=100%) Congested Travel (1.0=100%) Travel Time IndexTravel Time Index

Buffer IndexBuffer Index

Page 24: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

Orlando Eastbound I-4, Evening Peak Period, Weekdays

0

1

2

3

4

5

6

1 11 21 31 41 51 61 71

Days

Tra

ve

l Ra

te (

Min

ute

s p

er

Mile

)

Page 25: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

SUMMARYSUMMARY

MetricsMetrics

• Numerous travel-time based metrics are available Numerous travel-time based metrics are available

• Local conditions will indicate which ones are best, but Local conditions will indicate which ones are best, but multiple metrics should be used to meet a variety of needsmultiple metrics should be used to meet a variety of needs

• Summary metrics good for “report card”Summary metrics good for “report card”

• Decomposing metrics by at least 3 dimensions is very useful Decomposing metrics by at least 3 dimensions is very useful for investment decisionsfor investment decisions

- Time/Space/SourceTime/Space/Source

- Reliability becoming increasingly importantReliability becoming increasingly important

• ““Family Tree” of metrics, with output measures at the Family Tree” of metrics, with output measures at the bottom feeding into user-based measures should be bottom feeding into user-based measures should be developeddeveloped

Page 26: Beyond Gee-Whiz Statistics: Guiding Transportation Investments with Transportation System Performance Measures presented by Richard Margiotta, Principal

SUMMARY (cont.)SUMMARY (cont.)

Data to Support MetricsData to Support Metrics

• Operations sources can provide the data to support this Operations sources can provide the data to support this level of detail, but barriers existlevel of detail, but barriers exist

- Data quality, coverage, consistencyData quality, coverage, consistency

• Models do not now provide emerging performance metrics, Models do not now provide emerging performance metrics, especially Reliabilityespecially Reliability

Investment Decisions Investment Decisions

• Currently, short-range decisions most easily supportedCurrently, short-range decisions most easily supported

• Profession needs to evolve toward a broader framework Profession needs to evolve toward a broader framework using the full range of performance measures for all levels using the full range of performance measures for all levels of investment, from the “here and now” to long-range of investment, from the “here and now” to long-range planningplanning