Conference Proceedings 26 - Transportation Research Board

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208 PERFORMANCE MEASURES TO IMPROVE TRANSPORTATION SYSTEMS AND AGENCY OPERATIONSthe population and jobs, and 80 percent of industrialwarehouse facilities are within 5 miles of the highwaysystem. For metropolitan transit systems, accessibilitymeasures include coverage, frequency, and span ofservice. These data are generally available from existingsources.• Utilization measures relate demand to capacityand describe the efficiency with which the systemprovides mobility. These measures tend to reflect thedepartment’s perspective rather than that of the customer,and they include the percentage of the systemthat is heavily congested, vehicles per lane mile (adensity measure), duration of congestion, and transitload factors.Data IssuesData Collection FDOT applies a combination of estimatedand observed data at the system level andprimarily observed data at the corridor level. The departmentfocuses on data that are already being collected,with refinement as necessary to meet the needsof the performance measures. Some special data collectionis required to support the measures, such asvehicle occupancy, as well as speed and volume datato support reliability measures.Changes to FDOT’s data-collection program requiredto support the mobility program measures includeimplementation of a short-term traffic monitoringsystem (TMS) to extend the time period forwhich traffic data are collected and eventually a permanentTMS that can provide 15-minute intervalpolling on demand.Data Modeling Issues Consistency across the statewidesystem is deemed more important than greaterprecision on local segments. To help manage expectations,FDOT advises against mapping data at alevel that would generate suspicion or complaints.Such a strategy helps to ensure that data are used atthe statewide system level for which they are intended.Traffic congestion spillbacks are not yet consideredby FDOT’s travel models; thus, congestionstatewide may be underestimated by the models.Nonetheless, trends rather than spot values have themost value.ITS Data IntegrationAn effort to integrate data collected through thestate’s ITS infrastructure is under way. FDOT is developingstatewide data architecture, addressing thefollowing needs:• Data retrieval: there is a proliferation of detectorsand sensors, but can they provide needed data?• Data storage: what data should be kept and bywhom? How should data be stored and for howlong?• Data reporting: who are the users, and how doesFDOT need to package the data for them?FDOT acknowledges the need to identify both architectureand protocols for data sampling and manipulationto distill the vast pool of ITS data for planningand monitoring activities.Data Quality Florida has a well-established qualityassurance and quality control program, and it usesother sources and validated models to supplementand check its data quality.Audience for Performance Measures and ReportingMechanisms FDOT’s audience includes the generalpublic, department staff, elected officials, legislativestaff, and other decision makers. Legislative staff aretaking more interest in the program and are startingto appreciate the results and benefits.At the district level, staff want more detailed informationthan is currently generated for the departmentlevel. There are three areas of reporting:• Entire state highway system,• Florida Intrastate highway system, and• Corridors, particularly those connecting majorurban areas.Future Directions FDOT will continue to improveand develop its performance measurement program.Among those areas identified for development are thefollowing:• Person-trip–based measures,• Dynamic display of measures,• Refinement of reliability measures,• Corridor-level reporting,• Incorporating ITS data and analysis, and• Wider distribution of results.Additional IsuesOther members of the committee expressed interestin FDOT’s substantial reliance on outside consultantsto help design and implement highly technical andlabor-intensive programs. It was apparent from thediscussion that some states do not do this to the sameextent as FDOT or are not able to do use consultantsin this fashion. FDOT considers the use of ongoing
SUMMARY OF PEER EXCHANGE ON DATA FOR PERFORMANCE MEASURES 209consultant support an extension of its staff. The currentprivatization initiative at the state level in Floridafurther supports such an approach.California Department of <strong>Transportation</strong>’sSystem Performance MeasuresTremain Downey, chief of the Office of PerformanceMeasures and Data Analysis, presented the performancemeasurement effort of the California Departmentof <strong>Transportation</strong> (Caltrans), focusing on theaccomplishments to date and status of implementation.Objectives were established through committeeswith broad representation from outside the department.There was acknowledgment that performancemeasurement can focus on department performance,modal system performance, or multimodal system;Caltrans chose to focus on the multimodal system.Uses of Performance DataCaltrans intends to monitor and evaluate system performancein a way that is complementary to what isalready under way at several major MPOs in thestate. The department intends to share existing dataand future forecasts of performance. Objectives includedevelopment of mode-neutral customer anddecision-support information. Caltrans hopes toimprove consensus-building efforts in the transportationplanning context by providing objective, understandableinformation. Although part of themotivation is to improve accountability by the department,there is also an attempt to improve informationon those elements of performance for whichCaltrans is not directly responsible.Key Elements of SystemThe performance measurement system builds on fiveimportant concepts:• Outcome based,• Multimodal in scope,• Easy to understand,• Supportable with existing data, and• Useable to monitor and forecast performance.Caltrans is well into its three-phase project: spanningdesign, proof-of-concept testing, and incrementalimplementation.Performance Outcomes and Current MeasuresCaltrans has defined nine outcome areas that guideselection of measures. Among them are mobility andaccessibility, reliability, cost-effectiveness, safety, equity,economic well-being, and environmental quality.Candidate measures or indicators have been definedin each area. Thus far, Caltrans has fully tested threemeasures: mobility and accessibility, reliability, andenvironmental quality. Other measures are currentlyundergoing testing.The measures of mobility include average point-topointtravel time and travel delay. Because of thedata-intensive nature of this travel time measure, thefocus is currently on travel delay. Delay is estimatedas the difference between free-flow travel time andaverage observed (or projected) travel time.Caltrans’s reliability measure is based on variabilityin service between the expected and actual traveltimes. Testing of the reliability measure in major metropolitanareas of the state reveals that peak periodvariability ranges from 10 percent to 50 percent, withmost segments experiencing variability within 30 percentof expected travel time. An interesting observationis that reliability is not necessarily correlated withdelay. Some segments or corridors may have high delaybut relatively low variability in travel time. Amongthe factors that Caltrans has identified in contributingto reliability and variability are distances between interchangesand highway geometrics.Data IssuesCaltrans embarked on an aggressive data-integrationsystem. It will provide integrated data on performance,physical characteristics, boundaries, environmental,and financial aspects of the transportation infrastructure.Data collected by TMCs will be routedto a single centralized location rather than to districtoffices, as at present. Through this centralized clearinghouse,users and customers will have access to abroad array of data by way of user-friendly interfaces.Several steps remain in designing and implementingthe system, including making decisions on what informationshould be collected and stored, what technologywill be used to collect and manage the data (particularlyin expansion areas not currently served byTMCs), how to convert data to useful information,and how to best provide user access to the data.Relationship to Decision MakingCaltrans believes that integrating data, as previouslydescribed, is the biggest challenge and most impor-
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National Academy of SciencesNationa
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Workshop Summary ..................
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General OverviewIntroductionExecuti
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4 PERFORMANCE MEASURES TO IMPROVE T
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Linking Performance Measures withDe
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Panel DiscussionJohn Poorman, Capit
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Workshop SummaryJohn Basilica, Loui
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RESOURCE PAPERImplementing Performa
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IMPLEMENTING PERFORMANCE MEASUREMEN
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Panel DiscussionJennifer Finch, Col
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FIGURE 2Level of measures and align
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PANEL DISCUSSION: AGENCY IMPLEMENTA
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WORKSHOP SUMMARY: AGENCY IMPLEMENTA
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Selecting Measures, Data Needs, and
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Panel Discussion, Part 1Anita Vande
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Panel Discussion, Part 2Douglas Zim
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FIGURE 11 Example data
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Workshop SummaryBrenda Berg, Trans
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RESOURCE PAPERMeasuring That Which
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MEASURING THAT WHICH CANNOT BE MEAS
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TABLE 1Sustainability MeasuresNewma
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PANEL DISCUSSION: CONNECTING SYSTEM
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Workshop SummaryScott Bassett, Oreg
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Freight Performance MeasuresCurrent
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APPENDIX ASummaries of 20 Poster Se
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Page 167 and 168: TABLE 1(continued) WSDOT Outcomes,
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Page 187 and 188: TABLE 6Mobility Performance Measure
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Page 225 and 226: LIST OF PARTICIPANTS 217University,
Page 227: LIST OF PARTICIPANTS 219Darwin Stua
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Conference Proceedings 26 - Transportation Research Board

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