EVALUATIONREVIEW / APRIL 2002 DeHart-Davis et al. / VEHICLE INSPECTION On-roadremotesensingdataisanincreasinglypopularsourceofevaluationinformationfor vehicleinspection/maintenance(I/M)programs.Thisarticleconductsonesuchremotesensing dataevaluationfortheAtlanta,Georgia,I/Mprogram.Thereferencemethodinvolvescompar- ingemissionsdifferencesinI/Mandnon-I/Mfleetvehicleswiththosepredictedbyaregulatory computermodel.Assumingthaton-roademissionsdifferencesrepresentobservedeffectiveness andmodel-predictedemissionsdifferencesrepresenteffectivenessgoals,theAtlantaenhanced I/Mprogramappearstobeachieving83%ofitstargetedemissionsreductions.Themethodcom- paresfavorablywithotherremotesensingevaluationmethodsinitsabilitytobeappliedover timeanditsrelativelysmallsamplesizerequirement.Thechieflimitationtotheapproachisits relianceonarepresentativenon-I/Mfleet,whichmaydifferincharacteristicsforwhichcontrols aredifficulttolocate.Suchpotentialconfoundingfactorsincludediscrepanciesinmaintenance trends,socioeconomicconditions,andvehiclequality. EVALUATING VEHICLE INSPECTION/ MAINTENANCE PROGRAMS USING ON-ROAD EMISSIONS DATA The Atlanta Reference Method LEISHA DEHART-DAVIS ELIZABETH CORLEY MICHAEL O. RODGERS GeorgiaInstituteofTechnology The 1990 Clean Air Act (CAA) Amendments made sweeping changes in the scope and stringency of vehicle inspection/maintenance (I/M) programs. Driven by persistent growth in vehicle travel and chronic air pollution in the nation’s largest metropolitan areas, the legislation requires that enhanced I/M programs employ advanced testing technologies and procedures as a way to 111 AUTHORS’ NOTE: This research was supported by the Georgia Department of Natural Resources(GDNR)undercontractsAGRDTD970530and773-10072.Additionalfundingwas provided by the U.S. Environmental Protection Agency (EPA) under the former Cooperative Agreementno.823020andthecurrentCooperativeAgreementno.R-82838501-0.Thefindings aresolelytheauthors’anddonotnecessarilyrepresentthoseoftheGDNRorEPA.Allcorre- spondenceshouldbeaddressedtothefirstauthoratleisha.davis@ce.gatech.edu. EVALUATION REVIEW, Vol. 26 No. 2, April 2002 111-146 © 2002 Sage Publications at ARIZONA STATE UNIV on April 4, 2016 erx.sagepub.com Downloaded from