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Real-World Vehicle Emissions: A Summary of the 15th Coordinating Research Council On-Road Vehicle Emissions Workshop

Posted on: Sunday, 26 February 2006, 03:02 CST

By Cadle, Steven H; Belian, Timothy C; Black, Kevin N; Carlock, Mark A; Et al

ABSTRACT

The Coordinating Research Council held its 15th workshop in April 2005, with nearly 90 presentations describing the most recent mobile source-related emissions research. In this paper, the authors summarize the presentations from researchers who are engaged in improving our understanding of the contribution of mobile sources to air quality. Participants in the workshop discussed emission models and emission inventories, results from gas- and particle-phase emissions studies from spark-ignition and diesel-powered vehicles (with an emphasis in this workshop on particle emissions), effects of fuels on emissions, evaluation of in-use emissions control programs, and efforts to improve our capabilities in performing on- board emissions measurements, as well as topics for future research.

INTRODUCTION

The 15th Coordinating Research Council (CRC) On-Road Vehicle Emissions Workshop was held April 4-6, 2005, in San Diego, CA. Nearly 200 representatives from industry, government, academia, and consulting groups from Australia, Austria, Belgium, Canada, Finland, France, Hong Kong, Japan, Portugal, Sweden, and the United States participated in the meeting. The objectives of the workshop were to present the most recent results from research on:

* U.S. Environment Protection Agency's (EPA) new Motor Vehicle Emission Simulator (MOVES) model;

* Vehicle emission modeling and activity data;

* Gasoline and diesel vehicle emission factors;

* Emission measurement methods;

* Emission control measures;

* Effects of fuel on emissions;

* Unregulated emissions; and

* Particulate matter (PM) from mobile sources.

This year's keynote speaker was Michael Savonis of the Federal Highway Administration (FHWA). He addressed transportation and air quality issues and discussed key questions for which answers are needed to address policy issues. Areas of interest are health- effects research, climate change, and the desire to use empirical data and observations as opposed to extensive reliance on modeldriven "reality." A significant challenge facing the FHWA is the need to make better air quality management decisions in light of significant uncertainties. He emphasized the need for policy- relevant research regarding issues of interest to the FHWA.

There were 56 presentations in nine sessions and 33 posters displayed in poster sessions during the workshop. In addition to the many technical workshop presentations, vendors, university groups, and government groups displayed new analytical capabilities and services related to vehicle emissions measurement. Tim Belian, Brent Bailey, and the CRC staff provided overall workshop coordination, with Steve Cadle (General Motors) and Mani Natarajan (Marathon Petroleum Co.) serving as workshop cochairmen. Session chairmen were Ed Nam of EPA, Kevin Black of the FHWA, Rob Graze of Caterpillar, Hannah Murray of Toyota, Tim Belian from the CRC, Fred Minassian of the South Coast Air Quality Management District, Doug Lawson of the National Renewable Energy Laboratory (NREL), and Mark Carlock from the California Air Resources Board (CARB).

The complete workshop proceedings are available from the Coordinating Research Council, 3650 Mansell Road, Suite 140, Alpharetta, Georgia 30022; phone: +1678-795-0506; fax: +1-678-795- 0509; e-mail address: jantucker@crcao.org. This paper summarizes presentations given in each session and includes a short summary of posters presented at the workshop. Summaries of the CRC workshops have been published in the journal of the Air & Waste Management Association; the three most recent summaries are found in Vol. 53, pp.152-167; Vol. 54, pp. 8-23; and Vol. 55, pp. 130-146.

MOVES MODEL

Edward Nam of EPA presented validation results from MOVES2004, the first version of EPA's new mobile modeling framework. It estimates energy consumption (total, petroleum-based, and fossil- based) and emissions of methane (CH^sub 4^) and nitrous oxide (N^sub 2^O) for on-road sources across the United States for years 1999 through 2050. This first version of MOVES estimates energy consumption to allow for evaluation of model performance. MOVES2004 estimates of fuel consumption are within 5% of independent top-down fuel sales data for both gasoline and diesel, providing encouragement that the underlying data and modeling methodology are sound. CH^sub 4^ and N^sub 2^O emissions are significantly lower than estimated by previous inventories based on revised emission rates from new data.

Ed Glover from EPA compared results from various remote sensing studies to evaluate their use for MOVES. Preliminary vehicle emission factors for hydrocarbons (HCs), carbon monoxide (CO), and nitrogen oxides (NO^sub x^) have been developed. The emission factors are a function of vehicle identification number, vehicle- specific power (VSP), calendar year of the test measurement, and the 1-sec remote sensing measurements. The database contains studies conducted by the University of Denver, Georgia Tech, and several individual state roadside monitoring efforts. Attempts were made to separately analyze measurements from inspection/maintenance (I/M) and non-I/M areas. Statistical analysis of remote sensing results versus test location, test year, VSP bin type, vehicle class, and I/ M program type were reported. Also, aggregate emission factor results derived from remote sensing data were compared with other sources.

James Warila of EPA described the compilation and analysis of second-by- second laboratory data from existing test programs to derive base running-operation criteria pollutant emission rates for light-duty vehicles (LDVs) and trucks (LDTs) for MOVES2006. The draft design classifies vehicles by fuel type, regulatory class (LDV/ LDT), and model-year group; preliminary analyses do not support the use of displacement or weight classes. The draft design describes driving activity through 24 operating modes, defined in terms of VSP, speed, and acceleration and proposes 11 age classes to account for emissions deterioration. Gaps in data coverage will require estimation of emission rates for existing vehicles at ages not represented by data, as well as for future vehicles, using statistical modeling or other tools.

Bob Giannelli representing EPA analyzed Tier 1 cold start emissions of HC, CO, and NO^sub x^ from EPA's vehicle emissions testing database (Mobile Source Observation Database) and soak time effects on cold start emissions from Tier O CARB data for MOVES. Time traces of Federal Test Procedure (FTP) "bagl-bag3" emissions were analyzed by fitting the emissions to the product of vehicle tractive power and a series of distributions functions, for which the relative magnitudes vary in time and depend on driving schedule. A semiempirical formula has been derived, and preliminary values of parameters have been determined. It allows for cold start emission estimations to within 15%. Comparisons among the SC03, STOl, and FTP test cycle CO emissions were given, and soak time effects for HC were presented.

VEHICLE EMISSION MODELING AND ACTIVITY DATA

David Brzezinski of EPA discussed quantifying the way vehicles are driven considering changes in traffic laws, speed limits, congestion, vehicle design, horsepower, and demographics. Recent studies have provided second-bysecond measurements of real-world driving, an approach being developed to provide data for EPA's new MOVES model. These data were compared with VSP data, because power demand is expected to correlate better with ex- ? haust emissions than average speed and acceleration. The amount of time spent in the highest VSP bins was greater than in the studies used to develop default vehicle activity for the MOBILE6 model. Fuel consumption increases ranged from 6 to 7%; however, criteria pollutants (HC, CO, and NO^sub x^) are likely to show larger differences.

Lap-Van Pao of the Hong Kong Environmental Protection Department presented vehicle activity data collected by on-board instruments for four vehicle classes: private cars, taxis, small buses, and franchised buses in Hong Kong. On-board and chase car techniques were used for all of the vehicle classes to obtain second-by-second data. The data were collected, processed, and analyzed for speed distribution, operating mode distribution, and vehicle kilometers traveled versus speed for each vehicle class and road type. Driving cycles were developed for each vehicle class and compared with the California driving cycles. These cycles will be used in dynamometer testing for emission measurements to be included into California's mobile emission factor model (EMFAC) adapted for Hong Kong.

Hiroshi Hirai from the Japan Petroleum Energy Center described the development of an emission inventory model for the Japan Clean Air Program. This model consists of an urban area model and a roadside model. The urban area model is based on vehicle miles traveled (VMT) and vehicle emission factors, and it estimates emissions from vehicles based on average velocity, temperature, high emitter status, and other parameters. Methods for estimating hourly cold start emissions and evaporative emissions based on user survey activity data were also de\veloped. The emission inventory model for roadside emissions is performed at a resolution of one meter and includes a microscale traffic model and exhaust gas model.

Randall Guensler of Georgia Tech presented an update of his Commute Atlanta Study, which uses 480 instrumented vehicles in the Atlanta area. Each vehicle is equipped with a Georgia Tech Trip Data Collector to monitor second-by-second travel activity for every trip (and engine parameters for more than half of these vehicles). To date, more than 1 million trips have been monitored on a second-by- second basis and processed into trip files. Household and vehicle trip summary statistics and speed versus speed limit data were highlighted. Analyses of speed/acceleration profiles, engine start, and soak distributions are forthcoming. The project has been reauthorized by the FHWA for 2005. Guensler concluded with a description of cents/mile pricing experiments currently under way.

Frank Di Geneva of Sierra Research discussed mileage accrual and full-life mileage of vehicles in California. The purpose was to examine CARB's method for estimating full-life mileage to comply with California Assembly Bill 1493 on greenhouse gases. Results from CARB's method were compared with data from the Smog Check (I/M) program, roadside pullovers, scrappage programs, Kelley Blue Book vehicle offerings, and other sources. He concluded that CARB's method is not corroborated by data, is significantly biased for older vehicles, ignores vehicle retirement, and significantly overestimates the full-life mileage of California vehicles. The overestimate of mileage is extremely important because of the way it affects emissions inventory and lifetime gasoline consumption.

Christopher Frey from North Carolina State University discussed results from his evaluation of the effect of road grade, alternative routes for origin/destination pairs, traffic flow patterns, and vehicle-specific energy use in emissions models. On-board instrumentation was used to test vehicles ranging from a compact sedan to a large sport utility vehicle. Preliminary results suggest that road grades of >2% can have a significant effect on vehicle emissions. The optimal choice of a route between a given origin and destination pair can differ depending on the pollutant and vehicle and emission rates. Total emissions for uncongested traffic flow were generally lower than for congested conditions.

Chi Pang Lee of the Hong Kong Polytechnic University discussed vehicle drive cycles. Using 205 min of valid data trips collected in selected urban and rural routes, standard statistical tests were used to identify the difference between chase vehicle data and target vehicle data. The results showed that the deviation of speed and acceleration between target and chase vehicles is not significant. The effects of road types and chase drivers are small compared with the engine power output difference between vehicles. Lee concluded that the car chasing technique is suitable in collecting target vehicle speed with precise instructions and a high- performance chase vehicle.

Randall Guensler described a load-based modal emissions model for heavy-duty (HD) diesel vehicles. The model predicts emissions from link-specific transportation networks within a geographic information systems framework. Inputs to the model include load- related parameters and emission rates under different power demand situations. Engine load is determined for each vehicle technology as a function of vehicle speed and acceleration profile, passenger/ freight load, roadway characteristics, inertial load parameters, and environmental conditions. Model upgrades include driver-vehicle patterns, vehicle system monitoring results, and emitter characterization, among others.

Seungju Yoon of Georgia Tech collected >6.5 million seconds of transit bus speed and position data using Georgia Tech Trip Data Collectors installed on two Atlanta Rapid Transit Authority buses. Using speed-accelerationgrade matrices created from the collected data, road linkspecific engine power demand was estimated. Estimation of transit bus activity used the number of buses, link length, and bus mean speeds from matrices. A polynomial relationship between engine power demand and NO^sub x^ emissions was derived from EPA transit bus test results. Engine power demand, bus activity, and the polynomial relationship were associated with simulated link level emissions. Simulated link level NO^sub x^ emissions correspond with 90% of MOBILE6.2 NO^sub x^ estimates with the R^sup 2^ of 0.75 at a 5% significance level.

Seungju Yoon also described a new HD vehicle (HDV) VMT estimation method, which can avoid uncertainties in VMT estimation based on registration and annual mileage accumulated rates. VMT uncertainties may lead to the underestimation of HDV emissions, especially for urban areas. The new method was used to estimate HDV VMT in the 20- county Atlanta region using data from the Georgia Tech HDV/Bus database, Georgia Highway Performance Monitoring System, FHWA Highway Statistics Series, and the Census Bureau Vehicle Inventory and Use Survey. With the new method, total HD fleet emissions increased 28% and 25%, respectively, for NO^sub x^ and PM.

Carla Silva of the Technical University of Lisbon discussed a numerical model, EcoGest, capable of predicting fuel consumption and tailpipe emissions of HC, CO, NO^sub x^, and carbon dioxide (CO2). If the fuel consumption, exhaust gas temperature, and emissions maps are not available from the original equipment manufacturers (OEMs), EcoGest uses an engine model to obtain them. Exhaust temperature and emissions are estimated as a function of the fuel consumption. Simulations were performed for a 3-L gasoline-powered low-emitting vehicle (LEV) over a monitored driving cycle and the FTP75 cycle, using both the OEM maps and the simulated engine maps. The results show similar predicted levels of fuel consumption and emissions, thereby indicating adequacy of the engine model.

Carla Silva also described EcoGest's projections for fuel consumption and emissions from a 1.2-L Euro IV gasoline vehicle monitored throughout 63 trips, covering stop-and-go situations. Eight trips were simulated in EcoGest and the Advanced Vehicle Simulator model. Both models show a good agreement in predicting instantaneous and average fuel consumption and CO2 emissions. HC, CO, and NO^sub x^ emissions are not well simulated by the models, but the predictions of both models are similar. These results indicate the probable inadequacy of the gas analyzer in measuring emission levels of Euro IV vehicles.

DIESEL VEHICLE EMISSION FACTORS

Nigel Clark from West Virginia University (WVU) summarized regulated emission measurements from 10 inuse, 1982 to 2002 model year, medium HD trucks (MHDTs) in Southern California. The MHDT test runs included a lower-speed transient mode (MHDTLO), a higher-speed transient mode, and a cruise mode. The trucks were tested "laden" at 75% of the gross vehicle weight rating and "unladen" at 50% of the gross vehicle weight rating. For diesel trucks on the MHDTLO laden, NO^sub x^ emissions ranged from 13.5 to 20.5 g/mile and PM emissions ranged from 0.28 to 1.31 g/mile. The influence of test weight (laden versus unladen) on PM was noticeably greater than for NO^sub x^.

Teresa Alleman from NREL presented results from a study where a 2002 Cummins ISM engine was modified to use gas-to-liquid (GTL) fuel and advanced emission controls. The modified engine was installed into a Class 8 vehicle and tested on a vehicle chassis dynamometer to assess driveability and to collect baseline emissions before a real-world operability demonstration. Emissions were collected over the Urban Dynamometer Driving Schedule (UDDS) and the New York City Cycle. NO^sub x^ and PM emissions averaged 10 and 0.01 g/mile, respectively. Good driveability was demonstrated over a variety of transient and steady-state tests.

Aniket Sawant of University of California Riverside College of Engineering-Center for Environmental Research and Technology (CE- CERT) described the investigation of emissions from three in-use diesel-electric switching locomotives using the CE-CERT mobile emissions laboratory. Emission rates (g/kg CO2) as a function of "notch position" (engine load) were presented for total HCs (THCs), CO, NO^sub x^, PM, elemental carbon (EC), organic carbon (OC), formaldehyde, and acetaldehyde. THC and carbonyl emissions were strongly dependent on notch position. Stack-to-stack variability was greatest for THCs at higher notch positions and lowest for EC and OC. The engines were found to compare favorably on a per unit energy (g/brake horsepower (bhp]-hr) basis with literature data. Issues relating to higher-than-expected emission rates for the three highest notches were also discussed.

Mridul Gautam from WVU summarized on-road measurements of in-use emissions from HD diesel (HDD) engines using the Micro-Mobile Emissions Measurement System (MEMS), which can be mounted directly on the exhaust stack. The MEMS minimizes: (1) system power requirements, (2) sample path lengths, (3) residence time, (4) sample dispersion in sampling lines, (5) set-up time, (6) operator intrusiveness, and (7) cost. Although vehicle acceleration and speed provide the criteria for characterization of driving modes, the MEMS provides engine parameter-based characterization (e.g., load, speed, injection timing, fueling) of emissions over a route. For most over- the-road HD engine applications, engine operation is largely bimodal, and the cruise mode operation occupies the majority of the engine operation in the not-toexceed (NTE) region.

Hector Maldonado from CARB presented a summary of the CRC E-55/ 59 HD truck (HDT) emissions testing project. The objectives of this project are to procure and test an in-use fleet of 75 HDTs using HDT cycles, perform chemical speciation on a subset of vehicles,and perform "opportunistic" vehicle repairs. For late-model HDTs, NO^sub x^ emission reductions are greater over highway cruise operation than over transient operation. For all of the HDTs, PM emissions were significantly higher over transient operation compared with highway cruise operation. High PM emitters occur throughout a wide range of model years, and those emissions can be reduced through repairs for newer vehicles, but may be problematic for older vehicles.

Aniket Sawant described the investigation of traffic congestion on PM emissions from an HDD tractor using the CE-CERT mobile emissions laboratory. Integrated PM, EC, and OC emission rates (g/ mile) for real-world traffic conditions were intermediate to values obtained for the CARB transient and cruise phases. Preliminary results using a Dekati DMM-230 analyzer showed the PM/NO^sub x^ tradeoff between lower and higher congestion conditions. The University of California Riverside/Caltech fast-scanning electrical mobility spectrometer was found to track the DMM-230 well. The DMM- 230 was also shown to correlate well with filter-based PM measurements. Preliminary results from the fast-scanning electrical mobility spectrometer suggested that significant increases in PM number concentration tracked real-world acceleration events.

Mridul Gautam presented results from a study designed to reduce emissions from a natural gas-fueled HDV with a custom designed exhaust after-treatment system composed of a catalyzed PM trap and oxidation catalyst. Gautam exploited the higher temperatures of the natural gas engine exhaust and located the oxidation catalyst downstream of the PM trap. Detailed emissions measurements conducted on the baseline engine at the beginning of the study served as the basis for design and develop- , ment of the after-treatment system. At the end of 6 months of in-field vehicle operation, emissions of lube oil-based elements, aldehydes, nanoparticles, and total PM emissions were found to be below tunnel background levels.

James Calcagno from the University of Tennessee described measurement of cold start, and his extendedidling emissions of CO, NO^sub x^, and PM were from HDD vehicles in the field using portable emission monitoring equipment. Results indicated that large variability exists between individual vehicles tested at different engine idling speeds and air-conditioner on/off modes of operation. Overall, the extended-idling emission factors com- , pared favorably but were slightly higher for NO^sub x^ than both the EPA suggested values for State Implementation Plans using truck stop electrification technology and the average literature values. The PM^sub 2,5^ emission rate fell between the EPA suggested value and the literature review average.

As part of the Advanced Petroleum-Based Fuels (APBF) program, U.S. Department of Energy (DOE) has engaged in several test projects under the APBF-Diesel Emission Control (DEC) activity. Matthew Thornton from NREL described the APBF-DEC NO^sub x^ Adsorber Catalyst/Diesel Particle Filter (NAC/DPF) Passenger Car Project, and provided chassis and engine test cell criteria emission results through 1000 hr (-50,000 mi) of NAC/ DPF system aging. The primary technology being addressed by these projects is the sulfur tolerance of the NAC/DPF system and the durability implications of varying fuel sulfur levels. One specific project is aimed at evaluating a light-duty passenger vehicle and the fuel implications associated with using a NAC/DPF system to meet the upcoming Tier 2 emissions standards.

David Cocker from CE-CERT summarized his studies on the detailed speciation of aircraft exhaust as a function of power, for which data are currently limited. EC emission rates and contributions of heavier particle-phase nalkanes were higher for higher power settings. Naphthalene was found to be the most significant contributor to the polycyclic aromatic HC (PAH) emission rate. General emission profiles (PAH, n-alkanes, carbonyls, and benzene/ toluene/ethylbenzene/xylenes) for aircraft emissions were found to be similar to other combustion sources. Uncombusted lubricating oil did not appear to play a significant role in the organic PM fraction.

David Cocker also presented results of on-road emissions testing of 11 HDD vehicles over the CARB 4-Phase Cycle and the UDDS. Emission rates were highly dependent on operating mode; simulated congestion yielded a three-fold increase in g/mile NO^sub x^ emissions relative to freeway cruising. NO^sub x^ and EMFAC baseline emission factors were within 5-40% for vehicles of various model years tested over the UDDS cycle. A comparison of NO^sub x^ emission factors for a weighted average of the CARB 4-Phase Cycle yielded values within 17-57% of EMFAC values. Generally, PM emission rates were lower than EMFAC values. Increasing cruise speeds from 55 to 65 mph yielded slight changes in per-mile emission rates of THC, CO, and NO^sub x^; however, fuel consumption increased by 45%.

Tao Huai of CARB described an evaluation by CECERT and CARB of 270 electronic control module (ECM) downloads from in-use HDD vehicles to investigate emission factors for the California on-road heavy HDD truck fleet. The ECM data included engine identification, current engine configuration, the vehicle operating summaries, and the vehicle activity record. Statistical analysis of the data yielded key characteristics of the on-road fleet, as well as an alternative means to estimate the contribution of these vehicles to the emissions inventory. Compared with traditional global positioning systems (GPS) and data logger survey studies, the new ECM approach is significantly more cost-effective and complete, because it includes lifetime vehicle operation.

MEASUREMENT METHODS

Imad Khalek of Southwest Research Institute reported the current status of CRC project E-66 that targets 2007-compliant diesel PM measurements. The use of Teflon membrane filters minimized the collection of gas-phase compounds (positive artifact) during PM sampling. A continuously regenerative technology diesel particle filter (CRT-DPF) in the exhaust of a 1998 HDD engine led to a PM emission level on the order of 0.0005-0.001 g/hp-hr, 90-95% below the 2007 PM standard. The TSI Engine Exhaust Particle Sizer (EEPS) and the Dekati DMM-230 PM instruments showed good linear correlation (R^sup 2^ of &0.95) with the filter-based method at an emissions level near the 2007 PM standard.

Alberto Ayala of CARB presented a correlation between a partial- flow diluter at CARB's Stockton HeavyDuty Emissions Laboratory (SL) and a full-flow constant volume sampler (CVS) in the CE-CERT Mobile Emissions Laboratory (MEL) for steady-state HD emissions measurement. The test vehicle, a 2000 model year tractor, was tested over multiple steady-state modes. R^sup 2^ values for linear regressions of the results were ≥0.92 (PM R^sup 2^ was 0.98). A systematic bias between SL and MEL results was detected. The percentage differences in SL average results relative to MEL were mode and pollutant dependent but were generally on the order of 15%, except for THC. Coefficients of variance for PM measurements were ≥29%. In conclusion, the chassis dynamometer laboratory demonstrated good performance.

Linsey Marr of Virginia Tech described a portion of the Mexico City Metropolitan Area field campaign from April 2003. During the campaign, the Aerodyne mobile laboratory was driven throughout the city and chased vehicles to measure pollutants in exhaust emissions. The main objective of this research was to determine fuelbased emission factors of CO, volatile organic compounds (VOC), NO^sub x^, black carbon (BC), and particle-phase PAH. A new method of classification of sampled plumes identified -36,000 exhaust plume points among the measurements. Emission factors were up to 10 times higher than those found in the United States. Resulting estimates of CO, VOC, and NO^sub x^ emissions from motor vehicles fell within 34% of the government's official inventory.

Guido Lenaers of the Flemish Institute for Technological Research developed an on-board system capable of quantifying ammonia (NH^sub 3^) emissions. The system, a Norsk Elektro Optikk tunable diode laser analyzer with the transmitter and receiver mounted on the opposite sides of a compact measurement cuvette, measures under full flow conditions. Extensive testing on board an HDV yielded sub-ppm zero stability and detection limit. Simultaneous retrieval of NH^sub 3^ and engine parameters together with regulated exhaust emission measurements allow for a quick link to relevant emission control system parameters as shown in an evaluation of a selective catalytic reduction (SCR)-equipped city bus. On this vehicle, tailpipe NO^sub x^ is reduced to 85%, whereas the average NH^sub 3^ slip ranges from 5 to 12 ppm.

Hiroshi Nakamura of Horiba detailed an improvement from their previous on-board emission measurement system, which used a heated nondispersive infrared analyzer. Their current system (OBS 2000) is improved by using a semivacuum-type heated flame-ionization detector, heated chemiluminescence detector (HCLD), and heated nondispersive infrared. These analyzers can decrease response time, power consumption, and dimensions of the total system, because a heated sample pump is not required; thus, the heated area can be minimized. This unit also includes a Pilot-type exhaust flow meter, an ambient temperature/humidity/pressure sensor, and GPS. The performance of the semivacuum-type heated flameionization detector and HCLD analyzers has been investigated and conforms to the CFR- 1065 specification.

Hector Maldonado described a project to evaluate portable emissions measurement systems (PEMS) in the context of data collection for emissions inventory purposes, as well as for purposes of implementation of the NTE portion of the 2007 regulations for HDD engines. The original project goals were t\o evaluate the PEMS using a back-up generator, testing a vehicle on a chassis dynamometer, and performing on-vehicle, over-the-road-testing using the PEMS. However, because of a request from the government-industry Calibration Standards Task Force, the project is expected to be rescoped after the conclusion of the chassis dynamometer testing. The project is ongoing with results expected during 2006.

Carl Fulper from EPA reported on the multisponsor Kansas City emission program highlighting PEMS device performance. The Kansas City program used PEMS to obtain an in-use emission factor from in- situ emissions and activity sampling. To ensure PEMS precision and accuracy, the device was initially compared with laboratorygrade instruments during a dynamometer test. second, measurements were collected during a short real-world highway test. Finally, a small set of vehicles installed PEMS and maintained regular operation over a longer time period. The results indicated that, despite some durability and installation limitations, which will be addressed during future testing, PEMS has good precision and accuracy.

John Storey of Oak Ridge National Laboratory (ORNL) presented a poster detailing activities at the Watt Road Environmental Laboratory Initiative. Watt Road Environmental Laboratory Initiative is a joint effort between ORNL and the University of Tennessee, Knoxville, for comprehensive studies of truck emissions in a 2.5- mile corridor in Knox County, TN. Sponsors include FHWA, EPA, and DOE. Recent studies have examined the impact of idling on regulated and unregulated pollutants at truck stops, in-cab air quality during overnight idling, and have isolated the contribution of heavy trucks to ambient fine PM (PM^sub 2.5^). Details of recent developments in remotesensing instrumentation for NO^sub x^ (ultraviolet spectroscopy) and PM (stepped frequency Light Detection and Ranging [LIDAR]) were also presented.

Thomas Dalton of the University of Denver (DU) explained how his group modified existing Fuel Efficiency Automobile Test (FEAT; or remote sensing) technology to include detection and quantification of nitrogen dioxide (NO^sub 2^). A detection limit of 414 ppm-cm was achieved, thereby exceeding the target of 500 ppm-cm. More than 100 measurements of NO^sub 2^ were made in parking lot tests. Data indicate successful measurement of NO^sub 2^ from diesel engines, with emissions ranging from 0.82 to 1.41 g/bhphr. Measurement noise was 0.06 g/bhp-hr, which ensures that the proposed 2007 CARB 20% NO^sub 2^ limit will be measured with a signal-to-noise ratio >8. Results of FEAT NO^sub 2^ detection technology have been corroborated with commercially available NO^sub 2^ detection systems.

Hesham Rakha of Virginia Tech exhibited research indicating that roadway grade is a critical variable affecting on-road vehicle emissions. Consequently, the accurate modeling of vehicle emissions requires accurate estimates of roadway grades. The research included information on the use of nondifferential GPS in estimating roadway grades. The study developed different stacking and Kernel smoothing techniques to remove errors in altitude estimates. Furthermore, the project demonstrated that by using these techniques, grades may be estimated to within 0.4% of the actual roadway grades.

Daniel Burgard and his group at DU modified existing FEAT or remote sensing technology to include detection and quantification of sulfur dioxide (SO^sub 2^) and NH^sub 3^. Parking lot tests have identified high-emitting vehicles of each pollutant. SO^sub 2^ in vehicle exhaust varies because of the highly variable diesel fuel sulfur content, typically 15-1000 ppm by weight (w) domestically and <5000 ppmw internationally. Vehicle SO^sub 2^ exhaust measurements ranged from 0 ppm by volume (v) to 200 ppmv. NH^sub 3^ seems to be highly variable and emitted only from newer vehicles with working catalysts. NH^sub 3^ measurements ranged from 0 to 540 ppmv. Instrument noise for the SO^sub 2^ and NH^sub 3^ channels was 3 ppmv and 4 ppmv, respectively.

Rob Graze from Caterpillar described 2007 model year-compliant PM measurement sensitivity. He discussed sensitivity of proportional sampling relative to diesel exhaust aerosol time of flight, system response characteristics of transient-capable partial flow sampling systems, and filter media PM collection sensitivity emission levels ≤0.01g/hp-hr. Highlights of the study include the successful sampling of diesel PM through a transient test cycle with a partial flow sampling system by way of quick responding intake airflow and fuel flow signals. Additionally, it was found that the optimal response time of the partial flow system must be aligned with the bulk exhaust flow time of flight from engine out to sampling zone locations.

Manfred Linke of AVL (Austria) discussed transient BC emission monitoring from internal combustion engines. Based on the photoacoustic principle, which has been optimized for automotive applications and easy use in test cells, the instrument has a sensitivity of ~5 g/m^sup 3^, which is lower than current particulate emission stan- ' dards in ambient air, and a time resolution of si sec. This allows accurate emission measurements of BC from diesel engines equipped with after-treatment systems. The microphone signals (corrected appropriately for a small zero offset) for soot deposit on the cell windows show a linear and unique, (i.e., generally applicable) relation to the BC PM concentrations in the exhaust of diesel engines.

Mridul Gautam presented a compliance test method that involves only the concentration measurement of pollutants to determine compliance with off-road emissions standards. The "Compliance Factor (F)"-based method requires neither measurement of exhaust flow rate nor engine power output. In addition, commercially available portable emission measurements systems may be used for determination of "in-use" concentrations. This F-value is in its simplest form a ratio of the in-field NO^sub x^/CO2 concentrations to the ratio of brake-specific weighted values of NO^sub x^ and CO2. The factor could then be compared with some established compliance criteria, which would need to include various stochastic components. This value could be tailor-matched to different engine applications, such as size and vocation.

GASOLINE VEHICLE EMISSION FACTORS

During the summer of 2004, EPA conducted the first phase of a study of emissions from LD gasoline vehicles in the Kansas City area. Cosponsors for this study with EPA were the DOE through NREL, the FHWA, and CRC. Carl Fulper from EPA described the study, for which the major objectives are to identify the distribution of PM emitters, determine the fraction of PM high emitters, expand data on PM emission rates, update PM and toxic speciation profiles, evaluate performance of the PEMS on-board sampling system, and expand the on- road database for vehicle emissions and activity and fuel economy. The testing portion of the four-phase study was completed in April 2005. The database will include testing of >480 randomly selected vehicles

Mia Zmud from NuStats described vehicle recruitment for the Kansas City study, which followed a random stratified sampling design and oversampled older vehicles in an attempt to capture "high- emitting" vehicles. Of 1130 eligible respondents, 497 proved unreachable, 169 participated, and 464 refused, of which 52 later agreed to participate. Despite small demographic differences, preliminary examination of particulate emissions for participants and "converted refusers" showed no obvious differences between the two groups. This finding suggests that in many cases, a respondent's refusal may be related to perceived burden or other causes, rather than to the owners' perceptions of their vehicles' emissions.

Eric Fujita of Desert Research Institute (DRI) described variations in chemical composition of emissions from . vehicles tested during the summer phase of the Kansas City study. All of the tested vehicles emitted BC. Coldstart BC and PM emission rates can be two to eight times greater than warm-start emission rates. Relatively clean spark-ignition (SI) vehicles have PM and BC emissions that generally follow the more aggressive portions of the driving cycle; higher emitters emit PM and BC during the entire driving cycle. Benzo(ghi)perylene, indeno[123-cd] pyrene, and coronene, potential markers for SI exhaust, correlate reasonably well with total carbon emissions. Emissions of volatile and semivolatile PAHs are substantially higher than particle-phase PAHs and could be an important source of secondary organic aerosols.

John Collins from CE-CERT is conducting an on-road study of extremely low-emitting vehicles (ELEV). The program has shown that publicly owned in-use LEVs are meeting performance expectations in Southern California. However, vehicles that have not been certified to the Supplemental Federal Test Procedure (SFTP) high-speed driving cycle (US06) had dramatic increases in on-road emissions during high- speed driving. Emissions from high-mileage in-use vehicles were within the standards and were not dramatically affected by nonstandard start cycles and soak times.

Michael Gebel representing CARB presented the results of a pilot study to measure refrigerant emissions from a vehicle fleet being driven through the Caldecott Tunnel near Oakland, CA. Emissions of 0.9 0.5 (1σ) mg R134a per vehicle mile (vehicles with R134a AC systems) were calculated using a carbon balance method. The variety of modes of vehicular emission of refrigerant was discussed, and comparisons were made to other studies. The comparisons indicate that the rate of emission by leakage increases during driving relative to at-rest conditions. The data are also suggestive of an additional rate increase while the air conditioning is operating. Future studies were suggested to verify this assertion.

Macq\uarie University and Commonwealth Scientific and Research Organization (CSIRO) of Sydney, Australia, are studying the effect of catalytic converter temperature on vehicle emissions with a focus on low-speed, long-idle on-road traffic conditions. Michael Patterson reported on their studies, where they have observed high CO and HC emissions occurring when the throttle is opened immediately after a long idle or engine operation. It is not clear whether this results from an inoperative converter or the engine operation. No hard accelerations that could induce open-loop fuel- enrichment are included in the test program.

In recent years, a vehicle remote sensing system (cross-plume) to measure on-road PM and gaseous (CO, NO, and HC) fuel-based emission factors was developed at DRI and tested in the field. Claudio Mazzoleni described an in-plume system, which samples automotive exhaust through a tube that was developed to assess the accuracy of the cross-plume system. The in-plume system includes a Fourier Transform Infrared (FTIR) spectrometer, electrical low-pressure impactor, and LI-COR analyzers to quantify gaseous and PM emissions. During winter 2004, a study to measure vehicle emission factors was conducted in Idaho. The cross-plume system was deployed together with the in-plume system to compare emission factors. Averaged PM and gaseous emission factors compared well.

EMISSIONS CONTROL MEASURES

Hannah Murray from Toyota Technical Center described how EPA's MOBILE6.2 assigns a consumer response rate to malfunction indicator lamp illumination outside I/M areas based on vehicle mileage. CRC sponsored a consumer response survey to assess these assumptions. The current model values are 90% response from 0 to 36,000 mi, 10% response between 36,000 and 80,000 mi, and 0% response past 80,000 mi. The study showed a 91% rate of positive response: 94% positive response for vehicles under warranty and 89% positive response for vehicles out of warranty. Preliminary analysis using the survey- derived response rates shows a significant impact on LD emission factors as modeled by the MOBILE6.2 model.

Steve Stewart of the British Columbia AirCare Program summarized a study showing that some vehicles have much more trouble with I/M programs than others. Although the overall failure rate for 1998 and newer vehicles in the AirCare program is <5%, there are 13 specific models with higher failure rates, which account for almost 30% of all failures. Their failure rates can be >30%, showing specific types of failure. Typically, the on-board diagnostics (OBD) system gives no indication of a problem, but FTP testing has confirmed the high emissions measured by the IM240 emissions test. For repair, owners can experience difficulty obtaining warranty coverage if no individual components or systems have been identified as faulty by OBD.

Thierry Leprince from Extengine Transport Systems discussed the fundamentals of SCR technology and how it can be applied to mobile applications. Diesel engines are significant contributors to the NO^sub x^ and PM emissions inventory. There has been relatively little activity in reducing NO^sub x^ emissions from existing diesel engines. SCR technology is an effective tool for reducing NO^sub x^ emissions from diesel engines and has been used for >20 yr in stationary applications. An example was given showing that, when a diesel engine is retrofitted with SCR and a DPF, emissions can be similar to those of a natural gas engine in terms of PM and NO^sub x^.

Ron Haste of CARB discussed the testing portion of a two-phase pilot study for determining the feasibility of obtaining emission reductions through an in-use evaporative emission canister retrofit program targeting older, on-highway vehicles. Existing canisters and related vapor lines were replaced by new ones on 48 1981-1994 passenger cars and LDTs. The evaporative test results are undergoing analyses for determining the amount of attainable emission reductions. Additional test results involving nine vehicles, which were later recaptured, will be used for assessing the durability of any reduction benefits. Early indications are that these replacements may not provide effective reductions.

Sharon Lemieux from CARB described a test plan conducted from October 2003 to July 2004 to determine the amenability of passive diesel PM retrofit systems to vehicles operated by public agencies and utilities. Fiftyseven vehicles were instrumented to collect second-bysecond exhaust temperatures from the most common vehicle types. The results of the study showed that 57% of the measured vehicles met the temperature criterion specified for four verified passive-diesel particle filters. Therefore, although public and utility fleets present unique retrofit challenges, such as low mileage accumulation and relatively mild duty cycles, the study demonstrates that temperature-dependent retrofits can be done.

Robert Slott, a consultant, presented results of an analysis of Missouri emissions databases, including IM240 tests, ambient data, and 5 million remote sensing (RS) measurements, which showed the following: NO^sub x^ humidity correction factors help adjust RS NO^sub x^; correlation improved between IM240 and RS measurements made on the same day when the RS measurements were divided by average miles/gallon; vehicles were identified as RS-fail and/or IM240-fail; and percentage of excess emissions identified by IM240- failed vehicles related to percentage of excess emissions found by RS-failed vehicles. RS results correlated better with IM240 results for 1981-1989 vehicles than for newer models.

Celia Shih from the New York State Department of Environmental Conservation presented the evaluation results from New York City's taxi fleet study. Black and yellow medallion taxicabs were identified from the I/M program database. They were compared with nontaxi vehicles in the area. The black medallion cabs have three emission tests per year. The yellow medallions had the highest average odometer readings, the highest failure rates, and the highest average HC/CO/NO^sub x^ emissions. Data suggest that the three-times-per-year I/M program for the black medallions is very effective, because 8-yr and older black medallion cabs, even with higher average odometer readings, have lower emissions than the nontaxi fleet in the area.

Steve Stewart of Dlex Corp. described that Urumqi, the capital of the Xinjiang Uygur Autonomous Region in the People's Republic of China, has >1 million people and 160,000 vehicles at present. Their existing Motor Vehicle Emissions Control Strategy includes idle emissions inspection and natural gas conversion for buses. Other initiatives have included roadside testing, retrofit devices, and fuel additives. The new Motor Vehicle Emissions Control Strategy is part of the Urumqi Urban Transport Project. It covers all motor vehicles. Many of its elements have not been used previously in Urumqi. An important upgrade will be made to the I/M program, which will change from an annual idle test for all vehicles to a system that integrates roadside testing, idle and acceleration simulation mode (ASM) tests, and some IM240 mass measurements.

Tom Wenzel from Lawrence Berkeley National Laboratory summarized findings from the Phoenix I/M program. On-board diagnostics- equipped (OBDII) cars have higher failure rates, repeat failure rates, and no-final-pass rates than non-OBDII cars. This is likely because the OBDII test is more stringent than the IM147 tailpipe emissions test administered in Phoenix. Large numbers of OBDII and non-OBDII cars failed an off-cycle test within a few months of passing their previous test. One possible : cause is gas cap "failures" that have a minimal impact on in-use emissions; however, only 20% of OBDII vehicles have gas cap failures. OBDII and non- OBDII cars suffer from the same emissions deterioration. Possible causes include inadequate repair and intermittent, variable emissions problems on "flipper" vehicles.

Mukaram Syed of Aaqius & Aaqius summarized improvements and durability of a new active DPF system for stop-and-go duty cycle vehicles. The fundamental process is based on variable filtration area and thermal management using a unique exhaust valve control system. The use of fuel injection and fuel-borne catalysts ensures the DPF regeneration in all driving conditions. The active strategy is fully controlled and managed by a specific electronic control unit. This DPF system is certified by Renault Trucks as an option for their EUROS Premium DCI 11 320 diesel engine for the garbage truck market. Field experiences in retrofit applications were presented. The system is under the diesel PM reduction certification process in Switzerland.

Fuel Effects on Vehicle Emissions

Harold Haskew, a consultant, summarized results from the CRC- sponsored E-65 program, designed to compare LD vehicle permeation emissions resulting from three gasoline fuels: containing methyl tert-butyl ether (MTBE), ethanol, or no oxygenate. The testing was conducted on a sample of 10 LD California vehicles that represented the in-use fleet in 2001. The vehicle liquid and vapor fuel systems were removed and installed on aluminum frames for evaluation. Average permeation emissions with a 5.7 volume percentage of ethanol gasoline were 1.4 g/day higher than permeation emissions from the MTBE gasoline and 1.1 g/day higher than permeation emissions with a nonoxygenated gasoline. The differences between the ethanol fuel and the other fuels are statistically significant at the 95% confidence level.

Steve Brisby of CARB presented the status of his agency's efforts to estimate the impact of the transition from MTBE to ethanol in gasoline on motor vehicle emissions in California. He described the results from recently completed studies on commingling, permeation, and vapor pressure and temperature effects on emissions. Test results showed that permeationemissions increased from the MTBE fuel to the ethanol fuel in the vehicles tested. On average, ethanol permeation emissions increased 65% relative to MTBE and 45% relative to nonoxygenated gasoline.

Ben Hancock summarized CARB's efforts in modeling the influence of increased permeation of VOC emissions from gasoline containing ethanol on air quality in the South Coast Air Basin and Sacramento metropolitan area. CARB used results from the CRC E-65 fuel permeation study to estimate that use of ethanol in gasoline would produce an additional 17 t/day (tpd), or 14%, increase of evaporative VOC emissions on a typical summer day in the South Coast Air Basin, and a 2.4 tpd, or 18%, increase in the Sacramento area. These increases are attributable to higher diurnal, running loss, and hot soak emissions.

Tom Darlington of Air Improvement Resource presented the effects of ethanol on permeation VOC inventories from on-road vehicles, off- road equipment, and off-road portable containers in California and other states that are considering switching from reformulated gasoline with MTBE to reformulated gasoline with ethanol. The study used data from the E-65 program for on-road vehicles and additional data on lawnmowers and portable containers from CARB. Permeation emission increases were developed for these sources, and temperature correction factors were also developed. Results showed that ethanol increased permeation VOC in California by 25 tpd in 2003 and by 17 tpd in 2015.

Tom Durbin of CE-CERT described the study design of the CRC- sponsored E-67 program on the effects of ethanol and volatility parameters on exhaust emissions from the latest technology gasoline vehicles. A total of 12 fuels with varying ethanol content (0-10%), mid-fill (T^sub 50^), and back-end (T^sub 90^) volatility were tested. The test fleet was composed of 12 in-use vehicles ranging from California LEV to super ultra low-emitting vehicle (SULEV) certification. Vehicles were tested over the FTP for regulated emissions and, for a subset of four fuels, detailed non-CH4 organic gas speciation. Results will be available in the first part of 2006.

Christopher Frey of North Carolina State University tested 12 HDD dump trucks during actual duty cycles using on-board instruments to evaluate the effect of operating mode, vehicle type, engine type, load, and fuel type on emissions. Fuel types included petroleum diesel and soy-based B20 biodiesel fuel (B20). When the total truck weight was doubled, -20-40% higher fuel use and emissions were observed. Fuel mass flow and total CO2 emissions increased slightly for B20 versus petroleum diesel, whereas CO, HC, nitric oxide (NO), and PM typically decreased by 10-20%. The effect of real-world duty cycles may be especially significant with respect to the finding for NO.

John Kinsey from EPA summarized his on-road study of fine particle emissions from an HDD tractor trailer while burning low sulfur diesel and a biodiesel blend. EPA constructed a new Diesel Emissions Aerosol Laboratory (DEAL) to sample "real-world" diesel emissions for this project. Using the DEAL plume sampling system, a comprehensive on-road study was performed at steady state, near- zero grade conditions. A total of 16 tests were performed to determine PM^sub 2.5^ emission factors, particle size distributions, and chemical source profiles for the two test fuels while operating at two different weight and speed conditions. Data reduction and chemical analyses are under way and will be published in the future.

Teresa Alleman of NREL presented the impact of GTL fuel and catalyzed DPFs on a fleet of vehicles. Data were collected for two rounds of chassis emissions over a period of 6 months on 2001 International DT 466 in-line six cylinder 195-hp trucks. Results showed that the use of GTL fuel with a DPF did not impact the fleet operability. Emissions testing results showed a decrease in emissions when GTL fuel was used. Larger reductions in emissions are possible when GTL fuel is used with a DPF. Fuel economy was not impacted.

Tom Durbin of CE-CERT described a multigroup evaluation of the potential emissions benefits/liabilities of biodiesel in vehicles/ equipment specific to military applications. The testing encompassed a range of different vehicle types including two medium-duty trucks, a Humvee, a heavy-HDD truck, two buses, two stationary back-up generators, a forklift, and an airport tow vehicle. Fuels tested included an ultralow sulfur diesel fuel, different blend ratios of two different yellow-grease biodiesels and one soy-based biodiesel, JP-8, and yellow-grease biodiesel blends with two different NO^sub x^ reduction additives. Effects of biodiesel can vary depending on application, blend, and use cycle. PM after-treatment produces a reduction in PM, CO, and HC emissions.

UNREGULATED EMISSIONS

Doug Lawson from NREL presented a progress report on the DOE Gasoline/Diesel PM Split Study. The study's objective is to quantify the relative contributions of emissions from gasoline- and diesel- powered engines to ambient PM^sub 2.5^ in the Los Angeles area. In this study, several groups worked cooperatively on sample collection and quality assurance aspects of the study but worked independently to perform chemical and data analysis and source apportionment. Lawson reported that chemical species can be used to perform source apportionment of gasoline- and diesel-powered vehicles and that chemical composition of high-emitting vehicles is extremely important in determining source attribution. Study results were submitted for peer-reviewed publication in the latter part of 2005.

Charles Blanchard of Envair summarized his evaluation of day-of- week differences in average ambient concentrations of ozone (O^sub 3^) precursors (NO, NO^sub x^, CO, and VOC) using 1998-2003 data from monitoring sites in 23 states in New England, the Midwest, the Mid-Atlantic, and isolated urban areas in the western and southern United States. He observed substantially lower weekend than weekday concentrations of O^sub 3^ precursors in all of the study areas. However, the large reductions in ambient concentrations of ozone precursors on weekends did not produce large reductions of weekend O^sub 3^, and, in many places, higher O^sub 3^ was observed. Different reductions of O^sub 3^ precursor emissions than normally take place on weekends will be required before significant reductions in O^sub 3^ levels can be achieved.

Robert Harley of the University of California at Berkeley discussed changes in vehicle emissions on diurnal, weekly, and decadal time scales. During the 1990s in California, gasoline engine NO^sub x^ emissions decreased by 600 tpd, whereas diesel engine NO^sub x^ increased by 300 tpd, accounting for about half of all on- road NO^sub x^ as of 2000. Diesel truck emissions exhibit a strong weekly cycle with 60-80% reductions on weekends. These emission changes are consistent with the spread of weekday-weekend O^sub 3^ differences (higher O^sub 3^ on weekends despite lower emissions) to more surface measurement sites over time. EC concentrations decrease on weekends as expected with less diesel truck traffic.

Olavi Koskinen of the Finnish Ministry of Transport described his work on emission impacts of total traffic flow and its composition by vehicle categories. His analysis treats the heaviest vehicle categories (truck and trailer combinations) belonging to different emission classes (Euro 2 and Euro 3) as separate categories. The role of the heaviest vehicles on emissions is very dominant, especially for NO^sub x^, fuel consumption, and CO2, although their proportion in total traffic flow is very low. He reported that the change in fleet composition from Euro 2 vehicles to Euro 3 vehicles has significantly influenced NO^sub x^ emissions. His studies have examined the influence of road grade and terrain on fleet emissions as well.

Don Stedman from DU summarized his group's remote sensing measurements of on-road mass emissions of CO, HC, NO, and smoke per kilogram (or per liter) of fuel burned. On-road emissions measured in Asia show large geographic variability and that everywhere a few vehicles are responsible for most of the on-road emissions. He compared recent results from Singapore, India, Japan, and Sri Lanka with previous measurements in Singapore, Japan, and other Asian locations. In Singapore, Hong Kong, and Japan, current on-road emissions are not significantly different from U.S. locations, and emissions have been decreasing at about the same rate. In India and Sri Lanka, there are significant opportunities for emissions improvement.

Alan Gertler from DRI discussed his measurements of paved road dust resuspension from on-road vehicles using both instrumented vehicle and cross-roadway flux measurements. Studies were conducted in the Lake Tahoe Basin during a series of winter storms and continued through the spring. He reported that the use of liquid de- icers contributes less to road dust emissions than abrasives. Street sweeping was found to increase the re-entrainment rate of the remaining coarse PM (PM^sub 10^) road dust, indicating that this may not be an effective PM^sub 10^ control method. Emission factors for roads in the study area (a snowy mountain climate) tend to decrease significantly from late spring to early summer, by as much as a factor of four.

Kathleen Kozawa of the University of California, Los Angeles, described a study to evaluate the variables affecting children's exposure during school bus commutes in which video recordings of events ahead of the bus during selected commutes were analyzed along with real-time pollutant concentrations of BC, particle-bound PAHs, and NO^sub 2^. The goal of the videotape analysis was to gain a better understanding of the transient factors that affect pollutant concentrations inside school buses during commutes. The important dynamic variables governing children's exposuresduring these commutes included the type of vehicle being followed, presence of visible emissions from a leading vehicle, type of test bus, and window position.

Ali Ergudenler of the Greater Vancouver Regional District described modeled effects of HDDV emissions on ambient PM^sub 2.5^ near major roads in his region. Class 8a and 8b vehicles account for 65-70% of PM^sub 2.5^ emissions from all on-road HDDV sources. Despite projected increases in the HDDV fleet, emissions of criteria pollutants and air toxics are projected to decrease by 60-90% between 2000 and 2020. The highest PM^sub 2.5^ concentrations from bus and truck HDDV traffic, up to 6-8 g/^sup 3^, are predicted alongside major highways and expressways, with annual average PM^sub 2.5^ concentrations from HDDV emissions >1 g/^sup 3^ within 20-100 m of some roads and associated potential for increased human health risk.

Paving of road shoulders is a method to reduce road dust re- entrainment. Alan Gertler of DRI described a study to determine the impact of five different road shoulder treatments on PM resuspension. Measurements were performed in Phoenix during different pre- and post-shoulder treatment periods in 2004. For compacted aggregate base, asphalt, and Soil Sment, PM emissions generally decreased after the application of their respective amendments. Compacted 3/8-in minus granite and compacted asphalt millings were not as effective for reducing road dust re- entrainment; however, this result may have been biased by track-out from a nearby road.

PM CHARACTERIZATION

David Booker of Sensors Inc. reported on exhaust PM mass measurements being performed in the multisponsor LD gasoline PM study in Kansas City. The objectives of the analysis were to compare continuous PM measurements using quartz crystal microbalance technology (QCM) to a gravimetric filter reference and to evaluate the accuracy of the continuous measurements in light of this comparison. Preliminary results suggest that the QCM tends to overestimate PM emissions compared with the filter during cold start (-30%) and to underestimate missions during hot-start operation (20- 30%) because of the presence or absence of volatile components in either stage of vehicle operation.

Alberto Ayala of CARB presented the results of a study to measure the transient emissions of ultrafine particles from two transit buses. One vehicle was a 2000 model year compressed natural gas (CNG)-fueled bus, and the other was a 1998 bus equipped with a PM trap or an oxidation catalyst running on ultralow sulfur diesel fuel. The vehicles were operated on a chassis dynamometer over transient cycles, and samples were drawn from two locations: from raw exhaust using a minidiluter and from the CVS. Peaks in single- size number concentrations observed at both sampling locations corresponded with peaks in vehicle speed. The trap was found to reduce ultrafine particle emissions effectively. However, the emissions of the CNG bus displayed a tendency toward higher number concentrations of smaller particles.

Tim Johnson, representing TSI Inc., presented results of tests performed with TSI's EEPS spectrometer. These tests were performed with this instrument measuring fastchanging particle size distribution on a mobile platform to evaluate whether the noise from vibration would limit its use in this application. Tests were performed in various traffic conditions and evaluated concentration variability inside and outside the vehicle. The noise level increased slightly because of vibration, but on-road signals far exceeded the additional noise suggesting that this instrument could be a valuable tool for mobile on-road experiments.

David Kittelson from the University of Minnesota described particle size and concentration measurements made with the EEPS under both laboratory and real-world conditions. Transient laboratory measurements showed ~1-sec response and good agreement with a condensation particle counter (CPC). Sudden load increases led to sharp increases in engine-out nanoparticles that decayed after ~1 min. Bursts of particle nucleation occurred downstream of traps as temperatures increased. Total volume measurements track with mass and might be used in NTE testing. Near-roadway measurements tracked the decay of nanoparticles downwind of a freeway. The data fit well to an exponential decay with a characteristic 1/e distance of 90 m.

Nigel Clark of WVU presented results from the CRC E-55/59 project, where emissions data were collected from 10 in-use 1986- 2004 model year HHDD trucks in Southern California. Testing was performed over the UDDS and the CARB 5-mode test cycles on the WVU transportable laboratory. Idle emissions were characterized by a distinct nuclei mode for all vehicles, with a count mean diameter ~30-40 nm. The cruise and steady-state mode emissions from all vehicles were characterized by accumulation mode particles with a count mean diameter in the range of 60-100 nm. Chemical analysis showed that volatile compound emissions were higher during the idle mode. For most vehicles, VOCs and semi-VOCs were higher during the cruise mode.

Christine Gierczak presented a summary of an 8-month laboratory study conducted at Ford Motor Company designed to validate the long- term performance of a SEMTECH-D PEMS (Sensors, Inc.). The study was performed at a single-dynamometer test site on five dieselpowered trucks. The instantaneous concentration and cumulative mass modal data (all mass emissions computed using exhaust flow rates measured by the laboratory instruments) obtained using the SEMTECH-D and the Horiba MEXA 7500 HEGR analyzers were compared for 34 hot- and cold- start 505-sec transient test cycles. The SEMTECH-D proved to be accurate and consistent relative to the laboratory system with no significant systematic errors or bias observed in the data.

Thomas Lanni from the New York State Department of Environmental Conservation presented results of testing two particle samplers, the Electrical Aerosol Detector (EAD, TSI Model 3070A) and a portable CPC (TSI Model 3007) during a 2004 win

Source: Journal of the Air & Waste Management Association

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