Evaluating Vehicle Emissions Inspection and Maintenance Programs (2001) / Chapter Skim
Currently Skimming:
3 Vehicle Inspection and Maintenance Programs
3 Vehicle Inspection and Maintenance Programs
Pages 57-89
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 57... ...
For example, the Denver Regional Air Quality Council has recommended beginning a "clean screen" program in January 2002, where on-road remote-sensing measurements would be used to exempt vehicles from scheduled testing (Regional Air Quality Council 2000~. Missouri has been operating a remote-sensing clean screen program since early 2000.
|
From page 58... ...
Centralized Network A centralized network consists of a relatively small number (relative to a decentralized network) of stations that perform only emissions tests.
|
From page 59... ...
Since there are many more stations performing inspections in the decentralized network, the number of stations cited for testing fraud will likely be higher compared to a centralized program. However, the number of inspections an individual station may be perfo~ing could be low whereas testing fraud at a high-volume centralized testing facility may impact a large number of tests.
|
From page 60... ...
VEHICLE-EMISSIONS TESTING Vehicle emissions tests vary in terms ofthe complexity of driving conditions represented. An important issue is the need for the test to obtain an accurate measurement of emissions while keeping equipment costs low and test duration short.
|
From page 61... ...
1987~. Steady-State Versus Transient Testing Another way to differentiate vehicle emissions tests is by describing the conditions under which emissions are measured.
|
From page 62... ...
Exhaust Emissions Test Types A number of tests are commonly used to measure vehicle exhaust emissions. These range from unloaded idle tests to sophisticated transient-cycle mass emissions tests, such as the Federal Test Procedure (FTP)
|
From page 63... ...
in exhaust emissions fromidling vehicles. A high-idle test,in which engine speed is manually increased to ~2,500 revolutions per minute (~pm)
|
From page 64... ...
can be calculated from engine displacement volume, engine speed at idle, and measured tailpipe concentrations from the idle test. · ASM This series of loaded-mode steady-state emissions tests measures exhaust concentrations from motor vehicles operated on a dynamometer.
|
From page 65... ...
Comparison of Exhaust Emissions-Test Types .~ The California I/M pilot study (CARE 1996) provided the opportunity to compare emissions results from several candidate exhaust test types: the FTP, IM240, ASM5015, ASM2525, and low- and high-speed idle tests.
|
From page 66... ...
TM240 ASM Idle Test FIGURE 3-2 Comparison of FTP, IM240, ASM, and idle-test results for CO. Replicate emissions tests were not performed for the 380 vehicles.
|
From page 67... ...
Evaporative Emissions Tests Exhaust emissions are relatively easy to sample for routine inspection the exhaust exits from the tailpipe and a collection hose is attached to the tailpipe for testing. Evaporative emissions can occur from many places on the vehicle.
|
From page 68... ...
— 0.63 (0.63) Idle tests 0.68 (0.72)
|
From page 69... ...
EPA has acknowledged problems with the current purge test. Therefore, states that have indicated they will perform a purge test when one is available may continue to take ~ 00°/0 ofthe emissions-reduction credit for the purge test, without actually performing such testing, until EPA develops an effective purge-test procedure.
|
From page 70... ...
Improvements in new vehicle standards will introduce advanced vehicle emissions-contro! technology, which may consist of · Fuel injectors.
|
From page 71... ...
· Turbocharged diesel engines. 71 With the introduction ofthese and other vehicle emissions-control technologies, emissions-related repairs will require that the automobile repair industry remain up to date on emissions-control repair protocols.
|
From page 72... ...
However, such controls might help abate average ozone levels on regional scales (NARSTO Synthesis Team 2000~. Cutpoints are set much higher than the EPA's new vehicle certification standards, shown in Table ~ -2.
|
From page 73... ...
. Because ofthe skewness ofthe fleet's emissions, an emissions cutpoint of ~ O times the certification standards would fait only 6% ofthe fleet but would still capture 20% ofthe total emissions above the certification standards and 12% ofthe Marginal emitters are those vehicles that fail emissions tests by only a small amount (Lawson 1995~.
|
From page 74... ...
Because of its importance in judging how well an I/M program is performing, this topic is discussed along with other criteria for evaluating I/M programs in Chapter 7 EFFECT OF CURRENT I/M PROGRAMS ON VEHICLE EMISSIONS . One method of evaluating the effectiveness of I/M programs is to measure their ability to reduce emissions.
|
From page 75... ...
These criteria include performing mess emissions testing on vehicles before and after repairs, and comparing results with MOBILE; conducting random audits of inspection stations to ensure that all aspects ofthe I/M test were being performed correctly; and comparing I/M test data with remote-sensing measurements made before and after testing. The results ofthis evaluation are then used to decide whether the program can receive all or a fraction of the emissions-reduction credits afforded a cenkalized program (ECOS/STAPPA/EPA 1998~.
|
From page 76... ...
Evaluations of California Smog Check Program The California Smog Checkprogram requires most vehicles in California to have a biennial emissions test. The Smog Check program began in ~ 984 with idle tests administered at privately owned inspection stations.
|
From page 77... ...
The Basic Smog Check operates inmost ofthe rest ofthe state and subjects vehicles to a two-speed idle test for HC and CO. Vehicles anywhere in the state are also subjected to emissions tests upon change of ownership.
|
From page 78... ...
released a separate evaluation ofthe Enhanced Smog Check program (IMRC 2000~. The IMRC evaluation focused on underlying factors that influence the effectiveness of the Enhanced Smog Check program.
|
From page 79... ...
was producing emissions reductions of 18°/O HC, 15% CO, and 7°/O NOX (IMRC 1993) at that time, and to data from vehicles that were given emissions tests before and after repairs.
|
From page 80... ...
Overall, the evaluation concluded that, depending on the method of analysis, the AIR programreduced 1999 CO emissions by 8-17%. The Tower estimate of emissions reductions was produced by using the in-program emissions data on fail-pass vehicles and by analyzing remote-sensing data from the area.
|
From page 81... ...
81 a, o v CQ To of N .
|
From page 82... ...
Wenzel ~ ~ 999a) compared emissions reductions based on IM240 test data with a large sample of remote-sensing readings.
|
From page 83... ...
Using air-quality data to evaluate I/M emissions benefits raises many issues. The committee recognizes that observing the effects of I/M programs on air quality is difficult because the level of emissions reductions have been relatively modest and there are numerous confounding variables.
|
From page 84... ...
compares vehicle emissions in an I/M city with those of a reference fleet in a city with similar socioeconomic and meteorological characteristics but with a different I/M program. This reference fleet could be from a non-~/M city in which case an evaluation would determine the reduction in emissions due to the I/M program—or from a city with a benchmark I/M program.
|
From page 85... ...
Random roadside surveys allow for inspection of vehicles as they are driven on the road, but many EPA surveys of centralized programs were done in the test lane, rather than on the road, which introduces bias into the results. Motorists were given no advance notice that they wilIbe stopped for aninspection.
|
From page 86... ...
SUMMARY Numerous variations of vehicle emissions I/M programs are in use today, each with its own attributes. One program type is the centralized program using transient emissions tests such as the IM240.
|
From page 89... ...
For example, the current California Smog Check program is a hybrid network that uses an ASM test to estimate CO, HC, and NO concentrations. Previous evaluations of I/M's emissions benefits have been based on MOBILE as well as direct estimates of vehicle emissions.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.