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NYC's Omnibus Fleet NYTEST Results for 2003

Mobile Emissions and Air Quality Section
Bureau of Air Quality and Research
Division of Air Resources
New York State Department of Environmental Conservation
625 Broadway
Albany, New York 12233

Executive Summary

The objectives of this report are to analyze the NYTEST data collected during calendar year 2003 from the omnibus vehicle fleet administered by the Taxi and Limousine Commission (TLC) in New York City and also to examine the benefit of multiple emissions test cycles during the year.

The omnibus fleet is characterized by a registration class of "OMc" where "c" is one of characters "F", "L", "R", "S", "T", or "V." The overwhelming majority of the omnibus fleet is of class "OMT" or omnibus taxi and are light duty vehicles (LDVs). The fleet was subject to three emissions test cycles in calendar year 2003. The three largest classes in the omnibus LDV fleet, OMT, OML, and OMS together, however, constitutes only 3.34% of the entire NYMA LDV fleet.

The TLC omnibus fleet tends to be a younger fleet than non-taxis. Because the omnibus fleet is a transportation service fleet, it accumulates mileage much more rapidly than the non-taxi fleet. The NYTEST failure rates for the omnibus fleet are generally higher than the overall NYMA fleet for model years 1996 and newer due mainly to higher omnibus vehicle mileage. The OMT omnibus class LDVs (taxis) had the lowest NYTEST failure rate of all vehicle classes - including the overall NYMA fleet - for model years 1988 to 1995. In addition, due to their small sample sizes the omnibus NYTEST failure rates for vehicles with pre-1991 model years are chaotic and unreliable.

The NYTEST per cent emissions reductions of the three regulated pollutants (HC/CO/NOx) from the omnibus vehicle classes were compared with those of the entire NYMA fleet. For the LDVs, the omnibus class OMS had the highest per cent emissions reductions for all pollutants. For LDTs, the omnibus class OMT had higher per cent emissions reductions than the NYMA fleet for all pollutants and the highest of all but OMS for HC. The overall emission reductions from the omnibus fleet are small, however, due to the relatively small number of vehicles.

Furthermore, the effect of the annual three emissions test cycles is examined by comparing a part of the OMT fleet - the black medallions (which received three emissions tests in 2003) with another part, yellow medallions, and the non-taxi NYMA fleet (both of which did not have three emissions tests in our 2003 database). This analysis was confined to LDVs because of the size of the sample. The average mileage for each model year is substantially higher for both black and yellow medallions than the non-taxi fleet. The yellow medallion taxi subgroup, which received only one emissions test in 2003, has a much higher NYTEST failure rate than the black medallion subgroup. The black medallions have both lower NYTEST failure rates and lower average pollutant values than the non-taxi NYMA fleet when the comparison is made with approximately the same average odometer readings.

I. Introduction

The Taxi and Limousine Commission (TLC) in New York City (NYC), under terms of a Consent Order filed on September 6, 1977, is required to provide emissions tests for its vehicle fleet ("medallion taxicabs" and "non-medallion livery vehicles") on a three times per year basis.

With the commencement of New York State's Enhanced I/M Program in 1998, emissions test data (based on either dyne-based NYTEST or one speed idle test) were collected from NYC's omnibus fleet and included in our Enhanced I/M Program database. With the start of an OBD II-based vehicle inspection program administered by TLC on December 8, 2003, all yellow medallions were safety and OBD inspected at TLC's testing facility located in Woodside of New York City.

The objective of this report is to analyze the NYTEST data collected during the calendar year 2003 (1/1/2003 through 12/31/2003) from these omnibus vehicles and to examine the benefit of multiple emissions test cycles.

II. Omnibus Fleet Data in I/M Program Database

Each year, approximately 4 million vehicles register and operate in the nine counties of the New York Metropolitan Area (NYMA). With the implementation of an enhanced I/M program in 1998, all vehicle information records and their emissions testing results, transmitted from NYMA testing facilities, were stored within DEC's I/M program database.

Six different "registration class codes,"¹ (namely, OMF, OML, OMR, OMS, OMT, and OMV) are specifically reserved for in-use omnibus fleet. From the year 2003 I/M Program database, with the assumption that all the registration class codes were entered "accurately," as shown in Table 1, a total of 51,284 vehicles, or 1.12% of the registered vehicles in NYMA, were identified to belong to one of the six omnibus vehicle registration classes. Among them, 46,964 (or 91.58%) were LDVs, 3,507 were LDTs, and 813 were HDVs ². Due to their relatively small sample sizes, the HDVs and a few light duty vehicles registered as OMR (8 LDVs and 13 LDTs) and OMV (5 LDVs) were excluded from this analysis.

Table 1: Types of Omnibus and Vehicle Counts

Registration Class Code		Description	Vehicle Count
Numeric Code	Character Abbreviation		LDVs	LDTs	HDVs
53	OMF	Public Service Omnibus	0	0	2
55	OML	Livery Omnibus	4,705	426	456
56	OMR	Regular Omnibus	8	13	148
52	OMS	Special Omnibus	5,473	2,138	128
54	OMT	Taxi Omnibus	36,773	930	79
57	OMV	Vanity Omnibus	5	0	0
Total			46,964	3,507	813

An additional check for inclusion in our sample selection was performed based upon the given 8-alphanumeric "license plate" data field³. It is assumed that vehicles from the same entity would be registered under the same registration class and would carry "similar" license plates. For example, using "n" to represent a numeric, "c" for an alphabetic character, and upper case letters for the actual letters on the plate, the majority of vehicles registered as OML or OMR were found to carry the license plate of "nnnncc" (e.g., "nnnnLA" for OML, "nnnnnBA" for OMR). OMS vehicles had the license plate of "cccnnnn" (e.g., "CFHnnnn"). For those registered as OMT, there were at least five different types of license plates⁴: "TnnnnnnC", "LTCnn," "nnnLTC," "nnnnnTX," and "ncnnA" (with variations of "ncnnB," "ncnnC").

The next step was to determine the "emissions test cycle" for each vehicle, identified by a unique "vehicle identification number" (VIN). An emissions test cycle (or a cycle) is defined as the combination of a safety inspection and an emissions test undergone by a vehicle within a certain time interval. For vehicles operating in NYMA, the "normal" cycle is 375 days (i.e., one year plus ten days). In addition, all vehicles are required to have a safety inspection/emissions testing at a vehicle ownership change. For vehicles under the TLC jurisdiction (based on the Consent Order discussed previously) it is expected there would be three emissions test cycles within each calendar year, with the intervals being approximately four months apart (or 120 days).

The emissions test cycle information for each VIN is based on a combination of emissions test dates, emissions test results, whether a valid certificate is issued, and the certificate expiration date ⁵. The assumption is that vehicles would not undergo an emissions test cycle unless absolutely required, as each inspection/emissions test cycle would cost the vehicle owner time, inconvenience (bringing the vehicle to the inspection station and picking it up later), and money (inspection/emissions testing fee of $37.00, possible repairs, and the time the taxi driver loses in making a living).

Only the results from the "initial" and the "final" emissions tests in each emission cycle were used for analysis. An "initial" emissions test should come from one of the following four scenarios:

• the only emissions test (a "pass");
• the first emissions test (usually a "fail" followed by re-tests and a final "pass" emission test result);
• emissions tests from additional emissions test cycles; or,
• emissions test due to vehicle ownership change.

Based on these scenarios, total counts of initial emissions tests by vehicle type and by the three omnibus registration classes (OML, OMS, and OMT) are summarized and presented in Table 2.

It is observed that:

• The majority of OML (e.g., 86.78% for LDVs) and OMS (e.g., 96.69% for LDVs) vehicles had only one initial emissions test.
• By examining the OML LDV sub-sample that had three initial emissions tests (195 VINs), 80% of the tests were from the four months emissions test cycle (with the testing dates between 100 and 140 days). From the OML LDV sub-sample that had two initial emissions tests (with 414 VINs), that 54% of the tests were also from the four months emissions test cycle.
• Because of their relatively smaller samples (180 and 2 VINs for the two and three initial emissions tests, respectively), it is not certain if OMS vehicles were also required to have three emissions tests per year (or those vehicles simply had "incorrect" registration class information).

Table 2: Omnibus Fleet and Their Initial Emissions Test Counts

Number of Initial Emissions Tests	# of LDV VINs			# of LDT VINs
	OML	OMS	OMT	OML	OMS	OMT
1	4,083	5,291	11,254	357	2,073	533
2	414	180	12,545	40	63	219
3	195	2	12,627	27	2	176
4	12	0	330	2	0	2
5	1	0	16	0	0	0
6	0	0	1	0	0	0
Total Initial Tests6	5,549	5,657	75,631	526	2,205	1,507

Thus, it can be concluded that the OML and OMT omnibus vehicles did have three emissions tests during 2003, even though, for many VINs, these three emissions test cycles were "interrupted" by an apparent vehicle ownership change.

Because of their specific function as a service vehicle for transportation, the omnibus fleet tends to have high accumulated mileage, much higher than the "normal" in-use private vehicle fleet. It is reasonable to believe that the omnibus fleet would undergo a vehicle ownership change more frequently than privately owned vehicles due to need (replacing vehicles with newer model year vehicles with lower odometer readings to reduce drivability problems and fuel cost). In addition, there may be a "regulatory" requirement for these omnibus vehicles ⁷ for a more frequent vehicle turnover.

This "interference"(vehicle ownership change) in the emissions test cycle has made it difficult for an impact/benefit analysis based on their three emissions test cycles. Therefore, a more generalized analysis and comparison will be made and presented in Section III based on all the initial emissions test results from the three omnibus vehicle classes (OML, OMS, and OMT) for the two vehicle types (LDVs and LDTs). A more detailed analysis of the three emissions test cycle data will be made and presented in Section IV based only on the OMT vehicles, the only omnibus class that had a sufficient number of three emissions test cycle data to produce statistically significant results.

III. Year 2003 Initial Emissions Test Results

The objectives of this section are to examine the initial emissions test results obtained in 2003 from the three classes of omnibus vehicles (OMT, OML, and OMS) and to compare them with the overall NYMA results ⁸. As can be seen from Table 3, the initial emissions test counts from the three types of omnibus vehicles represented only 3.34% of the NYMA LDV fleet, and 0.37% of the NYMA LDT fleet. In terms of the average odometer values, OMT vehicles had the highest while the OMS vehicles had the lowest.

Table 3: Overall Sample Comparison

Vehicle Type	Omnibus Class	Count	Average Odometer (Miles)	% Had NYTEST	% Had Idle
LDVs	OML	5,549	171,917	83.76	16.24
	OMS	5,657	81,004	95.17	4.83
	OMT	75,631	196,083	88.89	11.11
	NYMA	2,599,956		93.46	6.54
LDTs	OML	526	131,985	76.24	23.76
	OMS	2,205	84,824	78.50	21.50
	OMT	1,507	175,455	84.47	15.53
	NYMA	1,157,177		74.44	25.56

Figure 1 shows the vehicle model year distributions, for each of the two vehicle types (LDVs and LDTs) and from the three omnibus vehicle classes as well as the overall NYMA fleet. It is observed that:

1. The vehicle model year distributions from OMT (red circles) and OML (green diamonds) were similar, while, except for model year 2001 LDVs, those from OMS (blue triangles) and the overall NYMA (yellow squares) were similar.
2. There were fewer "old" model year vehicles in the OMT/OML fleet. For example, less than 1% of the LDVs and less than 2% of the LDTs were from pre-1990 model years. In addition, there were no 1985 and pre-1984 OMT LDVs, no 1984 and pre-1983 OML LDVs. In contrast, the OMS fleet contained 12.75% of the LDVs and 8.95% of the LDTs from pre-1990 model years.
3. Large portions of the OMT and OML vehicle fleet were from a few late model years. For example, model years 1995-1996, and 1998-1999 constituted 50.66% of the OMT LDV sample, while model years 1998-2000 made up 43.01% of the OML LDV fleet. Similarly, 57.66% of the OMT LDTs were from model years 1996 through 1999, 46.58% of the OML LDTs were from model years 1998 to 2000.

Figure 2 shows the average odometer readings (reported in miles) for 1981 and later model years for the three omnibus classes by each vehicle type. These average values were compared to the mileage values used by the EPA MOBILE6 model ⁹ (light blue stars), which are considered to be the national averages. It is noted that:

1. Only the average miles from the OMS vehicles (blue triangles) were lower than the EPA averages (light blue stars).
2. The average miles from the OMT (red circles) appeared to be similar to those from the OML vehicles (green diamonds), and were distinct from the OMS vehicles (blue triangles).
3. For the OMT and OML vehicles, the average mileage for pre-1990 model year LDVs and pre-1991 model year LDTs should be ignored due to their small sample sizes. For 1990+ LDVs and 1991+ LDTs, it is apparent that both OMT and OML had average odometer readings significantly higher than the EPA averages, with the LDVs usually two times higher.
4. There were "dips" for model years 1991 and 1992 LDVs (for both OMT and OML vehicles), probably due to their relatively smaller sample sizes where one might expect greater variability.
5. For both OMT and OML vehicles, the accumulated mileages from the LDVs were usually higher than those from the LDTs ¹⁰. This could be due to the fact that LDT samples (1,507 in OMT and 526 in OML) were significantly smaller than the LDV samples (75,631 in OMT and 5,549 in OML).

Figure 3 is a graphic presentation of the NYTEST failure rates comparison among the three omnibus vehicle fleets as well as those obtained from the entire NYMA I/M Program¹¹. It is observed that:

1. Because of their extremely small sample sizes, the NYTEST failure rates for many "earlier" model years (pre-1990 LDVs and pre-1991 LDTs) shown in Figure 3 were very "unstable": with the failure rates either "off the charts" (i.e., the failure rates are higher than 50%) or jumping from 0% in one model year to 30 or 40% in the next. These model year data should be ignored.
2. For LDVs, the failure rates from OML (green diamonds) and OMS (blue triangles) vehicles were higher than the overall NYMA (yellow squares).
3. The OMT (red circles) LDV failure rates were lower than OML/OMS/NYMA for 1990 through 1995 model years, and were higher for 1996 and later model years.
4. For the LDTs, the failure rates from the OMT (red circles) were lower than OML/OMS/NYMA for 1991 through 1994 model years, and were higher for 1995 and later model years.

In general, higher NYTEST failure rates are correlated with vehicles' higher accumulated mileage. This phenomenon was true only for the OMT 1996+ LDVs and 1995+ LDTs. The OMT failure rates actually were nearly constant for 1990 through 1996 LDVs and increasing for 1991 through 1994 LDTs. One possibility is that this sample was not homogeneous. More detailed analysis on OMT vehicles is provided in Section IV.

The NYTEST emission reductions¹² from three regulated pollutants (HC/CO/NOx) and CO2 from these three omnibus vehicle classes were compared with those obtained from the entire NYMA database with the results presented in Figure 4. It is noted that:

1. The percent emission reductions from OMS vehicles (blue bars) for HC/CO/NOx, for both LDVs and LDTs, were consistently higher than the overall NYMA values (yellow bars). This is due to the fact that higher failure rates were observed from the OMS fleet.
2. The percent emission reductions from OML (green bars) vehicles, for both LDVs and LDTs, were all lower than the overall NYMA numbers (yellow bars).
3. For the OMT vehicles (red bars), the percent emission reductions from LDVs were lower, while those from LDTs were higher, than the overall NYMA numbers (yellow bars). These mixed results are to be explored in the next section.

The overall impact of emissions reductions from these three classes of omnibus vehicles is small, mainly due to the fact that these vehicles accounted for only a small portion of the overall NYMA fleet population. As stated previously, the initial emissions test counts from the three classes of omnibus vehicles represented only 3.34% of the NYMA LDV fleet, and 0.37% of the NYMA LDT fleet.

IV. OMT Vehicles

The objectives of this section are to obtain homogeneous groups of the initial emission test results from OMT vehicles and to compare them among themselves as well as with the overall NYMA results.

During the data review process, it was noted that there were at least five different types of license plates registered as OMT vehicles: "ncnnA," "LTCnn," "nnnLTC," "nnnnnTX," and "TnnnnnnC." Vehicles having a license plate of "ncnnA" were identified by TLC as the "yellow medallions ¹³" and all others as the "black medallions." The sample counts are shown in Table 4. Since the LDT samples from both the black and yellow medallion fleet were relatively small (less than 1,000 vehicles), all LDTs were excluded from the analysis.

Table 4: OMT Vehicles and Their Initial Emissions Test Counts

Number of Initial Tests	# of LDV Medallions		# of LDT Medallions
	Black	Yellow	Black	Yellow
1	7,213	4,041	275	258
2	12,444	101	215	4
3	12,626	1	176	0
4	329	1	2	0
5	16	0	0	0
6	1	0	0	0

The yellow medallions (those with license plate of "ncnnA") are those truly with yellow exterior (while the black medallions, sometimes referred to as "for hire" vehicles, can be of other than black exterior colors). They were all from 1996 and later model years, with 72.61% of the fleet (or 3,009) from model years 2000 and 2001 ¹⁴. The fleet had a very "uniform" vehicle make and model composition: 99.76% of the fleet were Ford Crown Victorias. Of the remaining ten vehicles, six were Chevrolet Caprice/Impala's (model year 1996) and four Lincoln Town Cars (one from model year 1997 and three from model year 2001). As can be seen from Table 4, 97.51% of the yellow medallions (or 4,041) had only one initial emissions test. Among the 101 VINs that had two initial emissions tests, only 16 of them (15.84%) were tested four months apart. This seems to suggest that the yellow medallions in year 2003 did not have three emissions test cycles ¹⁵.

Based on the vehicle make and model composition, the black medallions were in general larger in sizes and with higher engine power ratings.¹⁶ The majority of these black medallions had three emissions test cycles.

Due to a lack of LDTs and pre-1990 LDVs in the sample, it was decided that the analysis be based on the 1990 and later model year LDVs that had NYTEST results. This additional requirement of having NYTEST results further reduced the "usable" sample sizes for both black medallions and yellow medallions. For example, the black medallions sample was reduced from 12,626 to 9,500 vehicles, as 24.76% of the VINs had one or more idle tests among their three emissions cycle tests. The yellow medallions sample was only reduced from 4,041 to 4,030 VINs.

The three groups of vehicles included in analysis are:

1. 9,500 black medallions that had three emissions test cycle data;
2. 4,030 yellow medallions that had only one initial emissions test result, and,
3. the overall NYMA emissions tested LDV fleet with the three emissions test cycle black medallions and one initial emissions tested yellow medallions removed from the sample (or briefly called as "non-taxi").

Figure 5 shows the vehicle count by model year for each of the three vehicle groups, with the "non-taxi" fleet represented by one hundredth of the actual vehicle count. It is observed that except for a few model years (1996 yellow medallions with a sample size of 51, 1998 yellow medallions, 1990 and 1991 black medallions each with sample sizes close to 200), the two OMT vehicle samples had more than 200 vehicles for all other model years, with more than 1,000 vehicles for some model years.

Figure 6 shows the sample comparisons (comparisons based on average odometer readings, reported in miles, and the NYTEST failure rates, in %) for the three vehicle groups. The average odometer readings were also compared with the values used by the EPA MOBILE6 model, which are considered to be the national averages.

From the average odometer readings chart, it is noted that:

1. The average mileages from each of the NYMA vehicle groups (yellow medallions, three cycles of black medallions, and the "non-taxi" fleet) were all higher than the EPA averages (light blue stars).
2. The average mileages from the yellow medallions (orange triangles), were almost three times higher than the EPA averages (light blue stars), and two times higher than those from the first emissions test cycle results obtained from the black medallions (red circles).
3. The average mileages from the yellow medallions (orange triangles) and the black medallions (circles) were all higher than the "non-taxi" fleet (yellow squares).
4. Average mileages from the yellow medallions (orange triangles) for model years 1996 and 1997 were lower than that for model year 1998.
5. The reported odometer readings from the black medallions showed "good" consistency - the average mileage values from the third emissions test cycle (dark blue circles) were slightly higher than those from the second emissions test cycle (green circles), and those from the second emissions test cycle were slightly higher than those from the first emissions test cycle (red circles).
6. It is interesting to note that there is a "dip" in the black medallions' average mileage values for model years 1991 and 1992.

From the NYTEST failure rate (in %) chart, it is observed:

1. The failure rates from the yellow medallions (orange triangles) were the highest, because of their higher average odometer readings.
2. Except for model year 1996, the yellow medallion fleet (orange triangles) failure rates increased for vehicles with older model years (from 12.84% to 35.39%), with an overall failure rate of 21.54%.
3. There was no consistency in the black medallions' failure rates (circles of 3 colors) among their three emissions test cycles. That is, the failure rates from the second emissions test cycle (green circle) were not necessarily always higher than that from the first cycle (red circles), and the third emissions test cycle (dark blue circles) were not necessarily always higher than that from the second cycle (green circles).
4. For 1996+ model years (or ages 8 and newer), the failure rates from the black medallions from all three emissions test cycles were higher than those from the "non-taxi" fleet, which is consistent with the fact that the black medallions had higher reported odometer readings.
5. For pre-1995 model years (or ages 9 and older), the failure rates from the black medallions from all three emissions test cycles were lower than those from the "non-taxi" fleet. Since the average odometer readings from the black medallions were consistently higher than the "non-taxi" fleet, these lower NYTEST failure rates seemed to suggest that there is an additional "significant" factor that resulted in a negative correlation between the tailpipe emissions and vehicle mileage (or age).
6. In general, the failure rates from the black medallions increased with older vehicle model years until model year 1995. Then the NYTEST failure rates actually decreased down to 5% at age 9, and gradually increased after age 10 at a much slower rate.

One plausible explanation of the observed black medallion failure rates being substantially lower than those of the yellow medallions is the effect of the three emissions test cycle requirement. The more frequent inspection schedule (every 4 months) leads to a better maintained vehicle, at least near the end of a four month segment, for a failed vehicle must pass a subsequent testing which may require repair or adjustment.

Figures 7 and 8 show the average NYTEST exhaust emissions (in grams per mile, or g/mi) from the three vehicle groups. Except for CO2, the emission trend vs. vehicle model year for the three regulated pollutants (HC, CO, and NOx) were very similar to those observed from the NYTEST failure rate chart. In general, higher failure rates resulted in high g/mi emissions.

The effect of the three emissions test cycles can also be observed by comparing the black medallion fleet with the non-taxi fleet at common values of average odometer readings (Figure 2). For example, at 150,000 miles the black medallion NYTEST failure rate (model year 1999) is about 5% vs. 15% for the non-taxi fleet (model year 1990). The average emissions for the black medallions are also significantly lower than the non-taxi fleet - 0.2 g/mi vs. 0.5 g/mi for HC, 3 g/mi vs. 6 g/mi for CO, and 0.6 g/mi vs. 1.2 g/mi for NOx. Similar results are obtained when other common values of average odometer readings are used in the comparison of the two fleets.

V. Conclusions

It is observed from the year 2003 I/M Program database that:

• Because of their higher than "normal" odometer readings, both OML and OMT vehicles had a high frequency in vehicle ownership change, hence interrupting their three emissions test cycles.
• By examining only the LDVs, the OML and OMT vehicles were very similar in their model year composition and average odometer readings.
• Two subgroups of OMT vehicles were compared: the yellow medallions, which were found to have only one NYTEST test cycle, and the black medallions, which did have three emissions test cycles. For each model year (1996 through 2001), the yellow medallions, with very high odometer readings (Figure 6), had very high NYTEST failure rates (Figure 6) and very high average exhaust emission values (Figures 7 and 8). For model years 1993 through 1995, the black medallions, with average odometer readings higher than the NYMA "non-taxi" fleet (Figure 6), but having lower NYTEST failure rates and lower average HC, CO emissions.
• The effect of the three emissions test cycles is to generate a lower NYTEST failure rate and lower average HC, CO, and NOx emissions for the black medallion fleet as compared to the yellow medallion fleet.
• The three emissions test cycles also have the same effect for the black medallion fleet as compared to the non-taxi fleet when the comparison is made at approximately the same average odometer readings.

Figure 1: Vehicle Model Year Distributions
(Year 2003 I/M Program Data)

Figure 2: Average Odometer Readings
(Year 2003 I/M Program Data)

Figure 3: NYTEST Failure Rates
(Year 2003 I/M Program Data)

Figure 4: NYTEST Emissions Reductions
(Year 2003 I/M Program Data)

Figure 5: LDV Sample
(Year 2003 I/M Program Data)

Figure 6: LDV OMT Sample Comparisons
(Year 2003 I/M Program Data)

Figure 7: LDV Average HC/CO Emissions (G/M)
(Year 2003 I/M Program Data)

Figure 8: LDV Average NOx/CO2 Emissions (G/M)
(Year 2003 I/M Program Data)

Footnotes

1. A 3-alpha-character data field (with a corresponding two digit numeric code) named "registration class," which is defined by the New York State Department of Motor Vehicles, is employed to describe vehicle use. Some examples are: "PAS" (passenger), "COM" (commercial), "HIS" (historical), "DLR" (dealer), "STA" (state agencies), and "MED" (medical doctor). This registration class code is assigned to the vehicle at the time of its registration. At the time of the vehicle's annual inspection or change of ownership inspection, this registration class data field is to be transmitted into the database either by scanning a 2-D bar code from the vehicle registration document or entered manually by the inspector.

2. The majority of the HDVs were Ford E350 Econolines, with a few Dodge Ram B350 Wagons, Ford Excursions, and Chevrolet G30 Chevy Vans.

3. Note that in year 2003 I/M Program database, 6.24% of the vehicles did not report a "valid" license plate - i.e., the license plate data field contained "NO PLATE", "NONE", or blanks (" ").

4. It was indicated that medallions under the TLC jurisdiction (for three emissions tests per year) were all registered under OMT (or code 54), with their license plates starting with a "T" and ending with a "C." Discrepancies were noted based on the I/M Program database, however.

5. The algorithm starts with sorting all "valid" emissions test data by VIN and inspection date/time. The cycle starts with an "initial test," ends with a "final test," and with retests in between. The cycle is complete when a valid (i.e., not "00000000" or blank) certificate is issued (assigned by the NYTEST software) with an updated "expiration date."

6. "Total initial tests" are the sum of the products of the "number of initial emissions tests" times the "# of VINs." For example, for OML,
5,549 = [(1*4,083)+(2*414)+(3*195)+(4*12)+(5*1)+(6*0)].

7. We were informed by TLC staff that TLC specifically requires that the taxicab fleet vehicles be replaced after a fixed number of years of operation -- three years for a fleet driver and five years for a private owner.

8. Based on all emissions tested LDVs and LDTs in NYMA, including those omnibus vehicles as well as all other privately owned vehicle fleet. Statistics were extracted from the report entitled: "New York State Enhanced Motor Vehicle Inspection/Maintenance Program, 2003 Annual Report," July 2004.

9. "Update of Fleet Characterization Data for Use in MOBILE6 - Final Report," USEPA , EPA420-P-98-016, June 1998, page 4-33, Table 4-4.

10. For privately owned vehicles, various data has shown that, for the same model year, the LDT average mileages are usually higher than those from the LDVs.

11. "Failure Rate Analysis of Year 2003 Data," Mobile Emissions and Air Quality Section, Bureau of Air Quality and Research, June 28, 2004, Appendix B.

12. The emission reductions were calculated based on the emissions differences between the failed initial test and the final test.

13. TLC has provided us with their OBD II data collected since 12/08/2003 from all yellow medallions under their jurisdiction. It was verified that all the yellow medallions have the license plate of "ncnnA" (or some variations of "ncnnA," such as "ncnnB" or "ncnnC").

14. There were no emissions test data from 2 years and newer yellow medallions in our I/M Program database, probably due to the conditions imposed by the NYTEST software.

15. It was noted that the yellow medallions might have been "directed" to have a total of three tests with only one emissions test done at any NYS-certified testing facilities and data transmitted to the data manager. There were no records indicating if or where the yellow medallions received their two other emissions tests.

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  Division of Air Resources
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