1 

 Envirotest Systems 

5175 Marshall St., 

Arvada, Colorado 80002 

The Colorado Remote Sensing Program 

January – December 2011

November 2012 

Prepared for: 

The Colorado Department of Public Health and 

Environment 

Prepared by: 

Peter M McClintock, Ph.D. 

Applied Analysis 

13700 Marina Pointe Drive #432. 

Marina Del Rey CA 90292-9259

pm2pt5@gmail.com
2 

Acknowledgments 

The author wishes to acknowledge the support and input given by a number of individuals and 

organizations. Particular thanks are extended to the following contributors: 

CDPHE for providing many helpful comments and suggestions. 

Drew Rau, Envirotest Program Operations Division and the Remote Sensing unit of 

Envirotest, Tucson for providing data access and operational information. 

 
3 

Table of Contents 

I. SUMMARY .................................................................................................................................................... 5

II. DESCRIPTION OF THE DENVER CLEAN SCREENING PROGRAM ........................................... 8

A. I/M PROGRAM OVERVIEW ........................................................................................................................ 8

B. MEASUREMENT SITES ............................................................................................................................. 13

C. SOURCES OF DATA AND DESCRIPTION OF ELEMENTS ............................................................................. 18

III. SUMMARY OF DATA COLLECTION ................................................................................................ 21

A. MONTHLY COLLECTION ACTIVITY ......................................................................................................... 21

B. MEASUREMENTS BY HOUR OF DAY ........................................................................................................ 21

C. COMPOSITION OF VEHICLES MEASURED ................................................................................................. 23

IV. CLEAN SCREENING PROGRAM PERFORMANCE ....................................................................... 25

A. VEHICLES SELECTED, NOTICES AND REDEMPTIONS ............................................................................... 25

B. CLEAN SCREEN PROGRAM EFFECTIVENESS ............................................................................................ 27

C. GAS CAP EVAPORATIVE EMISSIONS ....................................................................................................... 31

D. HYBRID RSD-LEI VS. 2-HIT RSD ........................................................................................................... 34

V. ESTIMATE OF OVERALL I/M PROGRAM BENEFITS AND CLEAN SCREEN IMPACT ....... 37

A. CONVERSION OF IDLE TESTS TO IM240 EQUIVALENT EMISSIONS ........................................................... 37

B. ANNUAL MILEAGE WEIGHTING .............................................................................................................. 41

C. ANNUAL EMISSIONS REDUCTIONS .......................................................................................................... 42

VI. REVIEW OF CLEAN SCREEN STANDARDS AND PROCEDURES ............................................. 44

VII. IM240 PROJECTED EMISSIONS BY MODEL YEAR ..................................................................... 45

REFERENCES 

APPENDICES 

 A1 COLORADO 2011 TRANSIENT TEST EMISSIONS REDUCTIONS 

 A2 COLORADO 2011 CLEAN SCREEN AUDIT TRANSIENT TEST EMISSION REDUCTIONS 

 B COLORADO 2011 TRANSIENT TEST REDUCTION TONS 
4 

List of Tables 

TABLE II-1 NORTHERN FRONT RANGE ................................................................................................................... 14

TABLE II-2 DENVER RSD SITES............................................................................................................................. 15

TABLE II-2 DENVER RSD SITES CONTINUED ......................................................................................................... 16

TABLE II-3 EL PASO RSD SITES ............................................................................................................................. 16

TABLE II-4 VEHICLE MEASUREMENT INFORMATION ............................................................................................. 19

TABLE III-1 COLLECTION SUMMARY ...................................................................................................................... 21

TABLE III-2 SOURCE OF VEHICLE REGISTRATIONS MEASURED BY RSD .............................................................. 23

TABLE III-3 TYPE OF VEHICLES MEASURED BY RSD WITHIN REGISTRATION JURISDICTION ................................ 24

TABLE III-4 REGISTERED JURISDICTION AND AGE OF VEHICLES MEASURED BY RSD ........................................... 24

TABLE IV-1 VEHICLES QUALIFIED AS MEETING CLEAN SCREENING CRITERIA BY STATUS ................................... 25

TABLE IV-2 NOTIFICATIONS TRANSMITTED TO DOR ............................................................................................. 26

TABLE IV-3 CLEAN SCREEN AUDIT TEST PASS / FAIL STATISTICS ........................................................................ 26

TABLE IV-4 TRANSIENT TEST EMISSION REDUCTIONS FOR 1982-1985 PASSENGER VEHICLES ............................. 29

TABLE IV-5 CLEAN SCREEN EMISSIONS IMPACT FOR TAILPIPE EMISSIONS ........................................................... 30

TABLE IV-6 CLEAN SCREEN IMPACT ON EVAPORATIVE HC EMISSIONS ................................................................ 32

TABLE IV-7 GAS CAP RELATED BENEFIT TONS..................................................................................................... 33

TABLE IV-8 AVERAGE EMISSIONS PER VEHICLE ................................................................................................... 35

TABLE V-1 LOW SPEED IDLE TO IM240 ................................................................................................................. 38

TABLE V-2 HIGH SPEED IDLE TO IM240 ................................................................................................................ 39

TABLE V-3 ESTIMATED ANNUAL MILEAGE IN 2011 ............................................................................................... 41

TABLE V-4 ESTIMATED ANNUAL TONS OF REDUCTION (IM240 AND IDLE TESTED VEHICLES .............................. 43

List of Figures 

FIGURE I-1 AVERAGE IM240 EMISSIONS REDUCTIONS ............................................................................................ 7

FIGURE II-1: TAGEDITTM SCREEN ........................................................................................................................... 12

FIGURE II-2 A: SITE LOCATIONS NORTHERN FRONT RANGE ................................................................................... 17

FIGURE II-2 B: SITE LOCATIONS – DENVER METRO AREA ...................................................................................... 18

FIGURE III-1 MONTHLY RSD MEASUREMENTS ...................................................................................................... 22

FIGURE III-2 MEASUREMENTS BY TIME OF DAY .................................................................................................... 22

FIGURE IV-1 GAS CAP PRESSURE FAILURE RATES ................................................................................................ 31

FIGURE IV-2 AVERAGE INITIAL IM240 EMISSIONS ................................................................................................ 35

FIGURE IV-3 AVERAGE IM240 EMISSIONS REDUCTIONS ....................................................................................... 36

FIGURE V-1 RSD VS. IDLE TEST EMISSIONS .......................................................................................................... 38

FIGURE V-2 RSD VS. 2500 IDLE TEST EMISSIONS ................................................................................................. 39

FIGURE V-3 RSD VS. 2500 IDLE TEST EMISSIONS ................................................................................................. 40

FIGURE VII-1 LDGV HC REDUCTIONS AND REMAINING EMISSIONS .................................................................... 46

FIGURE VII-2 LDGT HC REDUCTIONS AND REMAINING EMISSIONS ..................................................................... 46

FIGURE VII-3 LDGV CO REDUCTIONS AND REMAINING EMISSIONS .................................................................... 47

FIGURE VII-4 LDGT CO REDUCTIONS AND REMAINING EMISSIONS ..................................................................... 47

FIGURE VII-5 LDGV NOX REDUCTIONS AND REMAINING EMISSIONS .................................................................. 48

FIGURE VII-6 LDGT NOX REDUCTIONS AND REMAINING EMISSIONS .................................................................. 48
5 

I. Summary 

The Colorado Department of Public Health & Environment (CDPHE) and the Department of 

Revenue (DOR) have operated an Enhanced Inspection and Maintenance (I/M) program in 

the Denver metropolitan area (DMA) since 1995. Operations for a remote sensing clean 

screening element commenced in 2003. Previous reports, “The Colorado Clean Screening 

Program’ reports for July 2003 – December 2004 and annual reports for 2005-20101 described 

on-road measurement activities and the vehicles exempted from inspection. This report 

covers calendar year 2011. 

The clean screening program uses remote sensing to measure the tailpipe emissions of 

vehicles as they drive by measuring equipment positioned on the side of the road. Vehicles 

that are determined to have low tailpipe emissions are granted an exemption from the I/M 

inspection. Clean screening improves convenience of the I/M program for vehicle owners. 

In order to exempt vehicles from inspection, computer systems and procedures are required 

for administering the program and notifying vehicle owners of their inspection exemption. 

The I/M program is registration enforced and the administration of the clean screening 

program requires the transmission of information among the contractor, CDPHE and DOR 

who manage motor vehicle registrations. 

Collection Activity 

In 2011, eighteen RSD vans were deployed in the DMA with an additional 4 in the Northern 

Front Range (NFR). Twenty-four different RSD systems were used as some units were 

rotated for preventive or corrective maintenance. Van’s deployed at 90 locations in the DMA, 

42 sites in the NFR and 2 sites in Colorado Springs for a total of 24,878 active collection 

hours. A total 7.7 million emission measurements were collected and successfully matched to 

Colorado registered vehicles. Additional remote sensing productivity information is provided 

in Section IV. 

Expanded vehicle emissions testing began in parts of Weld and Larimer counties in late 2010. 

Vehicle owners with December 2010 renewal dates were the first required to get a test. 

2010 vs 2011 Collection Comparison 

In 2010, RSD performed over nine million emission measurements at 47 locations in the 

DMA and 16 locations in the NFR. In 2011 there were 1.3 million fewer emission 

measurements but measurements were collected from almost twice the number of locations 

than in 2010. Despite the reduction in the quantity of emission measurements the number of 

clean screens issued increased by 50,000 vehicles. This was partly due to the application of 

new location performance metrics by the contractor that resulted in less focus on high traffic 

sites having many repeat measurements of vehicles and more use of a larger number of lower 

traffic sites to measure a broader section of active vehicles. This provided qualifying 

measurements on a larger number of vehicles and allowed more owners to participate in the 

clean screen program. Other factors included the addition of an RSD NO standard that 

eliminated some vehicles from consideration and the addition of the NFR for the full year. 
6 

Vehicle Exemptions 

Almost 300,000 vehicles measured on-road initially met the clean screening exemption 

criteria. Two percent of these were reserved to provide a program audit sample and others 

were eliminated during the QA reviews, for example, as a result of vehicle plate changes. The 

owners of the remaining 289,768 vehicles meeting the clean screening criteria were issued 

notices granting exemption from the I/M test at an inspection station. Approximately 246,700 

(85%) of the vehicle owners took advantage of the Clean Screen exemption. 

Two methods were used to qualify vehicles, 2-RSD and Hybrid. With the 2-RSD method, 

vehicles qualified for an exemption if they had two or more on-road measurements and the 

most recent two measurements both showed emissions within the clean screen standards. 

With the ‘Hybrid’ clean screening method vehicles measured once by remote sensing 

qualified for clean screening if the emissions measurement was within the clean screen 

standards and the vehicle model had a historically low rate of emissions problems. 

A 2% random sample of vehicles that qualified was not issued exemption notices and 4,958 of 

these vehicles were subsequently inspected at an enhanced inspection station. The results of 

the station inspections were used to evaluate the effectiveness of the program. Additional 

information about vehicles mailed notices is provided in Section IV. 

Clean Screen Program Effectiveness 

In a Clean Screen program, some vehicles passing the clean screen emissions criteria might 

have failed if inspected at an inspection station. Therefore, a Clean Screen program, while 

greatly improving convenience for vehicle owners, can slightly reduce the overall 

effectiveness of the I/M program. 

On May 5th 2008, IM240 Denver Metro Area station test standards were tightened – 

especially for HC and NOx – to bring them into closer alignment with EPA final standards. 

The LEI table was updated with subsequent IM240 results to reflect consequent changes in 

inspection result statistics for vehicle models in December 2008, and periodically in 2009, 

2010 and 2011.. The RSD standards were updated in October 2010 with the addition of an 

RSD NO standard of 1000ppm that first applied to December 2010 registrants. 

Figure I-1 compares the average IM240 exhaust reductions per vehicle inspected at stations to 

those of the 2-RSD audit sample and the Hybrid RSD-LEI audit sample. The RSD-2 and 

RSD-LEI methods showed similar reductions for HC. For CO and NOx pollutants the RSDLEI audit sample showed smaller reductions than RSD-2 indicating the hybrid RSD-LEI 

method performed better. 
7 

Figure I-1 Average IM240 Emissions Reductions 

For 2011, based on the 2% random audit vehicles tested with IM240, it was projected that 

99.1%, 97.9% and 97.3% of HC, CO and NOx of program exhaust emission reductions were 

retained. The impact on gas cap related evaporative emissions was projected to be another 

3.1% of HC reductions. 

The methodology for estimating clean screen effectiveness only allows for a score of 100% or 

less and uses the IM240 test as a “gold’ standard. Any variations in vehicle performance or 

the IM240 test procedure that produce an anomalous IM240 test failure are scored against 

Clean Screen. Therefore, it is possible the Clean Screen effectiveness was better than 

projected. 

0.00

0.02

0.04

0.06

0.08

0.10

Station

RSD-2

RSD-LEI

g/mi

HC

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Station

RSD-2

RSD-LEI

CO

0.00

0.02

0.04

0.06

0.08

0.10

Station

RSD-2

RSD-LEI

NOx
8 

II. Description of the Denver Clean Screening Program 

A. I/M Program Overview 

The Colorado Department of Public Health & Environment (CDPHE) operates an enhanced 

Inspection and Maintenance (I/M) program in the Denver metropolitan area (DMA) and the 

Northern Front Range (NFR). The clean screening component of the IM program uses remote 

sensing equipment to measure the tailpipe emissions of vehicles as they drive by the 

measuring equipment. Vehicles that are determined to have low tailpipe emissions are granted 

an exemption from their I/M inspection. 

Operating rules for the Clean Screening program are contained in the Air Quality Control 

Commission’s Regulation 112

. The Regulation defines the maximum percentages of vehicles 

that may be evaluated by the clean screen program in the enhanced I/M area. In 2006, the 

percentage of vehicles allowed to be evaluated using remote sensing was decreased from 80% 

to 50% as part of an Early Action Compact (EAC) to achieve an earlier attainment 

designation for ozone. 

Clean Screening regulations were expanded in 2007 to allow use of a single RSD 

measurement combined with an index of low emitting vehicles to evaluate exemption 

candidates. The Low Emitter Index (LEI) was developed using I/M240 data to identify 

vehicle groups that historically have a very low probability of failing. The current 

requirement for a vehicle group to qualify as a low emitter is they must have an I/M240 pass 

rate of 98% or greater. 

There are multiple requirements and restrictions for vehicles to participate in the Clean Screen 

program as defined in Regulation 11. The following are the primary elements for vehicles to 

qualify for a clean screen exemption. 

 The applicable observations were within twelve months prior to the individual 

vehicles registration renewal date, 

 The two most recent observation results are below, 200ppm, 0.5%, and 

1000ppm for HC, CO, and NOx respectively, (NOx standard implemented 

October 2010) 

 The two most recent observations must have occurred on a different day or on 

the same day at different site locations, 

Contractor

Envirotest (Envirotest) was contracted to operate the enhanced program by a competitive bid 

process and the contract was subsequently amended to include clean screening in the Denver 

area. Envirotest uses technology derived from that originally developed at Denver University 

with whom Envirotest has a royalty agreement. 

Theory of operation 

The RSD is a system designed for a non-intrusive measurement of vehicle emissions. It 

generates and monitors a non-dispersive infrared and dispersive ultra-violet beam emitted and 
9 

reflected approximately 10 to 18 inches above ground preferably across a single lane road. 

Gasoline, diesel, or other fossil fuel powered vehicles drive through this beam and the exhaust 

interferes with this transmission of the beam. Quantifying the interference enables the 

calculation of tailpipe concentrations of CO, HC, CO2, NO and particulate matter. A camera 

simultaneously captures a digitized video image of the rear of the vehicle and its license plate. 

Equipment 

The equipment initially deployed in the Northern Front Range counties were RSD-3000 

mobile units also called AccuScanTM. Successor RSD 4000 units were introduced in 2003. 

Both systems were based on a technical platform developed at the University of Denver by 

Dr. Donald Stedman. In 2007, additional RSD4600 units were added. The RSD4600 is very 

similar to the RSD4000-L3 system described below. The RSD4600 has a more compact 

speed and acceleration measurement bar and more diagnostic ports. Functionally, the two 

systems are the same. One RSD 5000, the latest generation of RSD systems passed 

acceptance testing in 2011 and began data collection in December 2011. The RSD 5000 is 

more compact, requires less power and supports remote wireless operation. 

AccuScan measures the exhaust of a passing motor vehicle in less than 0.7 seconds. Nondispersive infrared (IR) spectroscopy, the same analytical technique used in garage based twospeed idle and ASM equipment is used to measure concentrations of CO, HC, and CO2. 

Dispersive ultraviolet (UV) spectroscopy is used to measure NOx. The system is based on the 

original designs and patents of Dr. Donald Stedman, professor emeritus at the University of 

Denver. 

The following elements comprise a complete RSD4600 unit: 

 RSD 4-gas analyzer Source Detector Module 

 Corner Cubed Mirror Module (CCM) 

 Two Alignment stands, one each for SDM and CCM 

 Speed/Acceleration subsystem consisting of: 

 Two Speed/Acceleration bars: one emitter and one detector bar with 

adjunct hardware 

 Speed/Acceleration computer 

 Digital Video camera and speed subsystem 

 Computer control console subsystem consisting of: 

 Video monitor 

 PentiumTM–based PC 

 Additional PC cards and internal hardware PC cards: 

 Hard drive 

 Removable Mass Storage 

 Matrox video 

 Serial and COM port 

 RSD operation (data collection) software 

 RSD compatible license plate tag-editing software 
10 

 Calibration and auditing subsystem consisting of: 

 Calibration gas cell 

 Audit tube 

 Audit gas bottle 

 Pressure regulator 

 Hoses with quick disconnects 

 RSD shipping container for SDM and CCM 

The following elements comprise an AccuScanTM van: 

 Ford one-ton truck 

 Triton V-8 engine with 4-speed automatic transmission 

 12 – 14 foot box on bed of truck 

 Roof-mounted 13,500 BTU Coleman air-conditioner 

 5 kW Onan generator 

 Connector panel for quick connection of external cables and cal gas 

hoses 

The RSD unit takes multiple rapid readings for each vehicle to characterize the exhaust plume 

profile and evaluate whether a valid measurement of a vehicle’s exhaust has been achieved. 

The criteria include how much vehicle exhaust plume is available for the duration of the 

sampling period, evaluation of whether plume measurements are consistent with normal 

plume dissipation, and correction for changes in background concentrations of emissions. 

The RSD units comply with the CDPHE, “Colorado On-road Vehicle Emissions Remote 

Sensing System (COVERS) Specifications” Amended July 20103

: The COVERS accuracy 

specifications are consistent with the California BAR OREMS Specification:1

 and include: 

Detector accuracy: 

1. The CO2% reading shall be within  10% of the Certified Gas Sample, or an absolute 

value of  0.25, or shall be within published manufacturer’s specification – whichever 

is less restrictive. Negative values shall be included and shall not be rounded to zero. 

2. The CO% reading shall be within  15% of the Certified Gas Sample, or an absolute 

value of  0.25 (whichever is greater). Negative values shall be included and shall not 

be rounded to zero. 

3. The HC reading (ppm propane) shall be within  15% of the Certified Gas Sample, or 

an absolute value of  250ppm (whichever is greater). Negative values shall be 

 

1

 On Road Emissions Measurement System OREMS) Specifications, Revision L, Bureau of Automotive Repair, Engineering 

and Technical Research Branch, 10240 Systems Parkway, Sacramento, CA 95827; 2001 California DCA/BAR; p. 5. 
11 

included and shall not be rounded to zero. 

4. The NOx reading (ppm) shall be within  15% of the Certified Gas Sample, or an 

absolute value of  250 ppm (whichever is greater). Negative values shall be included 

and shall not be rounded to zero. 

5. COVERS shall submit readings within the following limits: 

CO + CO2  21.0 %, HC  35,000 ppm hexane, CO2  16.0 %, and NO  7000 ppm. 

6. The system shall record at least three and display at least two measures of plume 

characteristics, for example the maximum number of CO2 molecules seen, the average 

number of CO2 molecules seen, and the number of valid samples (measurements) 

made. 

7. Each unit shall demonstrate during controlled acceptance testing the above criteria 

98% of the time. Ninety-eight percent (98%) shall mean that one hundred percent 

(100%) of the valid records shall have the following fields filled correctly with 

accurate data, ninety-eight percent (98%) of the time: 

CO2% 

CO % 

HC ppm hexane 

NO ppm 

Speed and Acceleration Accuracy: 

1. The vehicle speed measurement should be accurately recorded within  1.0 mile 

per hour. 

2. The vehicle acceleration measurement should be accurately recorded within  0.5 

mile per hour / second. 

3. The speed and acceleration system shall demonstrate during controlled acceptance 

testing the above criteria ninety-five percent 95% of the time. Ninety-five percent 

(95%) shall mean that one hundred percent (100%) of the valid records shall have 

the speed and acceleration fields filled correctly with accurate data, ninety-five 

percent (95%) of the time. 

4. VSP shall be calculated during host processing using the most recent CDPHE 

approved equation. 

Vehicle Identification 

The system captures emissions readings and rear pictures of vehicles that pass through the 

RSD infrared beam. The video and emissions readings taken are stored directly on a 

removable media disk and can be used for future reference. 
12 

Envirotest’s TagEditTM software is used to transcribe vehicle license plate information. 

Figure II-1 below shows an example of a TagEditTM screen. This license plate editing service 

is superior to an automatic license plate reader because: 

 All video images associated with valid emissions data get processed. This ensures the 

highest possible vehicle capture rate. 

 Vehicles with special plates are also processed. This is especially important in areas 

where many unique license plates are issued. Failure to process all plate types can create 

a statistically skewed database that could be misinterpreted by the public as “targeting” 

only certain vehicle classes. 

A special registration database was created for the Clean Screen program to allow vehicles to 

be identified (VINs) from Clean Screen license photos captured days prior to their data 

processing. This Clean Screen registration database is updated nightly with all the changes 

statewide that affect what VIN is associated with what plate. A lag time interval is 

incorporated to allow time for updates to get from the County Clerks Offices to the DOR 

database. The separate Clean Screen Registration Database on the Envirotest host contains all 

vehicle registration records statewide, even though only certain counties are expected to 

participate in the Clean Screen program. The future growth of registration could require some 

housekeeping, but there is plenty of hardware scalability to handle this growth. 

Figure II-1: TagEditTM Screen 
13 

B. Measurement Sites 

Good remote sensing sites are critical for obtaining RSD measurements that are representative 

of vehicle operation. Recommended site attributes include: 

(1) Absence of cold start vehicle operating conditions 

(2) Sites where vehicles will generally be accelerating or driving at a steady speed 

uphill to ensure adequate engine power and exhaust plumes and avoid the problem of 

RSD not measuring vehicles that have virtually no exhaust under deceleration 

(3) Absence of enrichment due to high load conditions 

(4) Single lane operation 

(5) High volume traffic 

(6) Unobtrusive siting of the remote sensing equipment 

(7) Adequate median space for safe operation of the RSD equipment. 

Table II-1 lists the RSD sites in the Northern Front Range (NFR), the number of days each 

site was used, the total hours during which measurements were collected and the number of 

vehicles measured per hour. The hours shown do not include travel time to and from the site, 

equipment set-up and equipment takedown time. 

Table II-2 lists the Denver Metro Area (DMA) site locations. 

Table II-3 lists the El Paso County (Colorado Springs) locations where a small number of 

measurements are made annually. 

Site locations in the NFR and DMA are illustrated in Figures II-2a and IIb. Blue sites are 

active. Red sites are no longer permitted. The X's represent HQ and other stations where RSD 

vans are housed. 
14 

Table II-1 Northern Front Range 

Site 

Code Location City

Active 

Days

Total 

Active 

Hours

Registered 

Vehicles 

Measured

Veh's 

Per 

Hour

2132 NB SHIELDS 100' PAST VINE DR FT COLLINS 17 116 13,864 120

2143 NB OVERLAND TRAIL NORTH OF DRAKE FT COLLINS 13 90 11,997 134

2989 EB US 34 BYPASS FROM 23RD AVE GREELEY 56 434 59,582 137

3017 EB TRILBY ROAD EAST OF SHIELDS STREET FORT COLLINS 44 283 63,146 223

3019 ON RAMP TO NB I-25 FROM 402 (CR-54) LOVELAND 14 95 9,740 103

3020 ON RAMP TO SB I-25 FROM 402 (CR-54) LOVELAND 34 217 26,447 122

3506 ONRAMP TO NB US-85 FROM HWY 52 FT. LUPTON 10 77 4,834 63

3507 ONRAMP TO SB US-85 FROM HWY 52 FT. LUPTON 23 153 23,246 152

3508 ONRAMP TO NB I-25 FROM HARMONY RD. FT. COLLINS 4 29 2,341 81

3509 ONRAMP TO NB I-25 FROM PROSPECT RD. FT. COLLINS 3 20 1,107 57

3510 SB SHIELDS ST. AFTER FOSSIL CREEK FT. COLLINS 4 26 4,167 162

3511 OFF-RAMP FROM NB I-25 TO WB MULBERRY ST. FT. COLLINS 7 54 13,911 258

3512 SB TIMBERLINE RD. JUST BEFORE WILLOW SPRINGS RD. FT. COLLINS 8 65 8,953 139

3513 NB SHIELDS RD. AFTER BON HOMME RD. FT. COLLINS 4 28 2,353 83

3514 NB TAFT HILL RD. AFTER HARMONY RD. FT. COLLINS 17 116 34,931 302

3515 ONRAMP TO NB I-25 FROM WB US-34 FT. COLLINS 11 75 10,361 138

3516 ONRAMP TO NB I-25 FROM CROSSROADS BLVD. FT. COLLINS 8 51 3,835 76

3518 ONRAMP TO SB I-25 FROM SR-60 LOVELAND 3 18 1,079 59

3519 ONRAMP TO SB I-25 FROM SR-56 BERTHOUD 4 26 1,131 44

3520 ONRAMP TO SB I-25 FROM SR-66 LONGMONT 3 22 2,426 112

3521 ONRAMP TO SB I-25 FROM SR-52 LONGMONT 15 101 24,460 243

3522 ONRAMP TO SB I-25 FROM CR-8 DACONO 4 25 1,738 68

3523 ONRAMP TO NB I-25 FROM CR-8 DACONO 5 33 267 8

3524 ONRAMP TO NB I-25 FROM SR-52 LONGMONT 2 13 1,206 91

3525 ONRAMP TO NB I-25 FROM SR-119 LONGMONT 12 80 10,889 136

3526 ONRAMP TO NB I-25 FROM SR-66 LONGMONT 2 11 732 68

3572 WB US-34 JUST PAST GRAND ESTATES DR. ESTES PARK 2 8 988 118

3573 EB US-36 BETWEEN MILE MARKERS 2 AND 3 ESTES PARK 2 11 1,026 93

3574 EB US-34 BETWEEN VISTA LN. AND HILLSIDE LN. ESTES PARK 2 13 2,057 158

3575 SB SH-7 JUST PAST LEXINGTON LN. ESTES PARK 1 7 1,000 138

8037 EB US-34 BYPASS FRONTAGE ROAD JUST EAST OF 35TH AVE. GREELEY 43 333 24,409 73

8041 WB US-287 JUST WEST OF SHIELDS ST. FT COLLINS 41 302 46,902 155

8042 ONRAMP TO SB I-25 FROM EAST PROSPECT FT COLLINS 32 202 38,966 193

8043 ONRAMP TO WB US-34 FROM 27TH ST GREELEY 59 501 98,906 198

8044 ONRAMP TO EB US-34 FROM SH-257 GREELEY 8 55 3,558 65

8045 ONRAMP TO EB US-34 BYPASS FROM SH-257 GREELEY 6 43 3,201 74

8048 ONRAMP TO WB US-34 FROM SH-257 GREELEY 10 75 3,420 46

8049 ONRAMP TO SB I-25 FROM HARMONY RD FT COLLINS 48 319 72,777 228

8050 ONRAMP TO SB I-25 FROM LCR-32 WINDSOR 4 27 4,344 161

8051 ONRAMP TO NB I-25 FOM LCR-32 WINDSOR 30 226 53,551 237

8052 NB SH-1 JUST EAST OF INTERSECTION WITH US-287 FT COLLINS 44 280 46,585 166

8053 EB US-287 ABOUT 500' EAST OF LCR-17 BERTHOUD 7 50 2,336 46

Subtotal 666 4,708 742,769 158
15 

Table II-2 Denver RSD Sites 

Site 

Code Location City

Active 

Days

Total 

Active 

Hours

Registered 

Vehicles 

Measured

Veh's 

Per 

Hour

2169 ONRAMP TO NB I-25 FROM 136TH AVE. THORNTON 3 23 1,925 83

2170 ONRAMP TO NB I-225 FROM BELLEVIEW AVE. CHERRY HILLS 4 27 3,665 137

2172 ONRAMP TO EB C-470 FROM BOWLES AVE. LAKEWOOD 6 50 7,322 146

2174 ONRAMP TO WB C-470 FROM WADSWORTH PKWY LAKEWOOD 5 37 4,052 110

2176 ONRAMP TO WB C-470 FROM KEN CARYL AVE LAKEWOOD 26 183 50,963 278

2179 ONRAMP TO EB I-70 FROM SB SHERIDAN BLVD DENVER 13 80 9,330 116

2319 ONRAMP TO EB C-470 FROM LUCENT BLVD HIGHLANDS RANCH 20 162 36,087 223

2320 ONRAMP TO EB C-470 FROM BROADWAY HIGHLANDS RANCH 47 344 187,186 545

2321 ONRAMP TO EB C-470 FROM UNIVERSITY BLVD HIGHLANDS RANCH 17 108 25,306 234

2322 ONRAMP TO WB C-470 FROM UNIVERSITY BLVD HIGHLANDS RANCH 1 7 1,701 234

2323 ONRAMP TO WB C-470 FROM LUCENT BLVD. HIGHLANDS RANCH 1 8 1,062 132

2325 ONRAMP TO EB C-470 FROM QUINCY AVE LAKEWOOD 4 33 3,249 98

2400 ONRAMP TO WB C-470 FROM NB US-285 (HAMPDEN AVE) LAKEWOOD 24 171 46,618 272

2456 ONRAMP TO SB I-225 FROM PEORIA ST DENVER 13 88 11,927 135

2457 ONRAMP TO EB US-6TH AVE FROM SIMMS ST LAKEWOOD 3 18 1,651 90

2458 ONRAMP TO WB US-6TH AVE FROM SIMMS ST LAKEWOOD 32 316 84,241 267

2461 ONRAMP TO WB US-6TH AVE FROM NB WADSWORTH BLVD LAKEWOOD 19 146 30,709 210

2462 ONRAMP TO EB I-76 FROM NB BRIGHTON BLVD COMMERCE CITY 8 59 5,712 97

2512 ONRAMP TO NB SH-157 FROM PEARL ST. BOULDER 12 84 12,162 145

2513 ONRAMP TO SB DIAGONAL HWY FROM NB BOULDER RD BOULDER 3 17 870 51

2514 ONRAMP TO 96TH AVE FROM SH-42. BOULDER 19 151 32,035 213

2560 ONRAMP TO EB US-6TH AVE FROM SB I-25 DENVER 2 26 6,058 234

2572 ONRAMP TO SB I-25 FROM EB US-6TH AVE LAKEWOOD 19 128 36,416 285

2573 ONRAMP TO WB I-270 FROM QUEBEC ST. COMMERCE CITY 1 7 672 93

2574 ONRAMP TO NB I-25 FROM WB COUNTY LINE RD. HIGHLANDS RANCH 25 201 25,631 127

2575 ONRAMP TO WB US-36 FROM NB SHERIDAN BLVD WESTMINSTER 3 24 3,210 136

2576 ONRAMP TO SB I-25 FROM EB COUNTY LINE RD. HIGHLANDS RANCH 84 629 151,953 242

2577 ONRAMP TO NB I-25 FROM EB COUNTY LINE RD. HIGHLANDS RANCH 123 923 431,356 468

2808 ONRAMP TO SB I-25 FROM 136TH AVE THORNTON 5 31 5,053 165

2809 ONRAMP TO SB I-25 FROM 144TH AVE THORNTON 5 32 1,806 57

2811 ONRAMP TO I-25 FROM WB SPEER DENVER 80 760 248,133 327

2812 OFF-RAMP FROM NB I-25 ONTO WB C-470 HIGHLANDS RANCH 3 22 4,753 216

2815 OFF-RAMP FROM WB US-36 ONTO SOUTH FEDERAL WESTMINSTER 3 23 3,119 136

2816 ONRAMP TO WB US-36 FROM FEDERAL WESTMINSTER 4 19 1,747 91

2819 ONRAMP TO SB 121 FROM WB 287 WESTMINSTER 109 1,164 342,283 294

2821 ONRAMP TO NB I-25 FROM 120TH AVE WESTMINSTER 7 46 7,084 155

2822 ONRAMP TO SB FEDERAL FROM WB COLFAX LAKEWOOD 14 106 8,415 80

2826 ONRAMP TO EB US-36 FROM MCCASLIN LOUISVILLE 28 216 42,218 196

2827 ONRAMP TO WB US-36 FROM INTERLOCKIEN LOOP LOUISVILLE 22 155 23,035 148

2828 ONRAMP TO NB DIAGONAL FROM NB 119 BOULDER 11 89 7,716 86

2971 EB DILLON RD EAST OF US-287 BROOMFIELD 39 328 99,376 303

3498 ONRAMP TO WB I-76 FROM 74TH AVE. COMMERCE CITY 6 61 10,807 177

3499 ONRAMP TO SB I-25 FROM WB I-76 DENVER 20 201 44,613 222

3500 ONRAMP TO SB I-25 FROM WB LINCOLN AVE. LONE TREE 7 55 1,852 34

3501 ONRAMP TO NB I-25 FROM EB LINCOLN AVE LONE TREE 43 329 111,764 340

3503 ONRAMP TO EB I-70 FROM QUEBEC ST. DENVER 23 207 34,520 166

3504 ONRAMP TO EB I-70 FROM PEORIA ST. DENVER 5 32 9,672 306

3505 ONRAMP TO WB I-70 FROM QUEBEC ST. DENVER 13 120 41,039 341

8057 ON-RAMP TO SB SH 157 FROM PEARL ST. BOULDER 30 217 41,635 192

8058 ONRAMP TO WB I-76 FROM SHERIDAN BLVD. ARVADA 42 377 87,345 231

8059 ONRAMP TO NB SANTA FE FROM US-285 (HAMPDEN AVE) ENGLEWOOD 68 506 113,484 224

8060 EXIT LOOP TO NB SPEER BLVD FROM NB I-25 DENVER 3 21 4,002 194

8061 SB HERITAGE RD. AT INTERSECTION WITH US-40 (COLFAX) GOLDEN 2 11 948 88

8064 ONRAMP TO NB SH 157 FROM EB TABLE MESA BOULDER 27 193 42,225 219

8068 ONRAMP TO EB I-70 FROM HARLAN ST. ARVADA 10 53 10,261 194

8069 ONRAMP TO WB I-70 FROM KIPLING ST. WHEATRIDGE 39 347 88,618 255

8072 ONRAMP TO NB I-25 FROM 84TH AVE. THORNTON 16 124 22,979 186

8073 ONRAMP TO NB I-25 FROM 104TH AVE. NORTHGLENN 22 160 23,009 144

8077 ONRAMP TO EB C-470 FROM QUEBEC ST. HIGHLANDS RANCH 116 897 489,125 545

8079 ONRAMP TO WB US-36 FROM WADSWORTH PKWY BROOMFIELD 113 1,132 379,830 335

8081 ONRAMP TO EB I-70 FROM HAVANA ST. DENVER 2 17 1,405 84

8083 ONRAMP TO SB I-25 FROM FOUNDERS PARKWAY (EXIT 184) CASTLE ROCK 44 329 53,876 164

8084 ONRAMP TO SB I-25 FROM LINCOLN AVE. LITTLETON 32 240 26,701 111
16 

Table II-2 Denver RSD Sites continued 

Table II-3 El Paso RSD Sites 

Site 

Code Location City

Active 

Days

Total 

Active 

Hours

Registered 

Vehicles 

Measured

Veh's 

Per 

Hour

8085 ONRAMP TO NB I-25 FROM WOLFENSBERGER RD. (EXIT 182) CASTLE ROCK 36 263 80,006 304

8086 ONRAMP TO NB I-25 FROM FOUNDERS PARKWAY (EXIT 184) CASTLE ROCK 41 285 87,611 307

8087 ONRAMP TO WB I-70 FROM AIRPORT BLVD. AURORA 6 44 6,543 150

8088 ONRAMP TO WB I-76 FROM 88TH AVE COMMERCE CITY 2 15 1,757 116

8089 ONRAMP TO WB I-76 FROM 96TH AVE COMMERCE CITY 16 111 21,157 191

8090 ONRAMP TO EB I-76 FROM PECOS ST. DENVER 1 8 630 81

8091 ONRAMP TO WB I-76 FROM BROMLEY LN. BRIGHTON 4 25 3,420 139

8093 ONRAMP TO WB I-70 FROM NB I-25 DENVER 214 2,308 1,338,408 580

8097 ONRAMP TO WB US-6TH AVE FROM NB I-25 DENVER 149 1,055 765,099 725

8098 ONRAMP TO NB I-225 FROM ILLIFF AVE AURORA 14 96 13,620 142

8100 ONRAMP TO WB US-6TH AVE FROM SB KIPLING ST. LAKEWOOD 4 29 6,313 214

8106 ONRAMP TO NB US-285 FROM KIPLING BLVD. DENVER 12 91 22,802 249

8107 ONRAMP TO WB US-36 FROM BROADWAY DENVER 56 418 160,556 384

8108 ONRAMP TO WB SH-58 FROM MCINTYRE ST. GOLDEN 3 14 612 43

8109 ONRAMP TO WB SH-58 FROM WASHINGTON AVE GOLDEN 2 9 761 82

8110 ONRAMP TO EB SH-58 FROM WASHINGTON AVE GOLDEN 15 124 26,758 216

8111 ONRAMP TO EB SH-58 FROM MCINTYRE ST. GOLDEN 10 79 20,483 260

8112 ONRAMP TO WB C-470 FROM MORRISON RD. MORRISON 14 87 11,410 131

8115 ONRAMP TO EB I-76 FROM FEDERAL BLVD DENVER 12 84 13,717 163

8121 ONRAMP TO SB I-225 FROM MISSISSIPPI AVE AURORA 19 141 36,518 259

8122 ONRAMP TO NB I-25 FROM PARK AVE DENVER 118 1,109 366,521 330

8123 ONRAMP TO NB I-25 FROM 58TH AVE. DENVER 43 326 112,488 346

8125 ONRAMP TO NB I-25 FROM THORNTON PKWY THORNTON 8 53 8,691 163

8126 ONRAMP TO EB I-70 FROM PECOS ST DENVER 37 292 90,608 310

8129 ONRAMP TO WB I-76 FROM PECOS ST DENVER 8 56 12,745 227

8130 ONRAMP TO EB I-76 FROM SHERIDAN BLVD ARVADA 26 234 53,716 230

8131 ONRAMP TO EB I-70 FROM SHERIDAN BLVD. ARVADA 4 20 3,143 160

Subtotal 2,424 20,046 6,913,610 345

Site 

Code Location City

Active 

Days

Total 

Active 

Hours

Registered 

Vehicles 

Measured

Veh's 

Per 

Hour

2518 ONRAMP TO E.PLATTE AVE FROM NB ACADEMY BLVD COLORADO SPRINGS 8 52 10,055 193 

2520 ONRAMP TO NB I-25 FROM N.ACADEMY BLVD COLORADO SPRINGS 10 72 12,417 173 

Subtotal 18 124 22,472 181

Total 3,108 24,878 7,678,851 309
17 

Figure II-2 a: Site Locations Northern Front Range 
18 

Figure II-2 b: Site Locations – Denver Metro Area 

C. Sources of Data and Description of Elements 

Data used in the analyses in this report come from three primary sources: 

 Remote sensing unit measurements 

 The DMV database maintained on the AIR program contractor host computer 
19 

 I/M test database maintained on the AIR program contractor host computer 

Data from the RSD units are loaded into a database maintained by the centralized 

contractor, Envirotest. Using the vehicle plate identified by RSD, the registration file is 

accessed to determine the vehicle identification number (VIN) and vehicle registration 

information. Envirotest uses the Polk VIN Decoder to add additional information about 

each vehicle. The combined data fields are shown in Table II-4. 

Table II-4 Vehicle Measurement Information 

Field Name Description 

V_DATA_VER Data version 

V_DATE_TIME Date and time of measurement 

V_RSD_UNIT RSD system number 

V_SEQ_NUM Measurement sequence number 

V_SITE_CODE Site reference 

V_PROGRAM_CODE I/M Program 

V_VAN_OPERATOR_ID 

V_CO Carbon monoxide emissions % 

V_CO2 Carbon dioxide emissions % 

V_MAX_CO2 Maximum observed CO2 

V_CO2_VOLUME Volume of CO2 observed 

V_HC Hydrocarbon emissions ppm hexane equivalent 

V_NOX Oxides of nitrogen emissions ppm (NOx) 

V_NOX_FLAG Validity of NOx measurement 

V_OPAC Opacity measurement 

V_SPEED Speed MPH 

V_ACCEL Acceleration MPH/S 

V_SA_UNITS Units of speed and acceleration 

V_TEMPERATURE Ambient temperature 

V_HUMIDITY Ambient humidity 

V_WIND_SPEED Ambient wind speed 

V_WIND_DIRECTION Ambient wind direction 

V_WEATHER_UNITS 

V_PLATE_CONFIDENCE Reserved for future use 

V_ALPR_VENDOR Reserved for future use 

V_TEST_COUNTY Reserved for future use 

V_CRC 

V_TAG_EDIT_MODE 

V_TAG_EDIT_ID_1 

V_TAG_EDIT_ID_2 

V_TAG_EDIT_ID_3 

V_TAG_EDIT_EMP_1 

V_TAG_EDIT_EMP_2 

V_TAG_EDIT_EMP_3 

V_PLATE License plate 

V_PLATE_STATE State issuing license plate 

V_PLATE_TYPE Type of plate 

V_VIN Vehicle Identification Number 
20 

Field Name Description 

V_LZIP Zip code for legal owner address 

V_STATE_MAKE Make code 

V_STATE_MODEL Model code 

V_COUNTY County of registration 

V_VEH_YEAR Model year 

V_EM_FLAG Subject to emissions test 

V_POLK_VEH_YEAR Polk decoded model year 

V_POLK_MAKE Polk decoded make 

V_POLK_VEH_TYPE Polk decoded vehicle type (P-pass, T-truck, U-unknown) 

V_POLK_MODEL Polk decoded model 

V_POLK_DISP Polk decoded engine displacement 

V_VSP Calculated vehicle specific power during measurement 
21 

III. Summary of Data Collection 

Up to 22 remote sensing units were deployed for 3,108 days during 2011 to collect 6.9M 

measurements in the Denver metropolitan area (DMA)Metro Area, 743,000 measurements in the 

Northern Front Range (NFR) and 22,000 measurements in El Paso County having a visible plate 

and valid HC, CO, speed and acceleration values. Plates were matched to registrations to 

determine vehicle information. Clean screen exemption notices were issued for 242,824 DMA 

vehicles and 46,944 NFR vehicles scheduled to renew their registration in 2011 and due for 

emissions testing (Table III-1). 

Vehicles registered in the DMA accounted for 6.3M measurements, the NFR for 788,000, and El 

Paso County 125,000. Another 279,000 measurements were of vehicles registered in other 

Colorado counties (Table III-2). 

In 2010, RSD performed over nine million emission measurements at 47 locations in the DMA 

and 16 locations in the NFR. In 2011, 1.3 million fewer emission measurements were made but 

the measurements were taken at almost twice the number of locations than in 2010. Despite the 

reduction in the quantity of emission measurements, and the addition of the RSD NO standard 

for the full year, the number of clean screens issued increased by 50,000 vehicles. 

The increase in clean screens was partly due to the application of location performance metrics 

by the contractor that resulted in less focus on high productivity sites having many repeat 

measurements and more use of a wider variety of sites. On a monthly basis a ratio of unique 

vehicles seen per hour of active collection by location on a 10.5 month rolling window was 

calculated and used for van scheduling. The ratio provided a metric of potential site saturation 

and allowed the contractor to adjust the van schedule accordingly. This approach allowed more 

vehicle owners to participate in the clean screen program. The addition of the NFR for the full 

year also increased the eligible vehicles. 

Table III-1 Collection Summary 

A. Monthly Collection Activity 

Figure III-1 shows the monthly RSD measurements. Collection rates were lower during severe 

winter months. 

B. Measurements by Hour of Day 

Figure III-2 ‘Measurements by Hour of Day’ shows the number of vehicles measured during 

each hour of the day. The shape of the curve is indicative of when measurements were collected 

and does not represent the level of traffic during the day. Most measurements were collected 

between 8:00am and 6:00pm. 

Statistic

Denver Metro 

Area

Northern 

Front Range

Colorado 

Springs Total

Sites Used 90 42 2 134 

Collection Van Days 2,424 666 18 3,108 

Active Collection Van Hours 20,046 4,708 124 24,878 

Matched to Registration 6,913,610 742,769 22,472 7,678,851 

Notices Generated for 2011 renewals 242,824 46,944 289,768
22 

Figure III-1 Monthly RSD Measurements 

Figure III-2 Measurements by Time of Day 

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

900,000

Jan

FebMar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Measurements

Measurements by Month

El Paso

County

Northern

Front Range

Denver Metro

Area

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

900,000

1,000,000

Before 6 am

6-7 am7-8 am8-9 am

9-10 am

10-11 am11-12 am

12 -1 pm

1-2 pm2-3 pm3-4 pm4-5 pm5-7 pm6-7 pm7-8 pm

Measurements

Measurements by Time of Day

El Paso

County

Northern

Front Range

Denver Metro

Area
23 

C. Composition of Vehicles Measured 

Table III-2, Source of Vehicle Registrations Measured by RSD, shows the number of vehicles 

registered in each program area and the area where they were measured. The majority (98%) of 

Denver metropolitan area registered vehicles were measured in the DMA . A majority (76%) of 

Northern Front Range registered vehicles were measured in NFR with the remaining 24% being 

measured in the DMA. 

Table III-3, Type of Vehicles Measured by RSD within Registration Jurisdiction, shows that 

81.6% of vehicles measured were registered in the DMA, 10.3% in the NFR, 1.6% in El Paso 

County (Colorado Springs), 3.6% in other non-I/M counties, and 2.8% were not matched. This 

can occur when plates are transferred by an owner to a new vehicle. These numbers are 

indicative of on-road activity – not unique registrations. The same vehicle may be measured 

more than once. 

Table III-4 shows the distribution of vehicle measurements by vehicle type, age group and 

registration jurisdiction. The vehicle types were identified by the Polk VIN decoder. The model 

years of 1980 and older vehicles and some of the newest models were determined from the 

registration information but the vehicle type was not available. These were classified as 

Unknown in Table III-3. Four hundred measurements of motorcycles were also included as 

Unknown. 

Table III-2 Source of Vehicle Registrations Measured by RSD 

Measured In

Denver Metro Area Northern Front Range El Paso

Adams 986,605 98% 19,345 2% 207 0% 1,006,157 

Arapahoe 812,498 98% 14,842 2% 582 0% 827,922 

Boulder 385,475 96% 16,894 4% 57 0% 402,426 

Broomfield 289,565 99% 2,512 1% 24 0% 292,101 

Denver 1,035,463 98% 16,533 2% 575 0% 1,052,571 

Douglas 1,035,561 99% 6,297 1% 616 0% 1,042,474 

Jefferson 1,598,911 99% 12,613 1% 299 0% 1,611,823 

State of Colorado 27,310 85% 4,351 14% 395 1% 32,056 

Subtotal Denver Metro 6,171,388 98% 93,387 1% 2,755 0% 6,267,530 

Larimer 63,473 15% 361,006 85% 69 0% 424,548 

Weld 128,054 35% 235,935 65% 66 0% 364,055 

Subtotal Northern Front Range 191,527 24% 596,941 76% 135 0% 788,603 

El Paso El Paso 101,502 81% 5,766 5% 17,932 14% 125,200 

Non I/M 255,698 92% 21,997 8% 1,070 0% 278,765 

Not Matched 218,753

Total 6,720,115 718,091 21,892 7,678,851 

Northern Front 

Range

Denver Metro Area

Program Registered 

County

Total
24 

Table III-3 Type of Vehicles Measured by RSD within Registration Jurisdiction 

Table III-4 Registered Jurisdiction and Age of Vehicles Measured by RSD 

Program County Pass Truck Unknown Total %

Adams 412,934 588,777 4,446 1,006,157 13.1%

Arapahoe 340,202 479,958 7,762 827,922 10.8%

Boulder 190,247 210,733 1,446 402,426 5.2%

Broomfield 133,378 157,654 1,069 292,101 3.8%

Denver 454,790 586,727 11,054 1,052,571 13.7%

Douglas 372,375 667,248 2,851 1,042,474 13.6%

Jefferson 675,939 929,961 5,923 1,611,823 21.0%

State of Colorado 9,980 21,416 660 32,056 0.4%

Denver Metro 2,589,845 3,642,474 35,211 6,267,530 81.6%

Larimer 166,302 255,030 3,216 424,548 5.5%

Weld 149,397 212,378 2,280 364,055 4.7%

Subtotal North Front Range 315,699 467,408 5,496 788,603 10.3%

El Paso El Paso 52,880 71,448 872 125,200 1.6%

Non I/M 100,873 175,372 2,520 278,765 3.6%

Not Matched 2.8% 218,753

Total 3,059,297 4,356,702 44,099 7,678,851 100.0%

Denver Metro

Northern Front 

Range

 Vehicle 

Type Model Year 

 Denver 

Metro Area 

 Northern 

Front Range El Paso 

 NonI/M Total 

Pass 1981 & older 461 133 9 50 653 

1982-1990 49,064 9,185 1,049 3,285 62,583 

1991-1995 183,895 29,086 3,595 9,037 225,613 

1996-2000 541,872 72,757 10,985 21,693 647,307 

2001-2005 894,241 107,754 18,302 35,633 1,055,930 

2006-2010 813,072 88,938 17,176 28,478 947,664 

2011 & newer 107,240 7,846 1,764 2,697 119,547 

 Light 

Truck 1981 & older 407 228 19 137 791 

1982-1990 38,131 8,775 793 3,681 51,380 

1991-1995 151,339 26,103 3,020 9,965 190,427 

1996-2000 631,679 90,506 11,809 32,036 766,030 

2001-2005 1,333,712 169,381 26,766 62,499 1,592,358 

2006-2010 1,327,050 156,526 26,669 61,063 1,571,308 

2011 & newer 160,156 15,889 2,372 5,991 184,408 

Unknown 1981 & older 12,122 2,929 491 1,513 17,055 

1982-1990 359 131 16 108 614 

1991-1995 532 154 23 73 782 

1996-2000 2,576 410 45 126 3,157 

2001-2005 2,533 449 72 221 3,275 

2006-2010 2,719 716 115 252 3,802 

2011 & newer 13,865 707 110 227 14,909 

Total 788,603 6,267,025 125,200 278,765 7,459,593 
25 

IV. Clean Screening Program Performance 

A. Vehicles Selected, Notices and Redemptions 

In 2011, there were 299,445 vehicles that qualified to participate in the clean screen program. 

Table IV-1 summarizes the monthly number of vehicles meeting screening criteria each month, 

to include the number withheld for the random sample and the number rejected through QA 

checks. 

 

A random sample of two percent of vehicles meeting Clean Screen criteria are not mailed 

notices. These vehicles are required to go to a test station to obtain the station-based emission 

inspection. This random sample of vehicles is used to evaluate the effectiveness of the Clean 

Screen program. 

Not all vehicles notified for clean screen or withheld in the random sample redeem the clean 

screen or obtain a test at that time, for example vehicles that changed owner are likely to have 

obtained an earlier station inspection. Compared to the 289,768 vehicles notified in the year, 

fewer vehicles 206,790 (85%) obtained a clean screen. 

Table IV-1 Vehicles Qualified As Meeting Clean Screening Criteria by Status 

 Table IV-2 lists the number of vehicles by month and city that were notified via the Department 

of Revenue. Table IV-3 shows inspection results of the audit sample. Just 0.3% of the audit 

sample failed their exhaust emissions inspection down from 1.2% in 2010. Gas cap pressure test 

failures of 2.8% were also down from 3.1% in 2010. 

Reg 

Year

Reg 

Month

Random 

Sample QA failed Notified

Total 

Qualified

Random 

% of 

Qualified

2011 Jan 488 269 23,551 24,308 2.0%

2011 Feb 494 283 23,558 24,335 2.0%

2011 Mar 528 317 25,104 25,949 2.0%

2011 Apr 465 275 22,175 22,915 2.0%

2011 May 463 345 22,313 23,121 2.0%

2011 Jun 515 307 25,021 25,843 2.0%

2011 Jul 564 311 26,800 27,675 2.0%

2011 Aug 563 287 27,238 28,088 2.0%

2011 Sep 552 335 26,084 26,971 2.0%

2011 Oct 526 311 25,337 26,174 2.0%

2011 Nov 418 311 19,968 20,697 2.0%

2011 Dec 463 287 22,619 23,369 2.0%

Total 6,039 3,638 289,768 299,445 2.0%
26 

Table IV-2 Notifications Transmitted to DOR 

Table IV-3 Clean Screen Audit Test Pass / Fail Statistics 

Registration Renewal Month

City Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total

DENVER 3,551 3,676 3,697 3,386 3,439 3,930 4,091 3,996 4,032 4,089 3,690 3,872 45,449

AURORA 1,648 1,731 1,860 1,614 1,665 1,720 1,815 1,744 1,678 1,689 1,495 1,515 20,174

FT COLLINS 1,626 1,546 1,806 1,575 1,665 1,868 2,016 2,081 1,656 1,180 325 1,055 18,399

LITTLETON 1,380 1,346 1,408 1,205 1,246 1,410 1,400 1,468 1,404 1,360 1,242 1,197 16,066

ARVADA 1,200 1,120 1,269 1,116 1,044 1,271 1,315 1,389 1,377 1,430 1,149 1,236 14,916

HIGHLAND RCH 1,119 1,260 1,238 1,087 1,151 1,334 1,428 1,410 1,318 1,329 1,069 1,081 14,824

LAKEWOOD 927 961 1,020 959 877 1,014 1,009 1,187 1,249 1,285 1,123 1,117 12,728

WESTMINSTER 974 918 1,025 845 868 1,006 1,128 1,078 1,092 1,113 984 994 12,025

CENTENNIAL 1,024 978 1,032 904 881 986 1,057 1,071 1,045 1,016 865 838 11,697

THORNTON 785 855 889 761 773 876 980 948 919 1,019 898 881 10,584

PARKER 768 691 744 661 661 761 812 818 775 747 651 650 8,739

CASTLE ROCK 677 654 758 648 660 735 791 746 794 784 664 663 8,574

BROOMFIELD 688 683 697 581 643 710 765 780 745 823 621 627 8,363

BOULDER 693 664 635 640 590 619 646 768 723 845 622 706 8,151

LOVELAND 655 700 744 682 704 745 763 800 684 485 132 405 7,499

GREELEY 584 557 658 624 590 602 787 711 626 385 104 439 6,667

GOLDEN 558 501 522 469 441 497 590 589 539 639 523 564 6,432

ENGLEWOOD 391 428 450 408 370 421 459 476 440 444 377 400 5,064

LONGMONT 339 345 351 277 329 318 419 396 401 457 332 397 4,361

BRIGHTON 245 257 278 242 227 242 307 314 273 281 272 256 3,194

WINDSOR 238 282 305 265 285 290 342 396 326 210 50 180 3,169

WHEAT RIDGE 238 239 252 235 196 221 259 270 265 285 243 275 2,978

NORTHGLENN 244 235 249 200 231 266 284 253 258 289 214 218 2,941

COMMERCE CITY 212 180 212 206 194 215 257 218 242 237 216 242 2,631

LOUISVILLE 164 189 196 164 188 186 218 221 204 217 187 172 2,306

LAFAYETTE 158 156 169 140 148 180 226 200 205 242 192 178 2,194

GREENWOOD VLG 183 167 180 160 147 175 180 197 177 191 150 166 2,073

EVERGREEN 125 133 174 118 141 163 172 175 191 209 173 189 1,963

ERIE 151 160 169 142 147 175 150 179 184 160 68 150 1,835

LONE TREE 138 148 155 145 130 151 133 185 160 176 135 167 1,823

CASTLE PNS N 131 128 144 115 124 160 150 183 161 146 134 133 1,709

SUPERIOR 113 109 120 89 103 95 106 150 147 120 100 119 1,371

MORRISON 105 110 112 87 78 91 106 135 138 145 114 147 1,368

EVANS 128 128 126 115 130 138 153 121 127 69 20 89 1,344

JOHNSTOWN 110 78 94 118 80 105 122 122 117 63 10 63 1,082

BERTHOUD 75 63 72 58 47 91 86 89 81 59 9 67 797

CHERRY HL VLG 64 69 73 71 50 69 59 80 78 67 55 47 782

LARKSPUR 66 63 60 76 41 78 54 68 69 66 46 63 750

FT LUPTON 67 64 57 54 59 61 74 81 69 73 22 62 743

OTHER 1,009 986 1,104 933 970 1,046 1,091 1,145 1,115 913 692 999 12,003

Total 23,551 23,558 25,104 22,175 22,313 25,021 26,800 27,238 26,084 25,337 19,968 22,619 289,768

Vehicle Type Vehicles

Fail 

Emissions

Fail Gas 

Cap / 

Pressure

Fail 

Inspection

Passenger 2,054 4 56 58 

Light Truck 2,904 12 81 95 

Total 4,958 16 137 153 

Percentage 0.3% 2.8% 3.1%
27 

B. Clean Screen Program Effectiveness 

The emissions reductions obtained during the station testing of the audit sample vehicles are used 

to project the total emissions reductions foregone as a result of the Clean Screen program. 

Pass / Fail Statistics 

Matching initial tests for audit vehicles were limited to those occurring after the second RSD 

measurement and before expiration of the assigned Clean Screen period. Matching reinspections following an initial failure were sought through the end of February 2012. The 

inspections identified for audit sample vehicles and the inspection results are tabulated in Table 

IV-3. As noted earlier, some of the anticipated random vehicles did not obtain a test within the 

Clean Screen period. In aggregate, 0.3% of the tested audit vehicles failed their tailpipe 

emissions inspection, and 2.8% of the tested audit vehicles failed their gas cap pressure test2

. 

The 0.3% of emissions failures in 2011 was 75% lower than in 2010. The addition of the RSD 

NO standard is believed to be mostly responsible for the reduction in exhaust emission failures. 

Continued LEI updates may also have contributed. The reduction in audit vehicle gas cap 

failures of 2.8% down from 3.1% in 2010 was also a positive result. 

Following sections describe in detail how these results are used to evaluate the emissions impact 

of the Clean Screen program. 

Tailpipe Emissions 

Over 90% of inspected vehicles, and 95% of the clean screen audit vehicles, were tested using 

IM240. Models inspected using the idle test included 1981-and-older models and 1982-andnewer trucks over 8500 lbs GWWR plus some four-wheel drive and traction control vehicles. 

Few of these were clean screened. The IM240 test provides a more accurate estimate of in-use 

vehicle exhaust emissions than the idle tailpipe test. Therefore, the results of the clean screen 

audit sample vehicles tested using IM240 were used to evaluate the exhaust emissions 

effectiveness of the clean screen program. 

Vehicle test results were sorted by VIN and test date. Vehicles were then further classified based 

on their first and last test result during the period. To avoid potential double counting of 

emissions reductions, the emissions analysis only considered the first and last result for each 

vehicle during the year and interim results were ignored. 

In the list below, the first and last results are indicated in parenthesis, where P is pass, F is fail, 

W is waiver and null indicates that there was only a single test result for a particular vehicle. 

The expected combinations that apply to the vast majority of vehicles are underlined. 

 P – Passed initial test (P/null, P/P, P/F, P/W) 

 R – Failed and successfully repaired (F/P) 

 U – Failed unresolved (F/null, F/F) 

 

2

 Note that the number of emissions fails plus the number of Gas Cap / Gas Cap Pressure failures does not always equal the total

number of inspection failures. In a few cases a vehicle may fail both Emissions and Gas Cap. In a few cases, vehicles fail for 

other reasons. 
28 

 W – Failed and wavered (F/W) 

The difference between the initial and final tests is used to determine the percentage of tailpipe 

emissions reduction of each group. For vehicles with only one test, the final result is the same as 

the initial result. 

Adjustment of Fast-Pass Results 

A majority of vehicles tested on IM240 fast pass the test in less than the 240-second driving 

cycle. To allow for comparison of emissions of vehicles tested over different durations of the 

IM240 test cycle, the emission results for vehicles that fast-pass the IM240 inspection must be 

extrapolated. A method for projecting full test emissions was developed and implemented in the 

I/M program in 19964 and the projected full test emissions values are stored in the test records 

and reported as the emissions results. 

Unresolved Vehicles 

When vehicles fail their initial inspection, they must obtain a repair and return for re-inspection. 

This process is normally completed in 30 days, but can take longer. Vehicles that had initial 

tests in late 2011 but completed repair and final test after February of the following year are 

treated as unresolved. Thus, the “Fail unresolved” category may be somewhat over-stated. 

A number of vehicles never complete the repair/re-inspection process. In most cases, these 

vehicles are either scrapped or removed from the non-attainment area, which does reduce 

emissions in the area. Surveys in Arizona5

 and Colorado6 found that some vehicles continued to 

operate in the area in violation of the program rules, either with expired license plates or with 

stolen license plates or license plate stickers. In this report, it is assumed that two-thirds of these 

unresolved vehicles leave the area and one third continues to operate. Studies in progress in 

Colorado preliminarily indicate the percentage leaving the area is closer to 80%. 

To minimize the number of unresolved Clean Screen audit vehicles, retests of audit vehicles 

were included through the end of February 2012 and the audit vehicles were all assumed to 

remain in the area. 

First and Final Emissions Results 

Table IV-4 contains an example of the initial and final tailpipe results for 1982 to 1985 passenger 

vehicles inspected using the IM240 test. The table shows the average initial and average final 

emissions for each group of vehicles together with the percentage reduction. 

For example, of the 1,562 1985 model year passenger vehicles tested using the IM240 transient 

test, 15.5% of vehicles initially failed inspection and were repaired (Pass) with HC and CO 

reductions of 61.6% and 74.5% and a NOx increase of 0.2%. Another 7.5% of vehicles failed 

their initial inspection and had not successfully passed a retest by end February 2012 

(Unresolved). Reductions from these vehicles are estimated to be approximately 67% for HC, 

CO and NOx, because follow-up studies have shown that more than two thirds cease operating in 

the area. Finally, 0.6% of vehicles were waived (Waiver) with HC and CO increases of 20.5%, 

and 30.1% and NOx reductions of 22%. In aggregate, including vehicles that passed their initial 

inspection, emission reductions for 1985 passenger vehicles were 31.4% for HC, 37.3% for CO 

and 5.2% for NOx. 

Complete tables by model year and vehicle type are provided in Appendix A for vehicles tested 

using the IM240. Tables are also provided for the Clean Screen audit sample vehicles. 
29 

Table IV-4 Transient Test Emission Reductions for 1982-1985 Passenger Vehicles 

Colorado 2011 Transient Test Emissions Reductions

Unresolved fails remaining in area 33%

Model First Last Initial Final Reduction 

Year/Type Result Result Vehicles Fail% HC CO NOX HC CO NOX HC CO 

1982 Pass - 275 1.64 19.26 2.09 1.64 19.26 2.09 0.0% 0.0% 

P Fail Pass 44 12.4% 3.39 37.77 2.06 1.42 19.68 1.90 58.2% 47.9% 

Fail Unresolv. 36 10.1% 8.10 79.73 2.00 2.26 25.03 0.58 72.1% 68.6% Fail Waiver 1 0.3% 25.47 339.07 0.12 7.62 20.53 0.70 70.1% 93.9% 

Total Fail% 356 22.8% 2.57 28.56 2.08 1.69 19.90 1.91 34.3% 30.3% 

1983 Pass - 601 1.31 16.42 1.95 1.31 16.42 1.95 0.0% 0.0% 

P Fail Pass 147 17.9% 3.33 46.98 2.05 1.30 14.25 1.97 60.8% 69.7% 

Fail Unresolv. 69 8.4% 5.75 77.48 1.93 1.81 26.15 0.61 68.6% 66.3% Fail Waiver 6 0.7% 11.41 131.35 0.87 10.14 136.65 0.90 11.2% -4.0% 

Total Fail% 823 27.0% 2.11 27.84 1.96 1.41 17.73 1.83 33.2% 36.3% 

1984 Pass - 777 1.30 14.54 1.98 1.30 14.54 1.98 0.0% 0.0% 

P Fail Pass 183 17.3% 2.65 40.06 1.91 1.32 12.53 2.06 50.3% 68.7% 

Fail Unresolv. 92 8.7% 6.85 88.17 1.79 2.29 29.20 0.57 66.6% 66.9% Fail Waiver 3 0.3% 4.20 83.39 1.35 5.24 72.01 1.75 -24.8% 13.7% 

Total Fail% 1,055 26.4% 2.03 25.58 1.95 1.40 15.64 1.87 30.9% 38.9% 

1985 Pass - 1,562 1.04 11.53 1.94 1.04 11.53 1.94 0.0% 0.0% 

P Fail Pass 318 15.5% 2.82 37.80 1.90 1.08 9.63 1.91 61.6% 74.5% 

Fail Unresolv. 153 7.5% 4.70 57.95 1.92 1.51 18.91 0.61 67.8% 67.4% Fail Waiver 13 0.6% 3.11 49.33 1.74 3.74 64.16 1.36 -20.5% -30.1% 

Total Fail% 2,046 23.7% 1.61 19.32 1.93 1.10 12.12 1.83 31.4% 37.3% 
30 

Audit Sample Reductions and Projected Impact 

Table IV-5 shows the aggregate first and final results for the 95% of the inspected audit 

sample vehicles that were tested using IM240. The average per vehicle emissions reductions 

from the audit sample are multiplied by the number of exempted clean screen vehicles to 

project the reductions that could have been achieved if the clean screen vehicles had instead 

been inspected at the stations. This amount is then compared to the total emission reductions 

from vehicles tested at stations to determine the impact of the Clean Screen program and the 

percentage of emissions reductions retained. 

For vehicles subject to the IM240 test, the Clean Screen program retained 98.0% to 99.1% of 

the exhaust HC, CO and NOx reductions. These reductions assume all vehicles are driven the 

same number of miles each year. Mileage adjusted emission reductions are calculated in 

section V. 

Table IV-5 Clean Screen Emissions Impact for Tailpipe Emissions 

IM240 Tailpipe Emissions

Vehicles HC g/mi CO g/mi NOx g/mi

Audit Sample 4,681

Mean Initial 0.115 1.907 0.373

Mean Final 0.112 1.836 0.369

Emissions reduction 0.003 0.072 0.004

Clean Screens 246,768

Potential Reductions 679 17,661 1,063 

Station Vehicles 832,100

Mean Initial 0.354 4.599 0.739

Mean Final 0.269 3.530 0.678

Emissions reduction 0.085 1.070 0.061

In station reductions 71,072 890,014 50,955 

Combined CS & Stn 1,078,868 71,751 907,675 52,018 

Clean Screen Impact 0.9% 1.9% 2.0%

Retained Reductions 99.1% 98.1% 98.0%
31 

C. Gas Cap Evaporative Emissions 

The evaporative emissions test used in the I/M Program is a gas cap pressure test. Leaking 

gas caps allow evaporated gasoline (HC) to escape from vehicle gas tanks into the 

atmosphere. The impact of leaking gas caps on the Clean Screen program is only evaluated in 

this report in terms of the failure rate, not in terms of repairable gas cap emissions reductions3

. 

Figure IV-1 compares the average gas cap failure rate of the Clean Screen audit sample 

vehicles to the average failure rate of the non-audit vehicles tested at stations. The failure rate 

of vehicles exempted via Clean Screen methods was 35% lower than the failure rate of 

vehicles that received a station-based test (See Figure IV-1). This result is expected because 

remote sensing is directed towards measuring tailpipe emissions. A gas cap evaporative leak 

would have to be quite large to be detected by RSD units. Clean screen models were newer 

than the overall tested fleet. 

Figure IV-1 Gas Cap Pressure Failure Rates 

Using the fail rates identified in the audit sample, Table IV-6 shows the projected gas cap 

failures that would have been found in the exempted clean screen vehicles. These projected 

gas cap failures are added to the actual gas cap failures identified in initial inspections at the 

test stations to provide the total possible gas cap failure rate for the program. Vehicle counts 

in Figure IV-6 are higher than IV-5 because they include gas cap tests on vehicles tested using 

idle tests as well as those tested using IM240. Vehicles with a redeemed Clean Screen notice 

3

 Although the gas cap leak rates are measured in the I/M Program, it is not clear that leak rates are directly related to the 

amount of evaporative HC emissions released from the gas tank. A small pressure leak may have the same effect as a 

large pressure leak, as long as it is sufficient to release internal gas tank pressure over a period of an hour or so. 

0.0%

0.5%

1.0%

1.5%

2.0%

2.5%

3.0%

3.5%

4.0%

4.5%

Pressure Failure Missing Cap

Nature of Failure

2011 Gas Cap Pressure Failure Rates

Clean Screen Station
32 

account for 14.5% of the total possible gas cap failures. Therefore, 85.5% of evaporative gas 

cap HC emission reductions were retained. 

In general, it is desirable to use direct measurements of emissions to evaluate program 

performance rather than a model. Unlike exhaust emissions that are directly measured using 

tailpipe tests, however, emissions rates from gas caps cannot easily be directly measured. 

Emissions rates of vapor leaks are typically determined in a test laboratory by enclosing a 

vehicle in a sealed compartment and measuring the emissions released into the compartment 

over time, which is impractical for testing many vehicles. Therefore, the EPA mobile source 

emissions model, Mobile6.2, was used to estimate the fraction of emissions benefits derived 

from gas cap inspections. 

CDPHE provided results from Mobile6.2 models of the benefits of the I/M program for 2011. 

The projected average reduction in HC emissions of the area fleet was 0.084 g/mi. This was 

comprised of 0.066 g/mi resulting from exhaust emissions inspections and 0.018 g/mi from 

the Gas Cap testing. The measured I/M exhaust reductions (see section V) were 696.7 tons. 

Assuming the 0.066 g/mi corresponded to 696.7 tons, the Gas Cap related HC reductions were 

projected to be 190.0 tons. These results are shown in Table IV-7. The RapidScreen impact 

was projected as 27.6 tons or 3.1% of the I/M program reductions. 

Table IV-6 Clean Screen Impact on Evaporative HC Emissions 

Initial Tests

Pressure 

Failure

Missing 

Cap

Total 

Fails

RapidScreen Audit 4,958 133 4 137 

2.7% 0.1% 2.8%

Projected RapidScreen 246,768 6,620 199 6,819 

Station GC Tests 932,977 38,767 1,336 40,103 

4.2% 0.1% 4.3%

Total Program 1,179,745 45,387 1,535 46,922 

RapidScreen Impact 20.9% 14.6% 13.0% 14.5%

Retained Reductions 79.1% 85.4% 87.0% 85.5%
33 

Table IV-7 Gas Cap Related Benefit Tons 

 

Mobile6 Estimates (from CDPHE)

2011 M6 

g/mi HC

I/M 

2011 

HC tons

I/M Exhaust emission reductions 0.066 696.7

Projected Gas Cap Evap Emissions reductions 0.018 190.0

I/M Program total HC reductions 0.084 886.7

Gas Cap Evap RapidScreen impact 14.5% 0.003 27.6

% of I/M program HC benefit 3.1%
34 

D. Hybrid RSD-LEI vs. 2-hit RSD 

Envirotest compared the effectiveness of the ‘Hybrid’ and ‘2-RSD’ screening methods. The 

Hybrid method uses a single RSD measurement and a low emitter index (LEI) table. The 2-

RSD method uses two RSD measurements. 

The audit sample of vehicles with IM240 tests contained 3,444 vehicles screened using the 2-

RSD method and 1,237 vehicles screened using Hybrid RSD-LEI method. Table IV-8 shows 

the emissions reductions for these two samples and the average for all vehicles inspected at 

stations. Figures IV-2 and IV-3 show the average initial emissions and emissions reductions 

for each sample. 

The 2-RSD method audit vehicles had initial emissions that were 40%, 50% and 59% of the 

overall I/M fleet average for HC and CO and NOx respectively. These percentages were 

lower than the equivalent percentages in 2010 of 52%, 59% and 74% respectively. 

The Hybrid RSD-LEI method audit vehicles had lower initial emissions that were 32%, 42% 

and 51% of the I/M fleet average for HC and CO and NOx respectively. These percentages 

were also lower than the 2010 equivalents of 38%, 50% and 56%. 

The introduction of the RSD NO starting with December 2010 registrations is believed to be 

the principle reason for the lower average emissions of clean screen vehicles compared to the 

overall fleet. 

Average I/M emissions reductions for the 2-RSD audit vehicles were 0.9%, 2.3% and 0.9% of 

fleet average initial emissions for HC and CO and NOx respectively. Average emissions 

reductions for the Hybrid RSD-LEI audit vehicles were 1.0%, 0.4% and 0.0% of fleet average 

initial emissions for HC and CO and NOx respectively. These compared to station average 

reductions of 28.6%, 26.9% and 9.4% for HC, CO and NOx respectively. 

The Hybrid RSD-LEI audit vehicles had lower initial emissions of HC, CO and NOx and 

smaller reductions of CO and NOx than the 2-RSD audit vehicles. HC reductions were the 

same. 
35 

Table IV-8 Average Emissions per Vehicle 

 

Figure IV-2 Average Initial IM240 Emissions 

Vehicle IM240 Tailpipe Emissions

Sample Vehicles HC g/mi CO g/mi NOx g/mi

I/M vehicle initial mean 

emissions 0.299 3.980 0.655

2-RSD Audits 3,444

Mean Initial 0.121 1.991 0.388

Mean Final 0.118 1.899 0.383

Emissions reduction 0.003 0.092 0.006

 % of I/M vehicle initial mean emissions 0.9% 2.3% 0.9%

Hybrid Audits 1,237

Mean Initial 0.097 1.673 0.331

Mean Final 0.094 1.659 0.331

Emissions reduction 0.003 0.015 0.000

 % of I/M vehicle initial mean emissions 1.0% 0.4% 0.0%

All Station Tests 832,100

Mean Initial 0.354 4.599 0.739

Mean Final 0.269 3.530 0.678

Emissions reduction 0.085 1.070 0.061

 % of I/M vehicle initial mean emissions 28.6% 26.9% 9.4%

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

Station

RSD-2

RSDLEI

g/mi

HC

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

Station

RSD-2

RSDLEI

CO

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

Station

RSD-2

RSDLEI

NOx
36 

Figure IV-3 Average IM240 Emissions Reductions 

 

0.00

0.02

0.04

0.06

0.08

0.10

Station

RSD-2

RSD-LEI

g/mi

HC

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Station

RSD-2

RSD-LEI

CO

0.00

0.02

0.04

0.06

0.08

0.10

Station

RSD-2

RSD-LEI

NOx
37 

V. Estimate of Overall I/M Program Benefits and Clean Screen 

Impact 

Overall I/M program emission reductions derive from two main components: 

○ Reductions resulting directly from I/M inspections and consequent repairs; 

○ Reductions from repair activities that are performed in anticipation of an I/M 

inspection. 

In previous years, it was assumed the vast majority of emissions reductions were directly 

measurable by comparing the initial and final I/M inspection emissions results, i.e. the first 

component described above. This report uses the same methodology. However, it is 

acknowledged that by 2007 most vehicles were equipped with OBD-II malfunction indicator 

lights. It is believed that some repairs of these newer model vehicles are performed in 

response to warning lights before the initial inspection. The benefits of these repairs are not 

directly measurable in the program testing. 

The Clean Screen disbenefit can be projected directly from the emissions testing of the audit 

sample. There may be unmeasured offsetting benefits if the Clean Screen program 

encourages owners to maintain malfunctioning vehicles sooner than otherwise. 

For this report, measured I/M exhaust emissions benefits were projected from the IM240 and 

Idle emissions tests. In the case of Idle tests, idle test emission concentrations were converted 

to equivalent IM240 g/mi emissions. 

For each model year, the IM240 g/mi emissions values were weighted by the annual vehicle 

miles traveled to project the emissions inventory for initial and final test and, hence, the direct 

program benefits. 

The following sections project the directly measured tons of emissions and reductions 

A. Conversion of Idle Tests to IM240 Equivalent emissions 

On-road remote sensing emissions of vehicles inspected at I/M stations have been used to 

project IM240 equivalent values for Idle test emissions. 

The idle test procedure includes a low-speed idle and a high speed idle at 2500rpm. Vehicles 

model year 1980 and older are required to pass the low-speed idle while 1981 and newer 

models must pass both the low-speed and the high-speed tests. 

Figures V-1 and V-2 show the correlation between idle tests and on-road HC and CO 

emissions of the same vehicles. Results are averaged by model year. Average initial and 

final test emissions were used for vehicles that initially failed and were retested. Model years 

were grouped together for 1965-and-older, 1966 to 1970, 1971 to 1975, 1976 to 1981, 1982 to 

1985, 1986 to 1990 and 2004-and-newer. Even with these groups, there were less than 100 

matching RSD measurements for Passenger vehicles in groups from 1982 to 1998. There 

were several hundred matching RSD measurements for each truck group. Trend lines were 

plotted with an intercept of zero to obtain RSD / Idle Test emissions ratios. 
38 

Similarly, Figure V-3 shows the correlation between IM240 and on-road emissions. Trend 

lines were plotted with an intercept of zero for HC and CO emissions to obtain IM240 / RSD 

emissions ratios. The results are summarized in Tables V-1 and V-2. 

Figure V-1 RSD vs. Idle Test Emissions 

Table V-1 Low Speed Idle to IM240 

Truck Idle Test and Matching Vehicle 

RSD Emissions

 (RSD N=57,867)

y = 1.0336x

R2

 = 0.9242

0

100

200

300

400

500

600

700

800

900

0 100 200 300 400 500 600 700 800

Idle HC ppm

RSD HC ppm

Passenger Idle Test and Matching

Vehicle RSD Emissions

 (RSD N=8,843)

y = 1.1007x

R2

 = 0.8169

0

100

200

300

400

500

600

- 100 200 300 400 500 600

Idle HC ppm

RSD HC ppm

Passenger Idle Test and Matching

Vehicle RSD Emissions

 (RSD N=8,843)

y = 1.3267x

R2

 = 0.712

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0.0 1.0 2.0 3.0 4.0

Idle CO %

RSD CO %

Truck Idle Test Test and Matching

Vehicle RSD Emissions

 (RSD N=57,867)

y = 1.5121x

R2

 = 0.7963

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

0.0 0.5 1.0 1.5 2.0 2.5 3.0

Idle CO %

RSD CO %

Low Speed Idle test to IM240 Projection

Passenger HC HC R2 CO CO R2

RSD / Idle 1.1007 0.81 1.3267 0.71

IM240 / RSD 0.0087 0.98 15.947 0.92

IM240 / Idle 0.0096 21.1569

Truck HC HC R2 CO CO R2

RSD / Idle 1.0336 0.92 1.5121 0.8

IM240 / RSD 0.0111 0.98 18.765 0.94

IM240 / Idle 0.0115 28.3746
39 

Figure V-2 RSD vs. 2500 Idle Test Emissions 

Table V-2 High Speed Idle to IM240 

Using the ratios derived above, IM240 g/mi equivalent emissions were projected for the 

vehicles tested with the idle test procedure. The low speed idle results were used to estimate 

emissions reductions as all model year vehicles tested at idle were required to pass the low 

speed idle test. 

Model Year Average Truck Idle 2500 Test and 

Matching Vehicle RSD Emissions

 (RSD N=57,867)

y = 1.548x

R2

 = 0.927

0

100

200

300

400

500

600

700

800

900

0 100 200 300 400 500 600 700 800

Idle HC ppm

RSD HC ppm

Model Year Average Passenger Idle 2500 Test 

and Matching Vehicle RSD Emissions (RSD 

N=8,843)

y = 1.5353x

R2

 = 0.8565

0

100

200

300

400

500

600

0 100 200 300 400 500 600

Idle HC ppm

RSD HC ppm

Model Year Average Passenger Idle 2500 Test 

and Matching Vehicle RSD Emissions (RSD 

N=8,843)

y = 1.1789x

R2

 = 0.8169

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0.0 1.0 2.0 3.0 4.0

Idle CO %

RSD CO %

Model Year Average Truck Idle 2500 Test and 

Matching Vehicle RSD Emissions

 (RSD N=57,867)

y = 1.4699x

R2

 = 0.8185

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Idle CO %

RSD CO %

2500 RPM Idle test to IM240 Projection

Passenger HC HC R2 CO CO R2

RSD / 2500 1.5353 0.86 1.1789 0.82

IM240 / RSD 0.0087 0.98 15.947 0.92

IM240 / 2500 0.0134 18.7999

Truck HC HC R2 CO CO R2

RSD / 2500 1.548 0.93 1.4699 0.82

IM240 / RSD 0.0111 0.98 18.765 0.94

IM240 / 2500 0.0172 27.5827
40 

Figure V-3 RSD vs. IM240 Test Emissions 

Model Year Average Passenger IM240 Test and 

Matching Vehicle RSD Emissions

 (RSD N=449,842)

y = 0.0087x

R2

 = 0.9812

0.0

0.5

1.0

1.5

2.0

2.5

0 50 100 150 200 250

RSD HC ppm

IM240 HC g/mi

Model Year Average Passenger IM240 Test and 

Matching Vehicle RSD Emissions

 (RSD N=449,842)

y = 15.947x

R2

 = 0.9229

0

5

10

15

20

25

30

0.0 0.3 0.5 0.8 1.0 1.3 1.5

RSD CO %

IM240 CO g/mi

Model Year Average Passenger IM240 Test and 

Matching Vehicle RSD Emissions

 (RSD N=449,842)

y = 0.0016x + 0.1754

R2

 = 0.9885

0.0

0.5

1.0

1.5

2.0

2.5

0 250 500 750 1000 1250 1500

RSD NO ppm

IM240 NOx g/mi

Model Year Average Truck IM240 Test and 

Matching Vehicle RSD Emissions

 (RSD N=423,746)

y = 0.0111x

R2

 = 0.9756

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

0 50 100 150 200 250 300 350 400

RSD HC ppm

IM240 HC g/mi

Model Year Average Truck IM240 Test and 

Matching Vehicle RSD Emissions

 (RSD N=423,746)

y = 18.765x

R2

 = 0.9368

0

10

20

30

40

50

60

0.0 0.5 1.0 1.5 2.0 2.5 3.0

RSD CO %

IM240 CO g/mi

Model Year Average Truck IM240 Test and 

Matching Vehicle RSD Emissions

 (RSD N=423,746)

y = 0.0016x + 0.3013

R2

 = 0.9785

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 500 1000 1500 2000

RSD NO ppm

IM240 NOx g/mi
41 

B. Annual Mileage Weighting 

Because of data entry errors and odometer rollover on older, high mileage vehicles, obtaining 

estimates of annual mileage from the I/M Program odometer readings for each model year 

and type of vehicle is not recommended. To avoid these problems, annual mileages for 

vehicles were taken from the 2008 ERG report on Colorado mileage accumulation rates7

. 

The estimated annual mileages are shown in Table V-3 for LDGVs and LDGTs. In Table VI3 the mileage accumulation rates for LDGT2, 3 and 4 were weighted together to obtain a 

single LDGT value. This table indicates that newer model year vehicles are driven more miles 

annually than older vehicles. It also indicates that 1995 and newer model year LDGTs, which 

emit greater masses of pollution than LDGVs are driven more miles annually than 1995 and 

newer model year LDGVs. 

` 

Table V-3 Estimated Annual Mileage in 2011 

Year LDGV LDGT

1982 4304 4,554 

1983 4304 4,562 

1984 4434 4,583 

1985 4481 4,630 

1986 4502 4,668 

1987 4552 4,741 

1988 4,780 4,851 

1989 5,088 5,019 

1990 5,430 5,256 

1991 5,672 5,519 

1992 6,002 5,824 

1993 6,331 6,135 

1994 6,653 6,471 

1995 6,974 6,940 

1996 7,369 7,437 

1997 7,764 7,863 

1998 8,188 8,345 

1999 8,613 8,900 

2000 9,032 9,502 

2001 9,450 10,087 

2002 9,905 10,727 

2003 10,360 11,245 

2004 10,746 11,817 

2005 11,132 12,303 

2006 11,870 12,834 

2007 12,023 13,215 

2008 12,307 13,433 

2009 12,357 13,514 

2010 11,600 12,428 

2011 9,650 8,995 
42 

C. Annual Emissions Reductions 

Annual tons of emissions were projected for vehicle type and model year by multiplying the 

numbers of vehicles by annual mileage and average g/mi emission levels. Results were 

projected for initial tests and final tests to determine the initial and final tons of emissions and, 

therefore, the tons of reduction. The results are listed in Appendix B for IM240 and Idle tests. 

Table V-4 first shows the reductions from the Clean Screen audit tests. Based on the audit 

tests, the second part of the table projects the potential reductions from the Clean Screen 

vehicles if all vehicles with redeemed Clean Screen notices had been tested at a station. The 

third part of the table shows the reductions from the vehicles that were tested at inspection 

stations, which includes the Clean Screen audit vehicles. The total potential reductions from 

the program are the combination of the potential reductions from the Clean Screened vehicles 

plus the actual reductions from the vehicles tested at stations. 

In Table IV-4, Clean Screen effectiveness was expressed without reference to the annual 

vehicle miles traveled (VMT) by each model year of vehicles. The more complete analysis in 

Table V-4 shows the Clean Screen program effectiveness when the VMT and Gas Cap4

estimates are factored in. During 2011, the Clean Screen program retained 96.1%, 98.1% and 

97.3% respectively of potential HC, CO and NOx emission reductions in vehicles subject to 

testing. 

For vehicles initially tested in calendar year 2011, the I/M Program is projected to have 

eliminated 851.8 tons of HC, 8,697.8 tons of CO and 443.9 tons of NOx for one year of 

vehicle travel – based on the IM240 driving cycle. 

Because the program is biennial, these reductions are approximately half of the reductions 

that would be measured over a full two-year cycle of the program. 

The tons of reductions cited here do not relate directly to the total mobile emissions inventory. 

The reductions cited are for tailpipe emissions and are in terms of the IM240 driving cycle. 

State Implementation Plan reductions are based on different driving cycles, are subject to 

many adjustments for speed, road type, temperature, air conditioning loads, etc., and therefore 

are larger than the IM240 measured reductions. 

As noted earlier, the reductions shown do not include reductions from maintenance actions 

performed on vehicles before their initial inspection. These may be quite substantial, 

especially for OBD-II vehicles that turn on the check engine light to alert owners to problems. 

 

4

 The evaporative emissions have not been adjusted for mileage but the effect of an adjustment would be small. Gas cap 

failures are more evenly distributed by age than tailpipe failures and only part of the evaporative emissions are running 

losses dependent on miles traveled. 
43 

Table V-4 Estimated Annual Tons Of Reduction (IM240 and Idle Tested Vehicles 

* NOx is not reported for idle tests. 

Table V-4 also shows that, during for the calendar year 2011, 246,768 vehicles were 

exempted through Clean Screen, and 910,181 vehicles received a station test. Therefore, 

21.3% of the 1,156,949 unique vehicles were Clean Screened. 

If the fraction of Clean Screen vehicles had been 30% of vehicles subject to inspection there 

would have been 347,085 Clean Screens and 809,864 Station tests. Assuming this increase 

was achieved by increasing on-road fleet coverage rather than by relaxing the Clean Screen 

standards, the projected emissions retained would have been 94.5%, 97.1% and 95.7% 

respectively of potential HC, CO and NOx tailpipe emission reductions. 

 Audit Vehicle Reductions (tons/yr)

Audit Tests

Unique 

Vehicles HC CO NOx

Enhanced IM240 4,681 0.14 3.24 0.23

Potential from RS Vehicles (tons/yr)

RapidScreen

Unique 

Vehicles HC CO NOx

Enhanced Area 246,768 7.2 170.9 12.4

Gas Cap estimate from Mobile6 27.6

Station Reductions (tons/yr)

Station I/M Vehicles

Unique 

Vehicles HC CO NOx

Enhanced IM240 832,100 519.7 6,535.1 443.9

Enhanced Idle* 78,081 169.7 2,162.7

Gas Cap estimate from Mobile6 162.4

 851.8 910,181 8,697.8 443.9 

Total Potential Reductions 886.7 8,868.7 456.2

RapidScreen Exhaust Impact 0.8% 1.9% 2.7%

Rapidscreen Gas Cap Impact 3.1%

Retained Reductions 96.1% 98.1% 97.3%
44 

VI. Review of Clean Screen Standards and Procedures 

The 2008 report8 contained an extensive ‘what if’ analysis to determine how clean screen 

standards could be adjusted to match the May 5, 2008 changes in I/M standards. Since then 

the LEI table has been updated several times to reflect the results of those changes and an 

RSD NO standard of 1000 ppm was implemented. 

The changes have improved results and resulted in fewer lost emissions reductions in 2011. 

Clean screens using the RSD-LEI method have fallen from 45% of the total in 2008 to 29% in 

2009 and 24% in 2011. This reduction is a combination the effective tightening of the LEI to 

match the new standards and an increase in the fraction of vehicles with two RSD 

measurements. 

New factors will potentially be coming into play in future years: 

 In September 2011, President Obama requested that EPA withdraw the draft National 

Ambient Air Quality Standards (NAAQS) for ozone. The statement was in response 

to a draft final rule EPA submitted to the Office of Information and Regulatory 

Affairs, (OIRA) for review in July 2011 that was anticipated to tighten the ozone 

standard. Under the Clean Air Act, (CAA) NAAQS must be reviewed every five 

years. Since ozone standards were last reviewed in 2008 EPA is required to review the 

NAAQS again in 2013, which may affect the Denver Metropolitan Area and Northern 

Front Range. A new ozone standard is possible before the CAA mandated 2013 

review. The American Lung Association, along with others, filed a motion on August 

8, 2011 asking the United States Court of Appeals for the District of Columbia to 

order EPA to issue its final rule. 

 EPA has introduced the MOVES model that will become the basis for future SIP 

modeling; 

 CDPHE will be performing a further study of OBD-II system effectiveness. 

Consequently, it would be beneficial to continue to refine methods and procedures to ensure 

the clean screen program continues to provide convenience to as many vehicle owners as 

possible consistent with maintaining air quality goals. 
45 

VII. IM240 Projected Emissions by Model Year 

Figures VII-1 through VII-6 show the annual emissions inventories and reductions by model 

year and vehicle type for the vehicles tested in 2011 at stations, based on the IM240 driving 

cycle. The projected exhaust emissions inventory for the Clean Screen vehicles and Idle 

tested vehicles are also shown. The biennial testing cycle of the Enhanced area causes the 

difference between the sizes of the bars for odd model year vehicles vs. even model year 

vehicles. 

Not included in these charts: 

 most 2008 and newer models that had not yet entered the testing program; 

 any estimate of pre-inspection emission reductions; 

 NOx emissions for 78,081 vehicles tested with the idle test: 1981 and older models 

15,817 (20%), 1982 and newer trucks 58,124 (74%), and 1982 & newer passenger 

vehicles 4,140 (5%). 

The Figures VII-1 to 6 illustrate that older vehicles, which are fewer in number and driven 

fewer miles each year, still contribute many tons of excess emissions in the I/M area – 

especially old trucks. 
46 

Figure VII-1 LDGV HC Reductions and Remaining Emissions 

Figure VII-2 LDGT HC Reductions and Remaining Emissions 

0

50

100

150

200

250

P 1965&older

P 1966-70P 1971-75P 1976-81

P 1982P 1983P 1984P 1985P 1986P 1987P 1988P 1989P 1990P 1991P 1992P 1993P 1994P 1995P 1996P 1997P 1998P 1999P 2000P 2001P 2002P 2003P 2004P 2005P 2006P 2007P 2008P 2009P 2010P 2011

IM240 Equivalent Exhaust Tons Per Year in 2011

Passenger HC

Idle Reduction HC

IM240 Reduction HC

Idle Final HC

IM240 Final HC

Clean Screen Vehicles HC

0

50

100

150

200

250

T 1965&older

T 1966-70T 1971-75T 1976-81

T 1982T 1983T 1984T 1985T 1986T 1987T 1988T 1989T 1990T 1991T 1992T 1993T 1994T 1995T 1996T 1997T 1998T 1999T 2000T 2001T 2002T 2003T 2004T 2005T 2006T 2007T 2008T 2009T 2010T 2011

IM240 Equivalent Exhaust Tons Per Year in 2011

Light Truck HC

Idle Reduction HC

IM240 Reduction HC

Idle Final HC

IM240 Final HC

Clean Screen Vehicles HC
47 

Figure VII-3 LDGV CO Reductions and Remaining Emissions 

Figure VII-4 LDGT CO Reductions and Remaining Emissions 

0

500

1,000

1,500

2,000

2,500

P 1965&older

P 1966-70P 1971-75P 1976-81

P 1982P 1983P 1984P 1985P 1986P 1987P 1988P 1989P 1990P 1991P 1992P 1993P 1994P 1995P 1996P 1997P 1998P 1999P 2000P 2001P 2002P 2003P 2004P 2005P 2006P 2007P 2008P 2009P 2010P 2011

IM240 Equivalent Exhaust Tons Per Year in 2011

Passenger CO

Idle Reduction CO

IM240 Reduction CO

Idle Final CO

IM240 Final CO

Clean Screen Vehicles CO

0

500

1,000

1,500

2,000

2,500

T 1965&older

T 1966-70T 1971-75T 1976-81

T 1982T 1983T 1984T 1985T 1986T 1987T 1988T 1989T 1990T 1991T 1992T 1993T 1994T 1995T 1996T 1997T 1998T 1999T 2000T 2001T 2002T 2003T 2004T 2005T 2006T 2007T 2008T 2009T 2010T 2011

IM240 Equivalent Exhaust Tons Per Year in 2011

Light Truck CO

Idle Reduction CO

IM240 Reduction CO

Idle Final CO

IM240 Final CO

Clean Screen Vehicles CO
48 

Figure VII-5 LDGV NOx Reductions and Remaining Emissions 

Figure VII-6 LDGT NOx Reductions and Remaining Emissions 

0

50

100

150

200

250

300

350

400

450

500

P 1965&older

P 1966-70P 1971-75P 1976-81

P 1982P 1983P 1984P 1985P 1986P 1987P 1988P 1989P 1990P 1991P 1992P 1993P 1994P 1995P 1996P 1997P 1998P 1999P 2000P 2001P 2002P 2003P 2004P 2005P 2006P 2007P 2008P 2009P 2010P 2011

IM240 Equivalent Exhaust Tons Per Year in 2011

Passenger NOx

Idle Reduction NOx n/a

IM240 Reduction NOx

Idle Final NOx n/a

IM240 Final NOx

Clean Screen Vehicles NOx

0

50

100

150

200

250

300

350

400

450

500

T 1965&older

T 1966-70T 1971-75T 1976-81

T 1982T 1983T 1984T 1985T 1986T 1987T 1988T 1989T 1990T 1991T 1992T 1993T 1994T 1995T 1996T 1997T 1998T 1999T 2000T 2001T 2002T 2003T 2004T 2005T 2006T 2007T 2008T 2009T 2010T 2011

IM240 Equivalent Exhaust Tons Per Year in 2011

Light Truck NOx

Idle Reduction NOx n/a

IM240 Reduction NOx

Idle Final NOx n/a

IM240 Final NOx

Clean Screen Vehicles NOx
49 

References 

 

1

 “The Colorado Remote Sensing Program January – December 2010”, Envirotest report for the 

Colorado Department of Public Health and Environment, June 2011 

2 Colorado Air Quality Control Commission, “Regulation Number 11, Motor Vehicle Emissions 

Inspection Program”, http://www.cdphe.state.co.us/regulations/airregs/5CCR1001-13.pdf 

3 Colorado Department Of Public Health and Environment, Air Pollution Control Division, Mobile 

Sources Section, “Colorado On-road Vehicle Emissions Remote Sensing System (COVERS) 

Specifications” Amended July 2010 

4

 Klausmeier R., “Technical Note: Estimating Full IM240 Emissions Based on Fast Pass Emission 

Results”, November 2005 

5

 Wenzel, T. “Evaluation of Arizona’s Enhanced I/M Program”, Presented at the 9th CRC On-Road 

Vehicle Emissions Workshop. April 1999. 

6

 McClintock, P. “The Denver Remote Sensing Clean Screening Pilot”, Envirotest report for the 

Colorado Department of Health and Environment, December 1999. 

7

 “Colorado Mileage Accumulation Rates from VID Odometer Readings Draft Report” for CDPHE by 

Eastern Research Group, Inc. June 30, 2008 

8

 “The Colorado Remote Sensing Program January – December 2008”, Envirotest report for the 

Colorado Department of Public Health and Environment, February 2010
Appendix A1 Colorado 2011 Transient Test Emissions Reductions

Unresolved fails remaining in area 33%

Model First Last Initial Final Reduction %

Year/Type Result Result Vehicles Fail% HC CO NOX HC CO NOX HC CO NOX

1982 Pass - 275 1.64 19.26 2.09 1.64 19.26 2.09 0.0% 0.0% 0.0%

P Fail Pass 44 12.4% 3.39 37.77 2.06 1.42 19.68 1.90 58.2% 47.9% 7.9%

Fail Unresolv. 36 10.1% 8.10 79.73 2.00 2.26 25.03 0.58 72.1% 68.6% 70.8%

Fail Waiver 1 0.3% 25.47 339.07 0.12 7.62 20.53 0.70 70.1% 93.9% -476.3%

Total Fail% 356 22.8% 2.57 28.56 2.08 1.69 19.90 1.91 34.3% 30.3% 7.8%

1983 Pass - 601 1.31 16.42 1.95 1.31 16.42 1.95 0.0% 0.0% 0.0%

P Fail Pass 147 17.9% 3.33 46.98 2.05 1.30 14.25 1.97 60.8% 69.7% 3.7%

Fail Unresolv. 69 8.4% 5.75 77.48 1.93 1.81 26.15 0.61 68.6% 66.3% 68.5%

Fail Waiver 6 0.7% 11.41 131.35 0.87 10.14 136.65 0.90 11.2% -4.0% -3.5%

Total Fail% 823 27.0% 2.11 27.84 1.96 1.41 17.73 1.83 33.2% 36.3% 6.4%

1984 Pass - 777 1.30 14.54 1.98 1.30 14.54 1.98 0.0% 0.0% 0.0%

P Fail Pass 183 17.3% 2.65 40.06 1.91 1.32 12.53 2.06 50.3% 68.7% -7.7%

Fail Unresolv. 92 8.7% 6.85 88.17 1.79 2.29 29.20 0.57 66.6% 66.9% 68.3%

Fail Waiver 3 0.3% 4.20 83.39 1.35 5.24 72.01 1.75 -24.8% 13.7% -29.8%

Total Fail% 1,055 26.4% 2.03 25.58 1.95 1.40 15.64 1.87 30.9% 38.9% 4.1%

1985 Pass - 1,562 1.04 11.53 1.94 1.04 11.53 1.94 0.0% 0.0% 0.0%

P Fail Pass 318 15.5% 2.82 37.80 1.90 1.08 9.63 1.91 61.6% 74.5% -0.2%

Fail Unresolv. 153 7.5% 4.70 57.95 1.92 1.51 18.91 0.61 67.8% 67.4% 68.0%

Fail Waiver 13 0.6% 3.11 49.33 1.74 3.74 64.16 1.36 -20.5% -30.1% 22.0%

Total Fail% 2,046 23.7% 1.61 19.32 1.93 1.10 12.12 1.83 31.4% 37.3% 5.2%

1986 Pass - 1,553 0.87 9.99 1.79 0.87 9.99 1.79 0.0% 0.0% 0.0%

P Fail Pass 260 13.5% 2.41 30.40 2.11 1.04 8.88 1.86 56.9% 70.8% 11.6%

Fail Unresolv. 112 5.8% 3.89 52.60 2.02 1.37 18.79 0.63 64.8% 64.3% 68.9%

Fail Waiver 2 0.1% 2.78 21.09 1.07 2.00 45.07 0.85 28.1% -113.7% 20.9%

Total Fail% 1,927 19.4% 1.25 15.23 1.85 0.92 10.39 1.73 26.5% 31.8% 6.2%

1987 Pass - 2,825 0.83 9.27 1.71 0.83 9.27 1.71 0.0% 0.0% 0.0%

P Fail Pass 401 11.9% 2.37 30.46 1.99 0.94 8.15 1.70 60.5% 73.2% 14.9%

Fail Unresolv. 148 4.4% 4.26 58.36 1.99 1.29 18.13 0.64 69.8% 68.9% 68.0%

Fail Waiver 6 0.2% 2.45 47.58 2.03 3.17 73.63 1.40 -29.2% -54.7% 30.8%

Total Fail% 3,380 16.4% 1.17 14.00 1.76 0.87 9.64 1.66 25.6% 31.1% 5.4%

1988 Pass - 2,383 0.76 8.99 1.59 0.76 8.99 1.59 0.0% 0.0% 0.0%

P Fail Pass 369 12.7% 2.13 28.43 1.94 0.90 8.23 1.73 57.7% 71.0% 10.7%

Fail Unresolv. 158 5.4% 4.62 52.02 1.88 1.48 17.27 0.56 68.0% 66.8% 70.3%

Fail Waiver 4 0.1% 3.41 70.78 1.48 3.18 71.71 1.22 6.7% -1.3% 17.3%

Total Fail% 2,914 18.2% 1.15 13.87 1.65 0.82 9.43 1.55 28.4% 32.0% 5.9%

1989 Pass - 4,690 0.67 8.22 1.48 0.67 8.22 1.48 0.0% 0.0% 0.0%

P Fail Pass 640 11.5% 2.15 29.27 1.75 0.84 8.15 1.67 61.0% 72.1% 4.6%

Fail Unresolv. 205 3.7% 4.39 45.57 1.98 1.51 16.29 0.62 65.7% 64.3% 68.6%

Fail Waiver 9 0.2% 1.99 38.18 1.71 2.51 47.82 1.59 -26.3% -25.2% 6.9%

Total Fail% 5,544 15.4% 0.98 12.08 1.53 0.72 8.57 1.47 26.2% 29.0% 3.9%

A1-1
Appendix A1 Colorado 2011 Transient Test Emissions Reductions

Unresolved fails remaining in area 33%

Model First Last Initial Final Reduction %

Year/Type Result Result Vehicles Fail% HC CO NOX HC CO NOX HC CO NOX

1990 Pass - 5,233 0.65 7.79 1.44 0.65 7.79 1.44 0.0% 0.0% 0.0%

P Fail Pass 663 10.8% 2.19 26.91 2.07 0.78 7.79 1.69 64.4% 71.0% 18.3%

Fail Unresolv. 224 3.7% 3.57 44.43 2.62 1.19 14.11 0.85 66.6% 68.2% 67.7%

Fail Waiver 7 0.1% 2.24 25.92 3.67 2.00 18.28 2.84 11.0% 29.5% 22.7%

Total Fail% 6,127 14.6% 0.92 11.22 1.56 0.68 8.03 1.45 26.0% 28.4% 6.9%

1991 Pass - 8,804 0.55 6.82 1.35 0.55 6.82 1.35 0.0% 0.0% 0.0%

P Fail Pass 1,065 10.4% 1.90 25.52 1.90 0.73 7.34 1.63 61.8% 71.2% 14.3%

Fail Unresolv. 358 3.5% 3.71 40.46 2.27 1.26 13.86 0.76 66.1% 65.8% 66.4%

Fail Waiver 4 0.0% 5.53 71.08 1.77 3.63 55.03 1.98 34.3% 22.6% -11.9%

Total Fail% 10,231 13.9% 0.80 9.97 1.44 0.60 7.14 1.35 25.9% 28.4% 5.7%

1992 Pass - 7,591 0.51 6.25 1.28 0.51 6.25 1.28 0.0% 0.0% 0.0%

P Fail Pass 994 11.1% 1.90 25.85 1.83 0.66 6.43 1.49 65.2% 75.1% 18.6%

Fail Unresolv. 379 4.2% 4.00 39.28 2.33 1.28 12.66 0.76 68.1% 67.8% 67.3%

Fail Waiver 7 0.1% 3.30 38.78 1.81 3.76 25.89 1.85 -14.2% 33.3% -2.0%

Total Fail% 8,971 15.4% 0.81 9.84 1.39 0.56 6.55 1.28 31.1% 33.4% 7.5%

1993 Pass - 12,042 0.49 5.69 1.27 0.49 5.69 1.27 0.0% 0.0% 0.0%

P Fail Pass 1,461 10.5% 1.83 22.56 1.98 0.65 6.30 1.57 64.4% 72.1% 20.7%

Fail Unresolv. 423 3.0% 3.50 38.03 2.42 1.13 12.37 0.81 67.8% 67.5% 66.6%

Fail Waiver 8 0.1% 2.83 19.13 2.54 4.89 17.04 1.80 -72.9% 10.9% 29.2%

Total Fail% 13,934 13.6% 0.72 8.45 1.38 0.53 5.97 1.29 26.9% 29.4% 6.7%

1994 Pass - 11,519 0.38 4.89 0.99 0.38 4.89 0.99 0.0% 0.0% 0.0%

P Fail Pass 1,224 9.3% 1.56 16.81 1.73 0.52 5.45 1.30 66.9% 67.6% 25.1%

Fail Unresolv. 376 2.9% 4.01 34.30 2.19 1.31 11.02 0.72 67.5% 67.9% 67.3%

Fail Waiver 10 0.1% 1.76 13.98 3.41 1.12 11.10 3.49 36.3% 20.6% -2.4%

Total Fail% 13,129 12.3% 0.59 6.85 1.09 0.42 5.13 1.01 29.7% 25.2% 7.6%

1995 Pass - 18,784 0.36 4.30 0.92 0.36 4.30 0.92 0.0% 0.0% 0.0%

P Fail Pass 1,861 8.8% 1.50 16.36 1.60 0.48 4.89 1.18 67.7% 70.1% 26.2%

Fail Unresolv. 509 2.4% 3.34 29.71 2.33 1.03 9.48 0.76 69.2% 68.1% 67.5%

Fail Waiver 11 0.1% 3.97 34.87 2.10 3.19 31.76 1.99 19.6% 8.9% 5.0%

Total Fail% 21,165 11.2% 0.53 5.99 1.01 0.39 4.49 0.94 27.3% 25.0% 7.4%

1996 Pass - 15,085 0.28 3.64 0.75 0.28 3.64 0.75 0.0% 0.0% 0.0%

P Fail Pass 1,415 8.4% 1.02 14.00 1.46 0.36 4.09 0.95 64.7% 70.8% 35.1%

Fail Unresolv. 399 2.4% 2.22 21.26 2.45 0.76 7.14 0.80 65.9% 66.4% 67.4%

Fail Waiver 6 0.0% 2.73 29.00 1.66 1.95 19.25 1.38 28.5% 33.6% 17.0%

Total Fail% 16,905 10.8% 0.39 4.93 0.85 0.30 3.77 0.77 23.1% 23.6% 9.6%

1997 Pass - 23,668 0.26 3.51 0.70 0.26 3.51 0.70 0.0% 0.0% 0.0%

P Fail Pass 2,132 8.1% 0.91 12.89 1.37 0.32 3.94 0.87 64.8% 69.4% 36.4%

Fail Unresolv. 416 1.6% 2.53 21.49 2.21 0.71 6.86 0.75 71.8% 68.1% 66.0%

Fail Waiver 12 0.0% 2.41 12.99 3.45 2.64 10.80 3.65 -9.2% 16.8% -5.9%

Total Fail% 26,228 9.8% 0.35 4.56 0.78 0.27 3.60 0.71 22.0% 21.1% 8.2%

A1-2
Appendix A1 Colorado 2011 Transient Test Emissions Reductions

Unresolved fails remaining in area 33%

Model First Last Initial Final Reduction %

Year/Type Result Result Vehicles Fail% HC CO NOX HC CO NOX HC CO NOX

1998 Pass - 19,918 0.22 3.28 0.59 0.22 3.28 0.59 0.0% 0.0% 0.0%

P Fail Pass 1,714 7.8% 0.78 11.63 1.26 0.26 3.73 0.68 66.9% 68.0% 46.0%

Fail Unresolv. 348 1.6% 1.68 19.21 2.12 0.54 5.98 0.72 67.9% 68.9% 66.3%

Fail Waiver 15 0.1% 1.10 18.22 3.07 1.03 15.19 2.76 6.5% 16.6% 9.9%

Total Fail% 21,995 9.4% 0.29 4.19 0.66 0.23 3.36 0.60 20.5% 19.7% 10.2%

1999 Pass - 28,705 0.19 3.01 0.55 0.19 3.01 0.55 0.0% 0.0% 0.0%

P Fail Pass 2,514 8.0% 0.70 10.07 1.24 0.21 3.10 0.66 69.8% 69.2% 47.3%

Fail Unresolv. 337 1.1% 1.61 18.63 2.29 0.53 6.10 0.76 66.9% 67.3% 67.0%

Fail Waiver 4 0.0% 11.27 89.82 1.27 2.32 26.85 2.24 79.4% 70.1% -76.7%

Total Fail% 31,560 9.0% 0.25 3.75 0.62 0.20 3.05 0.56 20.7% 18.6% 10.1%

2000 Pass - 24,854 0.15 2.78 0.47 0.15 2.78 0.47 0.0% 0.0% 0.0%

P Fail Pass 2,137 7.8% 0.63 8.77 1.34 0.18 2.92 0.55 71.5% 66.6% 58.7%

Fail Unresolv. 319 1.2% 1.77 17.24 2.43 0.53 5.22 0.81 70.0% 69.7% 66.5%

Fail Waiver 17 0.1% 3.07 15.52 2.75 3.11 13.98 3.16 -1.3% 9.9% -14.6%

Total Fail% 27,327 9.0% 0.21 3.42 0.56 0.16 2.82 0.48 23.7% 17.5% 14.3%

2001 Pass - 32,605 0.12 2.51 0.38 0.12 2.51 0.38 0.0% 0.0% 0.0%

P Fail Pass 1,822 5.3% 0.58 8.07 1.10 0.13 2.32 0.39 77.6% 71.3% 64.7%

Fail Unresolv. 194 0.6% 1.55 19.42 2.80 0.49 5.53 0.94 68.7% 71.5% 66.5%

Fail Waiver 4 0.0% 0.49 9.81 3.43 0.50 9.36 4.21 -2.1% 4.6% -22.8%

Total Fail% 34,625 5.8% 0.15 2.90 0.43 0.12 2.52 0.38 19.3% 13.1% 11.1%

2002 Pass - 23,363 0.11 2.37 0.34 0.11 2.37 0.34 0.0% 0.0% 0.0%

P Fail Pass 1,439 5.8% 0.43 6.75 1.06 0.11 1.92 0.33 74.2% 71.6% 68.7%

Fail Unresolv. 151 0.6% 1.24 13.33 2.45 0.45 4.79 0.82 63.4% 64.1% 66.5%

Fail Waiver 3 0.0% 0.09 0.88 5.81 0.04 0.58 3.90 56.7% 34.5% 32.9%

Total Fail% 24,956 6.4% 0.14 2.69 0.40 0.11 2.36 0.35 16.9% 12.3% 13.1%

2003 Pass - 31,254 0.09 2.17 0.31 0.09 2.17 0.31 0.0% 0.0% 0.0%

P Fail Pass 1,352 4.1% 0.45 5.85 0.79 0.09 1.63 0.26 80.9% 72.1% 67.8%

Fail Unresolv. 92 0.3% 1.07 13.16 2.55 0.32 4.09 0.80 70.0% 68.9% 68.7%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 32,698 4.4% 0.11 2.35 0.34 0.09 2.15 0.31 15.3% 8.5% 8.0%

2004 Pass - 18,169 0.09 2.12 0.28 0.09 2.12 0.28 0.0% 0.0% 0.0%

P Fail Pass 949 4.9% 0.37 6.30 0.68 0.07 1.47 0.18 81.2% 76.7% 73.0%

Fail Unresolv. 55 0.3% 1.50 13.71 2.35 0.49 4.27 0.74 67.4% 68.9% 68.4%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 19,173 5.2% 0.11 2.36 0.30 0.09 2.10 0.28 16.6% 11.3% 9.6%

2005 Pass - 31,789 0.08 2.02 0.27 0.08 2.02 0.27 0.0% 0.0% 0.0%

P Fail Pass 1,292 3.9% 0.26 4.41 0.57 0.05 1.10 0.15 79.1% 75.0% 73.7%

Fail Unresolv. 41 0.1% 1.27 25.45 2.11 0.42 7.75 0.71 66.8% 69.5% 66.1%

Fail Waiver 2 0.0% 0.40 9.23 2.30 0.26 11.09 1.50 35.7% -20.2% 34.8%

Total Fail% 33,124 4.0% 0.09 2.14 0.29 0.08 1.99 0.27 10.0% 7.0% 6.3%

A1-3
Appendix A1 Colorado 2011 Transient Test Emissions Reductions

Unresolved fails remaining in area 33%

Model First Last Initial Final Reduction %

Year/Type Result Result Vehicles Fail% HC CO NOX HC CO NOX HC CO NOX

2006 Pass - 19,526 0.08 1.98 0.25 0.08 1.98 0.25 0.0% 0.0% 0.0%

P Fail Pass 566 2.8% 0.32 5.35 0.91 0.05 1.19 0.14 83.2% 77.8% 84.2%

Fail Unresolv. 29 0.1% 1.95 17.09 2.72 0.67 6.91 0.90 65.7% 59.6% 67.0%

Fail Waiver 2 0.0% 1.29 28.29 1.68 1.41 25.70 3.77 -9.8% 9.1% -123.9%

Total Fail% 20,123 3.0% 0.09 2.10 0.27 0.08 1.97 0.25 10.4% 6.3% 8.8%

2007 Pass - 33,352 0.08 1.88 0.24 0.08 1.88 0.24 0.0% 0.0% 0.0%

P Fail Pass 653 1.9% 0.25 4.69 0.84 0.05 1.26 0.10 79.0% 73.1% 87.5%

Fail Unresolv. 16 0.0% 2.61 18.81 2.81 0.74 5.64 0.90 71.5% 70.0% 68.1%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 34,021 2.0% 0.08 1.94 0.25 0.08 1.87 0.24 5.8% 3.7% 5.9%

2008 Pass - 7,899 0.07 1.91 0.23 0.07 1.91 0.23 0.0% 0.0% 0.0%

P Fail Pass 137 1.7% 0.18 3.18 0.69 0.04 1.12 0.08 78.9% 64.7% 88.7%

Fail Unresolv. 12 0.1% 1.50 19.26 1.88 0.43 7.14 0.46 71.2% 62.9% 75.7%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 8,048 1.9% 0.08 1.95 0.25 0.07 1.90 0.23 5.0% 2.7% 5.1%

2009 Pass - 2,297 0.07 1.93 0.23 0.07 1.93 0.23 0.0% 0.0% 0.0%

P Fail Pass 30 1.3% 0.14 3.55 0.39 0.03 0.74 0.07 81.7% 79.2% 82.2%

Fail Unresolv. 3 0.1% 1.61 16.61 4.84 0.47 4.93 1.60 70.5% 70.3% 66.9%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 2,330 1.4% 0.08 1.97 0.24 0.07 1.92 0.23 3.8% 2.6% 3.4%

2010 Pass - 1,889 0.07 1.97 0.22 0.07 1.97 0.22 0.0% 0.0% 0.0%

P Fail Pass 20 1.0% 0.18 3.39 0.69 0.07 1.16 0.06 59.2% 65.7% 91.9%

Fail Unresolv. 3 0.2% 1.30 23.83 3.29 0.39 7.69 1.02 69.8% 67.7% 68.9%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 1,912 1.2% 0.08 2.02 0.23 0.07 1.97 0.22 3.3% 2.4% 4.5%

2011 Pass - 502 0.07 1.93 0.22 0.07 1.93 0.22 0.0% 0.0% 0.0%

P Fail Pass 1 0.2% 0.07 1.92 0.48 0.02 0.77 0.28 78.2% 59.8% 42.1%

Fail Unresolv. 1 0.2% 0.35 3.66 0.30 0.11 1.21 0.10 67.0% 67.0% 67.0%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 504 0.4% 0.08 1.93 0.22 0.07 1.92 0.22 0.8% 0.4% 0.4%

2012 Pass - 12 0.09 1.92 0.21 0.09 1.92 0.21 0.0% 0.0% 0.0%

P Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 12 0.0% 0.09 1.92 0.21 0.09 1.92 0.21 0.0% 0.0% 0.0%

Total Passenger Vehicles

All Pass - 393,526 0.21 3.28 0.57 0.21 3.28 0.57 0.0% 0.0% 0.0%

P Fail Pass 27,803 6.5% 1.07 14.17 1.37 0.36 4.13 0.86 66.1% 70.8% 37.2%

Fail Unresolv. 5,658 1.3% 3.10 32.97 2.28 1.00 10.76 0.75 67.9% 67.3% 67.2%

Fail Waiver 156 0.0% 3.26 36.73 2.43 2.94 33.31 2.34 9.9% 9.3% 3.5%

Total Fail% 427,143 7.9% 0.31 4.40 0.65 0.24 3.45 0.59 23.9% 21.6% 8.3%

A1-4
Appendix A1 Colorado 2011 Transient Test Emissions Reductions

Unresolved fails remaining in area 33%

Model First Last Initial Final Reduction %

Year/Type Result Result Vehicles Fail% HC CO NOX HC CO NOX HC CO NOX

1982 Pass - 245 2.80 31.83 2.70 2.80 31.83 2.70 0.0% 0.0% 0.0%

T Fail Pass 120 29.7% 4.75 63.86 2.66 2.51 29.28 2.65 47.2% 54.1% 0.5%

Fail Unresolv. 39 9.7% 7.67 101.37 2.21 2.56 35.32 0.74 66.7% 65.2% 66.5%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 404 39.4% 3.85 48.06 2.64 2.69 31.41 2.49 30.1% 34.6% 5.5%

1983 Pass - 535 2.77 31.44 2.72 2.77 31.44 2.72 0.0% 0.0% 0.0%

T Fail Pass 284 31.5% 4.54 57.64 2.86 2.58 29.84 2.79 43.1% 48.2% 2.4%

Fail Unresolv. 83 9.2% 8.23 99.74 2.35 2.44 31.13 0.79 70.4% 68.8% 66.3%

Fail Waiver 1 0.1% 0.39 2.49 10.28 1.52 10.58 9.71 -293.3% -324.4% 5.5%

Total Fail% 903 40.8% 3.82 45.93 2.74 2.68 30.88 2.57 30.0% 32.8% 6.0%

1984 Pass - 672 2.21 26.21 2.75 2.21 26.21 2.75 0.0% 0.0% 0.0%

T Fail Pass 302 27.4% 4.11 59.88 2.74 2.21 24.86 2.79 46.2% 58.5% -1.6%

Fail Unresolv. 121 11.0% 7.08 92.23 2.57 2.48 31.50 0.80 65.0% 65.8% 68.9%

Fail Waiver 6 0.5% 3.31 71.26 3.16 3.71 82.32 2.98 -12.3% -15.5% 5.6%

Total Fail% 1,101 39.0% 3.28 42.95 2.73 2.25 26.73 2.55 31.3% 37.8% 6.7%

1985 Pass - 1,341 1.99 22.26 2.74 1.99 22.26 2.74 0.0% 0.0% 0.0%

T Fail Pass 567 26.5% 3.82 55.28 2.69 1.92 22.20 2.90 49.8% 59.8% -7.9%

Fail Unresolv. 221 10.3% 6.32 95.23 2.48 2.12 31.54 0.83 66.5% 66.9% 66.7%

Fail Waiver 10 0.5% 7.44 93.58 3.98 6.09 81.47 3.09 18.1% 12.9% 22.3%

Total Fail% 2,139 37.3% 2.95 38.88 2.70 2.00 23.48 2.59 32.1% 39.6% 4.4%

1986 Pass - 1,345 1.73 17.42 2.69 1.73 17.42 2.69 0.0% 0.0% 0.0%

T Fail Pass 418 21.5% 3.51 46.49 2.78 1.74 18.59 2.65 50.3% 60.0% 4.8%

Fail Unresolv. 183 9.4% 5.75 79.59 2.71 1.77 25.86 0.88 69.3% 67.5% 67.4%

Fail Waiver 2 0.1% 1.33 46.63 1.14 1.33 46.63 1.14 0.0% 0.0% 0.0%

Total Fail% 1,948 31.0% 2.49 29.53 2.71 1.74 18.49 2.51 30.2% 37.4% 7.4%

1987 Pass - 2,278 1.37 13.50 2.30 1.37 13.50 2.30 0.0% 0.0% 0.0%

T Fail Pass 649 20.7% 2.89 35.65 2.64 1.44 13.60 2.47 50.1% 61.8% 6.4%

Fail Unresolv. 200 6.4% 4.98 74.47 2.37 1.69 24.40 0.78 66.0% 67.2% 66.9%

Fail Waiver 11 0.4% 6.38 88.72 2.40 4.24 81.70 1.13 33.5% 7.9% 53.0%

Total Fail% 3,138 27.4% 1.93 22.23 2.37 1.41 14.46 2.23 26.8% 35.0% 5.9%

1988 Pass - 2,260 1.26 12.42 2.08 1.26 12.42 2.08 0.0% 0.0% 0.0%

T Fail Pass 538 17.9% 3.24 32.12 2.73 1.33 12.00 2.31 58.9% 62.6% 15.6%

Fail Unresolv. 204 6.8% 6.22 61.35 2.89 2.10 20.14 0.94 66.2% 67.2% 67.4%

Fail Waiver 8 0.3% 4.27 80.27 2.32 3.11 78.83 2.28 27.1% 1.8% 1.9%

Total Fail% 3,010 24.9% 1.96 19.44 2.25 1.34 13.05 2.04 31.8% 32.9% 9.2%

1989 Pass - 4,025 1.17 11.47 2.05 1.17 11.47 2.05 0.0% 0.0% 0.0%

T Fail Pass 901 17.4% 2.96 33.00 2.73 1.39 12.13 2.44 53.0% 63.2% 10.9%

Fail Unresolv. 249 4.8% 5.48 56.24 2.87 1.73 18.44 0.94 68.4% 67.2% 67.2%

Fail Waiver 15 0.3% 7.82 68.73 3.26 5.10 59.54 2.46 34.9% 13.4% 24.6%

Total Fail% 5,190 22.4% 1.71 17.52 2.21 1.25 12.06 2.06 27.0% 31.2% 6.6%

A1-5
Appendix A1 Colorado 2011 Transient Test Emissions Reductions

Unresolved fails remaining in area 33%

Model First Last Initial Final Reduction %

Year/Type Result Result Vehicles Fail% HC CO NOX HC CO NOX HC CO NOX

1990 Pass - 3,119 1.08 10.74 2.05 1.08 10.74 2.05 0.0% 0.0% 0.0%

T Fail Pass 660 16.6% 2.71 28.35 2.87 1.32 11.81 2.43 51.3% 58.3% 15.3%

Fail Unresolv. 184 4.6% 4.70 49.98 2.94 1.55 16.63 0.96 67.0% 66.7% 67.5%

Fail Waiver 4 0.1% 3.76 85.96 3.48 3.66 63.95 1.38 2.6% 25.6% 60.2%

Total Fail% 3,967 21.4% 1.53 15.57 2.23 1.15 11.25 2.06 24.8% 27.8% 7.5%

1991 Pass - 5,809 0.89 9.46 1.70 0.89 9.46 1.70 0.0% 0.0% 0.0%

T Fail Pass 992 14.1% 2.38 27.36 2.32 1.11 10.64 2.05 53.5% 61.1% 12.0%

Fail Unresolv. 231 3.3% 4.80 54.54 2.76 1.54 19.42 0.87 67.8% 64.4% 68.6%

Fail Waiver 7 0.1% 6.04 40.90 3.54 4.66 26.08 3.04 22.8% 36.2% 14.0%

Total Fail% 7,039 17.5% 1.23 13.49 1.83 0.95 9.97 1.72 23.4% 26.1% 5.6%

1992 Pass - 4,706 0.87 9.46 1.78 0.87 9.46 1.78 0.0% 0.0% 0.0%

T Fail Pass 857 14.9% 2.62 28.01 2.60 1.14 11.12 2.18 56.6% 60.3% 16.1%

Fail Unresolv. 191 3.3% 4.68 48.78 3.37 1.48 16.58 1.05 68.3% 66.0% 68.8%

Fail Waiver 8 0.1% 4.59 61.47 3.62 2.81 38.47 3.62 38.8% 37.4% 0.1%

Total Fail% 5,762 18.3% 1.26 13.59 1.96 0.93 9.98 1.82 26.0% 26.6% 7.1%

1993 Pass - 9,307 0.87 8.74 1.74 0.87 8.74 1.74 0.0% 0.0% 0.0%

T Fail Pass 1,497 13.4% 2.34 23.29 2.62 1.10 10.25 2.19 52.7% 56.0% 16.3%

Fail Unresolv. 327 2.9% 5.24 45.90 2.95 1.75 14.82 0.97 66.7% 67.7% 67.1%

Fail Waiver 14 0.1% 6.82 48.14 3.93 5.88 46.45 3.54 13.9% 3.5% 9.9%

Total Fail% 11,145 16.5% 1.20 11.83 1.90 0.93 9.17 1.78 22.4% 22.5% 6.1%

1994 Pass - 9,952 0.65 7.04 1.46 0.65 7.04 1.46 0.0% 0.0% 0.0%

T Fail Pass 1,669 13.8% 2.16 22.84 2.77 0.87 8.84 1.92 59.9% 61.3% 30.9%

Fail Unresolv. 421 3.5% 4.14 39.53 3.63 1.29 12.55 1.19 68.7% 68.3% 67.0%

Fail Waiver 14 0.1% 7.25 38.25 3.63 6.85 36.94 3.67 5.5% 3.4% -1.0%

Total Fail% 12,056 17.5% 0.99 10.40 1.72 0.71 7.52 1.51 28.3% 27.7% 11.8%

1995 Pass - 14,573 0.61 6.15 1.54 0.61 6.15 1.54 0.0% 0.0% 0.0%

T Fail Pass 2,518 14.3% 2.12 20.88 2.66 0.87 8.66 1.94 58.9% 58.5% 27.0%

Fail Unresolv. 503 2.9% 4.72 38.46 3.38 1.43 11.86 1.11 69.7% 69.2% 67.2%

Fail Waiver 12 0.1% 3.90 38.03 2.80 3.79 29.84 3.06 2.8% 21.5% -9.2%

Total Fail% 17,606 17.2% 0.95 9.20 1.75 0.68 6.69 1.58 28.8% 27.3% 9.6%

1996 Pass - 11,737 0.36 4.27 1.23 0.36 4.27 1.23 0.0% 0.0% 0.0%

T Fail Pass 1,654 12.1% 1.20 14.90 2.22 0.44 5.37 1.51 63.2% 64.0% 31.8%

Fail Unresolv. 306 2.2% 2.64 23.92 3.59 0.87 8.65 1.17 67.3% 63.8% 67.4%

Fail Waiver 6 0.0% 2.30 56.53 3.23 2.01 42.82 3.05 12.7% 24.3% 5.6%

Total Fail% 13,703 14.3% 0.51 6.01 1.40 0.38 4.51 1.26 25.6% 24.9% 9.9%

1997 Pass - 20,353 0.32 4.17 1.16 0.32 4.17 1.16 0.0% 0.0% 0.0%

T Fail Pass 2,971 12.5% 0.91 13.21 1.96 0.41 5.49 1.39 55.5% 58.5% 29.3%

Fail Unresolv. 370 1.6% 2.77 27.93 3.38 0.91 9.56 1.10 67.1% 65.8% 67.4%

Fail Waiver 19 0.1% 2.15 28.91 2.98 2.02 25.41 2.46 6.0% 12.1% 17.6%

Total Fail% 23,713 14.2% 0.43 5.69 1.29 0.34 4.43 1.19 21.3% 22.1% 8.3%

A1-6
Appendix A1 Colorado 2011 Transient Test Emissions Reductions

Unresolved fails remaining in area 33%

Model First Last Initial Final Reduction %

Year/Type Result Result Vehicles Fail% HC CO NOX HC CO NOX HC CO NOX

1998 Pass - 18,675 0.26 3.45 0.99 0.26 3.45 0.99 0.0% 0.0% 0.0%

T Fail Pass 2,266 10.6% 0.86 11.68 2.15 0.34 4.57 1.27 60.5% 60.8% 40.9%

Fail Unresolv. 367 1.7% 2.27 24.38 3.35 0.71 8.08 1.14 69.0% 66.8% 66.0%

Fail Waiver 14 0.1% 1.68 34.62 3.51 1.24 28.41 3.47 26.3% 17.9% 1.1%

Total Fail% 21,322 12.4% 0.36 4.70 1.15 0.28 3.66 1.02 23.0% 22.1% 11.4%

1999 Pass - 28,102 0.22 2.76 0.79 0.22 2.76 0.79 0.0% 0.0% 0.0%

T Fail Pass 2,909 9.3% 0.79 9.69 1.90 0.31 3.77 1.06 60.4% 61.1% 44.4%

Fail Unresolv. 368 1.2% 2.34 23.37 3.12 0.73 7.80 1.01 68.6% 66.6% 67.6%

Fail Waiver 24 0.1% 2.19 17.91 3.20 1.60 16.43 2.99 27.1% 8.3% 6.7%

Total Fail% 31,403 10.5% 0.30 3.66 0.92 0.24 2.92 0.82 20.9% 20.0% 11.2%

2000 Pass - 21,630 0.18 2.41 0.66 0.18 2.41 0.66 0.0% 0.0% 0.0%

T Fail Pass 2,070 8.7% 0.71 10.19 1.55 0.24 3.29 0.87 66.1% 67.7% 44.1%

Fail Unresolv. 215 0.9% 1.33 16.67 3.00 0.43 5.63 0.96 67.6% 66.3% 68.0%

Fail Waiver 11 0.0% 1.84 50.64 2.71 1.00 34.56 2.46 45.8% 31.8% 9.4%

Total Fail% 23,926 9.6% 0.23 3.23 0.76 0.18 2.53 0.68 21.0% 21.8% 10.2%

2001 Pass - 29,189 0.12 1.90 0.48 0.12 1.90 0.48 0.0% 0.0% 0.0%

T Fail Pass 2,195 7.0% 0.40 6.49 1.09 0.16 2.70 0.58 59.6% 58.4% 47.0%

Fail Unresolv. 128 0.4% 1.97 20.09 2.78 0.52 6.26 0.94 73.7% 68.8% 66.4%

Fail Waiver 9 0.0% 0.91 21.61 3.26 1.48 32.48 3.16 -62.9% -50.3% 3.1%

Total Fail% 31,521 7.4% 0.15 2.30 0.54 0.12 1.98 0.49 15.2% 13.8% 8.1%

2002 Pass - 20,649 0.10 1.66 0.43 0.10 1.66 0.43 0.0% 0.0% 0.0%

T Fail Pass 1,331 6.0% 0.42 9.04 1.04 0.13 2.53 0.53 68.4% 72.0% 49.1%

Fail Unresolv. 89 0.4% 1.04 20.99 2.77 0.35 6.70 0.91 66.2% 68.1% 67.0%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 22,069 6.4% 0.12 2.18 0.48 0.10 1.73 0.44 17.0% 20.7% 8.0%

2003 Pass - 30,485 0.08 1.38 0.37 0.08 1.38 0.37 0.0% 0.0% 0.0%

T Fail Pass 1,558 4.9% 0.34 6.75 0.75 0.11 1.98 0.37 68.6% 70.7% 50.7%

Fail Unresolv. 49 0.2% 1.70 27.68 2.18 0.53 9.36 0.71 69.2% 66.2% 67.5%

Fail Waiver 1 0.0% 2.86 17.33 4.46 1.53 17.01 3.59 46.6% 1.9% 19.5%

Total Fail% 32,093 5.0% 0.10 1.69 0.39 0.08 1.43 0.37 13.7% 15.4% 5.3%

2004 Pass - 20,128 0.07 1.25 0.26 0.07 1.25 0.26 0.0% 0.0% 0.0%

T Fail Pass 861 4.1% 0.24 4.70 0.63 0.08 1.88 0.22 67.1% 60.0% 65.1%

Fail Unresolv. 21 0.1% 1.53 34.65 1.88 0.46 11.89 0.59 69.9% 65.7% 68.4%

Fail Waiver 1 0.0% 1.85 20.01 5.12 1.94 23.74 5.25 -5.2% -18.6% -2.6%

Total Fail% 21,011 4.2% 0.08 1.43 0.28 0.07 1.29 0.26 9.8% 9.7% 6.5%

2005 Pass - 35,166 0.06 1.08 0.22 0.06 1.08 0.22 0.0% 0.0% 0.0%

T Fail Pass 950 2.6% 0.18 3.81 0.47 0.06 1.48 0.18 63.1% 61.3% 62.0%

Fail Unresolv. 27 0.1% 1.63 17.63 2.37 0.55 5.32 0.86 66.1% 69.8% 63.5%

Fail Waiver 1 0.0% 0.62 9.63 3.32 0.61 9.45 3.32 1.9% 1.8% 0.0%

Total Fail% 36,144 2.7% 0.06 1.17 0.23 0.06 1.10 0.22 5.8% 6.1% 3.9%

A1-7
Appendix A1 Colorado 2011 Transient Test Emissions Reductions

Unresolved fails remaining in area 33%

Model First Last Initial Final Reduction %

Year/Type Result Result Vehicles Fail% HC CO NOX HC CO NOX HC CO NOX

2006 Pass - 20,391 0.06 1.00 0.21 0.06 1.00 0.21 0.0% 0.0% 0.0%

T Fail Pass 702 3.3% 0.14 2.64 0.35 0.05 1.01 0.14 63.5% 61.6% 58.5%

Fail Unresolv. 10 0.0% 0.43 5.98 1.58 0.15 2.06 0.53 66.2% 65.5% 66.6%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 21,103 3.4% 0.06 1.06 0.22 0.06 1.00 0.21 5.2% 5.3% 3.3%

2007 Pass - 37,592 0.05 0.90 0.19 0.05 0.90 0.19 0.0% 0.0% 0.0%

T Fail Pass 1,149 3.0% 0.10 2.09 0.28 0.04 0.99 0.09 62.3% 52.6% 68.8%

Fail Unresolv. 10 0.0% 0.20 2.22 0.70 0.06 0.73 0.23 67.0% 67.0% 67.0%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 38,751 3.0% 0.05 0.94 0.19 0.05 0.90 0.19 3.7% 3.5% 3.0%

2008 Pass - 8,311 0.04 0.89 0.19 0.04 0.89 0.19 0.0% 0.0% 0.0%

T Fail Pass 274 3.2% 0.05 1.51 0.23 0.04 1.13 0.07 34.5% 25.2% 69.4%

Fail Unresolv. 2 0.0% 0.18 22.60 0.63 0.06 7.46 0.21 67.0% 67.0% 67.0%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 8,587 3.2% 0.04 0.91 0.19 0.04 0.90 0.18 1.4% 1.7% 2.7%

2009 Pass - 1,790 0.04 0.91 0.18 0.04 0.91 0.18 0.0% 0.0% 0.0%

T Fail Pass 34 1.9% 0.05 0.83 0.16 0.02 0.77 0.04 54.7% 7.5% 74.2%

Fail Unresolv. 1 0.1% 0.23 38.96 0.01 0.08 12.86 0.00 67.0% 67.0% 67.0%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 1,825 1.9% 0.04 0.93 0.18 0.04 0.92 0.18 1.4% 1.7% 1.2%

2010 Pass - 1,758 0.04 0.86 0.17 0.04 0.86 0.17 0.0% 0.0% 0.0%

T Fail Pass 22 1.2% 0.04 0.84 0.18 0.01 0.40 0.03 65.7% 52.9% 82.3%

Fail Unresolv. 4 0.2% 0.05 0.89 0.16 0.02 0.29 0.05 67.0% 67.0% 67.0%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 1,784 1.5% 0.04 0.86 0.17 0.04 0.85 0.17 1.0% 0.8% 1.2%

2011 Pass - 571 0.04 0.95 0.17 0.04 0.95 0.17 0.0% 0.0% 0.0%

T Fail Pass 7 1.2% 0.05 1.00 0.21 0.01 0.58 0.02 76.2% 41.4% 89.9%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 578 1.2% 0.04 0.95 0.17 0.04 0.95 0.17 1.1% 0.5% 1.4%

2012 Pass - 15 0.06 1.02 0.14 0.06 1.02 0.14 0.0% 0.0% 0.0%

T Fail Pass 1 6.3% 0.09 2.15 0.11 0.05 0.70 0.11 46.9% 67.2% 2.5%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 16 6.3% 0.06 1.09 0.14 0.06 1.00 0.14 4.5% 8.2% 0.1%

Total Trucks

All Pass - 366,709 0.26 3.17 0.71 0.26 3.17 0.71 0.0% 0.0% 0.0%

T Fail Pass 32,926 8.1% 1.36 16.62 1.87 0.60 6.58 1.34 56.1% 60.4% 28.4%

Fail Unresolv. 5,124 1.3% 4.09 44.59 3.05 1.31 14.72 1.00 67.9% 67.0% 67.3%

Fail Waiver 198 0.0% 4.15 47.97 3.26 3.35 42.23 2.90 19.3% 12.0% 11.1%

Total Fail% 404,957 9.4% 0.40 4.81 0.84 0.30 3.62 0.77 24.3% 24.9% 8.3%

Fleet Total

All Pass - 760,235 0.24 3.23 0.64 0.24 3.23 0.64 0.0% 0.0% 0.0%

All Fail Pass 60,729 7.3% 1.23 15.50 1.64 0.49 5.46 1.12 60.1% 64.8% 31.8%

A1-8
Appendix A1 Colorado 2011 Transient Test Emissions Reductions

Unresolved fails remaining in area 33%

Model First Last Initial Final Reduction %

Year/Type Result Result Vehicles Fail% HC CO NOX HC CO NOX HC CO NOX

Fail Unresolv. 10,782 1.3% 3.57 38.49 2.65 1.15 12.64 0.87 67.9% 67.2% 67.3%

Fail Waiver 354 0.0% 3.76 43.01 2.90 3.17 38.30 2.66 15.7% 11.0% 8.3%

Total Fail% 832,100 8.6% 0.35 4.60 0.74 0.27 3.53 0.68 24.1% 23.3% 8.3%

A1-9
Appendix A2 Colorado 2011 Clean Screen Audit Transient Test Emissions Reductions

Unresolved fails remaining in area 100%

Model First Last Initial Final Reduction %

Year/Type Result Result Vehicles Fail% HC CO NOX HC CO NOX HC CO NOX

1982 Pass - 0 ------ - - -

P Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00 0.0% 0.0% 0.0%

1983 Pass - 0 ------ - - -

P Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00 0.0% 0.0% 0.0%

1984 Pass - 0 ------ - - -

P Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00 0.0% 0.0% 0.0%

1985 Pass - 0 ------ - - -

P Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00 0.0% 0.0% 0.0%

1986 Pass - 0 ------ - - -

P Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00 0.0% 0.0% 0.0%

1987 Pass - 1 0.60 8.11 0.81 0.60 8.11 0.81 0.0% 0.0% 0.0%

P Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 1 0.0% 0.60 8.11 0.81 0.60 8.11 0.81 0.0% 0.0% 0.0%

1988 Pass - 1 0.96 7.78 1.00 0.96 7.78 1.00 0.0% 0.0% 0.0%

P Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 1 0.0% 0.96 7.78 1.00 0.96 7.78 1.00 0.0% 0.0% 0.0%

1989 Pass - 5 0.64 7.49 1.60 0.64 7.49 1.60 0.0% 0.0% 0.0%

P Fail Pass 1 16.7% 0.61 7.49 0.69 0.23 2.82 0.33 61.8% 62.4% 53.0%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 6 16.7% 0.63 7.49 1.45 0.57 6.71 1.39 9.9% 10.4% 4.2%

A1-1
Appendix A2 Colorado 2011 Clean Screen Audit Transient Test Emissions Reductions

Unresolved fails remaining in area 100%

Model First Last Initial Final Reduction %

Year/Type Result Result Vehicles Fail% HC CO NOX HC CO NOX HC CO NOX

1990 Pass - 8 0.37 7.03 1.05 0.37 7.03 1.05 0.0% 0.0% 0.0%

P Fail Pass 1 11.1% 0.18 6.31 0.67 0.23 5.84 0.67 -27.0% 7.6% 0.7%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 9 11.1% 0.35 6.95 1.01 0.35 6.89 1.00 -1.5% 0.8% 0.1%

1991 Pass - 7 0.36 5.68 0.98 0.36 5.68 0.98 0.0% 0.0% 0.0%

P Fail Pass 2 22.2% 0.62 5.44 1.72 0.80 8.09 2.31 -28.3% -48.7% -33.9%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 9 22.2% 0.41 5.63 1.15 0.45 6.22 1.28 -9.4% -10.5% -11.3%

1992 Pass - 5 0.77 6.83 1.48 0.77 6.83 1.48 0.0% 0.0% 0.0%

P Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 5 0.0% 0.77 6.83 1.48 0.77 6.83 1.48 0.0% 0.0% 0.0%

1993 Pass - 14 0.48 4.96 1.22 0.48 4.96 1.22 0.0% 0.0% 0.0%

P Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 14 0.0% 0.48 4.96 1.22 0.48 4.96 1.22 0.0% 0.0% 0.0%

1994 Pass - 14 0.39 4.89 0.74 0.39 4.89 0.74 0.0% 0.0% 0.0%

P Fail Pass 1 6.7% 0.29 2.88 0.74 0.39 5.20 0.74 -34.7% -80.9% -0.3%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 15 6.7% 0.38 4.76 0.74 0.39 4.91 0.74 -1.8% -3.3% 0.0%

1995 Pass - 32 0.24 3.10 0.68 0.24 3.10 0.68 0.0% 0.0% 0.0%

P Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 32 0.0% 0.24 3.10 0.68 0.24 3.10 0.68 0.0% 0.0% 0.0%

1996 Pass - 39 0.25 3.19 0.63 0.25 3.19 0.63 0.0% 0.0% 0.0%

P Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 39 0.0% 0.25 3.19 0.63 0.25 3.19 0.63 0.0% 0.0% 0.0%

1997 Pass - 73 0.25 2.74 0.62 0.25 2.74 0.62 0.0% 0.0% 0.0%

P Fail Pass 3 3.9% 1.30 3.03 0.56 0.41 1.74 0.50 68.4% 42.7% 10.5%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 76 3.9% 0.30 2.75 0.62 0.26 2.70 0.62 11.9% 1.9% 0.4%

A1-2
Appendix A2 Colorado 2011 Clean Screen Audit Transient Test Emissions Reductions

Unresolved fails remaining in area 100%

Model First Last Initial Final Reduction %

Year/Type Result Result Vehicles Fail% HC CO NOX HC CO NOX HC CO NOX

1998 Pass - 52 0.25 3.54 0.53 0.25 3.54 0.53 0.0% 0.0% 0.0%

P Fail Pass 2 3.7% 0.29 4.85 1.07 0.16 1.65 0.26 44.6% 65.9% 75.7%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 54 3.7% 0.25 3.59 0.55 0.25 3.47 0.52 1.9% 3.3% 5.4%

1999 Pass - 132 0.19 2.89 0.48 0.19 2.89 0.48 0.0% 0.0% 0.0%

P Fail Pass 5 3.6% 0.33 2.22 1.19 0.22 2.58 0.77 32.6% -16.3% 35.3%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 137 3.6% 0.19 2.87 0.51 0.19 2.88 0.49 2.0% -0.5% 3.0%

2000 Pass - 105 0.13 2.61 0.42 0.13 2.61 0.42 0.0% 0.0% 0.0%

P Fail Pass 2 1.9% 0.10 1.68 0.55 0.13 0.44 0.75 -35.6% 73.8% -36.6%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 107 1.9% 0.13 2.59 0.42 0.13 2.57 0.43 -0.5% 0.9% -0.9%

2001 Pass - 198 0.11 2.26 0.36 0.11 2.26 0.36 0.0% 0.0% 0.0%

P Fail Pass 6 2.9% 0.14 2.53 0.47 0.07 1.19 0.26 47.5% 52.9% 44.1%

Fail Unresolv. 1 0.5% 0.09 1.99 0.30 0.09 1.99 0.30 0.0% 0.0% 0.0%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 205 3.4% 0.11 2.27 0.37 0.11 2.23 0.36 1.7% 1.7% 1.6%

2002 Pass - 165 0.11 2.28 0.34 0.11 2.28 0.34 0.0% 0.0% 0.0%

P Fail Pass 6 3.5% 0.06 2.07 0.25 0.04 0.87 0.23 29.3% 57.8% 8.1%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 171 3.5% 0.11 2.27 0.34 0.11 2.23 0.33 0.6% 1.8% 0.2%

2003 Pass - 299 0.09 2.17 0.30 0.09 2.17 0.30 0.0% 0.0% 0.0%

P Fail Pass 8 2.6% 0.27 1.89 0.36 0.02 0.45 0.13 91.3% 76.2% 63.4%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 307 2.6% 0.10 2.16 0.30 0.09 2.13 0.29 6.7% 1.7% 2.0%

2004 Pass - 100 0.08 2.00 0.26 0.08 2.00 0.26 0.0% 0.0% 0.0%

P Fail Pass 4 3.8% 0.20 1.19 0.26 0.03 0.43 0.11 83.9% 63.8% 58.3%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 104 3.8% 0.09 1.97 0.26 0.08 1.94 0.25 7.3% 1.5% 2.2%

2005 Pass - 303 0.08 1.93 0.26 0.08 1.93 0.26 0.0% 0.0% 0.0%

P Fail Pass 11 3.5% 0.08 2.16 0.27 0.02 0.78 0.14 73.2% 63.8% 47.8%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 314 3.5% 0.08 1.93 0.26 0.08 1.89 0.26 2.7% 2.5% 1.7%

A1-3
Appendix A2 Colorado 2011 Clean Screen Audit Transient Test Emissions Reductions

Unresolved fails remaining in area 100%

Model First Last Initial Final Reduction %

Year/Type Result Result Vehicles Fail% HC CO NOX HC CO NOX HC CO NOX

2006 Pass - 102 0.08 1.87 0.24 0.08 1.87 0.24 0.0% 0.0% 0.0%

P Fail Pass 1 1.0% 0.07 2.26 0.43 0.01 0.48 0.04 89.9% 79.0% 91.8%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 103 1.0% 0.08 1.87 0.25 0.08 1.85 0.24 0.8% 0.9% 1.6%

2007 Pass - 317 0.08 1.95 0.23 0.08 1.95 0.23 0.0% 0.0% 0.0%

P Fail Pass 3 0.9% 0.07 2.05 0.21 0.01 0.56 0.03 86.7% 72.4% 87.1%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 320 0.9% 0.08 1.95 0.23 0.08 1.94 0.23 0.8% 0.7% 0.8%

2008 Pass - 0 ------ - - -

P Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00 0.0% 0.0% 0.0%

2009 Pass - 0 ------ - - -

P Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00 0.0% 0.0% 0.0%

2010 Pass - 0 ------ - - -

P Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00 0.0% 0.0% 0.0%

2011 Pass - 0 ------ - - -

P Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00 0.0% 0.0% 0.0%

2012 Pass - 0 ------ - - -

P Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00 0.0% 0.0% 0.0%

Total Passenger Vehicles

All Pass - 1,972 0.12 2.36 0.36 0.12 2.36 0.36 0.0% 0.0% 0.0%

P Fail Pass 56 2.8% 0.25 2.51 0.51 0.12 1.44 0.35 52.4% 42.5% 30.8%

Fail Unresolv. 1 0.0% 0.09 1.99 0.30 0.09 1.99 0.30 0.0% 0.0% 0.0%

Fail Waiver 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00

Total Fail% 2,029 2.8% 0.13 2.36 0.36 0.12 2.33 0.36 2.8% 1.2% 1.2%

A1-4
Appendix A2 Colorado 2011 Clean Screen Audit Transient Test Emissions Reductions

Unresolved fails remaining in area 100%

Model First Last Initial Final Reduction %

Year/Type Result Result Vehicles Fail% HC CO NOX HC CO NOX HC CO NOX

1982 Pass - 0 ------ - - -

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00 0.0% 0.0% 0.0%

1983 Pass - 0 ------ - - -

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00 0.0% 0.0% 0.0%

1984 Pass - 0 ------ - - -

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00 0.0% 0.0% 0.0%

1985 Pass - 0 ------ - - -

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00 0.0% 0.0% 0.0%

1986 Pass - 0 ------ - - -

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00 0.0% 0.0% 0.0%

1987 Pass - 0 ------ - - -

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00 0.0% 0.0% 0.0%

1988 Pass - 1 1.19 18.51 1.30 1.19 18.51 1.30 0.0% 0.0% 0.0%

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 1 0.0% 1.19 18.51 1.30 1.19 18.51 1.30 0.0% 0.0% 0.0%

1989 Pass - 0 ------ - - -

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00 0.0% 0.0% 0.0%

A1-5
Appendix A2 Colorado 2011 Clean Screen Audit Transient Test Emissions Reductions

Unresolved fails remaining in area 100%

Model First Last Initial Final Reduction %

Year/Type Result Result Vehicles Fail% HC CO NOX HC CO NOX HC CO NOX

1990 Pass - 2 0.56 7.64 0.48 0.56 7.64 0.48 0.0% 0.0% 0.0%

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 2 0.0% 0.56 7.64 0.48 0.56 7.64 0.48 0.0% 0.0% 0.0%

1991 Pass - 1 2.07 13.87 2.40 2.07 13.87 2.40 0.0% 0.0% 0.0%

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 1 0.0% 2.07 13.87 2.40 2.07 13.87 2.40 0.0% 0.0% 0.0%

1992 Pass - 1 1.60 10.16 0.65 1.60 10.16 0.65 0.0% 0.0% 0.0%

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 1 0.0% 1.60 10.16 0.65 1.60 10.16 0.65 0.0% 0.0% 0.0%

1993 Pass - 6 0.82 8.60 1.64 0.82 8.60 1.64 0.0% 0.0% 0.0%

T Fail Pass 3 33.3% 0.80 8.29 1.73 0.60 7.23 1.75 25.3% 12.8% -1.3%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 9 33.3% 0.82 8.49 1.67 0.75 8.14 1.68 8.3% 4.1% -0.5%

1994 Pass - 8 0.60 6.23 1.29 0.60 6.23 1.29 0.0% 0.0% 0.0%

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 8 0.0% 0.60 6.23 1.29 0.60 6.23 1.29 0.0% 0.0% 0.0%

1995 Pass - 23 0.43 3.70 1.12 0.43 3.70 1.12 0.0% 0.0% 0.0%

T Fail Pass 2 7.7% 1.38 9.93 4.85 1.13 8.69 4.34 18.0% 12.5% 10.4%

Fail Unresolv. 1 3.8% 11.92 182.47 0.20 11.83 62.89 0.21 0.8% 65.5% -4.5%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 26 11.5% 0.94 11.06 1.37 0.92 6.36 1.33 2.4% 42.5% 2.8%

1996 Pass - 24 0.36 3.72 0.93 0.36 3.72 0.93 0.0% 0.0% 0.0%

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 24 0.0% 0.36 3.72 0.93 0.36 3.72 0.93 0.0% 0.0% 0.0%

1997 Pass - 56 0.20 3.00 0.90 0.20 3.00 0.90 0.0% 0.0% 0.0%

T Fail Pass 7 11.1% 0.15 2.77 0.78 0.26 3.05 1.01 -80.4% -10.2% -28.6%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 63 11.1% 0.20 2.98 0.88 0.21 3.01 0.91 -6.6% -1.1% -2.8%

A1-6
Appendix A2 Colorado 2011 Clean Screen Audit Transient Test Emissions Reductions

Unresolved fails remaining in area 100%

Model First Last Initial Final Reduction %

Year/Type Result Result Vehicles Fail% HC CO NOX HC CO NOX HC CO NOX

1998 Pass - 61 0.25 3.17 1.05 0.25 3.17 1.05 0.0% 0.0% 0.0%

T Fail Pass 3 4.7% 0.12 1.33 0.60 0.25 2.62 1.00 -110.4% -96.8% -68.2%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 64 4.7% 0.24 3.08 1.03 0.25 3.14 1.05 -2.5% -2.0% -1.8%

1999 Pass - 142 0.17 2.16 0.68 0.17 2.16 0.68 0.0% 0.0% 0.0%

T Fail Pass 8 5.3% 0.08 1.38 0.65 0.06 0.88 0.71 21.3% 36.2% -10.5%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 150 5.3% 0.16 2.12 0.68 0.16 2.09 0.68 0.5% 1.3% -0.5%

2000 Pass - 113 0.16 2.00 0.60 0.16 2.00 0.60 0.0% 0.0% 0.0%

T Fail Pass 8 6.6% 0.63 20.60 1.87 0.20 2.21 0.87 68.2% 89.3% 53.4%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 121 6.6% 0.19 3.23 0.68 0.17 2.02 0.62 14.6% 37.6% 9.7%

2001 Pass - 283 0.11 1.61 0.49 0.11 1.61 0.49 0.0% 0.0% 0.0%

T Fail Pass 7 2.4% 0.06 1.26 0.77 0.10 1.57 0.50 -58.9% -24.6% 35.0%

Fail Unresolv. 1 0.3% 3.03 14.46 1.28 3.03 14.46 1.28 0.0% 0.0% 0.0%

Fail Waiver 1 0.3% 0.61 21.44 0.80 1.68 21.77 2.46 -175.5% -1.6% -208.3%

Total Fail% 292 3.1% 0.12 1.71 0.50 0.12 1.72 0.50 -3.8% -0.5% 0.1%

2002 Pass - 169 0.08 1.31 0.39 0.08 1.31 0.39 0.0% 0.0% 0.0%

T Fail Pass 9 5.1% 0.34 2.16 0.50 0.07 2.34 0.42 78.3% -8.3% 16.4%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 178 5.1% 0.10 1.35 0.40 0.08 1.36 0.39 14.2% -0.7% 1.1%

2003 Pass - 387 0.07 1.25 0.35 0.07 1.25 0.35 0.0% 0.0% 0.0%

T Fail Pass 17 4.2% 0.12 2.49 0.50 0.10 2.69 0.37 11.5% -8.3% 25.5%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 404 4.2% 0.07 1.30 0.36 0.07 1.31 0.35 0.8% -0.7% 1.5%

2004 Pass - 151 0.06 0.95 0.24 0.06 0.95 0.24 0.0% 0.0% 0.0%

T Fail Pass 2 1.3% 0.08 2.61 0.12 0.01 1.08 0.06 85.4% 58.5% 50.2%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 153 1.3% 0.06 0.97 0.24 0.06 0.95 0.24 1.5% 2.1% 0.3%

2005 Pass - 462 0.06 0.99 0.19 0.06 0.99 0.19 0.0% 0.0% 0.0%

T Fail Pass 4 0.9% 0.10 1.36 0.26 0.04 0.42 0.09 63.3% 69.1% 65.3%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 466 0.9% 0.06 0.99 0.19 0.06 0.98 0.19 1.0% 0.8% 0.8%

A1-7
Appendix A2 Colorado 2011 Clean Screen Audit Transient Test Emissions Reductions

Unresolved fails remaining in area 100%

Model First Last Initial Final Reduction %

Year/Type Result Result Vehicles Fail% HC CO NOX HC CO NOX HC CO NOX

2006 Pass - 162 0.05 0.95 0.20 0.05 0.95 0.20 0.0% 0.0% 0.0%

T Fail Pass 3 1.8% 0.06 0.79 0.14 0.08 0.60 0.07 -23.6% 24.2% 54.2%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 165 1.8% 0.05 0.95 0.20 0.05 0.95 0.20 -0.5% 0.4% 0.7%

2007 Pass - 513 0.05 0.85 0.18 0.05 0.85 0.18 0.0% 0.0% 0.0%

T Fail Pass 11 2.1% 0.05 0.90 0.19 0.02 0.44 0.04 57.9% 51.6% 76.9%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 524 2.1% 0.05 0.86 0.18 0.05 0.85 0.18 1.3% 1.1% 1.6%

2008 Pass - 0 ------ - - -

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00 0.0% 0.0% 0.0%

2009 Pass - 0 ------ - - -

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00 0.0% 0.0% 0.0%

2010 Pass - 0 ------ - - -

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00 0.0% 0.0% 0.0%

2011 Pass - 0 ------ - - -

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00 0.0% 0.0% 0.0%

2012 Pass - 0 ------ - - -

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00 0.0% 0.0% 0.0%

Total Trucks

All Pass - 2,565 0.09 1.40 0.37 0.09 1.40 0.37 0.0% 0.0% 0.0%

T Fail Pass 84 3.2% 0.23 4.02 0.77 0.15 2.16 0.61 34.3% 46.3% 20.2%

Fail Unresolv. 2 0.1% 7.47 98.46 0.74 7.43 38.68 0.74 0.6% 60.7% -0.6%

Fail Waiver 1 0.0% 0.61 21.44 0.80 1.68 21.77 2.46 -175.5% -1.6% -208.3%

Total Fail% 2,652 3.3% 0.10 1.56 0.38 0.10 1.46 0.38 2.0% 6.7% 1.1%

A1-8
Appendix A2 Colorado 2011 Clean Screen Audit Transient Test Emissions Reductions

Unresolved fails remaining in area 100%

Model First Last Initial Final Reduction %

Year/Type Result Result Vehicles Fail% HC CO NOX HC CO NOX HC CO NOX

Fleet Total

All Pass - 4,537 0.11 1.81 0.36 0.11 1.81 0.36 0.0% 0.0% 0.0%

All Fail Pass 140 3.0% 0.24 3.41 0.66 0.14 1.87 0.51 42.0% 45.2% 23.5%

Fail Unresolv. 3 0.1% 5.01 66.31 0.59 4.98 26.45 0.59 0.6% 60.1% -0.5%

Fail Waiver 1 0.0% 0.61 21.44 0.80 1.68 21.77 2.46 -175.5% -1.6% -208.3%

Total Fail% 4,681 3.1% 0.11 1.91 0.37 0.11 1.84 0.37 2.4% 3.8% 1.2%

A1-9
Appendix B Colorado 2011

Enhanced IM240 Test Reduction Tons

Initial Tons/Yr Final Tons/Yr Reduction Tons/Yr

Type

 Annual 

Miles 

 Unique 

Vehicles HC CO NOx HC CO NOx HC CO NOx

P 1982 4,304 356 4.3 48.2 3.5 2.9 33.6 3.2 1.5 14.6 0.3

P 1983 4,304 823 8.3 108.7 7.6 5.5 69.2 7.2 2.7 39.5 0.5

P 1984 4,434 1,055 10.4 131.9 10.1 7.2 80.6 9.7 3.2 51.3 0.4

P 1985 4,481 2,046 16.2 195.3 19.5 11.1 122.5 18.5 5.1 72.8 1.0

P 1986 4,502 1,927 12.0 145.7 17.7 8.8 99.4 16.6 3.2 46.3 1.1

P 1987 4,552 3,380 19.8 237.5 29.8 14.7 163.5 28.2 5.1 74.0 1.6

P 1988 4,780 2,914 17.7 213.0 25.4 12.7 144.8 23.9 5.0 68.2 1.5

P 1989 5,088 5,544 30.4 375.6 47.5 22.5 266.6 45.7 8.0 109.0 1.9

P 1990 5,430 6,127 33.9 411.4 57.0 25.1 294.5 53.1 8.8 116.8 3.9

P 1991 5,672 10,231 51.5 637.9 91.9 38.1 456.9 86.7 13.4 181.0 5.2

P 1992 6,002 8,971 48.1 584.1 82.2 33.2 389.0 76.0 15.0 195.0 6.2

P 1993 6,331 13,934 70.4 821.8 134.2 51.4 580.2 125.3 18.9 241.6 9.0

P 1994 6,653 13,129 56.9 660.0 105.4 40.0 493.5 97.4 16.9 166.4 8.0

P 1995 6,974 21,165 86.3 974.1 164.8 62.7 730.6 152.7 23.6 243.5 12.2

P 1996 7,369 16,905 53.4 677.2 117.2 41.0 517.2 105.9 12.4 160.1 11.3

P 1997 7,764 26,228 78.3 1023.1 174.5 61.1 807.5 160.3 17.2 215.6 14.3

P 1998 8,188 21,995 56.7 832.1 131.9 45.1 667.8 118.4 11.7 164.3 13.4

P 1999 8,613 31,560 74.5 1123.2 186.3 59.1 914.5 167.4 15.4 208.7 18.9

P 2000 9,032 27,327 56.9 931.1 151.9 43.4 768.4 130.1 13.5 162.7 21.8

P 2001 9,450 34,625 55.2 1046.1 155.9 44.5 908.9 138.7 10.7 137.2 17.2

P 2002 9,905 24,956 37.3 733.3 108.7 31.0 643.3 94.5 6.3 90.0 14.2

P 2003 10,360 32,698 41.7 877.0 126.5 35.3 802.4 116.4 6.4 74.6 10.1

P 2004 10,746 19,173 24.3 537.1 69.2 20.3 476.6 62.6 4.0 60.5 6.6

P 2005 11,132 33,124 37.0 869.5 117.4 33.4 808.3 110.0 3.7 61.2 7.4

P 2006 11,870 20,123 23.3 553.8 71.9 20.9 519.0 65.6 2.4 34.8 6.3

P 2007 12,023 34,021 36.4 875.5 114.8 34.3 843.0 108.0 2.1 32.5 6.8

P 2008 12,307 8,048 8.6 213.4 26.8 8.2 207.6 25.4 0.4 5.8 1.4

P 2009 12,357 2,330 2.4 62.6 7.7 2.3 60.9 7.4 0.1 1.6 0.3

P 2010 11,600 1,912 1.9 49.4 5.5 1.8 48.2 5.3 0.1 1.2 0.2

P 2011 9,650 504 0.4 10.3 1.2 0.4 10.3 1.2 0.0 0.0 0.0

P 2012 9,650 12 0.0 0.2 0.0 0.0 0.2 0.0 0.0 0.0 0.0

P Total 427,143 1054.6 15959.9 2364.0 817.9 12929.0 2161.2 236.7 3030.9 202.8

T 1982 4,554 404 7.8 97.5 5.4 5.5 63.7 5.1 2.4 33.8 0.3

T 1983 4,562 903 17.4 208.5 12.4 12.2 140.2 11.7 5.2 68.3 0.8

T 1984 4,583 1,101 18.2 238.9 15.2 12.5 148.6 14.2 5.7 90.2 1.0

T 1985 4,630 2,139 32.2 424.5 29.5 21.8 256.3 28.2 10.3 168.2 1.3

T 1986 4,668 1,948 25.0 295.9 27.2 17.4 185.3 25.2 7.5 110.6 2.0

T 1987 4,741 3,138 31.7 364.6 38.9 23.2 237.1 36.6 8.5 127.5 2.3

T 1988 4,851 3,010 31.5 312.9 36.3 21.5 210.0 32.9 10.0 102.9 3.4

T 1989 5,019 5,190 49.0 503.1 63.5 35.8 346.2 59.2 13.2 156.9 4.2

T 1990 5,256 3,967 35.1 357.8 51.2 26.4 258.5 47.4 8.7 99.3 3.8

T 1991 5,519 7,039 52.8 577.7 78.2 40.5 426.8 73.8 12.3 150.9 4.4

T 1992 5,824 5,762 46.8 502.8 72.4 34.6 369.1 67.3 12.2 133.6 5.1

T 1993 6,135 11,145 90.6 891.8 143.2 70.3 690.9 134.4 20.3 200.9 8.7

T 1994 6,471 12,056 84.9 894.3 147.8 60.9 646.4 130.3 24.0 247.9 17.5

T 1995 6,940 17,606 127.8 1238.9 235.7 91.0 900.4 213.1 36.7 338.5 22.5

T 1996 7,437 13,703 57.7 675.3 157.5 42.9 507.0 141.9 14.8 168.3 15.6

T 1997 7,863 23,713 89.2 1169.9 265.8 70.2 911.4 243.6 19.0 258.4 22.2

T 1998 8,345 21,322 70.6 922.6 225.8 54.4 718.7 200.1 16.2 203.9 25.8

T 1999 8,900 31,403 93.0 1126.1 283.5 73.6 900.5 251.7 19.5 225.6 31.8

T 2000 9,502 23,926 58.2 809.5 189.7 45.9 633.3 170.3 12.2 176.2 19.4

T 2001 10,087 31,521 51.3 804.7 187.5 43.5 693.5 172.4 7.8 111.1 15.2

T 2002 10,727 22,069 31.1 568.9 125.3 25.8 451.3 115.3 5.3 117.6 10.0

T 2003 11,245 32,093 38.7 670.4 155.6 33.4 567.1 147.3 5.3 103.3 8.3

T 2004 11,817 21,011 21.3 390.0 76.9 19.2 352.2 72.0 2.1 37.8 5.0

T 2005 12,303 36,144 31.5 572.0 111.4 29.7 537.4 107.1 1.8 34.6 4.3

T 2006 12,834 21,103 17.4 315.2 65.4 16.5 298.5 63.3 0.9 16.7 2.2

T 2007 13,215 38,751 27.8 528.4 108.8 26.8 509.7 105.5 1.0 18.6 3.3

T 2008 13,433 8,587 5.7 115.9 24.1 5.6 113.9 23.4 0.1 2.0 0.7

T 2009 13,514 1,825 1.2 25.3 4.9 1.1 24.9 4.9 0.0 0.4 0.1

T 2010 12,428 1,784 1.0 21.1 4.1 1.0 20.9 4.0 0.0 0.2 0.1

T 2011 8,995 578 0.3 5.4 1.0 0.3 5.4 0.9 0.0 0.0 0.0

T 2012 8,995 16 0.0 0.2 0.0 0.0 0.2 0.0 0.0 0.0 0.0

T Total 404,957 1246.6 15630.0 2944.2 963.6 12125.8 2703.2 283.0 3504.2 241.0

Total 832,100 2301.2 31590.0 5308.3 1781.5 25054.8 4864.4 519.7 6535.1 443.9

23% 21% 8%

B-1
Appendix B - Colorado 2011

RapidScreen Audit IM240 Test Reduction Tons

Initial Tons/Yr Final Tons/Yr Reduction Tons/Yr

Type

 Annual 

Miles 

 Unique 

Vehicles HC CO NOx HC CO NOx HC CO NOx

P 1982 4,304 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

P 1983 4,304 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

P 1984 4,434 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

P 1985 4,481 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

P 1986 4,502 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

P 1987 4,552 1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

P 1988 4,780 1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

P 1989 5,088 6 0.0 0.3 0.0 0.0 0.2 0.0 0.0 0.0 0.0

P 1990 5,430 9 0.0 0.4 0.1 0.0 0.4 0.1 0.0 0.0 0.0

P 1991 5,672 9 0.0 0.3 0.1 0.0 0.3 0.1 0.0 0.0 0.0

P 1992 6,002 5 0.0 0.2 0.0 0.0 0.2 0.0 0.0 0.0 0.0

P 1993 6,331 14 0.0 0.5 0.1 0.0 0.5 0.1 0.0 0.0 0.0

P 1994 6,653 15 0.0 0.5 0.1 0.0 0.5 0.1 0.0 0.0 0.0

P 1995 6,974 32 0.1 0.8 0.2 0.1 0.8 0.2 0.0 0.0 0.0

P 1996 7,369 39 0.1 1.0 0.2 0.1 1.0 0.2 0.0 0.0 0.0

P 1997 7,764 76 0.2 1.8 0.4 0.2 1.8 0.4 0.0 0.0 0.0

P 1998 8,188 54 0.1 1.8 0.3 0.1 1.7 0.3 0.0 0.1 0.0

P 1999 8,613 137 0.3 3.7 0.7 0.2 3.7 0.6 0.0 0.0 0.0

P 2000 9,032 107 0.1 2.8 0.5 0.1 2.7 0.5 0.0 0.0 0.0

P 2001 9,450 205 0.2 4.8 0.8 0.2 4.8 0.8 0.0 0.1 0.0

P 2002 9,905 171 0.2 4.2 0.6 0.2 4.2 0.6 0.0 0.1 0.0

P 2003 10,360 307 0.3 7.6 1.0 0.3 7.5 1.0 0.0 0.1 0.0

P 2004 10,746 104 0.1 2.4 0.3 0.1 2.4 0.3 0.0 0.0 0.0

P 2005 11,132 314 0.3 7.5 1.0 0.3 7.3 1.0 0.0 0.2 0.0

P 2006 11,870 103 0.1 2.5 0.3 0.1 2.5 0.3 0.0 0.0 0.0

P 2007 12,023 320 0.3 8.3 1.0 0.3 8.2 1.0 0.0 0.1 0.0

P 2008 12,307 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

P 2009 12,357 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

P Total 2,029 2.7 51.4 7.7 2.6 50.7 7.6 0.1 0.7 0.1

T 1982 4,554 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

T 1983 4,562 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

T 1984 4,583 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

T 1985 4,630 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

T 1986 4,668 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

T 1987 4,741 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

T 1988 4,851 1 0.0 0.1 0.0 0.0 0.1 0.0 0.0 0.0 0.0

T 1989 5,019 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

T 1990 5,256 2 0.0 0.1 0.0 0.0 0.1 0.0 0.0 0.0 0.0

T 1991 5,519 1 0.0 0.1 0.0 0.0 0.1 0.0 0.0 0.0 0.0

T 1992 5,824 1 0.0 0.1 0.0 0.0 0.1 0.0 0.0 0.0 0.0

T 1993 6,135 9 0.0 0.5 0.1 0.0 0.5 0.1 0.0 0.0 0.0

T 1994 6,471 8 0.0 0.4 0.1 0.0 0.4 0.1 0.0 0.0 0.0

T 1995 6,940 26 0.2 2.2 0.3 0.2 1.3 0.3 0.0 0.9 0.0

T 1996 7,437 24 0.1 0.7 0.2 0.1 0.7 0.2 0.0 0.0 0.0

T 1997 7,863 63 0.1 1.6 0.5 0.1 1.6 0.5 0.0 0.0 0.0

T 1998 8,345 64 0.1 1.8 0.6 0.1 1.9 0.6 0.0 0.0 0.0

T 1999 8,900 150 0.2 3.1 1.0 0.2 3.1 1.0 0.0 0.0 0.0

T 2000 9,502 121 0.2 4.1 0.9 0.2 2.6 0.8 0.0 1.5 0.1

T 2001 10,087 292 0.4 5.5 1.6 0.4 5.6 1.6 0.0 0.0 0.0

T 2002 10,727 178 0.2 2.8 0.8 0.2 2.9 0.8 0.0 0.0 0.0

T 2003 11,245 404 0.4 6.5 1.8 0.4 6.6 1.8 0.0 0.0 0.0

T 2004 11,817 153 0.1 1.9 0.5 0.1 1.9 0.5 0.0 0.0 0.0

T 2005 12,303 466 0.4 6.3 1.2 0.3 6.2 1.2 0.0 0.1 0.0

T 2006 12,834 165 0.1 2.2 0.5 0.1 2.2 0.5 0.0 0.0 0.0

T 2007 13,215 524 0.3 6.5 1.4 0.3 6.5 1.4 0.0 0.1 0.0

T 2008 13,433 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

T 2009 13,514 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

T Total 2,652 3.0 46.6 11.4 3.0 44.1 11.3 0.1 2.6 0.1

Total 4,681 5.7 98.0 19.1 5.5 94.8 18.9 0.1 3.2 0.2

B-2