Envirotest Systems 

5175 Marshall St., 

Arvada, Colorado 80002 

The Colorado Remote Sensing Program 

January – December 2012

December 2013 

Prepared for: 

The Colorado Department of Public Health and 

Environment 

Prepared by: 

Peter M McClintock, Ph.D. 

Applied Analysis 

13700 Marina Pointe Drive #301 

Marina Del Rey CA 90292-9276

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

VIII. RAPIDSCREEN BENEFITS .............................................................................................................. 49

A. GREENHOUSE GAS AND POLLUTANTS FROM CLEAN SCREEN OPERATIONS ............................................ 49

1. RapidScreen Operating Vehicles ........................................................................................................... 49

2. Generators ............................................................................................................................................. 50

3. Calibration and Audit Gases .................................................................................................................. 50

4. RapidScreen Vehicle Emissions Reductions .......................................................................................... 50

B. RAPIDSCREEN VEHICLE OWNER SAVINGS .............................................................................................. 51

IX. RECOMMENDATIONS ......................................................................................................................... 52

REFERENCES 

APPENDICES 

 A1 COLORADO 2012 TRANSIENT TEST EMISSIONS REDUCTIONS 

 A2 COLORADO 2012 CLEAN SCREEN AUDIT TRANSIENT TEST EMISSION REDUCTIONS 

 B COLORADO 2012 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 2012 ............................................................................................... 41

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

TABLE VIII-1 REDUCTIONS IN GREENHOUSE GASES AND POLLUTANTS FROM RAPIDSCREEN OPERATIONS .......... 49

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. IM240 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 2005-20111 described 

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

covers calendar year 2012. 

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. 

Rapidscreen provided benefits to vehicle owners of $5.1M through reduced time and expense 

associated with eliminated inspection station visits. The reduction in station inspections also 

yielded net savings in greenhouse gases and 200,000 gallons of gasoline. 

Collection Activity 

In 2012, eighteen RSD vans were deployed in the DMA with an additional 4 in the Northern 

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

rotated for preventive or corrective maintenance. Van’s deployed at 80 locations in the DMA, 

35 sites in the NFR and 2 sites in Colorado Springs for a total of 24,204 active collection 

hours. A total 6.7 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. 

2011 vs 2012 Collection Comparison 

In 2011, RSD performed over 7.7 million emission measurements at 90 locations in the DMA 

and 42 locations in the NFR. In 2012 there were one million fewer emission measurements. 

Despite the reduction in the quantity of emission measurements the number of clean screens 

issued remained similar, 289,768 in 2011 vs. 280,310 in 2012. This was partly due to the 

application of new location performance metrics by the contractor. 
6 

Vehicle Exemptions 

Almost 290,000 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 280,310 vehicles meeting the clean screening criteria were issued 

notices granting exemption from the I/M test at an inspection station. Approximately 248,000 

(88%) 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 4,530 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 annually thereafter. 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. For all pollutants the 

RSD-LEI audit sample showed smaller reductions than 2-RSD indicating the hybrid RSD-LEI 

method performed better. 
7 

Figure I-1 Average IM240 Emissions Reductions 

For 2012, based on the 2% random audit vehicles tested with IM240, it was projected that 

97.4%, 97.1% and 93.9% 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 

2.5% 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

2-RSD

RSD-LEI

g/mi

HC

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Station

2-RSD

RSD-LEI

CO

0.00

0.02

0.04

0.06

0.08

0.10

Station

2-RSD

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 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 calibration 

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 passing 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 2 16 2,440 151

2144 NB STANDFORD FROM MONROE DR FT COLLINS 29 203 14,013 69

3017 EB TRILBY ROAD EAST OF SHIELDS STREET FORT COLLINS 24 185 41,775 226

3019 ON RAMP TO NB I-25 FROM 402 (CR-54) LOVELAND 4 20 1,766 90

3020 ON RAMP TO SB I-25 FROM 402 (CR-54) LOVELAND 22 143 17,868 125

3508 ONRAMP TO NB I-25 FROM HARMONY RD. FT. COLLINS 2 16 1,309 82

3509 ONRAMP TO NB I-25 FROM PROSPECT RD. FT. COLLINS 2 17 857 51

3510 SB SHIELDS ST. AFTER FOSSIL CREEK FT. COLLINS 5 35 6,469 182

3512 SB TIMBERLINE RD. JUST BEFORE WILLOW SPRINGS RD. FT. COLLINS 2 16 2,505 156

3513 NB SHIELDS RD. AFTER BON HOMME RD. FT. COLLINS 25 173 10,729 62

3514 NB TAFT HILL RD. AFTER HARMONY RD. FT. COLLINS 46 337 111,980 332

3515 ONRAMP TO NB I-25 FROM WB US-34 FT. COLLINS 26 198 25,233 127

3516 ONRAMP TO NB I-25 FROM CROSSROADS BLVD. FT. COLLINS 19 140 15,122 108

3517 ONRAMP TO SB I-25 FROM CROSSROADS BLVD. FT. COLLINS 33 248 27,200 110

3527 EB 392 AFTER INTERSECTION WITH CR-9 FT. COLLINS 14 102 11,537 113

3528 ONRAMP TO SB I-25 FROM EB MULBERRY ST. FT. COLLINS 13 91 5,764 63

8041 WB US-287 JUST WEST OF SHIELDS ST. FT COLLINS 26 193 31,169 161

8042 ONRAMP TO SB I-25 FROM EAST PROSPECT FT COLLINS 39 296 65,741 222

8049 ONRAMP TO SB I-25 FROM HARMONY RD FT COLLINS 20 155 34,018 220

8052 NB SH-1 JUST EAST OF INTERSECTION WITH US-287 FT COLLINS 15 103 14,457 141

8053 EB US-287 ABOUT 500' EAST OF LCR-17 BERTHOUD 19 125 4,850 39

2989 EB US 34 BYPASS FROM 23RD AVE GREELEY 60 470 68,758 146

3507 ONRAMP TO SB US-85 FROM HWY 52 FT. LUPTON 4 24 4,245 174

3519 ONRAMP TO SB I-25 FROM SR-56 BERTHOUD 17 109 4,938 45

3520 ONRAMP TO SB I-25 FROM SR-66 LONGMONT 2 14 1,348 97

3521 ONRAMP TO SB I-25 FROM SR-52 LONGMONT 15 96 20,815 216

3522 ONRAMP TO SB I-25 FROM CR-8 DACONO 38 242 17,304 72

3524 ONRAMP TO NB I-25 FROM SR-52 LONGMONT 9 62 4,876 79

3525 ONRAMP TO NB I-25 FROM SR-119 LONGMONT 10 64 9,388 148

3526 ONRAMP TO NB I-25 FROM SR-66 LONGMONT 12 67 4,786 71

8037 EB US-34 BYPASS FRONTAGE ROAD JUST EAST OF 35TH AVE. GREELEY 20 136 10,264 75

8043 ONRAMP TO WB US-34 FROM 27TH ST GREELEY 52 403 81,934 203

8044 ONRAMP TO EB US-34 FROM SH-257 GREELEY 18 129 13,761 107

8045 ONRAMP TO EB US-34 BYPASS FROM SH-257 GREELEY 20 150 16,383 109

8048 ONRAMP TO WB US-34 FROM SH-257 GREELEY 13 102 5,875 57

Subtotal 677 4,881 711,477 146
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 1,982 88

2462 ONRAMP TO EB I-76 FROM NB BRIGHTON BLVD COMMERCE CITY 2 15 2,999 203

2808 ONRAMP TO SB I-25 FROM 136TH AVE THORNTON 3 23 4,030 179

2819 ONRAMP TO SB 121 FROM WB 287 WESTMINSTER 101 1,048 313,405 299

2821 ONRAMP TO NB I-25 FROM 120TH AVE WESTMINSTER 35 260 55,600 214

2971 EB DILLON RD EAST OF US-287 BROOMFIELD 37 272 70,199 258

3498 ONRAMP TO WB I-76 FROM 74TH AVE. COMMERCE CITY 1 7 1,636 226

8073 ONRAMP TO NB I-25 FROM 104TH AVE. NORTHGLENN 58 517 92,141 178

8087 ONRAMP TO WB I-70 FROM AIRPORT BLVD. AURORA 29 235 46,281 197

8088 ONRAMP TO WB I-76 FROM 88TH AVE COMMERCE CITY 2 15 1,961 130

8093 ONRAMP TO WB I-70 FROM NB I-25 DENVER 205 2,011 1,032,654 514

8107 ONRAMP TO WB US-36 FROM BROADWAY DENVER 76 675 185,783 275

8115 ONRAMP TO EB I-76 FROM FEDERAL BLVD DENVER 6 32 4,489 141

8129 ONRAMP TO WB I-76 FROM PECOS ST DENVER 4 28 5,895 207

2170 ONRAMP TO NB I-225 FROM BELLEVIEW AVE. CHERRY HILLS 14 118 15,300 130

8095 ONRAMP TO SB I-225 FROM ILLIFF AVE. AURORA 4 29 2,820 97

8098 ONRAMP TO NB I-225 FROM ILLIFF AVE AURORA 7 62 10,225 164

8120 ONRAMP TO SB I-225 FROM ALAMEDA AVE AURORA 37 293 45,445 155

8121 ONRAMP TO SB I-225 FROM MISSISSIPPI AVE AURORA 28 224 58,143 260

2512 ONRAMP TO NB SH-157 FROM PEARL ST. BOULDER 32 239 36,142 151

2513 ONRAMP TO SB DIAGONAL HWY FROM NB BOULDER RD BOULDER 7 56 4,109 73

2514 ONRAMP TO 96TH AVE FROM SH-42. BOULDER 25 178 32,271 181

2826 ONRAMP TO EB US-36 FROM MCCASLIN LOUISVILLE 29 260 45,248 174

2827 ONRAMP TO WB US-36 FROM INTERLOCKIEN LOOP LOUISVILLE 10 63 7,961 127

2828 ONRAMP TO NB DIAGONAL FROM NB 119 BOULDER 8 58 5,758 99

8057 ON-RAMP TO SB SH 157 FROM PEARL ST. BOULDER 41 287 54,970 192

8064 ONRAMP TO NB SH 157 (FOOTHILLS PKAY) FROM EB TABLE MESA BOULDER 39 267 48,363 181

8079 ONRAMP TO WB US-36 FROM WADSWORTH PKWY BROOMFIELD 69 701 230,729 329

2171 ONRAMP TO WB I-70 FROM PECOS ST. DENVER 2 16 3,386 212

2456 ONRAMP TO SB I-225 FROM PEORIA ST DENVER 29 233 40,269 173

2560 ONRAMP TO EB US-6TH AVE FROM SB I-25 DENVER 19 208 47,788 230

2811 ONRAMP TO I-25 FROM WB SPEER DENVER 29 210 75,604 360

3504 ONRAMP TO EB I-70 FROM PEORIA ST. DENVER 71 509 146,717 289

3505 ONRAMP TO WB I-70 FROM QUEBEC ST. DENVER 14 107 42,352 396

8059 ONRAMP TO NB SANTA FE FROM US-285 (HAMPDEN AVE) ENGLEWOOD 51 367 76,924 210

8081 ONRAMP TO EB I-70 FROM HAVANA ST. DENVER 19 154 30,713 200

8094 ONRAMP TO SB US-285 (HAMPDEN AVE) FROM FEDERAL BLVD SHERIDAN 17 116 25,762 222

8096 ONRAMP TO NB US-285 (HAMPDEN AVE) FROM FEDERAL BLVD. SHERIDAN 15 96 15,790 164

8097 ONRAMP TO WB US-6TH AVE FROM NB I-25 DENVER 154 1,122 796,212 709

8113 ONRAMP TO SB US-285 (HAMPDEN AVE) FROM SHERIDAN BLVD. DENVER 30 224 48,187 215

8122 ONRAMP TO NB I-25 FROM PARK AVE DENVER 80 551 184,006 334

8123 ONRAMP TO NB I-25 FROM 58TH AVE. DENVER 73 691 177,902 258

8126 ONRAMP TO EB I-70 FROM PECOS ST DENVER 45 405 100,370 248

2319 ONRAMP TO EB C-470 FROM LUCENT BLVD HIGHLANDS RANCH 27 202 44,485 220

2320 ONRAMP TO EB C-470 FROM BROADWAY HIGHLANDS RANCH 50 393 176,585 449

2321 ONRAMP TO EB C-470 FROM UNIVERSITY BLVD HIGHLANDS RANCH 35 280 92,422 330

2322 ONRAMP TO WB C-470 FROM UNIVERSITY BLVD HIGHLANDS RANCH 17 124 26,139 210

2323 ONRAMP TO WB C-470 FROM LUCENT BLVD. HIGHLANDS RANCH 16 99 11,289 115

2574 ONRAMP TO NB I-25 FROM WB COUNTY LINE RD. HIGHLANDS RANCH 19 140 17,152 123

2576 ONRAMP TO SB I-25 FROM EB COUNTY LINE RD. HIGHLANDS RANCH 43 289 63,571 220

2577 ONRAMP TO NB I-25 FROM EB COUNTY LINE RD. HIGHLANDS RANCH 59 442 198,705 450

3501 ONRAMP TO NB I-25 FROM EB LINCOLN AVE LONE TREE 23 179 63,103 353
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

8077 ONRAMP TO EB C-470 FROM QUEBEC ST. HIGHLANDS RANCH 51 375 189,713 505

8083 ONRAMP TO SB I-25 FROM FOUNDERS PARKWAY (EXIT 184) CASTLE ROCK 36 280 49,064 175

8084 ONRAMP TO SB I-25 FROM LINCOLN AVE. LITTLETON 31 225 28,732 128

8085 ONRAMP TO NB I-25 FROM WOLFENSBERGER RD. (EXIT 182) CASTLE ROCK 44 328 108,266 331

8086 ONRAMP TO NB I-25 FROM FOUNDERS PARKWAY (EXIT 184) CASTLE ROCK 45 333 117,364 352

2172 ONRAMP TO EB C-470 FROM BOWLES AVE. LAKEWOOD 1 8 1,020 126

2173 ONRAMP TO EB C-470 FOM KEN CARYL AVE. LAKEWOOD 1 8 591 74

2174 ONRAMP TO WB C-470 FROM WADSWORTH PKWY LAKEWOOD 5 39 4,418 112

2175 ONRAMP TO WB C-470 FROM KIPLING ST. LAKEWOOD 2 16 1,558 98

2176 ONRAMP TO WB C-470 FROM KEN CARYL AVE LAKEWOOD 18 123 38,289 311

2325 ONRAMP TO EB C-470 FROM QUINCY AVE LAKEWOOD 4 31 3,137 100

2327 ONRAMP TO WB I-70 FROM WB US-6TH AVE GOLDEN 1 6 176 28

2400 ONRAMP TO WB C-470 FROM NB US-285 (HAMPDEN AVE) LAKEWOOD 30 206 53,721 261

2458 ONRAMP TO WB US-6TH AVE FROM SIMMS ST LAKEWOOD 4 47 14,063 297

2460 ONRAMP TO EB US-6TH AVE FROM SB WADSWORTH BLVD LAKEWOOD 4 24 4,446 182

2461 ONRAMP TO WB US-6TH AVE FROM NB WADSWORTH BLVD LAKEWOOD 26 184 44,776 243

2464 ONRAMP TO WB I-70 FROM NB WADSWORTH BLVD ARVADA 4 31 2,108 69

2572 ONRAMP TO SB I-25 FROM EB US-6TH AVE LAKEWOOD 7 36 8,675 242

8058 ONRAMP TO WB I-76 FROM SHERIDAN BLVD. ARVADA 25 154 35,186 229

8061 SB HERITAGE RD. AT INTERSECTION WITH US-40 (COLFAX) GOLDEN 2 11 601 56

8069 ONRAMP TO WB I-70 FROM KIPLING ST. WHEATRIDGE 20 188 51,107 272

8104 ONRAMP TO SB US-285 (HAMPDEN AVE) FROM WADSWORTH BLVD. DENVER 23 168 26,249 157

8105 ONRAMP TO SB US-285 (HAMPDEN AVE) FROM KIPLING BLVD. DENVER 15 171 25,840 151

8106 ONRAMP TO NB US-285 (HAMPDEN AVE) FROM KIPLING BLVD. DENVER 51 548 113,630 208

8110 ONRAMP TO EB SH-58 FROM WASHINGTON AVE GOLDEN 4 48 12,629 263

8111 ONRAMP TO EB SH-58 FROM MCINTYRE ST. GOLDEN 25 193 59,380 308

8112 ONRAMP TO WB C-470 FROM MORRISON RD. MORRISON 3 15 1,642 107

8130 ONRAMP TO EB I-76 FROM SHERIDAN BLVD ARVADA 25 251 58,605 233

Subtotal 2,356 19,196 5,976,958 311

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 7 43 6,785 158 

2520 ONRAMP TO NB I-25 FROM N.ACADEMY BLVD COLORADO SPRINGS 14 85 15,316 180 

Subtotal 21 128 22,101 173

Total 3,054 24,204 6,710,536 277
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 3,054 days during 2012 to collect 6.0M 

measurements in the Denver metropolitan area (DMA) Metro Area, 711,000 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 248,525 DMA 

vehicles and 31,785 NFR vehicles scheduled to renew their registration in 2012 and due for 

emissions testing (Table III-1). 

Vehicles registered in the DMA accounted for 5.3M measurements, the NFR for 722,000, and El 

Paso County 108,000. Another 240,000 measurements were of vehicles registered in other 

Colorado counties (Table III-2). 

In 2011, RSD performed over 7.7 million emission measurements at 90 locations in the DMA 

and 42 locations in the NFR. In 2012 there were one million fewer emission measurements. 

Despite the reduction in the quantity of emission measurements the number of clean screens 

issued remained similar, 289,768 in 2011 vs. 280,310 in 2012. This was partly due to the 

application of new location performance metrics by the contractor. 

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 7:00am and 7:00pm. 

Statistic

Denver Metro 

Area

Northern 

Front Range

Colorado 

Springs Total

Sites Used 80 35 2 117 

Collection Van Days 2,356 677 21 3,054 

Active Collection Van Hours 19,196 4,881 128 24,204 

Matched to Registration 5,976,958 711,477 22,101 6,710,536 

Notices Generated for 2012 renewals 248,525 31,785 280,310
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

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

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 within the DMA. A majority 

(77%) of Northern Front Range registered vehicles were measured in NFR with the remaining 

23% being measured in the DMA. 

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

79.7% of vehicles measured were registered in the DMA, 10.8% in the NFR, 1.6% in El Paso 

County (Colorado Springs), 3.6% in other non-I/M counties, and 4.3% 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 sixty-five measurements of motorcycles were also 

recorded. 

Table III-2 Source of Vehicle Registrations Measured by RSD 

Measured In

Denver Metro Area Northern Front Range El Paso

Adams 830,209 98% 17,376 2% 233 0% 847,818 

Arapahoe 724,946 98% 14,063 2% 608 0% 739,617 

Boulder 343,250 95% 19,889 5% 55 0% 363,194 

Broomfield 205,812 99% 2,469 1% 22 0% 208,303 

Denver 914,792 98% 15,654 2% 600 0% 931,046 

Douglas 806,102 99% 6,244 1% 673 0% 813,019 

Jefferson 1,404,645 99% 11,888 1% 315 0% 1,416,848 

State of Colorado 25,658 85% 4,009 13% 357 1% 30,024 

Subtotal Denver Metro 5,255,414 98% 91,592 2% 2,863 0% 5,349,869 

Larimer 55,554 14% 333,369 86% 89 0% 389,012 

Weld 108,180 32% 225,553 68% 86 0% 333,819 

Subtotal Northern Front Range 163,734 23% 558,922 77% 175 0% 722,831 

El Paso El Paso 85,039 79% 5,804 5% 17,398 16% 108,241 

Non I/M 217,540 90% 21,825 9% 1,032 0% 240,397 

Not Matched 289,198

Total 5,721,727 678,143 21,468 6,710,536 

Registered 

County

Total

Northern Front 

Range

Denver Metro Area

Program
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 340,951 503,676 3,191 847,818 12.6%

Arapahoe 308,905 428,482 2,230 739,617 11.0%

Boulder 167,557 194,531 1,106 363,194 5.4%

Broomfield 93,733 113,998 572 208,303 3.1%

Denver 396,661 529,474 4,911 931,046 13.9%

Douglas 284,314 527,344 1,360 813,018 12.1%

Jefferson 584,146 828,409 4,293 1,416,848 21.1%

State of Colorado 8,762 20,567 695 30,024 0.4%

Denver Metro 2,185,029 3,146,481 18,358 5,349,868 79.7%

Larimer 152,712 234,015 2,285 389,012 5.8%

Weld 132,925 199,193 1,701 333,819 5.0%

Subtotal North Front Range 285,637 433,208 3,986 722,831 10.8%

El Paso El Paso 44,436 63,171 634 108,241 1.6%

Non I/M 86,076 152,109 2,212 240,397 3.6%

Not Matched 4.3% 289,199

Total 2,601,178 3,794,969 25,190 6,710,536 100.0%

Denver Metro

Northern Front 

Range

 Vehicle 

Type Model Year 

 Denver 

Metro Area 

 Northern 

Front Range El Paso 

 NonI/M Total 

Pass 1981 & older 322 74 8 23 427 

1982-1990 37,203 6,400 830 2,628 47,061 

1991-1995 141,458 21,866 2,818 7,051 173,193 

1996-2000 422,976 58,897 8,352 17,462 507,687 

2001-2005 704,509 94,559 14,286 28,241 841,595 

2006-2010 658,390 81,696 13,924 24,416 778,426 

2011 & newer 220,171 22,145 4,218 6,255 252,789 

 Light 

Truck 1981 & older 371 151 13 120 655 

1982-1990 29,705 6,257 712 2,692 39,366 

1991-1995 118,236 20,502 2,501 7,872 149,111 

1996-2000 506,465 73,790 9,762 25,943 615,960 

2001-2005 1,068,502 147,376 22,277 50,183 1,288,338 

2006-2010 1,077,395 142,611 21,794 50,355 1,292,155 

2011 & newer 345,807 42,521 6,112 14,944 409,384 

Unknown 1981 & older 10,272 2,266 309 1,365 14,212 

1982-1990 276 87 54 81 498 

1991-1995 427 102 17 66 612 

1996-2000 1,509 268 37 147 1,961 

2001-2005 2,084 423 87 181 2,775 

2006-2010 2,130 621 72 194 3,017 

2011 & newer 815 155 19 93 1,082 

Motorcycles 277 64 39 85 465 

Total 722,831 5,349,300 108,241 240,397 6,420,769 
25 

IV. Clean Screening Program Performance 

A. Vehicles Selected, Notices and Redemptions 

In 2012, there were 289,965 vehicles qualifying for participation 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 changing owner were likely to have 

obtained an earlier station inspection. Compared to the 280,310 vehicles notified in the year, 

fewer vehicles 248,224 (88.6%) 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 notified via the Department of 

Revenue. Table IV-3 shows inspection results of the audit sample. Just 0.9% of the audit 

sample failed their exhaust emissions inspection up from 0.3% in 2011. Gas cap pressure test 

failures of 3.3% were also up from 2.8% in 2011. 

Reg 

Year

Reg 

Month

Random 

Sample QA failed Notified

Total 

Qualified

Random 

% of 

Qualified

2012 Jan 500 256 24,106 24,862 2.0%

2012 Feb 492 251 23,793 24,536 2.0%

2012 Mar 526 308 25,655 26,489 2.0%

2012 Apr 478 224 23,047 23,749 2.0%

2012 May 492 245 23,692 24,429 2.0%

2012 Jun 471 269 22,854 23,594 2.0%

2012 Jul 510 261 24,619 25,390 2.0%

2012 Aug 545 871 25,284 26,700 2.0%

2012 Sep 500 402 23,868 24,770 2.0%

2012 Oct 507 310 24,223 25,040 2.0%

2012 Nov 407 230 19,524 20,161 2.0%

2012 Dec 401 199 19,645 20,245 2.0%

Total 5,829 3,826 280,310 289,965 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 4,177 4,195 4,374 4,043 4,275 4,194 4,390 4,468 4,066 3,979 3,338 3,021 48,520

AURORA 1,609 1,566 1,868 1,631 1,696 1,610 1,766 1,879 1,775 1,785 1,453 1,426 20,064

LITTLETON 1,318 1,301 1,455 1,217 1,259 1,239 1,351 1,336 1,398 1,437 1,179 1,172 15,662

ARVADA 1,324 1,253 1,367 1,276 1,341 1,233 1,373 1,341 1,311 1,340 990 1,008 15,157

LAKEWOOD 1,147 1,126 1,321 1,166 1,175 1,055 1,141 1,235 1,182 1,229 985 972 13,734

HIGHLAND RCH 1,083 1,133 1,104 1,061 1,042 990 1,165 1,188 1,105 1,187 941 951 12,950

WESTMINSTER 985 1,033 1,113 994 1,052 1,020 1,076 1,095 1,074 1,091 797 826 12,156

THORNTON 1,004 994 1,040 924 951 925 994 974 930 955 750 776 11,217

FT COLLINS 977 895 982 813 805 831 999 1,050 910 947 723 865 10,797

CENTENNIAL 934 883 866 796 837 721 906 928 858 891 770 694 10,084

BOULDER 817 765 820 763 740 705 731 827 802 823 654 697 9,144

BROOMFIELD 741 676 793 716 724 694 815 838 760 799 612 620 8,788

CASTLE ROCK 719 744 798 657 727 653 757 751 754 708 578 565 8,411

PARKER 683 673 738 685 611 596 666 616 634 616 471 491 7,480

GOLDEN 651 617 677 643 601 553 581 617 573 604 472 481 7,070

LONGMONT 432 411 470 405 463 436 456 475 459 489 389 405 5,290

GREELEY 403 478 483 390 477 407 457 464 429 415 346 443 5,192

ENGLEWOOD 442 454 475 436 419 370 412 453 423 393 333 351 4,961

LOVELAND 353 402 421 408 378 372 423 438 359 378 342 391 4,665

BRIGHTON 273 301 322 272 306 309 309 293 253 271 210 209 3,328

COMMERCE CITY 270 286 286 283 299 341 286 276 229 255 177 201 3,189

NORTHGLENN 262 280 306 263 293 268 271 268 256 264 234 215 3,180

WHEAT RIDGE 278 253 271 256 234 298 253 275 250 278 228 236 3,110

LOUISVILLE 205 201 250 191 205 234 231 226 205 230 169 159 2,506

LAFAYETTE 217 190 215 206 176 200 229 215 230 221 181 162 2,442

EVERGREEN 228 198 204 191 187 208 210 187 190 206 165 162 2,336

LONE TREE 174 166 171 165 158 158 157 193 180 166 140 123 1,951

MORRISON 159 156 175 139 153 163 175 168 173 182 162 135 1,940

GREENWOOD VLG 209 167 178 157 169 140 168 162 145 161 119 94 1,869

WINDSOR 195 141 161 160 144 115 136 158 146 137 125 166 1,784

ERIE 157 142 179 157 149 135 136 148 134 128 121 152 1,738

CASTLE PNS N 144 146 137 132 133 126 146 163 143 145 109 105 1,629

SUPERIOR 144 127 142 120 139 129 141 141 129 121 119 106 1,558

CONIFER 59 81 99 83 87 81 100 89 113 97 74 89 1,052

EVANS 95 93 84 80 75 100 82 96 75 83 72 82 1,017

FREDERICK 71 56 76 56 89 78 83 72 76 63 57 85 862

JOHNSTOWN 70 72 85 59 61 71 59 76 50 61 67 72 803

FT LUPTON 81 71 96 77 66 81 73 51 57 50 34 49 786

LARKSPUR 58 72 69 53 65 55 45 71 57 61 51 53 710

OTHER 958 995 984 923 931 960 870 983 975 977 787 835 11,178

Total 24,106 23,793 25,655 23,047 23,692 22,854 24,619 25,284 23,868 24,223 19,524 19,645 280,310

Vehicle Type Vehicles

Fail 

Emissions

Fail Gas 

Cap / 

Pressure

Fail 

Inspection

Passenger 1,968 22 59 82 

Light Truck 2,627 19 92 103 

Total 4,595 41 151 185 

Percentage 0.9% 3.3% 4.0%
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 2013. 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, 0.9% of the tested audit vehicles failed their tailpipe 

emissions inspection, and 3.3% of the tested audit vehicles failed their gas cap pressure test2

. 

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

of the Clean Screen program. 

Tailpipe Emissions 

Over 91% of inspected vehicles, and 99% 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 there was only a single test result for a particular vehicle. The 

expected combinations applying 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) 

 W – Failed and wavered (F/W) 

 

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 

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 fast-passing 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 having initial tests 

in late 2012 but completing 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. Later studies in Colorado 

preliminarily indicate the percentage leaving the area may be as high as 80%. 

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

were included through the end of February 2013 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 1,271 1985 model year passenger vehicles tested using the IM240 transient 

test, 17.6% of vehicles initially failed inspection and were repaired (Pass) with HC, CO and NOx 

reductions of 56.8%, 69.1% and 7.8%. Another 8.3% of vehicles failed their initial inspection 

and had not successfully passed a retest by end February 2013 (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, CO and NOx reductions of 14.7%, 2.0% and 58.3%. In 

aggregate, including vehicles passing their initial inspection, emission reductions for 1985 

passenger vehicles were 32.7% for HC, 39.1% for CO and 7.3% 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 2012 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 C

1982 Pass - 332 1.57 18.62 2.14 1.57 18.62 2.14 0.0% 0.0% 

P Fail Pass 88 19.4% 3.57 54.77 2.11 1.68 20.21 2.18 52.9% 63.1% 

Fail Unresolv. 30 6.6% 6.56 73.58 2.62 1.89 23.65 0.89 71.1% 67.9% Fail Waiver 3 0.7% 5.12 158.57 0.31 2.72 112.36 0.37 46.8% 29.1% 

Total Fail% 453 26.7% 2.31 30.21 2.16 1.62 19.88 2.06 29.9% 34.2% 

1983 Pass - 334 1.34 13.07 2.05 1.34 13.07 2.05 0.0% 0.0% 

P Fail Pass 109 21.7% 3.44 49.99 2.10 1.32 14.15 2.02 61.7% 71.7% 

Fail Unresolv. 55 11.0% 4.98 78.39 1.66 1.58 25.81 0.54 68.3% 67.1% Fail Waiver 4 0.8% 5.02 99.89 1.67 12.41 122.60 1.65 -147.0% -22.7% 

Total Fail% 502 33.5% 2.22 28.93 2.01 1.45 15.57 1.88 34.8% 46.2% 

1984 Pass - 981 1.24 11.05 1.94 1.24 11.05 1.94 0.0% 0.0% 

P Fail Pass 204 15.9% 3.10 42.96 1.93 1.31 13.27 1.97 57.9% 69.1% 

Fail Unresolv. 89 7.0% 4.96 75.26 1.94 1.70 27.41 0.59 65.7% 63.6% Fail Waiver 5 0.4% 7.51 177.40 0.56 5.63 148.37 0.39 25.0% 16.4% 

Total Fail% 1,279 23.3% 1.82 21.26 1.93 1.30 13.08 1.84 28.6% 38.5% 

1985 Pass - 934 1.03 10.68 1.93 1.03 10.68 1.93 0.0% 0.0% 

P Fail Pass 224 17.6% 2.69 31.72 2.08 1.16 9.81 1.92 56.8% 69.1% 

Fail Unresolv. 105 8.3% 4.99 66.00 1.95 1.62 20.26 0.63 67.5% 69.3% Fail Waiver 8 0.6% 8.18 111.89 1.52 6.98 109.65 0.63 14.7% 2.0% 

Total Fail% 1,271 26.5% 1.69 19.59 1.96 1.14 11.94 1.81 32.7% 39.1% 
30 

Audit Sample Reductions and Projected Impact 

Table IV-5 shows the aggregate first and final results for the 99% of the inspected audit 

sample vehicles 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 97.3% of the 

exhaust HC and CO reductions and 95.2% of 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 4,530

Mean Initial 0.106 1.784 0.311

Mean Final 0.098 1.684 0.298

Emissions reduction 0.008 0.101 0.013

Clean Screens 248,224

Potential Reductions 2,063 24,980 3,204 

Station Vehicles 825,828

Mean Initial 0.340 4.475 0.696

Mean Final 0.251 3.369 0.619

Emissions reduction 0.089 1.106 0.077

In station reductions 73,834 913,391 63,444 

Combined CS & Stn 1,074,052 75,896 938,370 66,649 

Clean Screen Impact 2.7% 2.7% 4.8%

Retained Reductions 97.3% 97.3% 95.2%
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 19% lower than the failure rate of 

vehicles receiving 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 

 

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

2012 Gas Cap Pressure Failure Rates

Clean Screen Station
32 

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

account for 18% of the total possible gas cap failures. Therefore, 82% 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, MOVES, was used to estimate the fraction of emissions benefits derived 

from gas cap inspections. 

CDPHE provided results from MOVES models of the benefits of the I/M program for 2012. 

The projected average reduction in HC emissions of the area fleet was 0.169 g/mi. This was 

comprised of 0.145 g/mi resulting from exhaust emissions inspections and 0.024 g/mi from 

the Gas Cap testing. The measured I/M exhaust reductions (see section V) were 697.2 tons. 

Assuming the 0.145 g/mi corresponded to 696.7 tons, the Gas Cap related HC reductions were 

projected to be 114.7 tons. These results are shown in Table IV-7. The RapidScreen impact 

was projected as 20.6 tons or 2.5% 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 4,595 143 8 151 

3.1% 0.2% 3.3%

Projected RapidScreen 248,224 7,725 432 8,157 

Station GC Tests 926,945 35,722 1,553 37,275 

3.9% 0.2% 4.0%

Total Program 1,175,169 43,447 1,985 45,432 

RapidScreen Impact 21.1% 17.8% 21.8% 18.0%

Retained Reductions 78.9% 82.2% 78.2% 82.0%
33 

Table IV-7 Gas Cap Related Benefit Tons 

 

MOVES Estimates (from CDPHE)

2012 

MOVES 

g/mi HC

I/M 

2012 

HC tons

I/M Exhaust emission reductions 0.145 697.2

Projected Gas Cap Evap Emissions reductions 0.024 114.7

I/M Program total HC reductions 0.169 811.9

Gas Cap Evap RapidScreen impact 18.0% 0.004 20.6

% of I/M program HC benefit 2.5%
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 3,182 vehicles screened using the 2-

RSD method and 1,349 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 42%, 50% and 56% of the 

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

similar to the equivalent percentages in 2011 of 40%, 50% and 59% respectively. 

The Hybrid RSD-LEI method audit vehicles had lower initial emissions that were 26%, 38% 

and 39% of the I/M fleet average for HC and CO and NOx respectively. These percentages 

were lower than the 2010 equivalents of 32%, 42% and 51% 

Average I/M emissions reductions for the 2-RSD audit vehicles were 3.8%, 3.4% and 3.0% of 

fleet average initial emissions for HC and CO and NOx respectively. These percentages were 

higher than the comparable percentages in 2011 of 0.9%, 2.3% and 0.9%. Average emissions 

reductions for the Hybrid RSD-LEI audit vehicles were 0.8%, 0.9% and 0.1% of fleet average 

initial emissions for HC and CO and NOx respectively and were similar to the comparable 

2011 percentages of 1.0%, 0.4% and 0.0%. Average reductions in station tested vehicles were 

31.2%, 28.7% and 12.7% for HC, CO and NOx respectively. 

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

smaller reductions than the 2-RSD audit vehicles. Consideration should be given to adjusting 

the 2-RSD standards. The RSD-LEI method standards are in part automatically adjusted by 

annual updates to the LEI table. 
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 0.286 3.853 0.607

2-RSD Audits 3,181

Mean Initial 0.120 1.914 0.341

Mean Final 0.109 1.785 0.323

Emissions reduction 0.011 0.129 0.018

 % of I/M vehicle initial mean emission 3.8% 3.4% 3.0%

Hybrid Audits 1,349

Mean Initial 0.074 1.478 0.239

Mean Final 0.072 1.444 0.239

Emissions reduction 0.002 0.034 0.001

 % of I/M vehicle initial mean emission 0.8% 0.9% 0.1%

All Station Tests 825,828

Mean Initial 0.340 4.475 0.696

Mean Final 0.251 3.369 0.619

Emissions reduction 0.089 1.106 0.077

 % of I/M vehicle initial mean emission 31.2% 28.7% 12.7%

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

Station

2-RSD

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

2-RSD

RSDLEI

CO

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

Station

2-RSD

RSDLEI

NOx
36 

Figure IV-3 Average IM240 Emissions Reductions 

 

0.00

0.02

0.04

0.06

0.08

0.10

Station

2-RSD

RSD-LEI

g/mi

HC

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Station

2-RSD

RSD-LEI

CO

0.00

0.02

0.04

0.06

0.08

0.10

Station

2-RSD

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 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 initially failing and 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 1997 and newer model year LDGTs, which 

emit greater masses of pollution than LDGVs are driven more miles annually than 1997 and 

newer model year LDGVs. 

` 

Table V-3 Estimated Annual Mileage in 2012 

Year LDGV LDGT

1982 4304 4,550 

1983 4304 4,554 

1984 4304 4,562 

1985 4434 4,583 

1986 4481 4,630 

1987 4502 4,668 

1988 4552 4,741 

1989 4,780 4,851 

1990 5,088 5,019 

1991 5,430 5,256 

1992 5,672 5,519 

1993 6,002 5,824 

1994 6,331 6,135 

1995 6,653 6,471 

1996 6,974 6,940 

1997 7,369 7,437 

1998 7,764 7,863 

1999 8,188 8,345 

2000 8,613 8,900 

2001 9,032 9,502 

2002 9,450 10,087 

2003 9,905 10,727 

2004 10,360 11,245 

2005 10,746 11,817 

2006 11,132 12,303 

2007 11,870 12,834 

2008 12,023 13,215 

2009 12,307 13,433 

2010 12,357 13,514 

2011 11,600 12,428 

2012 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 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 2012, the Clean Screen program retained 94.8%, 97.1% and 

93.9% respectively of potential HC, CO and NOx emission reductions in vehicles subject to 

testing. 

For vehicles initially tested in calendar year 2012, the I/M Program is projected to have 

eliminated 770.1 tons of HC, 8,377.1 tons of CO and 538.2 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 calendar year 2012, 248,224 vehicles were exempted 

through Clean Screen, and 902,338 vehicles received a station test. Therefore, 21.6% of the 

1,150,562 unique vehicles were Clean Screened. 

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

would have been 345,159 Clean Screens and 805,393 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 92.8%, 95.6% and 90.8% 

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

 Audit Vehicle Reductions (IM240 tons/yr)

Audit Tests

Unique 

Vehicles HC CO NOx

Enhanced IM240 4,530 0.39 4.64 0.63

Potential from RS Vehicles (IM240 tons/yr)

RapidScreen

Unique 

Vehicles HC CO NOx

Enhanced Area 248,224 21.3 254.3 34.7

Gas Cap estimate from Mobile6 20.6

Station Reductions (IM240 tons/yr)

Station I/M Vehicles

Unique 

Vehicles HC CO NOx

Enhanced IM240 825,828 526.6 6,601.4 538.2

Enhanced Idle* 76,510 149.3 1,775.7

Gas Cap scaled from MOVES 94.1

 770.1 902,338 8,377.1 538.2 

Total Potential Reductions 811.9 8,631.4 572.9

RapidScreen Exhaust Impact 2.6% 2.9% 6.1%

Rapidscreen Gas Cap Impact 2.5%

Retained Reductions 94.8% 97.1% 93.9%
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 

and 2012. In previous years the RSD-2 method was equally or more effective than the RSDLEI method but in 2012, the RSD-2 method was less effective than the RSD-LEI method. 

Clean screens using the RSD-LEI method have fallen from 45% of the total in 2008 to 30% in 

2012. 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. 

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 2009 and newer models not yet subject to inspection; 

 any estimate of pre-inspection emission reductions; 

 NOx emissions for 76,510 vehicles tested with the idle test: 1981 and older models 

13,896 (18%), 1982 and newer trucks 58,446 (76%), and 1982 & newer passenger 

vehicles 4,168 (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 2011P 2012

IM240 Equivalent Exhaust Tons Per Year in 2012

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 2011T 2012

IM240 Equivalent Exhaust Tons Per Year in 2012

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 2011P 2012

IM240 Equivalent Exhaust Tons Per Year in 2012

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 2011T 2012

IM240 Equivalent Exhaust Tons Per Year in 2012

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 2011P 2012

IM240 Equivalent Exhaust Tons Per Year in 2012

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 2011T 2012

IM240 Equivalent Exhaust Tons Per Year in 2012

Light Truck NOx

Idle Reduction NOx n/a

IM240 Reduction NOx

Idle Final NOx n/a

IM240 Final NOx

Clean Screen Vehicles NOx
49 

VIII. RapidScreen Benefits 

Rapidscreen provided benefits to vehicle owners of $5.1M through reduced time and expense 

associated with eliminated inspection station visits. The elimination of station inspections 

also yielded net savings in greenhouse gases and 200,809 gallons of gasoline. This section 

summarizes the operational costs and benefits of the Rapidscreen program. 

A. Greenhouse Gas and Pollutants from Clean Screen Operations 

The following were considered in deriving the net emissions, greenhouse gas and fuel use 

associated with the RapidScreen program: 

- RSD van operations;

- RSD generators;

- RSD unit calibration and audit gases;

- Reductions from eliminated trips to inspection stations. 

Table VIII-1 summarizes these amounts. 

Table VIII-1 Reductions in Greenhouse Gases and Pollutants from RapidScreen Operations 

1. RapidScreen Operating Vehicles 

Emissions and fuel usage of RSD vans, audit trucks and maintenance vehicles associated with 

the RapidScreen program were developed from the average IM240 emissions of each vehicle 

from all inspections performed from 2010 through 2012. Idle test emissions were converted 

to IM240 g/mi using the conversion factors described in Section V. Emissions were scaled up 

to match MOVES estimates of running emissions vs. IM240. The scaling factors were 1.0 for 

hydrocarbons, 1.92 for CO and 2.23 for NOx. Odometer changes were pro-rated to provide 

annual mileages. Fuel use was calculated using EPA city fuel economies for the vehicle 

Activity HC t/yr CO t/yr NOx t/yr CO2 t/yr Fuel gal.

RapidScreen Operations

RapidScreen operating vehicles (vans, audit

trucks, maintenance) 0.054 1.50 0.065 94.6 10,605

Generators 1.038 25.37 0.091 61.3 10,685

Calibration and audit gases 0.005 0.05 0.003 0.5

Total Rapidscreen operations 1.097 26.92 0.159 156.4 21,290

RapidScreen Vehicle Emission Reductions

Station trip, waiting & testing 0.522 13.02 2.513 1981.1 222,098

Net benefit (cost) (0.58) (13.90) 2.354 1824.7 200,809
50 

models or similar models. CO2 tons were calculated at the rate of 8.92 x 10-3 tons per gallon 

(http://www.epa.gov/cleanenergy/energy-resources/refs.html). 

2. Generators 

Typical emissions and CO2 grams over a four minute period were obtained by collecting 

emissions from two generators using lane IM240 equipment. Emissions were collected from 

the generator while another vehicle was driven on the dynamometer. Emissions and CO2

grams were then multiplied by 15 to obtain g/hour and by the Active Collection Van Hours 

from Table III-1. Fuel gallons were back calculated from CO2 tons. 

Envirotest is investigating replacement of existing generators with newer, lower emitting 

models that would eliminate 67% of HC emissions and up to 98% of the generator NOx 

emissions. 

3. Calibration and Audit Gases 

Calibration and Audit Gas emissions were calculated directly from the use estimates 

presented in Table VIII-2. The liters of calibration and audit gases at 70F and normal 

pressure were multiplied by the pollutant concentration percentages and by the pollutant mass 

per liter to obtain tons. 

Table VIII-2 Calibration and Audit Gas Emissions 

4. RapidScreen Vehicle Emissions Reductions 

The RapidScreen program eliminated the need for 248,224 station inspections that would 

otherwise require travel, waiting and inspection. 

RSD VANS

AL

Cyls

BL

Cyls

CL

Cyls

Liters at

70F NP

CO

%

CO2

% HC % NO %

HC

PPM

NOX

PPM

CO

tons

CO2

tons

HC

tons

NO

tons

Calibration 240 30 0 1,028,820 3.00 12.90 0.15 0.15 1500 1500 0.0425 0.2874 0.0033 0.0023

2 Point Audit 80 10 342,940 0.50 14.70 0.04 0.10 400 1000 0.0024 0.1092 0.0003 0.0005

ATP / DOR

A 12 0 47,916 0.00 15.05 0.00 0.00 0 0 0.0000 0.0156 0.0000 0.0000

F 12 0 16 61,964 5.00 11.55 0.60 0.03 6000 250 0.0043 0.0155 0.0008 0.0000

G 12 0 47,916 0.20 14.91 0.01 0.15 100 1500 0.0001 0.0155 0.0000 0.0001

H 12 0 47,916 0.30 14.84 0.02 0.10 200 1000 0.0002 0.0154 0.0000 0.0001

J 12 0 16 61,964 0.50 14.70 0.04 0.10 400 1000 0.0004 0.0197 0.0001 0.0001

K 12 0 47,916 1.00 14.34 0.05 0.03 500 300 0.0007 0.0149 0.0001 0.0000

L 12 0 47,916 1.50 13.99 0.07 0.01 700 100 0.0010 0.0145 0.0001 0.0000

Q 12 0 16 61,964 3.00 12.92 0.11 0.05 1100 500 0.0026 0.0173 0.0001 0.0000

Total 416 40 48 1,797,232 0.0541 0.5249 0.0048 0.0031

Capacities and g/l

AL

Cyls

BL

Cyls

CL

Cyls

CO

%

CO2

% HC % NO %

Cylinder  L @2000psi 29.5 15.7 5.9 Mol. Wt 28 44 44 30

Liters gas at 70F NP 3993 2350 878 g/l 1.3 2.0 2.0 1.3
51 

The average round trip to a station was estimated to be 9.5 miles. For every two minutes a car 

is idling, it uses about the same amount of fuel it takes to go about one mile according to the 

Consumer Energy Center (http://www.consumerenergycenter.org/myths/idling.html). This 

implies the average waiting time of 12.3 minutes was equivalent to 6.2 miles of driving. The 

equivalent of another equivalent 2.2 miles of driving was spent moving through the inspection 

lane for a total equivalent of 17.9 miles per inspection. Eliminated trip/inspection emissions 

tons were calculated from the inspection mileage multiplied by the average IM240 g/mi 

emissions of the RapidScreen audit sample and the number of exempted vehicles. As noted 

above, IM240 emissions were scaled up to match MOVES estimates of running emissions vs. 

IM240. Gallons of fuel saved were estimated using an average of 20mpg. 

B. RapidScreen Vehicle Owner Savings 

Table VIII-3 quantifies the RapidScreen benefits to vehicle owners. The average round trip to 

an inspection station was assumed to take an average of 28.5 minutes (9.5 miles at 20mph). 

Average wait and test times were 12.3 minutes and 15.0 minute respectively. The waiting and 

testing fuel consumption was estimated to be the equivalent of driving another 8.4 miles. 

Vehicle owner time was assumed to be worth half the State’s average hourly wage of $23 per 

hour, or $11.50 per hour. 

Travel savings from were calculated at the IRS rate of 55.5c per mile per IRS Notice IR-2011-

116, Dec. 9, 2011. 

Total savings were $5.1M or $20.63 per vehicle. 

Table VIII-3 RapidScreen Vehicle Owner Savings 

Activity Vehicles Minutes Hours Unit $ $'M

Station round trip @ 20mph 248224 28.5 117906 11.50 $     $      1.36

Testing 248224 15.0 62056 11.50 $     $      0.71

Waiting 248224 12.3 50886 11.50 $     $      0.59

Miles

Driving miles equiv. 248224 17.9 0.56 $       $      2.47

Total vehicle ownersavings 5.12 $      
52 

IX. Recommendations 

In 2012 the 2-RSD clean screening method was relatively less effective than the RSD-LEI 

method (see Figure 4.3). The stringency of the RSD-LEI method has effectively tightened 

over time as the LEI table has been updated annually and older models no longer meeting the 

LEI fail rate threshold of 2% are dropped from consideration. On the other hand, the absolute 

effectiveness of the 2-RSD method in g/mi has not changed substantially since the 

introduction of the 1000 ppm NOx cutpoint in 2010. 

Changes to the program testing procedures are scheduled for 2015. New vehicles will be 

exempt for seven years instead of four years and most vehicles eight to eleven years old will 

be inspected using the OBD system instead of the IM240 test. Many vehicles failing OBD 

inspection do not have high exhaust emissions. Emissions control components can drift 

outside their design operating range, thus triggering a malfunction light, before significantly 

increasing emissions. In this situation, the application of a loose LEI standard to 2-RSD clean 

screen candidates is recommended to limit the number of candidates passing the on-road 

emissions screen but failing OBD. 

Appropriate clean screen standards for the new 2015 program could be evaluated and 

reviewed in the first quarter of 2014. This would allow time for regulatory approval and 

implementation of new standards in October 2014 when clean screen notices for January 2015 

registrations will be prepared. 

 
53 

References 

 

1

 “The Colorado Remote Sensing Program January – December 2011”, Envirotest report for the 

Colorado Department of Public Health and Environment, November 2012 

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 2012 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 - 332 1.57 18.62 2.14 1.57 18.62 2.14 0.0% 0.0% 0.0%

P Fail Pass 88 19.4% 3.57 54.77 2.11 1.68 20.21 2.18 52.9% 63.1% -3.3%

Fail Unresolv. 30 6.6% 6.56 73.58 2.62 1.89 23.65 0.89 71.1% 67.9% 66.1%

Fail Waiver 3 0.7% 5.12 158.57 0.31 2.72 112.36 0.37 46.8% 29.1% -19.1%

Total Fail% 453 26.7% 2.31 30.21 2.16 1.62 19.88 2.06 29.9% 34.2% 4.7%

1983 Pass - 334 1.34 13.07 2.05 1.34 13.07 2.05 0.0% 0.0% 0.0%

P Fail Pass 109 21.7% 3.44 49.99 2.10 1.32 14.15 2.02 61.7% 71.7% 3.5%

Fail Unresolv. 55 11.0% 4.98 78.39 1.66 1.58 25.81 0.54 68.3% 67.1% 67.3%

Fail Waiver 4 0.8% 5.02 99.89 1.67 12.41 122.60 1.65 -147.0% -22.7% 0.9%

Total Fail% 502 33.5% 2.22 28.93 2.01 1.45 15.57 1.88 34.8% 46.2% 6.9%

1984 Pass - 981 1.24 11.05 1.94 1.24 11.05 1.94 0.0% 0.0% 0.0%

P Fail Pass 204 15.9% 3.10 42.96 1.93 1.31 13.27 1.97 57.9% 69.1% -1.7%

Fail Unresolv. 89 7.0% 4.96 75.26 1.94 1.70 27.41 0.59 65.7% 63.6% 69.4%

Fail Waiver 5 0.4% 7.51 177.40 0.56 5.63 148.37 0.39 25.0% 16.4% 29.6%

Total Fail% 1,279 23.3% 1.82 21.26 1.93 1.30 13.08 1.84 28.6% 38.5% 4.6%

1985 Pass - 934 1.03 10.68 1.93 1.03 10.68 1.93 0.0% 0.0% 0.0%

P Fail Pass 224 17.6% 2.69 31.72 2.08 1.16 9.81 1.92 56.8% 69.1% 7.8%

Fail Unresolv. 105 8.3% 4.99 66.00 1.95 1.62 20.26 0.63 67.5% 69.3% 68.0%

Fail Waiver 8 0.6% 8.18 111.89 1.52 6.98 109.65 0.63 14.7% 2.0% 58.3%

Total Fail% 1,271 26.5% 1.69 19.59 1.96 1.14 11.94 1.81 32.7% 39.1% 7.3%

1986 Pass - 1,831 0.90 7.81 1.83 0.90 7.81 1.83 0.0% 0.0% 0.0%

P Fail Pass 300 13.3% 2.85 30.56 2.19 1.04 9.35 1.81 63.3% 69.4% 17.3%

Fail Unresolv. 112 5.0% 4.98 62.19 2.21 1.46 20.48 0.69 70.6% 67.1% 69.0%

Fail Waiver 6 0.3% 7.08 92.18 0.76 4.64 59.21 1.26 34.5% 35.8% -66.0%

Total Fail% 2,249 18.6% 1.38 13.78 1.90 0.95 8.78 1.77 30.7% 36.3% 6.6%

1987 Pass - 1,581 0.86 7.74 1.82 0.86 7.74 1.82 0.0% 0.0% 0.0%

P Fail Pass 265 13.6% 2.58 29.94 2.16 1.03 9.37 1.69 60.0% 68.7% 21.6%

Fail Unresolv. 101 5.2% 5.21 55.79 2.09 1.47 17.73 0.66 71.9% 68.2% 68.6%

Fail Waiver 7 0.4% 3.89 34.76 2.42 2.90 37.15 2.23 25.5% -6.9% 7.9%

Total Fail% 1,954 19.1% 1.33 13.33 1.88 0.92 8.58 1.74 30.7% 35.6% 7.3%

1988 Pass - 2,877 0.72 7.80 1.55 0.72 7.80 1.55 0.0% 0.0% 0.0%

P Fail Pass 426 12.3% 2.33 30.17 1.88 0.85 8.06 1.61 63.5% 73.3% 14.4%

Fail Unresolv. 158 4.6% 4.15 47.36 2.06 1.43 15.88 0.66 65.6% 66.5% 67.9%

Fail Waiver 10 0.3% 2.22 38.83 1.55 2.99 44.38 1.53 -34.7% -14.3% 1.2%

Total Fail% 3,471 17.1% 1.08 12.43 1.62 0.77 8.30 1.52 28.1% 33.2% 6.0%

1989 Pass - 2,775 0.73 7.99 1.62 0.73 7.99 1.62 0.0% 0.0% 0.0%

P Fail Pass 444 13.1% 2.04 24.64 1.93 0.89 8.15 1.66 56.4% 66.9% 14.0%

Fail Unresolv. 156 4.6% 4.27 48.62 2.12 1.28 15.18 0.73 69.9% 68.8% 65.7%

Fail Waiver 8 0.2% 3.01 63.88 1.99 2.31 44.41 2.22 23.2% 30.5% -11.8%

Total Fail% 3,383 18.0% 1.07 12.18 1.68 0.78 8.43 1.59 27.2% 30.8% 5.9%

A1-1
Appendix A1 Colorado 2012 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 - 5,834 0.68 7.68 1.59 0.68 7.68 1.59 0.0% 0.0% 0.0%

P Fail Pass 756 11.0% 2.07 25.49 2.13 0.77 7.79 1.62 62.7% 69.5% 23.8%

Fail Unresolv. 244 3.6% 4.28 44.90 2.48 1.41 15.16 0.78 67.0% 66.2% 68.4%

Fail Waiver 10 0.1% 3.02 46.28 2.71 2.82 39.27 2.78 6.8% 15.1% -2.6%

Total Fail% 6,844 14.8% 0.97 11.03 1.68 0.72 8.00 1.56 25.5% 27.4% 6.9%

1991 Pass - 5,638 0.60 6.90 1.49 0.60 6.90 1.49 0.0% 0.0% 0.0%

P Fail Pass 766 11.4% 2.19 25.21 2.12 0.71 7.32 1.56 67.5% 71.0% 26.5%

Fail Unresolv. 311 4.6% 3.88 36.85 2.57 1.25 12.50 0.84 67.9% 66.1% 67.3%

Fail Waiver 8 0.1% 3.88 54.73 2.03 2.80 48.70 2.21 27.8% 11.0% -8.6%

Total Fail% 6,723 16.1% 0.94 10.42 1.61 0.65 7.25 1.47 31.0% 30.4% 8.9%

1992 Pass - 8,140 0.55 6.19 1.41 0.55 6.19 1.41 0.0% 0.0% 0.0%

P Fail Pass 1,200 12.3% 1.86 24.87 1.86 0.62 6.27 1.47 66.4% 74.8% 21.0%

Fail Unresolv. 377 3.9% 3.30 37.82 2.28 1.10 12.01 0.75 66.6% 68.2% 67.1%

Fail Waiver 19 0.2% 4.09 26.91 2.53 4.42 22.27 2.15 -7.9% 17.2% 15.3%

Total Fail% 9,736 16.4% 0.82 9.76 1.50 0.59 6.45 1.40 28.8% 33.8% 7.2%

1993 Pass - 7,900 0.54 5.89 1.46 0.54 5.89 1.46 0.0% 0.0% 0.0%

P Fail Pass 1,014 11.0% 1.91 23.51 2.02 0.65 6.54 1.55 66.1% 72.2% 23.2%

Fail Unresolv. 324 3.5% 3.53 31.30 2.45 1.12 10.21 0.80 68.2% 67.4% 67.4%

Fail Waiver 13 0.1% 3.95 38.18 2.72 2.92 34.02 2.72 25.9% 10.9% 0.1%

Total Fail% 9,251 14.6% 0.80 8.76 1.56 0.58 6.16 1.45 27.9% 29.7% 7.0%

1994 Pass - 11,179 0.42 5.06 1.18 0.42 5.06 1.18 0.0% 0.0% 0.0%

P Fail Pass 1,333 10.3% 1.70 18.39 1.84 0.53 5.46 1.32 69.0% 70.3% 28.2%

Fail Unresolv. 462 3.6% 3.25 28.87 2.43 1.03 9.45 0.80 68.4% 67.3% 67.1%

Fail Waiver 15 0.1% 3.14 30.98 3.08 2.57 19.84 3.26 18.3% 35.9% -5.8%

Total Fail% 12,989 13.9% 0.65 7.31 1.29 0.45 5.27 1.18 30.5% 27.8% 8.6%

1995 Pass - 13,146 0.40 4.81 1.03 0.40 4.81 1.03 0.0% 0.0% 0.0%

P Fail Pass 1,453 9.6% 1.48 17.14 1.72 0.49 5.15 1.17 67.0% 69.9% 32.3%

Fail Unresolv. 500 3.3% 3.29 28.27 2.35 1.05 8.75 0.76 68.1% 69.1% 67.4%

Fail Waiver 21 0.1% 2.64 19.26 2.86 2.16 17.68 2.94 18.3% 8.2% -2.9%

Total Fail% 15,120 13.1% 0.60 6.79 1.14 0.43 4.99 1.03 28.3% 26.5% 9.3%

1996 Pass - 17,276 0.30 3.74 0.81 0.30 3.74 0.81 0.0% 0.0% 0.0%

P Fail Pass 1,710 8.8% 1.05 14.23 1.54 0.38 4.33 0.94 63.5% 69.6% 39.2%

Fail Unresolv. 408 2.1% 2.12 23.40 2.33 0.73 7.64 0.77 65.7% 67.4% 67.0%

Fail Waiver 13 0.1% 1.90 35.85 2.32 1.88 31.06 1.83 0.8% 13.4% 21.2%

Total Fail% 19,407 11.0% 0.40 5.10 0.91 0.32 3.89 0.82 21.8% 23.7% 9.5%

1997 Pass - 17,068 0.30 3.84 0.78 0.30 3.84 0.78 0.0% 0.0% 0.0%

P Fail Pass 1,745 9.1% 1.04 13.92 1.43 0.36 4.40 0.89 65.0% 68.4% 37.7%

Fail Unresolv. 400 2.1% 2.09 22.00 2.35 0.72 7.38 0.78 65.5% 66.5% 66.6%

Fail Waiver 16 0.1% 2.58 56.91 1.72 2.15 41.33 2.08 16.5% 27.4% -20.7%

Total Fail% 19,229 11.2% 0.41 5.18 0.87 0.32 4.00 0.79 22.1% 22.8% 9.4%

A1-2
Appendix A1 Colorado 2012 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 - 23,408 0.22 3.30 0.63 0.22 3.30 0.63 0.0% 0.0% 0.0%

P Fail Pass 2,263 8.6% 0.86 12.31 1.34 0.26 3.67 0.67 70.1% 70.2% 49.8%

Fail Unresolv. 475 1.8% 1.87 21.64 2.28 0.59 6.76 0.76 68.4% 68.7% 66.8%

Fail Waiver 25 0.1% 1.24 9.36 2.71 1.18 8.47 2.72 4.3% 9.5% -0.5%

Total Fail% 26,171 10.6% 0.31 4.42 0.72 0.23 3.40 0.64 24.4% 23.1% 11.8%

1999 Pass - 20,580 0.20 2.99 0.58 0.20 2.99 0.58 0.0% 0.0% 0.0%

P Fail Pass 2,181 9.4% 0.74 10.43 1.34 0.23 3.38 0.67 68.2% 67.6% 50.2%

Fail Unresolv. 415 1.8% 2.08 19.04 2.32 0.64 6.03 0.77 69.4% 68.3% 66.7%

Fail Waiver 15 0.1% 1.87 26.98 2.09 1.27 16.39 2.52 32.1% 39.3% -20.3%

Total Fail% 23,191 11.3% 0.28 4.00 0.69 0.21 3.09 0.60 26.1% 22.6% 13.2%

2000 Pass - 31,158 0.14 2.37 0.43 0.14 2.37 0.43 0.0% 0.0% 0.0%

P Fail Pass 2,614 7.6% 0.63 9.06 1.27 0.19 3.01 0.56 69.8% 66.8% 56.0%

Fail Unresolv. 445 1.3% 1.58 18.55 2.43 0.49 5.91 0.81 69.0% 68.1% 66.6%

Fail Waiver 19 0.1% 3.69 18.43 3.20 0.81 6.39 3.10 78.1% 65.3% 3.2%

Total Fail% 34,236 9.0% 0.20 3.10 0.52 0.15 2.46 0.45 25.3% 20.4% 14.4%

2001 Pass - 23,622 0.10 2.07 0.31 0.10 2.07 0.31 0.0% 0.0% 0.0%

P Fail Pass 1,709 6.7% 0.64 9.77 1.21 0.16 2.80 0.44 75.0% 71.3% 64.1%

Fail Unresolv. 204 0.8% 1.53 22.04 2.22 0.44 6.87 0.71 71.1% 68.8% 68.0%

Fail Waiver 15 0.1% 0.67 8.23 4.25 0.61 9.47 3.85 9.7% -15.1% 9.3%

Total Fail% 25,550 7.5% 0.15 2.75 0.39 0.11 2.16 0.32 27.6% 21.3% 16.6%

2002 Pass - 32,351 0.08 2.27 0.24 0.08 2.27 0.24 0.0% 0.0% 0.0%

P Fail Pass 1,818 5.3% 0.44 6.36 1.06 0.12 2.14 0.33 72.4% 66.4% 68.7%

Fail Unresolv. 186 0.5% 1.61 15.85 2.69 0.44 4.82 0.87 72.9% 69.6% 67.6%

Fail Waiver 9 0.0% 0.69 13.24 3.48 0.57 6.36 3.64 17.0% 52.0% -4.6%

Total Fail% 34,364 5.9% 0.11 2.56 0.30 0.08 2.28 0.25 21.6% 11.1% 16.0%

2003 Pass - 21,220 0.06 1.35 0.21 0.06 1.35 0.21 0.0% 0.0% 0.0%

P Fail Pass 1,137 5.1% 0.45 6.35 0.90 0.11 1.97 0.32 74.4% 69.0% 64.0%

Fail Unresolv. 109 0.5% 1.61 16.51 2.19 0.57 5.55 0.71 64.6% 66.4% 67.5%

Fail Waiver 5 0.0% 1.05 18.19 2.13 0.95 20.75 1.40 9.8% -14.0% 34.4%

Total Fail% 22,471 5.6% 0.08 1.68 0.25 0.06 1.41 0.22 25.9% 16.3% 14.4%

2004 Pass - 28,195 0.04 1.07 0.13 0.04 1.07 0.13 0.0% 0.0% 0.0%

P Fail Pass 1,302 4.4% 0.38 5.25 0.64 0.08 1.77 0.20 78.7% 66.4% 69.0%

Fail Unresolv. 78 0.3% 1.34 17.88 2.22 0.44 5.82 0.72 67.1% 67.4% 67.8%

Fail Waiver 6 0.0% 1.50 13.61 3.21 1.97 14.10 3.09 -31.1% -3.5% 4.0%

Total Fail% 29,581 4.7% 0.06 1.30 0.16 0.05 1.12 0.14 25.0% 14.2% 14.5%

2005 Pass - 18,095 0.04 0.94 0.12 0.04 0.94 0.12 0.0% 0.0% 0.0%

P Fail Pass 895 4.7% 0.32 5.48 0.56 0.07 1.55 0.17 78.1% 71.6% 68.8%

Fail Unresolv. 64 0.3% 1.69 24.18 1.85 0.63 8.62 0.65 63.1% 64.4% 64.6%

Fail Waiver 3 0.0% 1.00 18.93 2.46 1.08 18.42 2.30 -8.1% 2.7% 6.4%

Total Fail% 19,057 5.0% 0.05 1.23 0.15 0.04 1.00 0.13 28.1% 19.2% 14.9%

A1-3
Appendix A1 Colorado 2012 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 - 27,042 0.03 1.00 0.09 0.03 1.00 0.09 0.0% 0.0% 0.0%

P Fail Pass 924 3.3% 0.28 5.13 1.42 0.07 1.32 0.16 76.1% 74.2% 88.9%

Fail Unresolv. 52 0.2% 1.45 19.09 2.67 0.48 6.04 0.88 67.0% 68.4% 67.0%

Fail Waiver 3 0.0% 1.38 30.87 3.20 1.11 19.60 4.30 19.7% 36.5% -34.5%

Total Fail% 28,021 3.5% 0.04 1.17 0.14 0.04 1.02 0.10 20.1% 12.9% 31.7%

2007 Pass - 15,329 0.03 0.88 0.09 0.03 0.88 0.09 0.0% 0.0% 0.0%

P Fail Pass 449 2.8% 0.28 4.98 1.44 0.06 1.37 0.13 78.1% 72.4% 90.8%

Fail Unresolv. 16 0.1% 0.93 13.13 2.94 0.30 4.28 0.93 67.8% 67.4% 68.3%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 15,794 2.9% 0.04 1.01 0.13 0.03 0.90 0.09 18.8% 11.0% 30.8%

2008 Pass - 31,114 0.03 0.89 0.08 0.03 0.89 0.08 0.0% 0.0% 0.0%

P Fail Pass 753 2.4% 0.25 4.00 1.52 0.06 1.29 0.11 78.2% 67.8% 92.6%

Fail Unresolv. 26 0.1% 1.79 21.83 3.15 0.54 6.50 0.92 70.0% 70.2% 70.9%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 31,893 2.4% 0.03 0.98 0.11 0.03 0.90 0.08 16.8% 7.8% 30.8%

2009 Pass - 5,513 0.03 0.89 0.08 0.03 0.89 0.08 0.0% 0.0% 0.0%

P Fail Pass 98 1.7% 0.21 4.60 1.49 0.05 1.21 0.10 76.0% 73.6% 93.1%

Fail Unresolv. 9 0.2% 0.83 6.44 1.85 0.27 1.71 0.65 67.6% 73.5% 65.1%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 5,620 1.9% 0.03 0.96 0.10 0.03 0.90 0.08 11.6% 6.9% 25.2%

2010 Pass - 2,736 0.02 0.97 0.07 0.02 0.97 0.07 0.0% 0.0% 0.0%

P Fail Pass 28 1.0% 0.16 3.01 0.34 0.03 0.87 0.07 80.4% 71.2% 80.5%

Fail Unresolv. 6 0.2% 0.44 11.31 0.46 0.15 3.73 0.15 67.0% 67.0% 67.0%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 2,770 1.2% 0.03 1.02 0.07 0.02 0.98 0.07 7.3% 3.7% 4.9%

2011 Pass - 1,823 0.03 1.04 0.06 0.03 1.04 0.06 0.0% 0.0% 0.0%

P Fail Pass 27 1.5% 0.30 1.64 0.21 0.02 1.08 0.07 93.9% 34.2% 65.3%

Fail Unresolv. 3 0.2% 1.68 12.34 3.08 0.56 4.07 1.02 67.0% 67.0% 67.0%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 1,853 1.6% 0.03 1.06 0.07 0.03 1.04 0.06 18.5% 2.0% 7.7%

2012 Pass - 589 0.02 0.88 0.06 0.02 0.88 0.06 0.0% 0.0% 0.0%

P Fail Pass 3 0.5% 0.01 0.53 0.05 0.02 0.56 0.02 -27.2% -5.9% 60.0%

Fail Unresolv. 2 0.3% 1.56 0.61 0.02 0.51 0.20 0.01 67.0% 67.0% 67.0%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 594 0.8% 0.03 0.88 0.06 0.03 0.88 0.06 11.7% 0.1% 0.4%

2013 Pass - 23 0.02 0.67 0.05 0.02 0.67 0.05 0.0% 0.0% 0.0%

P Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 23 0.0% 0.02 0.67 0.05 0.02 0.67 0.05 0.0% 0.0% 0.0%

Total Passenger Vehicles

All Pass - 380,624 0.19 2.69 0.49 0.19 2.69 0.49 0.0% 0.0% 0.0%

P Fail Pass 28,238 6.8% 1.06 13.79 1.44 0.35 4.15 0.81 66.7% 69.9% 43.7%

Fail Unresolv. 5,922 1.4% 2.86 30.57 2.33 0.91 9.92 0.76 68.0% 67.5% 67.2%

Fail Waiver 266 0.1% 2.93 37.82 2.51 2.46 31.29 2.48 16.0% 17.3% 1.1%

Total Fail% 415,050 8.3% 0.28 3.86 0.59 0.21 2.91 0.52 26.7% 24.7% 11.1%

A1-4
Appendix A1 Colorado 2012 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 - 305 2.32 29.53 2.98 2.32 29.53 2.98 0.0% 0.0% 0.0%

T Fail Pass 149 28.2% 4.15 59.43 2.79 2.34 27.32 2.70 43.7% 54.0% 3.1%

Fail Unresolv. 74 14.0% 6.99 93.78 2.60 2.20 29.95 0.82 68.6% 68.1% 68.4%

Fail Waiver 1 0.2% 7.79 171.85 0.09 3.81 117.44 0.07 51.1% 31.7% 26.0%

Total Fail% 529 42.3% 3.50 47.21 2.87 2.31 29.13 2.60 34.0% 38.3% 9.5%

1983 Pass - 322 2.88 32.85 2.59 2.88 32.85 2.59 0.0% 0.0% 0.0%

T Fail Pass 166 29.5% 4.73 68.11 2.47 2.42 33.24 2.56 48.9% 51.2% -3.5%

Fail Unresolv. 75 13.3% 7.52 105.20 2.56 2.54 34.49 0.89 66.2% 67.2% 65.2%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 563 42.8% 4.04 52.89 2.55 2.70 33.19 2.36 33.3% 37.3% 7.7%

1984 Pass - 842 2.07 25.03 2.61 2.07 25.03 2.61 0.0% 0.0% 0.0%

T Fail Pass 386 27.6% 3.86 58.87 3.00 2.12 25.39 2.97 44.9% 56.9% 1.2%

Fail Unresolv. 162 11.6% 7.11 105.52 2.25 2.18 33.24 0.80 69.3% 68.5% 64.3%

Fail Waiver 8 0.6% 9.54 123.68 3.27 4.33 97.92 2.56 54.7% 20.8% 21.7%

Total Fail% 1,398 39.8% 3.19 44.27 2.68 2.11 26.50 2.50 33.8% 40.1% 6.8%

1985 Pass - 874 1.88 19.66 2.78 1.88 19.66 2.78 0.0% 0.0% 0.0%

T Fail Pass 329 24.3% 3.43 51.79 2.94 1.81 20.38 2.76 47.2% 60.6% 5.9%

Fail Unresolv. 139 10.3% 6.62 97.47 2.44 2.11 32.43 0.76 68.1% 66.7% 68.7%

Fail Waiver 11 0.8% 7.57 104.68 1.93 5.38 112.77 1.64 29.0% -7.7% 15.2%

Total Fail% 1,353 35.4% 2.79 36.16 2.78 1.92 21.91 2.56 31.3% 39.4% 7.8%

1986 Pass - 1,766 1.60 16.32 2.54 1.60 16.32 2.54 0.0% 0.0% 0.0%

T Fail Pass 536 21.4% 3.64 44.27 2.91 1.71 17.87 2.79 53.0% 59.6% 4.4%

Fail Unresolv. 191 7.6% 6.97 87.51 2.49 2.12 28.85 0.79 69.5% 67.0% 68.4%

Fail Waiver 6 0.2% 3.33 124.48 2.45 2.49 112.70 2.46 25.1% 9.5% -0.2%

Total Fail% 2,499 29.3% 2.45 28.01 2.61 1.67 17.84 2.46 32.1% 36.3% 6.0%

1987 Pass - 1,455 1.54 14.48 2.43 1.54 14.48 2.43 0.0% 0.0% 0.0%

T Fail Pass 404 20.1% 3.11 40.23 2.69 1.46 13.96 2.43 53.1% 65.3% 9.5%

Fail Unresolv. 147 7.3% 5.92 69.94 2.48 1.78 22.43 0.82 69.9% 67.9% 66.9%

Fail Waiver 3 0.1% 2.97 72.55 1.00 3.90 106.66 0.64 -31.6% -47.0% 35.7%

Total Fail% 2,009 27.6% 2.18 23.81 2.48 1.54 15.10 2.31 29.1% 36.6% 7.0%

1988 Pass - 2,886 1.29 11.94 2.22 1.29 11.94 2.22 0.0% 0.0% 0.0%

T Fail Pass 720 18.8% 3.07 32.70 2.92 1.33 11.93 2.37 56.8% 63.5% 18.6%

Fail Unresolv. 217 5.7% 5.18 59.54 2.74 1.64 18.21 0.87 68.3% 69.4% 68.4%

Fail Waiver 3 0.1% 18.79 174.72 1.51 1.37 23.98 4.31 92.7% 86.3% -186.2%

Total Fail% 3,826 24.6% 1.86 18.68 2.38 1.32 12.31 2.17 29.1% 34.1% 8.7%

1989 Pass - 2,575 1.27 12.74 2.21 1.27 12.74 2.21 0.0% 0.0% 0.0%

T Fail Pass 590 17.3% 3.26 31.49 2.95 1.40 12.46 2.36 57.1% 60.4% 20.0%

Fail Unresolv. 226 6.6% 5.20 58.92 3.12 1.60 18.63 1.01 69.3% 68.4% 67.6%

Fail Waiver 15 0.4% 8.06 75.88 3.00 4.77 43.74 2.88 40.8% 42.4% 4.1%

Total Fail% 3,406 24.4% 1.90 19.33 2.40 1.33 13.22 2.16 30.3% 31.6% 10.1%

A1-5
Appendix A1 Colorado 2012 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 - 3,896 1.17 11.32 2.19 1.17 11.32 2.19 0.0% 0.0% 0.0%

T Fail Pass 836 16.8% 2.66 28.97 2.80 1.24 11.73 2.24 53.2% 59.5% 20.1%

Fail Unresolv. 226 4.5% 4.41 44.60 3.24 1.46 14.44 1.07 66.9% 67.6% 67.0%

Fail Waiver 10 0.2% 8.16 59.87 2.98 3.75 36.06 2.86 54.1% 39.8% 4.1%

Total Fail% 4,968 21.6% 1.58 15.90 2.34 1.20 11.58 2.15 24.1% 27.2% 8.3%

1991 Pass - 3,632 1.00 11.59 1.89 1.00 11.59 1.89 0.0% 0.0% 0.0%

T Fail Pass 663 14.7% 2.67 31.90 2.57 1.07 11.10 2.05 60.1% 65.2% 20.2%

Fail Unresolv. 195 4.3% 4.91 48.64 2.75 1.60 16.95 0.89 67.5% 65.2% 67.7%

Fail Waiver 5 0.1% 6.85 37.70 3.66 2.63 31.27 3.53 61.6% 17.1% 3.8%

Total Fail% 4,495 19.2% 1.42 16.22 2.03 1.04 11.77 1.88 27.1% 27.4% 7.7%

1992 Pass - 5,554 1.01 10.87 1.95 1.01 10.87 1.95 0.0% 0.0% 0.0%

T Fail Pass 1,074 15.6% 2.63 28.91 2.73 1.14 10.85 2.14 56.6% 62.5% 21.7%

Fail Unresolv. 254 3.7% 5.73 51.92 3.08 1.80 17.22 1.01 68.6% 66.8% 67.1%

Fail Waiver 11 0.2% 7.61 78.48 2.08 5.19 53.36 1.51 31.8% 32.0% 27.5%

Total Fail% 6,893 19.4% 1.45 15.30 2.11 1.07 11.17 1.94 26.3% 27.0% 8.0%

1993 Pass - 6,186 1.03 10.86 2.14 1.03 10.86 2.14 0.0% 0.0% 0.0%

T Fail Pass 1,087 14.4% 2.59 27.50 2.86 1.11 10.81 2.12 57.1% 60.7% 26.0%

Fail Unresolv. 260 3.4% 5.34 50.52 3.09 1.72 16.26 1.03 67.7% 67.8% 66.7%

Fail Waiver 13 0.2% 3.20 46.84 4.95 3.19 42.72 4.39 0.2% 8.8% 11.4%

Total Fail% 7,546 18.0% 1.41 14.69 2.28 1.07 11.10 2.10 24.0% 24.5% 7.9%

1994 Pass - 10,187 0.78 8.80 1.83 0.78 8.80 1.83 0.0% 0.0% 0.0%

T Fail Pass 2,036 16.0% 2.28 22.42 2.93 0.87 8.73 1.93 62.0% 61.1% 34.3%

Fail Unresolv. 508 4.0% 4.54 39.63 3.63 1.31 12.56 1.17 71.1% 68.3% 67.9%

Fail Waiver 27 0.2% 3.06 31.71 3.83 2.95 31.17 3.42 3.6% 1.7% 10.7%

Total Fail% 12,758 20.2% 1.18 12.25 2.08 0.82 8.99 1.82 30.1% 26.6% 12.5%

1995 Pass - 10,020 0.74 8.56 1.82 0.74 8.56 1.82 0.0% 0.0% 0.0%

T Fail Pass 1,955 15.7% 2.20 21.80 2.90 0.82 8.75 1.87 62.9% 59.9% 35.7%

Fail Unresolv. 498 4.0% 3.93 35.20 3.65 1.24 11.32 1.20 68.3% 67.8% 67.3%

Fail Waiver 18 0.1% 3.61 45.38 3.15 2.88 33.94 3.00 20.1% 25.2% 4.8%

Total Fail% 12,491 19.8% 1.10 11.75 2.06 0.77 8.74 1.80 29.5% 25.6% 12.6%

1996 Pass - 13,822 0.40 5.28 1.34 0.40 5.28 1.34 0.0% 0.0% 0.0%

T Fail Pass 2,136 13.1% 1.14 14.52 2.38 0.44 5.44 1.49 61.4% 62.5% 37.4%

Fail Unresolv. 367 2.2% 2.81 27.95 3.67 0.90 9.38 1.18 67.8% 66.4% 67.8%

Fail Waiver 12 0.1% 2.61 17.78 4.20 2.86 17.97 3.78 -9.6% -1.1% 9.9%

Total Fail% 16,337 15.4% 0.56 7.00 1.53 0.42 5.40 1.36 24.1% 22.9% 11.3%

1997 Pass - 14,907 0.36 5.12 1.29 0.36 5.12 1.29 0.0% 0.0% 0.0%

T Fail Pass 2,425 13.6% 1.06 14.57 2.36 0.41 5.55 1.42 61.6% 61.9% 39.7%

Fail Unresolv. 427 2.4% 2.52 25.80 3.32 0.76 8.58 1.10 69.6% 66.8% 67.0%

Fail Waiver 19 0.1% 2.58 27.11 3.49 2.40 19.96 3.26 7.1% 26.4% 6.5%

Total Fail% 17,778 16.1% 0.51 6.93 1.49 0.38 5.28 1.31 25.8% 23.8% 12.2%

A1-6
Appendix A1 Colorado 2012 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 - 23,081 0.30 4.33 1.08 0.30 4.33 1.08 0.0% 0.0% 0.0%

T Fail Pass 3,069 11.5% 0.98 12.68 2.20 0.35 4.64 1.22 64.6% 63.4% 44.4%

Fail Unresolv. 485 1.8% 2.36 21.97 3.43 0.71 7.13 1.14 69.7% 67.6% 66.8%

Fail Waiver 18 0.1% 1.08 15.81 4.24 0.87 10.35 4.12 18.9% 34.5% 2.8%

Total Fail% 26,653 13.4% 0.42 5.62 1.25 0.31 4.43 1.10 24.6% 21.3% 12.3%

1999 Pass - 20,368 0.24 3.50 0.82 0.24 3.50 0.82 0.0% 0.0% 0.0%

T Fail Pass 2,647 11.3% 0.86 12.04 2.15 0.30 3.83 1.03 64.8% 68.2% 52.2%

Fail Unresolv. 449 1.9% 2.01 19.77 3.33 0.61 6.37 1.11 69.6% 67.8% 66.7%

Fail Waiver 19 0.1% 1.71 17.44 2.37 1.06 15.90 2.59 37.6% 8.9% -9.1%

Total Fail% 23,483 13.3% 0.34 4.78 1.02 0.25 3.60 0.85 26.3% 24.7% 16.6%

2000 Pass - 28,643 0.19 2.85 0.68 0.19 2.85 0.68 0.0% 0.0% 0.0%

T Fail Pass 2,901 9.1% 0.65 10.07 1.69 0.26 3.64 0.91 60.9% 63.9% 46.2%

Fail Unresolv. 352 1.1% 1.90 20.14 2.92 0.59 6.78 0.96 69.2% 66.3% 66.9%

Fail Waiver 19 0.1% 2.06 19.65 2.61 1.70 14.33 2.83 17.4% 27.1% -8.6%

Total Fail% 31,915 10.3% 0.26 3.70 0.80 0.20 2.97 0.71 19.9% 19.9% 11.5%

2001 Pass - 21,050 0.14 2.60 0.47 0.14 2.60 0.47 0.0% 0.0% 0.0%

T Fail Pass 1,783 7.8% 0.54 8.76 1.27 0.19 3.13 0.65 65.2% 64.3% 48.9%

Fail Unresolv. 160 0.7% 1.07 17.74 3.09 0.34 5.66 1.02 67.8% 68.1% 66.9%

Fail Waiver 8 0.0% 1.02 29.57 3.11 0.79 28.95 2.49 22.5% 2.1% 20.0%

Total Fail% 23,001 8.5% 0.17 3.19 0.55 0.14 2.67 0.49 18.7% 16.3% 11.3%

2002 Pass - 31,338 0.10 2.66 0.40 0.10 2.66 0.40 0.0% 0.0% 0.0%

T Fail Pass 1,908 5.7% 0.50 11.43 1.12 0.15 2.90 0.57 70.7% 74.6% 49.7%

Fail Unresolv. 143 0.4% 1.49 23.43 2.61 0.42 7.02 0.81 71.9% 70.0% 69.0%

Fail Waiver 11 0.0% 1.49 29.48 2.37 1.41 22.12 2.25 5.7% 25.0% 4.9%

Total Fail% 33,400 6.2% 0.13 3.26 0.45 0.11 2.70 0.41 19.2% 17.2% 8.9%

2003 Pass - 19,618 0.08 1.61 0.31 0.08 1.61 0.31 0.0% 0.0% 0.0%

T Fail Pass 1,211 5.8% 0.39 7.96 0.89 0.13 2.52 0.47 66.5% 68.3% 46.8%

Fail Unresolv. 89 0.4% 1.18 19.08 2.54 0.48 7.99 0.84 58.9% 58.1% 67.1%

Fail Waiver 3 0.0% 0.78 10.94 1.97 0.84 11.08 2.24 -8.9% -1.2% -13.7%

Total Fail% 20,921 6.2% 0.11 2.05 0.35 0.09 1.69 0.32 16.9% 17.6% 9.0%

2004 Pass - 34,717 0.05 1.21 0.16 0.05 1.21 0.16 0.0% 0.0% 0.0%

T Fail Pass 1,513 4.2% 0.27 5.14 0.58 0.09 2.09 0.24 67.8% 59.3% 59.3%

Fail Unresolv. 56 0.2% 1.08 19.55 2.56 0.35 6.40 0.84 67.8% 67.2% 67.1%

Fail Waiver 3 0.0% 0.91 18.18 2.43 0.88 16.32 2.99 2.6% 10.2% -23.2%

Total Fail% 36,289 4.3% 0.06 1.40 0.18 0.06 1.25 0.16 13.7% 10.5% 9.5%

2005 Pass - 20,352 0.05 1.00 0.12 0.05 1.00 0.12 0.0% 0.0% 0.0%

T Fail Pass 684 3.2% 0.22 4.22 0.64 0.09 1.92 0.25 59.8% 54.4% 60.9%

Fail Unresolv. 29 0.1% 0.85 13.99 2.65 0.32 4.87 0.91 61.9% 65.2% 65.8%

Fail Waiver 4 0.0% 1.41 18.09 1.93 0.75 15.75 2.47 46.9% 12.9% -27.8%

Total Fail% 21,069 3.4% 0.06 1.13 0.14 0.05 1.04 0.12 9.0% 7.8% 10.8%

A1-7
Appendix A1 Colorado 2012 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 - 29,143 0.04 0.91 0.10 0.04 0.91 0.10 0.0% 0.0% 0.0%

T Fail Pass 893 3.0% 0.19 3.13 0.67 0.06 1.19 0.17 68.7% 62.1% 74.8%

Fail Unresolv. 28 0.1% 1.15 13.68 2.96 0.53 8.43 0.93 53.9% 38.4% 68.6%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 30,064 3.1% 0.04 0.99 0.12 0.04 0.93 0.10 10.2% 6.3% 14.5%

2007 Pass - 17,899 0.03 0.80 0.08 0.03 0.80 0.08 0.0% 0.0% 0.0%

T Fail Pass 627 3.4% 0.11 2.53 0.47 0.05 1.34 0.10 59.8% 47.1% 79.0%

Fail Unresolv. 10 0.1% 0.46 4.20 1.23 0.15 1.21 0.35 68.4% 71.3% 71.4%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 18,536 3.4% 0.04 0.86 0.10 0.03 0.82 0.08 7.0% 4.9% 13.5%

2008 Pass - 36,404 0.03 0.77 0.08 0.03 0.77 0.08 0.0% 0.0% 0.0%

T Fail Pass 1,060 2.8% 0.05 2.44 0.33 0.04 1.50 0.06 34.7% 38.4% 80.3%

Fail Unresolv. 18 0.0% 0.35 5.63 1.62 0.12 1.86 0.53 65.4% 67.0% 67.1%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 37,482 2.9% 0.03 0.82 0.08 0.03 0.79 0.08 2.2% 3.5% 9.3%

2009 Pass - 4,548 0.03 0.75 0.08 0.03 0.75 0.08 0.0% 0.0% 0.0%

T Fail Pass 117 2.5% 0.08 1.48 0.34 0.03 1.10 0.07 64.8% 25.4% 80.4%

Fail Unresolv. 2 0.0% 0.04 3.10 0.03 0.01 1.02 0.01 67.0% 67.0% 67.0%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 4,667 2.5% 0.03 0.77 0.08 0.03 0.76 0.08 4.7% 1.3% 8.2%

2010 Pass - 2,629 0.03 0.74 0.06 0.03 0.74 0.06 0.0% 0.0% 0.0%

T Fail Pass 47 1.8% 0.03 1.14 0.14 0.02 0.75 0.05 22.1% 34.0% 67.1%

Fail Unresolv. 2 0.1% 0.02 0.40 0.06 0.01 0.13 0.02 67.0% 67.0% 67.0%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 2,678 1.8% 0.03 0.74 0.06 0.03 0.74 0.06 0.5% 0.9% 2.6%

2011 Pass - 1,318 0.03 0.79 0.05 0.03 0.79 0.05 0.0% 0.0% 0.0%

T Fail Pass 16 1.2% 0.06 1.81 0.24 0.02 0.74 0.02 61.6% 59.3% 90.8%

Fail Unresolv. 1 0.1% 0.06 0.70 0.07 0.02 0.23 0.02 67.0% 67.0% 67.0%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 1,335 1.3% 0.03 0.80 0.06 0.03 0.79 0.05 1.6% 1.6% 4.7%

2012 Pass - 412 0.03 0.68 0.05 0.03 0.68 0.05 0.0% 0.0% 0.0%

T Fail Pass 4 1.0% 0.03 1.11 0.04 0.01 0.72 0.03 50.9% 34.8% 31.3%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 416 1.0% 0.03 0.68 0.05 0.03 0.68 0.05 0.5% 0.5% 0.3%

2013 Pass - 20 0.02 0.52 0.04 0.02 0.52 0.04 0.0% 0.0% 0.0%

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 20 0.0% 0.02 0.52 0.04 0.02 0.52 0.04 0.0% 0.0% 0.0%

Total Trucks

All Pass - 370,769 0.25 3.43 0.66 0.25 3.43 0.66 0.0% 0.0% 0.0%

T Fail Pass 33,972 8.3% 1.34 16.72 1.98 0.55 6.33 1.27 59.0% 62.1% 35.9%

Fail Unresolv. 5,790 1.4% 3.83 41.46 3.13 1.19 13.48 1.03 68.8% 67.5% 67.3%

Fail Waiver 247 0.1% 3.92 45.79 3.12 2.67 36.25 2.96 32.0% 20.8% 4.9%

Total Fail% 410,778 9.7% 0.40 5.09 0.81 0.29 3.84 0.72 26.0% 24.7% 11.0% A1-8
Appendix A1 Colorado 2012 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

Fleet Total

All Pass - 751,393 0.22 3.05 0.58 0.22 3.05 0.58 0.0% 0.0% 0.0%

All Fail Pass 62,210 7.5% 1.21 15.39 1.74 0.46 5.34 1.06 62.0% 65.3% 38.8%

Fail Unresolv. 11,712 1.4% 3.34 35.95 2.73 1.05 11.68 0.89 68.5% 67.5% 67.2%

Fail Waiver 513 0.1% 3.41 41.66 2.80 2.56 33.68 2.72 24.9% 19.2% 3.1%

Total Fail% 825,828 9.0% 0.34 4.47 0.70 0.25 3.37 0.62 26.3% 24.7% 11.0%

A1-9
Appendix A2 Colorado 2012 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 - 1 0.56 7.44 1.48 0.56 7.44 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% 1 0.0% 0.56 7.44 1.48 0.56 7.44 1.48 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 - 1 1.10 9.95 2.51 1.10 9.95 2.51 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% 1.10 9.95 2.51 1.10 9.95 2.51 0.0% 0.0% 0.0%

1987 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%

1988 Pass - 2 0.80 6.06 1.36 0.80 6.06 1.36 0.0% 0.0% 0.0%

P Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 1 33.3% 15.99 6.36 1.54 15.99 6.36 1.54 0.0% 0.0% 0.0%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 3 33.3% 5.86 6.16 1.42 5.86 6.16 1.42 0.0% 0.0% 0.0%

1989 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%

A2-1
Appendix A2 Colorado 2012 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 - 5 0.99 10.27 1.79 0.99 10.27 1.79 0.0% 0.0% 0.0%

P Fail Pass 1 16.7% 1.03 7.22 2.07 0.25 2.41 1.27 75.3% 66.7% 38.6%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 6 16.7% 1.00 9.76 1.84 0.87 8.96 1.70 13.0% 8.2% 7.3%

1991 Pass - 1 0.50 8.13 1.61 0.50 8.13 1.61 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% 0.50 8.13 1.61 0.50 8.13 1.61 0.0% 0.0% 0.0%

1992 Pass - 9 0.35 4.93 0.92 0.35 4.93 0.92 0.0% 0.0% 0.0%

P Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 9 0.0% 0.35 4.93 0.92 0.35 4.93 0.92 0.0% 0.0% 0.0%

1993 Pass - 3 0.36 3.89 1.23 0.36 3.89 1.23 0.0% 0.0% 0.0%

P Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 3 0.0% 0.36 3.89 1.23 0.36 3.89 1.23 0.0% 0.0% 0.0%

1994 Pass - 23 0.46 4.50 1.04 0.46 4.50 1.04 0.0% 0.0% 0.0%

P Fail Pass 1 4.2% 1.71 0.90 1.09 0.66 0.15 1.10 61.4% 83.3% -0.6%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 24 4.2% 0.52 4.35 1.04 0.47 4.32 1.04 8.5% 0.7% 0.0%

1995 Pass - 16 0.40 3.08 0.98 0.40 3.08 0.98 0.0% 0.0% 0.0%

P Fail Pass 2 11.1% 2.65 11.34 1.04 0.49 4.53 1.04 81.5% 60.0% -0.1%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 18 11.1% 0.65 3.99 0.99 0.41 3.24 0.99 37.1% 18.9% 0.0%

1996 Pass - 30 0.32 3.24 0.85 0.32 3.24 0.85 0.0% 0.0% 0.0%

P Fail Pass 3 9.1% 0.64 8.21 1.34 0.30 2.40 0.53 53.4% 70.8% 60.2%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 33 9.1% 0.34 3.69 0.90 0.31 3.16 0.83 9.0% 14.3% 8.2%

1997 Pass - 39 0.38 3.19 0.77 0.38 3.19 0.77 0.0% 0.0% 0.0%

P Fail Pass 1 2.4% 1.23 22.96 0.28 0.18 12.53 0.14 85.2% 45.4% 49.1%

Fail Unresolv. 1 2.4% 0.42 6.96 2.23 0.42 6.96 2.23 0.0% 0.0% 0.0%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 41 4.9% 0.41 3.76 0.79 0.38 3.51 0.79 6.3% 6.8% 0.4%

A2-2
Appendix A2 Colorado 2012 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 - 72 0.27 3.22 0.68 0.27 3.22 0.68 0.0% 0.0% 0.0%

P Fail Pass 2 2.7% 0.13 2.13 0.82 0.07 2.47 0.69 41.3% -16.0% 16.2%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 74 2.7% 0.27 3.19 0.69 0.27 3.20 0.68 0.5% -0.3% 0.5%

1999 Pass - 75 0.18 2.76 0.55 0.18 2.76 0.55 0.0% 0.0% 0.0%

P Fail Pass 7 8.5% 0.30 5.47 1.05 0.17 2.22 0.72 44.8% 59.4% 31.8%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 82 8.5% 0.19 2.99 0.60 0.18 2.71 0.57 6.1% 9.3% 4.8%

2000 Pass - 137 0.12 2.05 0.40 0.12 2.05 0.40 0.0% 0.0% 0.0%

P Fail Pass 6 4.2% 0.86 15.09 0.82 0.28 3.90 0.40 67.2% 74.1% 51.6%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 143 4.2% 0.15 2.60 0.41 0.13 2.13 0.40 15.8% 18.1% 4.3%

2001 Pass - 126 0.11 2.03 0.33 0.11 2.03 0.33 0.0% 0.0% 0.0%

P Fail Pass 8 6.0% 0.08 2.79 0.35 0.08 2.27 0.16 0.8% 18.5% 54.1%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 134 6.0% 0.10 2.07 0.33 0.10 2.04 0.32 0.0% 1.5% 3.5%

2002 Pass - 224 0.07 2.16 0.24 0.07 2.16 0.24 0.0% 0.0% 0.0%

P Fail Pass 11 4.7% 0.11 2.96 0.25 0.10 1.52 0.22 7.9% 48.5% 11.5%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 235 4.7% 0.07 2.19 0.24 0.07 2.13 0.24 0.6% 3.1% 0.6%

2003 Pass - 136 0.06 1.25 0.20 0.06 1.25 0.20 0.0% 0.0% 0.0%

P Fail Pass 8 5.6% 0.24 10.27 0.69 0.10 1.28 0.19 59.5% 87.5% 72.3%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 144 5.6% 0.07 1.75 0.22 0.07 1.25 0.20 10.7% 28.5% 12.4%

2004 Pass - 251 0.04 0.93 0.14 0.04 0.93 0.14 0.0% 0.0% 0.0%

P Fail Pass 9 3.5% 0.02 0.69 0.06 0.02 0.77 0.07 -0.2% -13.0% -11.7%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 260 3.5% 0.04 0.92 0.14 0.04 0.92 0.14 0.0% -0.3% -0.2%

2005 Pass - 114 0.03 0.95 0.14 0.03 0.95 0.14 0.0% 0.0% 0.0%

P Fail Pass 4 3.4% 0.05 1.08 0.12 0.07 2.34 0.09 -36.7% -116.3% 27.8%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 118 3.4% 0.03 0.96 0.14 0.03 1.00 0.13 -1.9% -4.4% 0.8%

A2-3
Appendix A2 Colorado 2012 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 - 259 0.03 0.90 0.09 0.03 0.90 0.09 0.0% 0.0% 0.0%

P Fail Pass 4 1.5% 0.08 4.77 3.43 0.09 0.92 0.08 -15.9% 80.8% 97.5%

Fail Unresolv. 3 1.1% 0.10 1.06 3.40 0.06 0.53 3.93 41.8% 50.0% -15.3%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 266 2.6% 0.03 0.96 0.18 0.03 0.90 0.14 0.9% 6.6% 24.4%

2007 Pass - 64 0.03 0.77 0.08 0.03 0.77 0.08 0.0% 0.0% 0.0%

P Fail Pass 1 1.5% 0.02 0.03 5.77 0.01 0.22 0.24 72.9% -637.2% 95.8%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 65 1.5% 0.03 0.75 0.17 0.03 0.76 0.08 0.9% -0.4% 51.2%

2008 Pass - 284 0.03 0.97 0.08 0.03 0.97 0.08 0.0% 0.0% 0.0%

P Fail Pass 10 3.4% 0.06 2.17 0.90 0.03 1.06 0.04 52.5% 51.3% 95.2%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 294 3.4% 0.04 1.01 0.11 0.03 0.97 0.08 3.0% 3.8% 27.6%

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 - 1,872 0.09 1.63 0.26 0.09 1.63 0.26 0.0% 0.0% 0.0%

P Fail Pass 78 4.0% 0.30 5.13 0.82 0.12 1.94 0.29 59.7% 62.2% 65.3%

Fail Unresolv. 5 0.3% 3.34 3.30 2.80 3.32 2.98 3.11 0.8% 9.6% -11.2%

Fail Waiver 0 0.0% 0.00 0.00 0.00 0.00 0.00 0.00

Total Fail% 1,955 4.2% 0.11 1.77 0.29 0.10 1.64 0.27 6.7% 7.2% 7.1%

A2-4
Appendix A2 Colorado 2012 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 0.94 11.77 2.81 0.94 11.77 2.81 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% 0.94 11.77 2.81 0.94 11.77 2.81 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%

A2-5
Appendix A2 Colorado 2012 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 - 5 0.85 8.92 1.92 0.85 8.92 1.92 0.0% 0.0% 0.0%

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 5 0.0% 0.85 8.92 1.92 0.85 8.92 1.92 0.0% 0.0% 0.0%

1991 Pass - 3 0.57 9.40 0.96 0.57 9.40 0.96 0.0% 0.0% 0.0%

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 3 0.0% 0.57 9.40 0.96 0.57 9.40 0.96 0.0% 0.0% 0.0%

1992 Pass - 3 0.74 7.61 1.85 0.74 7.61 1.85 0.0% 0.0% 0.0%

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 3 0.0% 0.74 7.61 1.85 0.74 7.61 1.85 0.0% 0.0% 0.0%

1993 Pass - 1 0.71 5.33 2.37 0.71 5.33 2.37 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% 0.71 5.33 2.37 0.71 5.33 2.37 0.0% 0.0% 0.0%

1994 Pass - 10 0.78 9.15 1.41 0.78 9.15 1.41 0.0% 0.0% 0.0%

T Fail Pass 2 16.7% 1.41 21.09 4.82 1.00 12.94 2.49 28.8% 38.6% 48.3%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 12 16.7% 0.88 11.14 1.98 0.81 9.78 1.59 7.7% 12.2% 19.6%

1995 Pass - 16 0.81 8.61 1.83 0.81 8.61 1.83 0.0% 0.0% 0.0%

T Fail Pass 0 0.0% ------ - - -

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 16 0.0% 0.81 8.61 1.83 0.81 8.61 1.83 0.0% 0.0% 0.0%

1996 Pass - 24 0.44 5.13 1.37 0.44 5.13 1.37 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% 0.44 5.13 1.37 0.44 5.13 1.37 0.0% 0.0% 0.0%

1997 Pass - 34 0.29 4.47 1.26 0.29 4.47 1.26 0.0% 0.0% 0.0%

T Fail Pass 2 5.6% 0.70 5.11 1.47 0.79 5.57 1.40 -12.8% -9.1% 4.8%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 36 5.6% 0.32 4.50 1.27 0.32 4.53 1.26 -1.6% -0.6% 0.3%

A2-6
Appendix A2 Colorado 2012 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 - 63 0.27 3.36 1.08 0.27 3.36 1.08 0.0% 0.0% 0.0%

T Fail Pass 4 6.0% 0.46 6.29 1.81 0.32 3.78 1.10 29.6% 40.0% 39.0%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 67 6.0% 0.28 3.54 1.12 0.27 3.39 1.08 2.9% 4.2% 3.7%

1999 Pass - 89 0.20 3.30 0.75 0.20 3.30 0.75 0.0% 0.0% 0.0%

T Fail Pass 5 5.3% 0.21 4.45 1.10 0.16 4.04 1.14 25.6% 9.2% -3.4%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 94 5.3% 0.21 3.36 0.76 0.20 3.34 0.77 1.4% 0.6% -0.3%

2000 Pass - 145 0.20 2.65 0.66 0.20 2.65 0.66 0.0% 0.0% 0.0%

T Fail Pass 6 3.9% 0.16 2.56 1.57 0.29 3.66 0.98 -77.1% -43.0% 37.6%

Fail Unresolv. 2 1.3% 1.01 12.96 4.66 0.84 9.11 3.14 16.3% 29.7% 32.8%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 153 5.2% 0.21 2.78 0.75 0.22 2.77 0.70 -1.3% 0.3% 5.8%

2001 Pass - 120 0.12 2.28 0.43 0.12 2.28 0.43 0.0% 0.0% 0.0%

T Fail Pass 10 7.6% 0.62 10.01 0.66 0.22 2.09 0.61 65.2% 79.1% 7.2%

Fail Unresolv. 1 0.8% 1.30 45.26 2.82 0.52 26.94 1.93 60.3% 40.5% 31.8%

Fail Waiver 0 0.0% ------ - - -

Total Fail% 131 8.4% 0.17 3.19 0.47 0.13 2.45 0.46 21.8% 23.3% 2.3%

2002 Pass - 298 0.09 2.44 0.40 0.09 2.44 0.40 0.0% 0.0% 0.0%

T Fail Pass 18 5.7% 0.13 4.64 0.59 0.13 2.22 0.43 -6.4% 52.1% 28.3%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 316 5.7% 0.09 2.57 0.41 0.09 2.43 0.40 -0.5% 5.4% 2.3%

2003 Pass - 151 0.08 1.36 0.31 0.08 1.36 0.31 0.0% 0.0% 0.0%

T Fail Pass 6 3.8% 2.57 5.49 0.42 0.14 2.70 0.77 94.6% 50.8% -82.1%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 157 3.8% 0.17 1.52 0.31 0.08 1.41 0.33 53.9% 7.0% -4.2%

2004 Pass - 434 0.05 1.18 0.17 0.05 1.18 0.17 0.0% 0.0% 0.0%

T Fail Pass 21 4.6% 0.11 2.23 0.25 0.10 2.49 0.24 6.2% -11.7% 6.0%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 455 4.6% 0.05 1.23 0.17 0.05 1.25 0.17 0.6% -1.0% 0.4%

2005 Pass - 136 0.04 0.91 0.10 0.04 0.91 0.10 0.0% 0.0% 0.0%

T Fail Pass 3 2.2% 0.92 9.13 0.18 0.07 0.91 0.10 92.7% 90.1% 45.5%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 139 2.2% 0.06 1.09 0.10 0.04 0.91 0.10 30.1% 16.3% 1.8%

A2-7
Appendix A2 Colorado 2012 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 - 383 0.04 0.90 0.10 0.04 0.90 0.10 0.0% 0.0% 0.0%

T Fail Pass 10 2.5% 0.13 2.55 0.36 0.08 2.45 0.25 36.6% 3.9% 29.5%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 393 2.5% 0.04 0.94 0.11 0.04 0.94 0.11 3.0% 0.3% 2.4%

2007 Pass - 95 0.03 0.85 0.08 0.03 0.85 0.08 0.0% 0.0% 0.0%

T Fail Pass 2 2.1% 0.03 0.42 0.19 0.02 0.62 0.17 16.8% -49.5% 9.6%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 97 2.1% 0.03 0.84 0.09 0.03 0.84 0.09 0.3% -0.5% 0.4%

2008 Pass - 463 0.03 0.72 0.08 0.03 0.72 0.08 0.0% 0.0% 0.0%

T Fail Pass 9 1.9% 0.03 0.86 0.06 0.04 0.90 0.05 -46.6% -4.9% 17.0%

Fail Unresolv. 0 0.0% ------ - - -

Fail Waiver 0 0.0% ------ - - -

Total Fail% 472 1.9% 0.03 0.72 0.08 0.03 0.72 0.08 -0.8% -0.1% 0.3%

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 - 2,474 0.09 1.66 0.31 0.09 1.66 0.31 0.0% 0.0% 0.0%

T Fail Pass 98 3.8% 0.39 4.49 0.66 0.17 2.66 0.52 57.6% 40.8% 21.8%

Fail Unresolv. 3 0.1% 1.11 23.73 4.05 0.73 15.06 2.73 33.5% 36.5% 32.5%

Fail Waiver 0 0.0%

Total Fail% 2,575 3.9% 0.10 1.79 0.32 0.10 1.71 0.32 8.7% 4.5% 2.2%

A2-8
Appendix A2 Colorado 2012 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 - 4,346 0.09 1.65 0.29 0.09 1.65 0.29 0.0% 0.0% 0.0%

All Fail Pass 176 3.9% 0.35 4.77 0.73 0.15 2.34 0.42 58.4% 51.0% 43.4%

Fail Unresolv. 8 0.2% 2.50 10.96 3.27 2.35 7.51 2.97 6.2% 31.5% 9.1%

Fail Waiver 0 0.0%

Total Fail% 4,530 4.1% 0.11 1.78 0.31 0.10 1.68 0.30 7.8% 5.6% 4.2%

A2-9
Appendix B Colorado 2012

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 4,304 453 5.0 64.9 4.6 3.5 42.7 4.4 1.5 22.2 0.2

P 1983 4,304 502 5.3 68.9 4.8 3.5 37.1 4.5 1.8 31.8 0.3

P 1984 4,304 1,279 11.0 129.0 11.7 7.9 79.4 11.2 3.2 49.6 0.5

P 1985 4,434 1,271 10.5 121.7 12.2 7.1 74.2 11.3 3.4 47.6 0.9

P 1986 4,481 2,249 15.3 153.0 21.1 10.6 97.5 19.7 4.7 55.5 1.4

P 1987 4,502 1,954 12.9 129.3 18.2 8.9 83.2 16.9 3.9 46.1 1.3

P 1988 4,552 3,471 18.8 216.5 28.2 13.5 144.6 26.5 5.3 71.9 1.7

P 1989 4,780 3,383 19.1 217.2 30.0 13.9 150.3 28.3 5.2 66.9 1.8

P 1990 5,088 6,844 37.1 423.3 64.4 27.6 307.2 60.0 9.4 116.2 4.5

P 1991 5,430 6,723 37.8 419.5 64.9 26.1 291.9 59.2 11.7 127.6 5.8

P 1992 5,672 9,736 50.1 593.8 91.5 35.7 392.9 84.9 14.4 200.9 6.6

P 1993 6,002 9,251 49.2 536.2 95.3 35.5 376.7 88.6 13.7 159.4 6.7

P 1994 6,331 12,989 59.4 662.2 117.1 41.2 478.1 107.1 18.1 184.1 10.1

P 1995 6,653 15,120 66.7 752.6 126.5 47.8 553.1 114.7 18.9 199.5 11.7

P 1996 6,974 19,407 60.2 760.8 135.8 47.0 580.7 122.9 13.1 180.1 12.9

P 1997 7,369 19,229 63.5 809.0 135.6 49.4 624.5 122.9 14.1 184.5 12.7

P 1998 7,764 26,171 69.2 989.5 161.9 52.3 761.4 142.8 16.9 228.1 19.1

P 1999 8,188 23,191 58.9 836.5 144.0 43.5 647.5 125.0 15.4 188.9 19.0

P 2000 8,613 34,236 63.8 1006.8 170.4 47.7 801.2 145.9 16.1 205.7 24.5

P 2001 9,032 25,550 37.6 699.1 98.8 27.3 550.0 82.5 10.4 149.1 16.4

P 2002 9,450 34,364 38.3 917.1 108.1 30.0 815.1 90.9 8.3 102.1 17.3

P 2003 9,905 22,471 20.7 413.2 62.2 15.4 345.9 53.2 5.4 67.2 9.0

P 2004 10,360 29,581 20.8 439.2 54.9 15.6 376.7 46.9 5.2 62.5 8.0

P 2005 10,746 19,057 12.4 278.1 33.5 8.9 224.6 28.5 3.5 53.4 5.0

P 2006 11,132 28,021 15.1 403.3 48.8 12.1 351.4 33.4 3.0 51.9 15.5

P 2007 11,870 15,794 7.6 209.2 26.3 6.2 186.2 18.2 1.4 23.0 8.1

P 2008 12,023 31,893 14.4 412.9 48.0 12.0 380.6 33.2 2.4 32.3 14.8

P 2009 12,307 5,620 2.4 73.3 7.9 2.2 68.3 5.9 0.3 5.1 2.0

P 2010 12,357 2,770 1.0 38.3 2.6 0.9 36.9 2.5 0.1 1.4 0.1

P 2011 11,600 1,853 0.8 25.2 1.7 0.6 24.7 1.5 0.1 0.5 0.1

P 2012 11,600 594 0.2 6.7 0.4 0.2 6.7 0.4 0.0 0.0 0.0

P Total 415,027 885.0 12806.4 1931.5 653.9 9891.3 1693.8 231.1 2915.1 237.7

T 1982 4,550 529 9.3 125.3 7.6 6.1 77.3 6.9 3.2 48.0 0.7

T 1983 4,554 563 11.4 149.5 7.2 7.6 93.8 6.7 3.8 55.7 0.6

T 1984 4,562 1,398 22.4 311.2 18.9 14.8 186.3 17.6 7.6 124.9 1.3

T 1985 4,583 1,353 19.1 247.1 19.0 13.1 149.7 17.5 6.0 97.4 1.5

T 1986 4,630 2,499 31.3 357.3 33.4 21.3 227.5 31.3 10.0 129.8 2.0

T 1987 4,668 2,009 22.5 246.1 25.7 15.9 156.1 23.9 6.5 90.0 1.8

T 1988 4,741 3,826 37.2 373.4 47.6 26.4 246.1 43.5 10.8 127.4 4.1

T 1989 4,851 3,406 34.6 352.1 43.7 24.1 240.8 39.3 10.5 111.3 4.4

T 1990 5,019 4,968 43.5 437.1 64.3 33.0 318.4 59.0 10.5 118.8 5.3

T 1991 5,256 4,495 37.1 422.5 52.9 27.0 306.6 48.8 10.0 115.9 4.1

T 1992 5,519 6,893 60.6 641.6 88.5 44.7 468.3 81.4 16.0 173.3 7.1

T 1993 5,824 7,546 68.1 711.5 110.5 51.7 537.5 101.8 16.3 174.0 8.7

T 1994 6,135 12,758 101.5 1056.9 179.4 70.9 775.4 157.1 30.6 281.6 22.4

T 1995 6,471 12,491 97.8 1046.7 183.8 68.9 778.4 160.6 28.9 268.2 23.2

T 1996 6,940 16,337 69.5 875.3 191.5 52.7 674.8 169.9 16.8 200.5 21.6

T 1997 7,437 17,778 74.1 1009.9 216.7 55.0 769.3 190.3 19.2 240.6 26.4

T 1998 7,863 26,653 96.4 1299.2 289.3 72.7 1022.4 253.7 23.7 276.9 35.6

T 1999 8,345 23,483 73.6 1033.0 219.8 54.2 777.5 183.4 19.4 255.5 36.4

T 2000 8,900 31,915 80.1 1159.5 250.3 64.2 929.2 221.4 15.9 230.3 28.9

T 2001 9,502 23,001 42.1 768.2 133.6 34.2 642.8 118.6 7.9 125.4 15.1

T 2002 10,087 33,400 48.4 1209.4 166.0 39.2 1001.5 151.3 9.3 207.9 14.7

T 2003 10,727 20,921 26.2 507.6 86.5 21.8 418.1 78.8 4.4 89.6 7.8

T 2004 11,245 36,289 28.9 629.9 80.7 24.9 563.5 73.0 4.0 66.3 7.6

T 2005 11,817 21,069 15.9 309.4 37.9 14.5 285.4 33.8 1.4 24.0 4.1

T 2006 12,303 30,064 18.0 402.9 47.3 16.2 377.4 40.5 1.8 25.5 6.9

T 2007 12,834 18,536 9.4 224.8 25.1 8.7 213.7 21.7 0.7 11.0 3.4

T 2008 13,215 37,482 15.9 446.2 46.4 15.6 430.7 42.1 0.3 15.5 4.3

T 2009 13,433 4,667 2.0 53.2 5.7 1.9 52.5 5.3 0.1 0.7 0.5

T 2010 13,514 2,678 1.1 29.6 2.6 1.1 29.4 2.5 0.0 0.3 0.1

T 2011 12,428 1,335 0.5 14.7 1.0 0.5 14.4 1.0 0.0 0.2 0.0

T 2012 12,428 416 0.2 3.9 0.3 0.2 3.9 0.3 0.0 0.0 0.0

T Total 410,758 1198.8 16454.9 2683.2 903.2 12768.6 2382.8 295.6 3686.4 300.4

Total 825,785 2083.8 29261.3 4614.7 1557.1 22659.9 4076.6 526.6 6601.4 538.2

25% 23%

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 4,304 1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

P 1985 4,434 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

P 1986 4,481 1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

P 1987 4,502 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

P 1988 4,552 3 0.1 0.1 0.0 0.1 0.1 0.0 0.0 0.0 0.0

P 1989 4,780 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

P 1990 5,088 6 0.0 0.3 0.1 0.0 0.3 0.1 0.0 0.0 0.0

P 1991 5,430 1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

P 1992 5,672 9 0.0 0.3 0.1 0.0 0.3 0.1 0.0 0.0 0.0

P 1993 6,002 3 0.0 0.1 0.0 0.0 0.1 0.0 0.0 0.0 0.0

P 1994 6,331 24 0.1 0.7 0.2 0.1 0.7 0.2 0.0 0.0 0.0

P 1995 6,653 18 0.1 0.5 0.1 0.1 0.4 0.1 0.0 0.1 0.0

P 1996 6,974 33 0.1 0.9 0.2 0.1 0.8 0.2 0.0 0.1 0.0

P 1997 7,369 41 0.1 1.3 0.3 0.1 1.2 0.3 0.0 0.1 0.0

P 1998 7,764 74 0.2 2.0 0.4 0.2 2.0 0.4 0.0 0.0 0.0

P 1999 8,188 82 0.1 2.2 0.4 0.1 2.0 0.4 0.0 0.2 0.0

P 2000 8,613 143 0.2 3.5 0.6 0.2 2.9 0.5 0.0 0.6 0.0

P 2001 9,032 134 0.1 2.8 0.4 0.1 2.7 0.4 0.0 0.0 0.0

P 2002 9,450 235 0.2 5.4 0.6 0.2 5.2 0.6 0.0 0.2 0.0

P 2003 9,905 144 0.1 2.8 0.4 0.1 2.0 0.3 0.0 0.8 0.0

P 2004 10,360 260 0.1 2.7 0.4 0.1 2.7 0.4 0.0 0.0 0.0

P 2005 10,746 118 0.0 1.3 0.2 0.0 1.4 0.2 0.0 -0.1 0.0

P 2006 11,132 266 0.1 3.1 0.6 0.1 2.9 0.4 0.0 0.2 0.1

P 2007 11,870 65 0.0 0.6 0.1 0.0 0.6 0.1 0.0 0.0 0.1

P 2008 12,023 294 0.1 3.9 0.4 0.1 3.8 0.3 0.0 0.1 0.1

P 2009 12,307 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

P Total 1,955 1.9 34.8 5.5 1.8 32.3 5.1 0.1 2.5 0.5

T 1982 4,550 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

T 1983 4,554 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

T 1984 4,562 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

T 1985 4,583 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

T 1986 4,630 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

T 1987 4,668 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

T 1988 4,741 1 0.0 0.1 0.0 0.0 0.1 0.0 0.0 0.0 0.0

T 1989 4,851 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

T 1990 5,019 5 0.0 0.2 0.1 0.0 0.2 0.1 0.0 0.0 0.0

T 1991 5,256 3 0.0 0.2 0.0 0.0 0.2 0.0 0.0 0.0 0.0

T 1992 5,519 3 0.0 0.1 0.0 0.0 0.1 0.0 0.0 0.0 0.0

T 1993 5,824 1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

T 1994 6,135 12 0.1 0.9 0.2 0.1 0.8 0.1 0.0 0.1 0.0

T 1995 6,471 16 0.1 1.0 0.2 0.1 1.0 0.2 0.0 0.0 0.0

T 1996 6,940 24 0.1 0.9 0.3 0.1 0.9 0.3 0.0 0.0 0.0

T 1997 7,437 36 0.1 1.3 0.4 0.1 1.3 0.4 0.0 0.0 0.0

T 1998 7,863 67 0.2 2.1 0.7 0.2 2.0 0.6 0.0 0.1 0.0

T 1999 8,345 94 0.2 2.9 0.7 0.2 2.9 0.7 0.0 0.0 0.0

T 2000 8,900 153 0.3 4.2 1.1 0.3 4.2 1.1 0.0 0.0 0.1

T 2001 9,502 131 0.2 4.4 0.6 0.2 3.4 0.6 0.1 1.0 0.0

T 2002 10,087 316 0.3 9.0 1.4 0.3 8.5 1.4 0.0 0.5 0.0

T 2003 10,727 157 0.3 2.8 0.6 0.1 2.6 0.6 0.2 0.2 0.0

T 2004 11,245 455 0.3 7.0 1.0 0.3 7.0 1.0 0.0 -0.1 0.0

T 2005 11,817 139 0.1 2.0 0.2 0.1 1.7 0.2 0.0 0.3 0.0

T 2006 12,303 393 0.2 5.0 0.6 0.2 5.0 0.6 0.0 0.0 0.0

T 2007 12,834 97 0.0 1.2 0.1 0.0 1.2 0.1 0.0 0.0 0.0

T 2008 13,215 472 0.2 4.9 0.5 0.2 5.0 0.5 0.0 0.0 0.0

T 2009 13,433 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

T Total 2,575 2.8 50.2 8.6 2.5 48.0 8.5 0.3 2.2 0.2

Total 4,530 4.7 85.0 14.2 4.3 80.4 13.5 0.4 4.6 0.6

B-2