DRAFT

Maintenance Plan for the

Chicago Nonattainment Area

for the 1997 PM2.5 

National Ambient Air Quality Standards

AQPSTR 10-05

June 1, 2010

Illinois Environmental Protection Agency

1021 North Grand Avenue East

Springfield, Illinois 62794-9276
i

TABLE OF CONTENTS

 Page

LIST OF TABLES . . . . . . . . . iii

LIST OF FIGURES . . . . . . . . . iv

EXECUTIVE SUMMARY . . . . . . . . 5

1.0 INTRODUCTION . . . . . . . . 6

1.1 Regulatory Background . . . . . . 6

1.2 Status of Air Quality . . . . . . . 8

2.0 REDESIGNATION AND MAINTENANCE PLAN REQUIREMENTS 9

3.0 PM2.5 MONITORING . . . . . . . 11

3.1 Monitored Design Values . . . . . . 11

3.2 Quality Assurance . . . . . . . 12

3.3 Continued Monitoring . . . . . . 12

4.0 EMISSIONS INVENTORY. . . . . . . 14

4.1 Attainment Year Inventory . . . . . . 14

4.2 Air Quality Improvements and Emissions Controls . . . 15

4.3 Emissions Projections. . . . . . . 16

4.4 Demonstration of Maintenance . . . . . 16

4.5 Provisions for Future Updates . . . . . 18

5.0 CONTROL MEASURES AND REGULATIONS . . . 19

5.1 Control Measures . . . . . . . 19

5.2 Reasonable Further Progress (RFP) and

Reasonably Available Control Technology (RACT) . . . 20

5.3 Controls to Remain in Effect . . . . . . 20

5.4 Provisions for Permitting New or Modified Emissions Sources . 21

5.5 Transportation Conformity . . . . . . 21

6.0 CONTINGENCY MEASURES . . . . . . 23

6.1 Contingency Measures . . . . . . 23

6.2 Commitment to Revise Plan . . . . . . 25

6.3 Public Participation . . . . . . . 25

6.4 Legal Authority to Implement and Enforce . . . . 26

7.0 CONCLUSIONS . . . . . . . . 27
ii

TABLE OF CONTENTS (Continued)

APPENDIX A Summary of Ambient Air Monitoring Data (2007-2009) 28

APPENDIX B Transportation Conformity 30
iii

LIST OF TABLES

Page

Table 4.1 2008 PM2.5, NOx and SO2 Emissions . . . . . 15 

Table 4.2 2002 PM2.5, NOx and SO2 Emissions . . . . . 15 

Table 4.3 2015 PM2.5, NOx and SO2 Emissions . . . . . 16 

Table 4.4 2020 PM2.5, NOx and SO2 Emissions . . . . . 17 

Table 4.5 2025 PM2.5, NOx and SO2 Emissions . . . . . 17 

Table 4.6 Comparison of 2008, 2015, 2020 and 2025 Emissions . . 17

Table 5.1 Proposed 2008 and 2025 Motor Vehicle Emissions Budgets

Chicago Nonattainment Area PM2.5 Maintenance Plan. . . 22

Table 6.1 Contingency Plan for the Chicago PM2.5 Nonattainment Area . 24
iv

LIST OF FIGURES

Page

Figure 1.1 Chicago PM2.5 Nonattainment Area . . . . . 7

Figure 3.1 PM2.5 Monitors in the Chicago Nonattainment Area . . . 11

Figure 3.2 Comparison of PM2.5 Design Values for the Chicago

Nonattainment Area Between 2000-2002 and 2007-2009 . . 13
5

EXECUTIVE SUMMARY

This document describes Illinois’ Draft Maintenance Plan for the Illinois portion of the 

Chicago fine particulate matter (PM2.5) nonattainment area (NAA), hereafter referred to 

as the Chicago NAA. An approved Maintenance Plan is required before an area can be 

redesignated from nonattainment to attainment of a National Ambient Air Quality 

Standard (NAAQS). This document provides technical information required to support a 

request to redesignate the Chicago NAA to attainment of the 1997 annual PM2.5 NAAQS. 

Illinois intends to submit a final version of the Maintenance Plan to the U.S. 

Environmental Protection Agency (U.S. EPA) after consideration of public comments. 

The Indiana Department of Environmental Management (IDEM), has prepared a similar 

plan for the Indiana portion of the Chicago nonattainment area.

PM2.5 air quality has improved in the Chicago area as a result of the implementation of 

State and Federal emissions control measures since the designation of the area as 

nonattainment of the PM2.5 standard in 2004. These air quality improvements are due to 

permanent and enforceable emissions control measures. The entire Chicago

nonattainment area has at least three years of complete, quality assured ambient air 

quality monitoring data for 2007-2009 that demonstrates compliance with the 1997

NAAQS. The U.S. EPA has made a determination that the Chicago nonattainment area 

has attained the 1997 fine particle standard (40 CFR 52.74, p. 62243-62249).

This Maintenance Plan provides for continued attainment of the 1997 PM2.5 air quality 

standards for the Chicago nonattainment area for a period of at least ten years after U.S. 

EPA has formally redesignated the area to attainment. The Plan also provides assurances 

that, even if there is a subsequent violation of the air quality standard, contingency 

measures listed in the Plan will be triggered to prevent any future occurrences. Finally, 

the Plan includes on-road motor vehicle emissions budgets for the years 2008 and 2025

for use in transportation conformity determinations to assure that any increases in 

emissions from this sector do not jeopardize continued attainment of the PM2.5 standards

during the maintenance period.
6

1.0 INTRODUCTION

The Illinois Environmental Protection Agency (Illinois EPA) has prepared this document 

to describe Illinois’ PM2.5 Maintenance Plan for the Chicago NAA. This Maintenance 

Plan is required before the area can be redesignated from nonattainment to attainment of 

the annual National Ambient Air Quality Standard (NAAQS) for PM2.5 promulgated by 

the U.S. Environmental Protection Agency (U.S. EPA) in 1997. The Illinois EPA intends 

to submit such a request to the U.S. EPA in conjunction with this Maintenance Plan. The 

entire Chicago nonattainment area, including Lake and Porter counties in Indiana, has at 

least three years of complete, quality assured ambient air quality monitoring data for the 

most recent 3-year period, 2007-2009, demonstrating attainment with the annual PM2.5

NAAQS promulgated in 1997. U.S. EPA finalized its determination that the entire 

Chicago NAA attains the 1997 PM2.5 NAAQS in November 2009.

This document provides the technical information needed to support a request to 

redesignate the Chicago area to attainment of the 1997 annual PM2.5 NAAQS. Section 

107 of the Clean Air Act (CAA) establishes specific requirements to be met in order for a 

nonattainment area to be considered for redesignation. Before an area can be reclassified 

to attainment:

• U.S. EPA must make a determination that the area has attained the NAAQS based 

on at least three complete years of ambient monitoring data. 

• U.S. EPA must have approved a State Implementation Plan (SIP) for the area 

under Section 110 and Part D of the CAA. 

• The state must demonstrate that the improvement in air quality is due to 

permanent and enforceable reductions in emissions resulting from implementation 

of the SIP and other federal requirements. 

• The state must submit, and U.S. EPA must approve, a Maintenance Plan under 

Section 175(A) of the CAA, including provisions for contingency measures that 

will be implemented if future violations of the NAAQS are measured.

This Maintenance Plan provides for the continued attainment of the annual PM2.5

NAAQS for the Chicago NAA for a period of at least ten years after U.S. EPA has 

formally redesignated the area to attainment. The Plan also provides assurances that even 

if a subsequent violation of the annual PM2.5 NAAQS occurs, provisions in the Plan will 

prevent any future occurrences through the enactment of contingency measures that 

would be triggered upon such occurrence.

This document addresses the Maintenance Plan requirements established by the CAA and 

U.S. EPA, and includes additional information to support continued compliance with the 

PM2.5 NAAQS.

1.1 Regulatory Background

The CAA requires areas that fail to meet the NAAQS for PM2.5 to develop SIPs to 

expeditiously attain and maintain the NAAQS. Historically, one-year exceedances of the 

annual PM2.5 NAAQS have been monitored as recently as 2007 at one monitor in Cook 

county, but all monitors in the NAA are now in attainment of the PM2.5 NAAQS.
7

The Chicago NAA, which includes all of Cook, DuPage, Kane, Lake, McHenry and Will 

counties, as well as portions of Grundy and Kendall counties, was originally designated 

as nonattainment of the 1997 annual PM2.5 in 2004. The Chicago area was designated 

unclassifiable/attainment for the 24-hour PM2.5 standard that was also promulgated in 

1997, and revised in 2006. Since the Chicago area is not a nonattainment area for the 24-

hour PM2.5 NAAQS, any reference to the PM2.5 NAAQS in the remainder of this 

document refers only to the annual PM2.5 standard promulgated in 1997. Figure 1.1 

depicts the current Chicago NAA.

Figure 1.1- Chicago PM2.5 Nonattainment Area
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The following is a list of the counties contained in the Chicago PM2.5 nonattainment area:

• Cook County, IL

• DuPage County, IL

• Kane County, IL

• Lake County, IL

• McHenry County, IL

• Will County, IL

• Aux Sable and Goose Lake Townships in Grundy County, IL, and

• Oswego Township in Kendall County, IL

As a result of the nonattainment designation, these areas were subject to new 

requirements, including development of an attainment strategy that would allow the area 

to meet the federal PM2.5 NAAQS by June 15, 2010. The attainment strategy recognizes

the importance of reducing both locally-generated as well as incoming (transported) 

PM2.5 and precursor emissions. Both State and Federal emissions control measures have 

reduced primary and secondary PM2.5 emissions both locally and regionally and have 

allowed the Chicago NAA to attain the PM2.5 NAAQS by the attainment deadline 

established by the U.S. EPA.

1.2 Status of Air Quality

PM2.5 monitoring data for the most recent three-year period, 2007 through 2009, 

demonstrates that air quality has met the 1997 PM2.5 NAAQS in the Chicago NAA.

Information regarding the air monitoring network and air quality monitoring data is

included in Section 3.0 and Appendix A.
9

2.0 REDESIGNATION AND MAINTENANCE PLAN REQUIREMENTS

Sections 107 and 110 of the CAA list a number of requirements that must be met by 

nonattainment areas prior to consideration for redesignation to attainment. One of those 

requirements is the development of a Maintenance Plan, which describes a state’s plan 

for maintaining the NAAQS for a minimum ten-year period after redesignation. The 

Illinois EPA followed guidance published by the U.S.EPA entitled “Procedures for 

Processing Requests to Redesignate Areas to Attainment” (September 4, 1992).

Before a redesignation to attainment can be promulgated, U.S. EPA must:

• Determine that the NAAQS for PM2.5, as published in 40 CFR 50.4, has been 

attained. PM2.5 monitoring data must show that violations of the NAAQS are no 

longer occurring. This showing must rely on three consecutive years of data. The 

ambient air monitoring data must be quality assured in accordance with 40 CFR 

58.10, recorded in U.S. EPA’s Air Quality System (AQS) data base, and made

available to the public. U.S. EPA has already finalized and published a finding 

that the area has, in fact, attained the NAAQS. This finding was published in the 

Federal Register in November 2009. 

• Approve the state’s plan for demonstrating attainment. The attainment plan, 

which is based on air quality modeling, must contain enforceable control 

measures and must be submitted as a revision to the state’s SIP after a public 

hearing.

• Determine that the improvement in air quality between the year violations 

occurred and the year that attainment was achieved is based on permanent and 

enforceable emissions reductions.

• Approve the state’s Maintenance Plan. The requirements for the Maintenance 

Plan are discussed below.

• Determine that all other requirements applicable to nonattainment areas have been 

met.

A PM2.5 Maintenance Plan provides for the continued attainment of the PM2.5 NAAQS 

for a nonattainment area for a period of at least ten years after U.S. EPA has formally 

redesignated the area to attainment. To be approvable, the state is required to have a 

public hearing on the Maintenance Plan prior to adoption. The Maintenance Plan must 

contain the following elements:

• A comprehensive “attainment year” emissions inventory of primary PM2.5 and the 

precursors of secondary PM2.5: oxides of nitrogen (NOx) and sulfur dioxide (SO2);
10

• A projection of the emissions inventory forward to a year at least ten years after 

redesignation and a demonstration that the projected level of emissions is 

sufficient to maintain attainment of the PM2.5 NAAQS;

• A commitment that, once redesignated, the state will continue to operate an 

appropriate monitoring network to verify maintenance of the attainment status;

• A demonstration of legal authority to implement and enforce all control measures 

contained in the SIP;

• Provisions for future updates of the inventory to enable tracking of emissions

levels, including an annual emissions statement from major sources;

• Motor vehicle emissions budgets for transportation conformity for the ten-year 

maintenance period;

• A commitment to submit a revised Maintenance Plan eight years after 

redesignation;

• A commitment to enact and implement additional contingency control measures 

expeditiously in the event that future violations of the NAAQS occur; and 

• A list of potential contingency measures that would be implemented in such an 

event.

This Maintenance Plan has been prepared in accordance with the requirements specified 

in U.S. EPA’s guidance document and additional guidance received from U.S. EPA staff.

The following sections of this document describe how U.S. EPA’s requirements have 

been met.
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3.0 PM2.5 MONITORING

U.S. EPA’s published guidance document, “Procedures for Processing Requests to 

Redesignate Areas to Attainment” (September 4, 1992), details specific requirements 

regarding the collection and use of ambient air monitoring data needed to support a 

redesignation request. Before the Chicago NAA can be redesignated, Illinois must 

demonstrate that the PM2.5 NAAQS has been attained. PM2.5 monitoring data must show 

that violations of the NAAQS are no longer occurring within the nonattainment area. 

This showing must rely on three complete, consecutive calendar years of quality assured 

data. Further, the air monitoring data must be quality assured in accordance with 40 CFR 

58.10, recorded in U.S. EPA’s AQS data base, and made available to the public. As 

previously mentioned, U.S.EPA has made a finding that the Chicago NAA has met these 

requirements and is attaining the 1997 PM2.5 NAAQS. Finally, Illinois must commit to

continue to operate an appropriate monitoring network to verify the maintenance of the 

attainment status, once the area has been redesignated.

The following subsections describe how each of these requirements has been addressed.

3.1 Monitored Design Values

Currently there are 19 PM2.5 monitors located in the nonattainment counties in the Illinois

portion of the Chicago nonattainment area. Figure 3.1 shows the locations of these 

monitors. 

Figure 3.1 - PM2.5 Monitors in the Chicago Nonattainment Area
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To determine whether the NAAQS has been met, the annual PM2.5 design value has been 

calculated for the 3-year period, 2007-2009. The current U.S. EPA method for 

calculating the annual PM2.5 design value is to average each monitor’s annual average 

values over the appropriate 3-year period and compare the calculated design values to the 

15.0 microgram per cubic meter level of the NAAQS. The calculated annual PM2.5

design values for the monitors in the Chicago NAA for 2007-2009 are included as 

Appendix A of this report. Figure 3.2 compares the design values for 2000-2002, when 

the area was initially recommended for designation as a nonattainment area, and the 

2007-2009 period for monitoring stations in the Chicago region. The comparison shows 

that PM2.5 air quality has improved considerably since 2000-2002 throughout Chicago 

NAA. The 2007-2009 data shows that the design values at all monitoring sites are less 

than the level of the annual PM2.5 NAAQS, so the area now attains the annual PM2.5 air 

quality standard.

3.2 Quality Assurance

The Illinois EPA has quality assured all monitoring data shown in Appendix A for all 

sites located in Illinois in accordance with 40 CFR 58.10 and the Illinois EPA’s Quality 

Assurance Plan, which describes Illinois EPA’s standard operating procedures for 

operating the ambient monitoring network and validating the data. The Illinois EPA has 

recorded the monitoring data in the U.S. EPA’s AQS database, which is available to the 

public.

3.3 Continued Monitoring

Illinois commits to continue monitoring PM2.5 levels according to a U.S. EPA approved 

monitoring plan, as required to ensure maintenance of the PM2.5 NAAQS. Should 

changes in the location of a PM2.5 monitor become necessary, the Illinois EPA will work 

with U.S. EPA to ensure the adequacy of the monitoring network. The Illinois EPA will 

continue to quality assure the monitoring data to meet the requirements of 40 CFR 58. 

The Illinois EPA will continue to enter all data into AQS on a timely basis in accordance 

with federal guidelines.
13

Figure 3.2 - PM2.5 Design Values for the Chicago Nonattainment Area

Between 2000-2002 and 2007-2009

 2000-2002 Design Values 2007-2009 Design Values
14

4.0 EMISSIONS INVENTORY

A redesignation request must contain a demonstration that the improvement in air quality 

between the year that violations occurred and the year that attainment was achieved is 

based on permanent and enforceable emissions reductions. As described previously in 

Section 3.0, a three-year monitoring period is used to evaluate whether actual air quality 

attainment has been achieved. In this Section, the “attainment year” refers to the midpoint year (2008) of the three-year period (2007-2009) used to demonstrate attainment. 

As required by U.S.EPA redesignation guidance, this request also includes a projection 

of the emissions inventory to a year at least 10 years following redesignation, a 

demonstration that the projected level of emissions is sufficient to maintain the PM2.5

NAAQS, and a commitment to provide future updates of the inventory to enable tracking 

of emissions levels during the 10-year maintenance period.

4.1 Attainment Year Inventory

The Illinois EPA has prepared a comprehensive emissions inventory for the Chicago 

PM2.5 nonattainment area, including point, area, and on-road and off-road mobile sources 

for primary PM2.5 as well as precursors of PM2.5 (NOx and SO2) for the year, 2008. The 

Illinois EPA selected 2008 emissions data to represent the “attainment year” since it is 

the middle year of the 3-year period (2007-2009) which demonstrates monitored 

attainment. This inventory is based on actual activity levels. Point source information 

was compiled from 2008 Annual Emissions Reports (AERs) submitted to the Illinois 

EPA by emissions sources. Area source emissions were calculated using the most 

recently available methodologies and emissions factors from U.S. EPA along with 

activity data (typically population, employment, fuel use, etc.) specific to 2008. On-road 

mobile source emissions were calculated using U.S. EPA’s MOBILE6.2 emissions model 

with 2008 vehicle miles traveled (VMT) data provided by the Illinois Department of 

Transportation (IDOT). Off-road mobile source exhaust emissions, such as those from 

lawn and garden equipment, agricultural equipment, and construction equipment were 

calculated for summer 2008 using U.S. EPA’s NONROAD emissions model. Emissions 

sources such as commercial marine vessels, locomotives and aircraft are not included in 

the NONROAD model and are calculated separately. Biogenic emissions are not 

included in these summaries. 

Table 4.1 summarizes the 2008 emissions estimates for the Chicago PM2.5 nonattainment 

area.

Table 4.1

2008 PM2.5, NOx, and SO2 Emissions (tons per year)

Source Category PM2.5 NOx SO2

Point Sources 3,859 35,939 90,706

Area Sources* 9,189 32,318 4,109

On-Road Mobile Sources 1,816 99,627 575

Off-Road Mobile Sources 3,653 51,184 779

Total 18,517 219,068 96,169

*does not include fugitive dust emissions from construction (residential, road and other) and 

agricultural tilling
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4.2 Air Quality Improvements and Emissions Controls

The Chicago area was designated as nonattainment of the 1997 PM2.5 NAAQS in 2004. 

Since that time, permanent and enforceable reductions of primary PM2.5 and secondary 

PM2.5 precursor emissions have contributed to improvements in PM2.5 air quality and to 

the attainment of the PM2.5 NAAQS. Some of these emissions reductions were due to the 

application of tighter federal emissions standards on motor vehicles and fuels, and some 

due to the requirements of the federal NOx SIP Call. Section 5.0 of this report describes 

these reductions in more detail, along with an explanation of their regulatory status. In 

this subsection, the 2008 attainment year emissions levels are compared to the base year 

2002 emissions levels.

The U.S. EPA’s PM2.5 Emissions Inventory Guidance requires that states with PM2.5

nonattainment areas prepare and submit a 2002 base year inventory of anthropogenic 

sources of direct PM2.5 and precursors of secondary PM2.5 emissions, namely NOx and 

SO2. This base year inventory included emissions from point, area, on-road mobile and 

off-road mobile emissions. The Illinois EPA prepared and submitted this inventory in 

May 2006. Table 4.2 summarizes 2002 emissions by major source category and by 

pollutant for the Chicago NAA.

Table 4.2

2002 PM2.5 NOx, and SO2 Emissions (tons per year)

Source Category PM2.5 NOx SO2

Point Sources 2,757 54,050 121,598

Area Sources 8,441 32,325 3,290

On-Road Mobile Sources 3,071 167,620 3,850

Off-Road Mobile Sources 4,834 87,426 3,743

Total 19,103 341,421 132,481

An updated methodology was used to calculate residential wood combustion emissions in 

2008. In order to be able to compare 2002 emissions to 2008 emissions, the original 

2002 estimates were revised using the updated methodology.

Comparing the 2002 inventory to that for 2008 indicates that the total direct PM2.5 

emissions in the Chicago area were reduced by approximately 580 tons per year. NOx 

emissions in the Chicago area decreased significantly, about 122,300 tons per year, 

during the same time period. These reductions were primarily from on-road and off-road 

mobile sources. SO2 emissions in the Chicago area decreased by about 36,300 tons per 

year, due largely to reductions from point sources. These sizeable emissions reductions 

in direct PM2.5 emissions and secondary PM2.5 precursor emissions, as well as

corresponding reductions in upwind areas in Illinois and other nearby states resulted in a 

substantial improvement in PM2.5 air quality in the Chicago area, ultimately resulting in 

attainment of the 1997 PM2.5 NAAQS.
16

4.3 Emissions Projections

A Maintenance Plan must contain a demonstration that the level of emissions projected 

for the ten-year period following redesignation are sufficient to maintain the NAAQS. 

Accordingly, Illinois EPA has projected PM2.5, NOx, and SO2 emissions for the Chicago 

NAA for 2025. Illinois EPA has also projected emissions to 2015 and 2020 to represent 

midpoint years during the maintenance period. Emissions for these projection years are 

compared to emissions levels in 2008 to determine if emissions are sufficient to maintain 

the NAAQS during this period.

Chicago area point and area source emissions for 2015, 2020, and 2025 were estimated 

using the 2008 base year inventory and growth factors appropriate for each source 

category. The effect of Illinois’ recently adopted NOx RACT requirement on NOx 

emissions in future years was estimated and applied, as appropriate, to the point source 

inventory. Off-road emissions projections were developed using the growth factors 

contained in U.S. EPA’s NONROAD model. On-road motor vehicle emissions were 

estimated using U.S. EPA’s MOBILE6.2 motor vehicle emissions model. The figures 

assume the continued use of reformulated gasoline, the continued phase-in of the Tier 2 

motor vehicle emissions standards, and operation of an enhanced vehicle inspection and 

maintenance program. Total vehicle miles of travel (VMT) for 2015, 2020 and 2025

were assumed to increase at a rate of 1.5 percent per year from 2008.

Tables 4.3, 4.4 and 4.5 include the direct NOx, PM2.5 and SO2 emissions estimates for the 

years 2015, 2020 and 2025 respectively, for the Chicago nonattainment area.

Table 4.3

2015 PM2.5, NOx, and SO2 Emissions (tons per year)

Source Category PM2.5 NOx SO2

Point Sources 4,169 27,082 58,092

Area Sources 9,676 32,997 4,266

On-Road Mobile Sources 1,231 49,746 651

Off-Road Mobile Sources 2,995 35,927 866

Total 18,071 145,752 63,875

4.4 Demonstration of Maintenance

Table 4.6 provides a comparison of emissions for the years 2008, 2015, 2020, and 2025. 

The table demonstrates that the level of emissions projected through the maintenance 

period are less than emissions estimated for the attainment year and are, therefore,

sufficient to maintain the PM2.5 NAAQS. As shown in the table, both SO2 and NOx 

emissions within the nonattainment area are expected to decrease significantly between 

2008 and 2025 with PM2.5 decreasing slightly. Projected emissions of those pollutants 

for the mid-point years of 2015 and 2020, are also less than their respective emissions 

levels in 2008. Based on these emissions trends it is expected that air quality will 

continue to meet the PM2.5 NAAQS throughout the maintenance period.
17

Table 4.4

2020 PM2.5 NOx, and SO2 Emissions (tons per year)

Source Category PM2.5 NOx SO2

Point Sources 4,391 28,499 53,452

Area Sources 10,009 33,277 4,332

On-Road Mobile Sources 1,043 29,102 681

Off-Road Mobile Sources 2,398 28,271 919

Total 17,841 119,149 59,384

Table 4.5

2025 PM2.5 NOx, and SO2 Emissions (tons per year)

Source Category PM2.5 NOx SO2

Point Sources 4,604 29,638 56,310

Area Sources 10,377 33,687 4,407

On-Road Mobile Sources 1,064 23,687 734

Off-Road Mobile Sources 2,267 27,173 1,215

Total 18,312 114,185 62,666

Table 4.6

Comparison of 2008, 2015, 2020 and 2025 Emissions

(Emissions stated in tons per year)

2008 2015 2020 2025 Decrease

(2008-2015)

Decrease 

(2008-2020)

Decrease 

(2008-2025)

PM2.5 18,517 18,071 17,841 18,312 446 676 205

NOx 219,068 145,752 119,149 114,185 73,315 99,919 104,883

SO2 96,169 63,875 59,384 62,666 32,294 36,785 33,503

In addition to the overall emissions reductions projected to occur within the 

nonattainment area, significant reductions of statewide NOx and SO2 emissions resulting 

from implementation of Illinois’ multi-pollutant standards affecting electric utilities 

during the maintenance period, will also help to ensure continued attainment of the PM2.5

NAAQS.

It should also be noted that the emissions projections included here do not reflect the 

reductions expected from a range of measures being implemented to reduce diesel 

emissions in the Chicago NAA. These measures have been funded through sources such 

as the:

• U.S. EPA’s Midwest Clean Diesel Initiative 

• Congestion Mitigation and Air Quality Improvement (CMAQ) Program 

• Diesel Emissions Reduction Act (DERA)
18

• American Recovery and Reinvestment Act of 2009

• Various Supplemental Environmental Projects 

These projects include the installation of particulate filters, diesel oxidation catalysts, 

closed-crankcase ventilation systems, and direct-fired heaters on school and transit buses, 

and municipally-owned utility vehicles, repowering diesel locomotive engines with 

generator sets, upgrading diesel construction engines with engines meeting more 

stringent emissions standards, and installing auxiliary power units on over-the-road 

trucks to reduce idling. We anticipate DERA and CMAQ funding to continue to support 

additional diesel emissions reduction projects in the near future.

4.5 Provisions for Future Updates

As required by Section 175A(b) of the CAA, Illinois commits to submit to U.S. EPA, 

eight years after redesignation, a revised version of this Maintenance Plan. The revision 

will contain Illinois’ plan for maintaining the PM2.5 NAAQS for ten years beyond the 

initial maintenance period.
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5.0 CONTROL MEASURES AND REGULATIONS

This section provides specific information on the control measures implemented in the 

Chicago nonattainment area. These include CAA requirements, and other state and 

federal measures. These control measures have been fully promulgated, and will provide 

emissions reductions in future years. Illinois EPA commits to keep these measures in 

effect after redesignation, or to provide equivalent emissions levels using alternate 

measures. Illinois’ SIP contains acceptable provisions to provide for preconstruction 

review of new emissions sources. After redesignation to attainment, Prevention of 

Significant Deterioration (PSD) requirements will apply to the construction of new major 

sources and to significant modifications of existing sources. Illinois has accepted 

delegation from U.S. EPA of this program. Illinois further commits to continue to 

require that all future transportation plans in the Chicago area conform with the SIP.

5.1 Control Measures

A variety of control measures are in place that reduce emissions of direct PM2.5, NOx and 

SO2, and have contributed to the attainment of the annual fine particle standard. The 

emissions reduction measures for demonstrating attainment of the PM2.5 standard are as 

follows:

• NOx SIP Call and Clean Air Interstate Rule (CAIR)

• New Source Performance Standards (NSPS) and National Emissions Standards 

for Hazardous Air Pollutants (NESHAPS)/Maximum Achievable Control 

Technology (MACT) Standards 

• VOM Solvent Categories: Aerosol Coatings, Architectural and Industrial 

Maintenance (AIM) Coatings, Consumer Solvents

• Vehicle Inspection & Maintenance Program 

• Reformulated Gasoline 

• Tier 2 Motor Vehicle Emissions Standards and Gasoline Sulfur Control 

Requirements

• On-Highway Heavy-Duty Engine and Vehicle Standards and Highway Diesel 

Fuel Sulfur Control Requirements

• Federal Emissions Standards for Off-Road Equipment (e.g., Nonroad Diesel 

Engine Rule, Evaporative Large Spark Ignition and Recreational Vehicle 

Standards) incorporated into NONROAD Model

• Tier 4 Nonroad Diesel Engine Standards and Diesel Fuel Sulfur Content 

Restrictions 

• Marine Compression-Ignition Engine Standards and Locomotive Engine 

Standards

• Consent Decrees (Citgo and ExxonMobil)
20

5.2 Reasonable Further Progress (RFP) and Reasonably Available Control 

Technology (RACT)

Since U.S. EPA has published an attainment finding for the Chicago area for the 1997 

PM2.5 standard, the requirements for Illinois to submit an attainment demonstration, 

RACM, RFP, contingency measures, and any other planning SIP’s related to attainment 

are suspended for so long as the areas continue to attain the 1997 PM2.5 NAAQS.

5.3 Controls to Remain in Effect

Illinois will maintain all of the control measures listed in this Section to ensure 

maintenance of the annual PM2.5 NAAQS. Any revisions to the control measures 

included as part of the Maintenance Plan will be submitted as a SIP revision to U.S. EPA 

for approval, and will be accompanied by a showing that such changes will not interfere 

with maintenance of the NAAQS.

In addition to the control measures identified in subsection 5.1, additional control 

measures that will remain in effect are:

• NOx RACT, as a requirement for the 1997 ozone NAAQS attainment 

demonstration.

• Multi-Pollutant Standard/Combined Pollutant Standards---Ameren, Midwest 

Generation, and Dynegy (35 Ill. Adm. Code Part 225)

• VOC RACT (incomplete)

VOC RACT is incomplete at this time, since three CTG’s have been submitted to the 

Illinois Pollution Control Board, but have not been submitted to the U.S. EPA. Though 

Illinois believes that control of organic compounds may help improve PM air quality, we 

have not relied on the control of organics, consistent with the PM2.5 Implementation Rule.

In addition, clean construction standards are in place as part of Cook County Ordinance 

No. 09-O-36, 5-19-2009 (Article IX, Section 30-952) that mandate any public works 

contractor must use Ultra Low Sulfur Diesel fuel in diesel vehicles, nonroad vehicles, and 

stationary generators used in the performance of contract duties. Furthermore, by the start 

of 2014, any primary contractor working on a construction project in Cook County shall 

be required to meet a PM emission reduction of at least 85% from uncontrolled for any 

heavy duty diesel vehicle or diesel nonroad vehicle. This level of control of diesel 

vehicles must be met by subcontractors by the start of 2016. This is not included as a 

contingency measure, but is further evidence of current and future PM emissions 

reduction in the heart of the urban area.

The O’Hare Airport Modernization Program already has in place an Ultra Low Sulfur 

Diesel fuel requirement for all off-road diesel powered vehicles and equipment (both 

mobile and stationary) that are utilized on-site. (O’Hare Modernization Project Site 
21

Preparation, Project No. OH6126.200.50.023, specification no. 35491) This requirement 

is in place for the remainder of the project. 

The Illinois EPA has the necessary resources to enforce any violations of its rules or 

permit provisions. After redesignation, it intends to continue enforcing all rules that 

relate to the emissions of primary PM2.5 and precursors to secondary PM2.5 in the Chicago

nonattainment area.

5.4 Provisions for Permitting New or Modified Emissions Sources

Illinois has longstanding and fully implemented programs for the review of new major 

sources and significant modifications of existing sources. The PSD program, which 

includes requirements for Best Available Control Technology (BACT) on major new 

sources or significant modifications of existing sources, will be applicable in the Chicago

area once the area has been redesignated to attainment. Illinois has been delegated full 

authority to implement the PSD program by U.S. EPA.

5.5 Transportation Conformity

The purpose of this section is to describe and establish the Chicago nonattainment area 

motor vehicle emissions budgets associated with the PM2.5 Maintenance Plan SIP. 

Annual motor vehicle emissions budgets are being proposed for the attainment year, 

2008, and for the final year of the Maintenance Plan, 2025, for primary PM2.5 and the 

precursor pollutant NOx. The Maintenance Plan also includes motor vehicle emissions 

estimates for the interim years 2015 and 2020 in order to demonstrate that total emissions 

remain below the 2008 attainment year total; however, these interim year motor vehicle 

emissions estimates are not being proposed as formal motor vehicle emissions budgets. 

The proposed 2008 and 2025 motor vehicle emissions budgets were developed 

consistent with the motor vehicle activity assumptions and emissions control strategies 

incorporated into the 8-hour ozone Attainment Demonstration and Maintenance Plan 

SIPs. The budgets reflect an emissions level determined using actual motor vehicle VMT 

for 2008 and VMT growth at an annual rate of 1.5% from year 2008 levels to 2025. 

A motor vehicle emissions budget is that portion of the total allowable emissions 

allocated to highway and transit vehicle use that are defined in the SIP for a certain year. 

The rules governing transportation conformity require certain transportation activities to 

be consistent with motor vehicle emissions budgets contained in control strategy 

implementation plans (40 CFR § 93.118). Section 93.101 of the rule defines a “control 

strategy [State] implementation plan revision” as a “plan which contains specific 

strategies for controlling the emissions and reducing ambient levels of pollutants in order 

to satisfy CAA requirements of reasonable further progress and attainment.” In order to 

demonstrate conformity to the motor vehicle emissions budget, emissions from the 

implementation of a transportation plan or a transportation improvement program must 

be less than or equal to the budget level (40 CFR § 93.118(a)).

The motor vehicle emissions budgets established and described herein were developed 
22

consistent with the methodology and control strategy assumptions used in the PM2.5

attainment demonstration. The effects of motor vehicle control measures are 

incorporated into the emissions factors produced by the U.S. EPA’s MOBILE6.2 model. 

These control measures include the implementation of national motor vehicle emissions 

standards, the operation of a vehicle inspection and maintenance (I/M) program, and the 

required use of reformulated gasoline and low sulfur gasoline and diesel fuel.

Since the Chicago PM2.5 Maintenance Plan has been under development for several 

months, the MOBILE6.2 model is being used rather than the recently-released 

MOVES2010 model. The motor vehicle emissions budgets proposed herein will be 

updated using the MOVES2010 model within the allotted two-year grace period. 

Following is a discussion of the inputs and assumptions used in the development of the 

motor vehicle emissions budgets.

The motor vehicle emissions budgets, which reflect the VMT and control program 

assumptions and methodology described here, are listed in Table 5.1.

Table 5.1

Proposed 2008 and 2025 Motor Vehicle Emissions Budgets 

Chicago PM2.5 Maintenance Plan

(tons per year)

Year PM2.5 NOx

2008 1,816 99,627

2025 1,064 23,687

Complete details on the derivation of the motor vehicle emissions budgets, including 

discussion of the MOBILE6 model inputs and assumptions are included in Appendix B 

of this report.
23

6.0 CONTINGENCY MEASURES

6.1 Contingency Measures

Section 175(A) of the CAA specifies the requirements for Maintenance Plans, including 

provisions for contingency measures that will be implemented if violations of the annual 

PM2.5 NAAQS are measured after redesignation to attainment. A list of potential 

contingency measures that would be implemented in such an event should also be 

included in the Maintenance Plan. Finally, the plan should provide a commitment to 

submit a revised Maintenance Plan eight years after redesignation to ensure continued 

maintenance for the next ten-year maintenance period.

Contingency measures are intended to provide further emissions reductions in the event 

that violations of the annual PM2.5 NAAQS occur after redesignation to attainment. 

While these measures do not need to be fully adopted by the Illinois Pollution Control 

Board (IPCB) prior to the occurrence of NAAQS violations, the contingency plan should 

ensure that the contingency measures are adopted expeditiously once they are triggered. 

The Maintenance Plan must identify the triggers that determine when contingency 

measures will be adopted, and the measures that the state will consider.

Illinois EPA’s contingency plan for the Chicago NAA is described in Table 6.1. 

Consistent with this plan, Illinois agrees to adopt and implement, as expeditiously as 

practicable, the necessary corrective actions in the event that violations of the annual 

PM2.5 NAAQS occur within the Chicago maintenance area after redesignation to 

attainment. As described in Section 5.0 of this report, Illinois has adopted and is 

continuing to implement a range of control measures that will greatly reduce precursor 

emissions, both locally and statewide. Illinois commits to continue to implement the 

identified control measures, although the Illinois EPA anticipates that these emissions

reductions will be sufficient to mitigate exceedances or violations of the NAAQS that 

may occur in the coming years without further regulatory action. 

The contingency plan provides for different levels of corrective responses should ambient

annual PM2.5 levels exceed the NAAQS in any year; if emissions in the NAA increase 

significantly above current attainment levels; or if the NAAQS is violated. A Level I 

response would occur in the event that: 1) the average of the annual PM2.5 concentration 

for the three most recent years at any monitoring site in the Illinois portion of the Chicago

NAA exceeds 15 micrograms per cubic meter, or 2) if SO2 or NOx emissions increase 

more than 5% above the levels contained in the attainment year (2008) emissions 

inventory. If exceedances of the annual PM2.5 NAAQS are observed in Lake and Porter 

counties in Indiana, Illinois commits to work with the Indiana Department of 

Environmental Management (IDEM) to develop appropriate corrective measures. It 

should be noted that U.S. EPA does not require a state to implement contingency 

measures when occasional exceedances are recorded. The Illinois EPA’s voluntary 

commitment to initiate a Level I response is intended to prevent future violations of the 

NAAQS from ever occurring.
24

Table 6.1

Contingency Plan for the Chicago PM2.5 Nonattainment Area 

 

Contingency Measure 

Trigger Action to be Taken List of Potential Contingency Measures

Level I Trigger

• Highest monitored 

PM2.5

concentration 

exceeding 15.0 

ug/m**3 in any 

year at any 

monitoring station 

in the Chicago

maintenance area.

• The Chicago

maintenance area’s 

PM2.5, NOx or 

SO2 emissions 

increase more than 

5% above the 

levels included in 

the 2008 emissions 

inventories.

IL will evaluate air quality, or 

determine if adverse emissions trends 

are likely to continue. If so, IL will 

determine what and where controls 

may be required, as well as level of 

emissions reductions needed, to avoid a 

violation of the NAAQS. The study 

shall be completed within 9 months. If 

necessary, control measures shall be 

adopted within 18 months of 

determination and implemented as 

expeditiously as practicable, taking into 

consideration the ease of 

implementation and the technical and 

economic feasibility of the selected 

measures. 

Point Source Measures

• IL Multi-Pollutant Program for 

electric generating units

• Phase II of the Clean Air 

Interstate Rule, after 

promulgation by U.S.EPA

• Best Available Retrofit 

Technology (BART)

Mobile Source Measures

• Tier 2 Vehicle Standards and Low 

Sulfur Fuel

• Heavy Duty Diesel Standards and 

Low Sulfur Diesel Fuel

• High-enhanced I/M (OBDII)

• Federal railroad/locomotive 

standards

• Federal commercial marine vessel 

engine standards

• Portable fuel containers

Area Source Measures

• Architectural/Industrial 

Maintenance (AIM) Coatings

• Commercial and Consumer 

Products

• Aerosol coatings

• Broader geographic applicability 

of existing measures

Level II Trigger

• A violation of the 

NAAQS at any 

monitoring station 

in the Chicago

maintenance area.

IL will conduct a thorough analysis to 

determine appropriate measures to 

address the cause of the violation. 

Analysis shall be completed within 6 

months. Selected measures shall be 

implemented within 18 months of a 

violation.

Illinois commits to compiling PM2.5, SO2, and NOx emissions inventories for the Chicago 

area every three years for the duration of the Maintenance Plan to facilitate the 

emissions trends analysis included in the contingency plan under Level I. The Illinois 

EPA will evaluate the causes of high PM2.5 levels or the emissions trends and to 

determine appropriate control measures needed to assure continued attainment of the 

annual PM2.5 NAAQS. Under Level I, measures that could be implemented in a short 

time would be selected so as to be in place quickly after the Illinois EPA is aware that 

corrective measures have been triggered. Control measures selected under Level I will be 

adopted in most cases within 18 months after a determination is made, and implemented, 

generally, within 24 months of adoption by the IPCB. 

A Level II response would be implemented in the event that a violation of the annual 

PM2.5 NAAQS were to be measured at a monitoring site within the Chicago maintenance 
25

area (including sites in Indiana and Illinois). In order to select appropriate corrective 

measures, the Illinois EPA will work with IDEM to conduct a comprehensive study to 

determine the causes of the violation and the control measures necessary to mitigate the 

problem. The analysis will examine the following factors:

• the location and severity of the ambient PM2.5 exceedances;

• the weather patterns contributing to the elevated PM2.5 levels;

• potential contributing emissions sources;

• the geographic applicability of possible contingency measures;

• emissions trends, including timeliness of implementation of scheduled control 

measures;

• current and recently identified control technologies; and

• air quality contributions from outside the maintenance area.

Contingency measures will be selected from those listed in Table 6.1 or from any other 

measure deemed appropriate and effective at the time the selection is made. It is 

expected that implementation of only a few of these measures would be necessary. The 

selection between measures will be based upon cost-effectiveness, emissions reduction 

potential, ease and timing of implementation, and other appropriate factors. 

Implementation of necessary controls in response to a Level II trigger will take place as 

expeditiously as possible, but in no event later than 18 months after the Illinois EPA 

makes a determination, based on quality-assured ambient data, that a violation of the 

NAAQS has occurred.

Adoption of additional control measures is subject to necessary administrative and legal 

processes. The Illinois EPA will solicit input from all interested and affected persons in 

the area prior to selecting appropriate control measures. No contingency measure will be 

implemented without providing the opportunity for full public participation. This process 

will include publication of notices, an opportunity for public hearing, and other measures 

required by Illinois law.

6.2 Commitment to Revise Plan

As noted in Section 4.5 above, the Illinois EPA commits to review its Maintenance Plan 

eight years after redesignation, as required by Section 175(A) of the CAA. The 

Maintenance Plan revision is intended to ensure continued attainment of the annual PM2.5

NAAQS for an additional ten-year period.

6.3 Public Participation

In accordance with Section 110(a)(2) of the CAA, the Illinois EPA is required to hold a 

public hearing prior to adoption of this Maintenance Plan and submittal to U.S. EPA. 

Public participation in the SIP process is provided for as follows:
26

• Notice of availability of the Chicago PM2.5 Maintenance Plan document and the 

time and date of the public hearing will be published in the Chicago Sun-Times

no later than June 14, 2010.

• The public hearing to receive comments on the Chicago Maintenance Plan will be 

held at 1:00 p.m. on July 14, 2010 at the James R. Thompson Center, 100 West 

Randolph Street, in Chicago. 

• A 30-day public comment period will also be available after the public hearing to 

receive comments on the Maintenance Plan. A summary of the comments 

received and Illinois EPA’s responses thereto will be included as part of the 

submittal to U.S. EPA.

6.4 Legal Authority to Implement and Enforce

The Maintenance Plan must contain a demonstration that the State of Illinois has the 

necessary legal authority to implement and enforce the measures relied upon to attain and 

maintain the NAAQS. Illinois has the legal authority to implement and enforce the 

requirements of this SIP submittal pursuant to the Illinois Environmental Protection Act.
27

7.0 CONCLUSIONS

The Chicago nonattainment area has attained the 1997 annual PM2.5 NAAQS and has 

complied with the applicable provisions of the CAA required of PM2.5 NAAs. Illinois 

has performed an analysis that demonstrates that the Chicago NAA has attained the 1997 

annual PM2.5 NAAQS and believes the air quality improvements are due to permanent 

and enforceable control measures. Supporting documentation is contained herein.

The Illinois EPA has prepared a Maintenance Plan that meets the requirement of the 

Clean Air Act. This Maintenance Plan provides for the continued attainment of the 1997 

annual PM2.5 NAAQS for a period of at least ten years after U.S. EPA has formally 

redesignated the area to attainment. This Maintenance Plan provides adequate 

contingency measures for potential, additional emissions reductions in the event that 

future violations of the 1997 annual PM2.5 NAAQS are observed in the area. 

The Illinois EPA has prepared a comprehensive emissions inventory of PM2.5 and its

precursors for the “attainment” year, 2008, and has prepared projections of the emissions

inventory to 2015, 2020 and 2025. These emissions projections indicate that emissions 

levels in the Chicago nonattainment area will continue to decrease from the levels 

occurring in the attainment year, thereby maintaining the PM2.5 NAAQS in future years. 

The Illinois EPA commits to continue to operate an appropriate air quality monitoring 

network to verify the maintenance of the attainment status once the area has been 

redesignated. The Illinois EPA has the legal authority to implement and enforce all 

control measures.

Finally, the Chicago PM2.5 Maintenance Plan includes year 2008 and 2025 on-road motor 

vehicle emissions budgets for use in transportation conformity determinations to assure 

that any increases in emissions from this sector do not jeopardize continued attainment of 

the annual PM2.5 standard during the ten-year maintenance period. The Chicago

Maintenance Plan has been prepared in accordance with the requirements specified in 

U.S. EPA’s guidance document, and additional guidance received from U.S. EPA staff.
28

APPENDIX A

Summary of Ambient Air Monitoring Data 

(2007-2009)
29

Table A.1

2007-2009 Annual PM2.5 Design Values 

for Monitors in the Chicago Nonattainment Area

*- Annual Standard does not apply at these monitoring sites

Annual averages listed in underlined italics based on incomplete data.

County Monitoring Site 2007 2008 2009 Design 

Value

Cook Blue Island 14.3 12.5 11.7 12.8

Cook Chicago-Com Ed 14.3 11.9 11.1 12.4

Cook Chicago-Springfield 15.2 12.0 11.3 12.8

Cook Chicago-Mayfair 15.5 12.2 12.7 13.5

Cook Chicago-SE Police 14.1 11.8 11.0 12.3

Cook Chicago-Washington 15.7 12.5 11.6 13.3

Cook Cicero 14.8 13.3 12.0 13.4

Cook Des Plaines 12.7 11.4 11.0 11.7

Cook McCook* 15.6 12.9 12.6 13.7

Cook Northbrook 13.2 10.1 9.3 10.9

Cook Schiller Park* 15.4 13.6 12.9 14.0

Cook Summit 14.8 12.0 11.6 12.8

Du Page Naperville 13.8 11.3 9.8 11.6

Kane Aurora 13.2 10.3 10.0 11.2

Kane Elgin 14.5 10.8 9.6 11.6

Lake Zion 11.9 9.3 8.8 10.0

McHenry Cary 11.6 10.1 9.6 10.4

Will Braidwood 12.1 10.3 8.7 10.4

Will Joliet 14.6 11.7 10.5 12.3

Lake IN Franklin School 14.4 12.0 11.3 12.6

Lake IN Griffith 13.2 11.7 11.0 12.0

Lake IN Madison St. 14.6 12.3 12.1 13.0

Lake IN Hammond-Purdue 13.8 11.7 15.9 13.8

Lake IN Clark HS 13.7 12.4 10.8 12.3

Porter IN Ogden Dunes 13.8 10.9 11.3 12.0
30

APPENDIX B

Transportation Conformity
31

TRANSPORTATION CONFORMITY

This section describes the development of the Chicago nonattainment area (NAA) motor 

vehicle emissions budgets associated with the PM2.5 Maintenance Plan State 

Implementation Plans (SIP). Annual motor vehicle emissions budgets are being proposed 

for the attainment year, 2008, and 2025, the final year of the initial maintenance period

for direct motor vehicle PM2.5 emissions and for the precursor pollutant oxides of 

nitrogen (NOx). These budgets were developed consistent with the motor vehicle 

activity assumptions and emissions control strategies incorporated into the PM2.5

maintenance plan analysis. The budgets reflect an emissions level determined using 

motor vehicle VMT and fleet mix provided by the Chicago Metropolitan Agency for 

Planning (CMAP). 

Background

Section 176(c)(4) of the Clean Air Act (CAA) Amendments of 1990 requires that 

transportation plans, programs, and projects which are funded or approved under Title 23 

USC must be determined to conform with State or Federal air implementation plans. A 

motor vehicle emissions budget is that portion of the total allowable emissions allocated 

to highway and transit vehicle use that are defined in the SIP for a certain year. Section 

93.101 of the rule defines a “control strategy [State] implementation plan revision” as a 

“plan which contains specific strategies for controlling the emissions and reducing 

ambient levels of pollutants in order to satisfy CAA requirements of reasonable further 

progress and attainment.” In order to demonstrate conformity to the motor vehicle 

emissions budget, emissions from the implementation of a transportation plan or a 

transportation improvement program (TIP) must be less than or equal to the budget level 

(40 CFR § 93.118(a)).

Transportation conformity will be based on these submitted on road motor vehicle 

emissions budgets after the U.S. Environmental Protection Agency (“U.S.EPA”) 

determines that the budgets meet the adequacy criteria of the transportation conformity 

rule under §93.118(e). The motor vehicle emissions budgets in this submittal are 

adequate as each of the six criteria under §93.118(e) is satisfied. These six criteria 

include:

1. The submitted control strategy implementation plan revision or maintenance plan was 

endorsed by the Governor (or his or her designee) and was subject to a State public 

hearing.

2. Before the control strategy implementation plan or maintenance plan was submitted 

to EPA, consultation among federal, State, and local agencies occurred: full 

implementation plan documentation was provided to [US]EPA; and [US]EPA’s 

stated concerns, if any, were addressed;

3. The motor vehicle emissions budgets(s) is clearly identified and precisely quantified;
32

4. The motor vehicle emissions budget(s), when considered together with all other 

emission sources, is consistent with all applicable requirements for reasonable further

progress, attainment, or maintenance (whichever is relevant to the given 

implementation plan submission);

5. The motor vehicle emissions budget(s) is consistent with and clearly related to the 

emissions inventory and the control measures in the submitted control strategy 

implementation plan revision or maintenance plan, and

6. Revisions to previously submitted control strategy implementation plans explain and 

document any changes to previously submitted budgets and control measures, 

impacts on point and area source emissions; any changes to established safety 

margins; and reasons for the changes (including the basis for any changes related to 

emission factors or estimates of vehicle miles traveled).

The PM2.5 attainment demonstration SIP and the associated motor vehicle emissions 

budgets have been developed by the Illinois Environmental Protection Agency (Illinois 

EPA), the designated air quality agency for the State of Illinois. The required public 

hearing to accept public comment on the proposed motor vehicle emissions inventory 

will be held at ?? AM, on ????, ?? 2010 in Room ??? of the James R. Thompson Center 

in downtown Chicago. Notification of this hearing will be printed in a local newspaper 

of broad circulation. Comments on the proposed attainment demonstration and motor 

vehicle emissions budgets will be accepted for 30 days after the public hearing. A 

“Responsiveness Summary” which addresses the written comments received will be 

prepared and included in the final submission.

In compliance with adequacy criterion #2, an interagency consultation meeting will be

held with members of the CMAP Tier 2 Consultation Team prior to submittal of the plan. 

At this meeting, the Illinois EPA representative will discuss the requirements for the 

maintenance plan as they relate to transportation conformity and explain the derivation of 

the proposed motor vehicle emissions budgets. Compliance with the remaining adequacy 

criteria is contained within the narrative of the attainment demonstration document and 

this transportation conformity section.

The Chicago PM2.5 Maintenance Plan Motor Vehicle Emissions Budgets

The motor vehicle emissions budgets proposed and described herein were developed 

consistent with the methodology and control strategy assumptions used in the 

development of the emissions estimates contained in the Chicago PM2.5 Maintenance 

Plan. The effects of these controls are incorporated into the emissions factors produced 

by the U.S.EPA’s MOBILE6.2 model. Since the Chicago PM2.5 Maintenance Plan has 

been under development for several months, the MOBILE6.2 model is being used rather 

than the recently-released MOVES2010 model. The motor vehicle emissions budgets 

proposed herein will be updated using the MOVES2010 model within the allotted twoyear grace period. Following is a discussion of the inputs and assumptions used in the 

development of the motor vehicle emissions budgets.
33

The attainment year 2008 motor vehicle emissions estimates contained Chicago PM2.5

Maintenance Plan incorporate county-and township-level 2008 annual vehicle miles 

traveled (VMT) levels from the Illinois Department of Transportation (IDOT). The 2008 

annual VMT total for the 6-county-3-township Chicago NAA was approximately 58.8 

million miles. For future year emission estimates, VMT was grown to the target year at a 

compound growth rate (CGR) of 1.5% per year. Applying this growth factor to the 2008 

VMT level yields future year annual VMT projections of 65.2 million for 2015, 70.3 

million for 2020, and 75.7 for 2025.

Following is a summary of the information and MOBILE6.2 model assumptions used 

included in the development of the draft motor vehicle emissions budgets.

Year: VMT estimates and motor vehicle emissions factors were developed 

representative of 2008, 2015, 2020, and 2025 for the modeled PM2.5 attainment 

demonstration. 

Annual Emissions as Sum of Monthly Emissions: The 2008 Chicago PM2.5

Maintenance Plan emissions inventory is based on annual activity. Estimates of motor

vehicle emissions were made for each month of the year, using average monthly 

information, and summed to get annual emissions. The primary parameters affected by 

the choice to calculate monthly emissions and sum then are the representative 

temperatures, fuel volatilities, and the estimation of VMT for the various months to 

account for month-to-month changes in travel. 

Temperatures: U.S. EPA guidance for the use of the MOBILE6.2 model calls for the 

use of representative temperatures. For the Chicago area, the representative monthly 

summer temperatures are the National Weather Service’s (NWS) monthly average 

minimum and maximum temperatures at Chicago’s O’Hare Airport in 2008. 

2008 Maximum and Minimum 

Temperatures for Chicago, from O’Hare NWS Data

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

Max, °F 32 30 43 60 66 81 84 82 75 62 46 32

Min, °F 15 16 27 39 45 61 64 64 57 44 32 14

2008 Absolute Humidity Corresponding

to the Temperatures Above 

AH, grains/lb 17 14 21 34 41 73 83 74 71 39 25 15

For forecast emissions for later years than 2008, the appropriate temperatures inputs are 

the climatological averages. The climatological data are based on observed temperature 

and humidity observations in the period 1970-2000, as published by the NWS and are as 

follows:

Climatological Average Maximum and Minimum 

Temperatures for Chicago

Parameter Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
34

Max, °F 30 35 46 58 70 79 84 81 74 62 47 34

Min, °F 14 19 29 38 48 57 63 62 54 42 32 20

Climatological Absolute Humidities Corresponding

to the Temperatures Above 

AH, 

grains/lb 21 22 25 45 48 92 98 101 75 43 28 21

Absolute Humidity: U.S. EPA guidance calls for the use of the lowest absolute 

humidity (AH) corresponding to the actual (or climatological) temperatures in the region 

as calculated from local actual (or climatological) humidity data published by the NWS. 

The AHs corresponding to the actual 2008 and climatological monthly temperatures are 

shown in the tables above. AHs are calculated from NWS temperature, humidity, and 

pressure data using a U.S.EPA-supplied utility. MOBILE6 requires that AH inputs be 20 

or greater, so the AH inputs for the months of January, February, and December 2008 

were set to 20 rather than the actual AHs of 17, 14, and 15. 

Motor Vehicle Emission Controls: The primary motor vehicle emission control 

programs that were in place in the Chicago NAA in 2008 are (1) an OBD-II-based 

vehicle inspection and maintenance (I/M) program, and (2) the requirement that gasoline 

sold in the area be “reformulated gasoline”, fuel that is specially formulated to reduce 

emissions.

Inspection and Maintenance (I/M): The I/M program in effect since February 

2007 requires biennial On-Board Diagnostics (OBD) testing on all model year (MY) 

1996 and newer (MY96+) light-duty gasoline vehicles, and biennial exhaust idle and 

gas cap testing on MY96+ heavy-duty gasoline vehicles including gasoline-powered 

buses, registered in the I/M testing area. The program includes a 4-year grace period 

for new vehicles such that a MY 2004 car would not be tested until 2008. The 2007 

I/M program, established after the Illinois legislature amended the Illinois Vehicle 

Inspection law in 2005, also removed the requirement to conduct dynamometer 

testing (IM240 test) of vehicles and dropped the requirement for testing compliant 

pre-MY1996 vehicles. See Attachment A for additional information about the post-

’07 I/M program and the inputs to the MOBILE6 model. (In 2008, but not in later 

years, there were still residual benefits from the pre-2007 I/M program; they were 

accounted for in the emission calculations. The pre-’07 program will be discussed in 

Attachment A.)

The Chicago vehicle testing domain is based upon urbanized areas and includes all of 

Cook, DuPage, and Lake Counties, and parts of Kane, McHenry, Will, and Kendall 

Counties. Some of the VMT in the Chicago area is generated by vehicles that come 

from outside the testable area and are therefore not required to undergo I/M testing; 

therefore VMT estimates used when calculating I/M emissions reduction benefits for 

a county or township are adjusted to reflect VMT from vehicles subject to I/M only. 

This is done using I/M coverage factors derived ultimately from transportation 

modeling outputs from CMAP. The coverage factors are 98% for Cook and DuPage 

Counties (that is, 98% of the gasoline-vehicle VMT in the county is from vehicles 
35

subject to I/M) , 95% for Lake County, 81% for Kendall County’s NAA township, 

65% for Will County, 60% for Kane County, 50% for McHenry County, and 25% for 

Grundy County’s NAA townships. 

Fuels: Reformulated gasoline (RFG) has been required in the Chicago NAA since 1995. 

The attainment demonstration and RFP plan both assume all gasoline sold in the Chicago 

NAA since 1995 is “Northern” grade RFG.

Gasoline Sulfur: Gasoline sulfur levels were assumed to be 30 parts per million 

(ppm) in 2008 and in future years in accordance with the federal Tier 2 gasoline 

regulations which required the 30 ppm level beginning in 2006. An input for gasoline 

sulfur is not required, since the MOBILE6.2 model assumes 30 ppm gasoline sulfur 

for RFG after 2006.

Diesel Sulfur: Diesel sulfur levels were assumed to be 15 parts per million in2008 in 

accordance with the U.S. EPA’s Highway Diesel Rule which was finalized in January 

2001. This regulation required the sale of on-road diesel fuel with no greater than 15 

ppm of sulfur beginning in June 2006. Diesel fuel sulfur concentrations are a 

required input to the MOBILE6.2 model when particulate emission factors are to be 

evaluated.

Fuel Volatility: Fuel volatility is a required input to the MOBILE6.2 model, 

although this input is ignored when the use of RFG is being modeled. Fuel RVP 

varies from month to month during the year. The following table shows the monthly 

fuel RVP inputs for the Chicago area in 2008 as well as the expected values for future 

years.

Monthly Fuel Volatility (Reid Vapor Pressure or RVP) 

of Reformulated Gasoline (RFG) 

in the Chicago Area by Month

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

Actual RVP, 

psi 13.4 10.9 7.2 10.9 13.1

Expected 

RVP for

future years

14.0 10.9 6.7 10.9 14.0

The 2008 monthly RVP inputs are from actual measured winter and summer RVP data 

for northern Illinois as reported in Motor Gasolines Summer 2008 (NGMS-258 PPS

(2009/1) (the “NIPER” reports). Future year expected monthly RVPs were taken from 

U.S.EPA’s National Emissions Inventory inputs. 

Speeds: The MOBILE6.2 model contains a default speed distribution file (SVMT.D); 

however, the Illinois EPA assumed area-specific vehicle speed distributions. This 

distribution below is based on 2007 CMAP transportation model output, deemed 

representative for 2008. 
36

VMT Fraction by Road Type by Hour by Speed

 1 1 0.0001 0.0000 0.0050 0.0075 0.0043 0.0103 0.0253 0.0254 0.0452 0.0638 0.1040 0.3767 0.1943 

0.1383

 1 2 0.0001 0.0080 0.0148 0.0466 0.0625 0.0859 0.0908 0.1456 0.1013 0.1130 0.1416 0.1285 0.0299 

0.0316

 1 3 0.0001 0.0080 0.0148 0.0466 0.0625 0.0859 0.0908 0.1456 0.1013 0.1130 0.1416 0.1285 0.0299 

0.0316

 1 4 0.0001 0.0048 0.0307 0.0799 0.0662 0.0918 0.1283 0.1232 0.0962 0.1322 0.1209 0.0715 0.0286 

0.0256

 1 5 0.0000 0.0002 0.0012 0.0103 0.0282 0.0531 0.0824 0.0971 0.1819 0.1460 0.1768 0.1341 0.0358 

0.0529

 1 6 0.0000 0.0002 0.0012 0.0103 0.0282 0.0531 0.0824 0.0971 0.1819 0.1460 0.1768 0.1341 0.0358 

0.0529

 1 7 0.0000 0.0002 0.0012 0.0103 0.0282 0.0531 0.0824 0.0971 0.1819 0.1460 0.1768 0.1341 0.0358 

0.0529

 1 8 0.0000 0.0002 0.0012 0.0103 0.0282 0.0531 0.0824 0.0971 0.1819 0.1460 0.1768 0.1341 0.0358 

0.0529

 1 9 0.0000 0.0002 0.0044 0.0256 0.0476 0.0554 0.0941 0.1110 0.1631 0.1493 0.1555 0.1277 0.0264 

0.0395

 1 10 0.0000 0.0002 0.0044 0.0256 0.0476 0.0554 0.0941 0.1110 0.1631 0.1493 0.1555 0.1277 0.0264 

0.0395

 1 11 0.0000 0.0083 0.0147 0.0337 0.0587 0.0474 0.0728 0.1249 0.1122 0.1205 0.1318 0.1771 0.0449 

0.0530

 1 12 0.0000 0.0083 0.0147 0.0337 0.0587 0.0474 0.0728 0.1249 0.1122 0.1205 0.1318 0.1771 0.0449 

0.0530

 1 13 0.0000 0.0001 0.0044 0.0012 0.0133 0.0118 0.0238 0.0312 0.0561 0.0519 0.1358 0.3491 0.1903 

0.1310

 1 14 0.0000 0.0001 0.0044 0.0012 0.0133 0.0118 0.0238 0.0312 0.0561 0.0519 0.1358 0.3491 0.1903 

0.1310

 1 15 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0023 0.0201 0.0151 0.0416 0.0454 0.0992 0.6347 

0.1414

 1 16 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0023 0.0201 0.0151 0.0416 0.0454 0.0992 0.6347 

0.1414

 1 17 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0023 0.0201 0.0151 0.0416 0.0454 0.0992 0.6347 

0.1414

 1 18 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0023 0.0201 0.0151 0.0416 0.0454 0.0992 0.6347 

0.1414

 1 19 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0023 0.0201 0.0151 0.0416 0.0454 0.0992 0.6347 

0.1414

 1 20 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0023 0.0201 0.0151 0.0416 0.0454 0.0992 0.6347 

0.1414

 1 21 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0023 0.0201 0.0151 0.0416 0.0454 0.0992 0.6347 

0.1414

 1 22 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0023 0.0201 0.0151 0.0416 0.0454 0.0992 0.6347 

0.1414

 1 23 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0023 0.0201 0.0151 0.0416 0.0454 0.0992 0.6347 

0.1414

 1 24 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0023 0.0201 0.0151 0.0416 0.0454 0.0992 0.6347 

0.1414

 2 1 0.0000 0.0008 0.0034 0.0102 0.0177 0.0367 0.1027 0.1775 0.1839 0.2465 0.0867 0.1338 0.0000 

0.0000

 2 2 0.0017 0.0254 0.0689 0.0968 0.1127 0.1207 0.1452 0.1356 0.1088 0.0924 0.0445 0.0474 0.0000 

0.0000

 2 3 0.0017 0.0254 0.0689 0.0968 0.1127 0.1207 0.1452 0.1356 0.1088 0.0924 0.0445 0.0474 0.0000 

0.0000

 2 4 0.0050 0.0531 0.1042 0.1302 0.1335 0.1256 0.1265 0.1096 0.0819 0.0645 0.0314 0.0345 0.0000 

0.0000

 2 5 0.0003 0.0070 0.0329 0.0740 0.1233 0.1356 0.1577 0.1579 0.1184 0.0963 0.0417 0.0547 0.0000 

0.0000

 2 6 0.0003 0.0070 0.0329 0.0740 0.1233 0.1356 0.1577 0.1579 0.1184 0.0963 0.0417 0.0547 0.0000 

0.0000

 2 7 0.0003 0.0070 0.0329 0.0740 0.1233 0.1356 0.1577 0.1579 0.1184 0.0963 0.0417 0.0547 0.0000 

0.0000

 2 8 0.0003 0.0070 0.0329 0.0740 0.1233 0.1356 0.1577 0.1579 0.1184 0.0963 0.0417 0.0547 0.0000 

0.0000

 2 9 0.0008 0.0120 0.0470 0.0938 0.1316 0.1388 0.1523 0.1449 0.1091 0.0837 0.0382 0.0476 0.0000 

0.0000

 2 10 0.0008 0.0120 0.0470 0.0938 0.1316 0.1388 0.1523 0.1449 0.1091 0.0837 0.0382 0.0476 0.0000 

0.0000

 2 11 0.0032 0.0375 0.0866 0.1239 0.1277 0.1268 0.1365 0.1206 0.0909 0.0680 0.0356 0.0428 0.0000 

0.0000

 2 12 0.0032 0.0375 0.0866 0.1239 0.1277 0.1268 0.1365 0.1206 0.0909 0.0680 0.0356 0.0428 0.0000 

0.0000

 2 13 0.0000 0.0015 0.0097 0.0286 0.0596 0.0997 0.1556 0.1827 0.1639 0.1548 0.0635 0.0805 0.0000 

0.0000

 2 14 0.0000 0.0015 0.0097 0.0286 0.0596 0.0997 0.1556 0.1827 0.1639 0.1548 0.0635 0.0805 0.0000 

0.0000
37

 2 15 0.0000 0.0000 0.0000 0.0000 0.0000 0.0003 0.0615 0.1295 0.1536 0.3574 0.0745 0.2231 0.0000 

0.0000

 2 16 0.0000 0.0000 0.0000 0.0000 0.0000 0.0003 0.0615 0.1295 0.1536 0.3574 0.0745 0.2231 0.0000 

0.0000

 2 17 0.0000 0.0000 0.0000 0.0000 0.0000 0.0003 0.0615 0.1295 0.1536 0.3574 0.0745 0.2231 0.0000 

0.0000

 2 18 0.0000 0.0000 0.0000 0.0000 0.0000 0.0003 0.0615 0.1295 0.1536 0.3574 0.0745 0.2231 0.0000 

0.0000

 2 19 0.0000 0.0000 0.0000 0.0000 0.0000 0.0003 0.0615 0.1295 0.1536 0.3574 0.0745 0.2231 0.0000 

0.0000

 2 20 0.0000 0.0000 0.0000 0.0000 0.0000 0.0003 0.0615 0.1295 0.1536 0.3574 0.0745 0.2231 0.0000 

0.0000

 2 21 0.0000 0.0000 0.0000 0.0000 0.0000 0.0003 0.0615 0.1295 0.1536 0.3574 0.0745 0.2231 0.0000 

0.0000

 2 22 0.0000 0.0000 0.0000 0.0000 0.0000 0.0003 0.0615 0.1295 0.1536 0.3574 0.0745 0.2231 0.0000 

0.0000

 2 23 0.0000 0.0000 0.0000 0.0000 0.0000 0.0003 0.0615 0.1295 0.1536 0.3574 0.0745 0.2231 0.0000 

0.0000

 2 24 0.0000 0.0000 0.0000 0.0000 0.0000 0.0003 0.0615 0.1295 0.1536 0.3574 0.0745 0.2231 0.0000 

0.0000

* Fraction of vehicle miles traveled within an hour within an average speed bins by hour of the day. 

The first hour is 6 a.m.

* Speed Bins:

* Hr 2.5 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 65.0+

Speed bins extend 2.5 mph on either side of the bin name (i.e., the 30-mph speed bin encompasses 

speeds from 27.5 to 32.5 mph), except for the first (2.5 mph) bin (0 to 2.5 mph) and the last (65+ 

mph) bin (62.5 mph and above). 

The above data are for the Chicago NAA and for Freeways and Arterials only. Locals and Ramps have a 

fixed speed in built into the M6 model, and therefore are not affected by this file. 

The first number in each line is roadway type: 1 = Freeways; 2 = Arterials. The second number is the 

hour of the day, hour 1 being hour beginning at 6 AM, and hour 24 being hour beginning at 5 AM the 

next day. The third and subsequent numbers are the fractions of VMT in that hour that occurs within 

the specified speed bins. Note that, for Freeways, most VMT is in the 45-50-55-60-mph speed bins, 

with lower speeds more common during Peak hours. Much the same holds for Arterials, where most VMT is 

in the 30-35-40-45 mph speed bins.

VMT Mix: The regional VMT mix inputs used for 2008 were based on Chicago-areaspecific VMT-by-vehicle-type data supplied by CMAP from transportation model output 

which were adapted to represent fractions of the vehicle types in MOBILE’s descriptive 

output for different road types. The VMT Mix used in Annual emission calculations is an 

aggregated mix for all road types. This information is used in the MOBILE model to 

compute the average emission factors for certain combined vehicle classes, and the allvehicle emission rate. 

Registration Distribution (RD): A Chicago-area-specific vehicle registration 

distribution profile based upon 2008 information data developed by Illinois EPA’s 

Division of Mobile Source Programs from data provided by the Illinois Secretary of 

State’s Department of Motor Vehicles. The file was generated using U.S.EPA’s 

recommended method from its MOBILE6.2 training material. 

Emissions Computation: Illinois EPA calculated annual motor vehicle emissions 

budgets using the basic formula: Emissions of a given pollutant = VMT * Emission 

Factor (EF) for that pollutant. The VMT in that formula is further broken down into 

VMT by vehicle type, which, for a specific vehicle type, equals Total VMT * VMT Mix 

for that vehicle type, such that Emissions of a given pollutant for a specific vehicle type = 

Total VMT * VMT Mix for that vehicle type * EF for that pollutant and vehicle type. 

For each county or county subdivision in the Chicago NAA, emissions for each pollutant 

are calculated by month and vehicle type, and summed to give emissions by month for all 
38

vehicle types. Those monthly totals are further summed to give annual emissions by 

county for each pollutant. In those counties or sub-county areas where there is I/M, I/M 

benefits were calculated using the same formula except that EF was replaced by “I/M 

Benefit EF” (IMBEF), where IMBEF = EF assuming no I/M – EF assuming I/M 

program), and the I/M coverage factor was included. For I/M counties, No-I/M 

Emissions were calculated, then I/M Benefits; and Net Emissions were simply No-IM 

Emissions minus I/M Benefits. . 

Attachment A of this section provides additional details on the MOBILE6 model inputs 

used in the development of the 2008 and 2025 Chicago NAA motor vehicle emissions 

budgets. Following is a discussion of how the data for the spreadsheet are generated and 

used:

Annual VMT by county and by month. 

1. Aggregate each county’s average daily (ADVMT) by Highway Performance 

Monitoring System (HPMS) functional class (FC) into ADVMT by the four road 

types (Rural Interstate, Rural Other Functional Classes, Urban Interstate, and 

Urban Other Functional Classes). 

2. Estimate monthly county VMT for January by multiplying the ADVMT for each 

of four road types by the number of days in the month (31) and the appropriate 

month-long count division factors (e.g., 0.8572 for Rural Interstates in the 

Chicago area) from Table below (i.e., by the Monthly Factors in the columns on 

the right side of that Table—25.57 for January Chicago Rural Interstates), and 

summing the resulting Monthly VMTs by road type to get total Monthly VMT for 

that month and that county. 

3. Do the same for each of the other months, and sum the 12 Monthly results to get 

total Annual VMT for the county. As a check, multiply the actual or forecast 

ADVMT by 365 and compare to the total from Step 2. The two Annual estimates 

should be very close—usually within 0.05%. The difference is due to rounding.

Factors for Estimating Monthly VMT from ADVMT

Based on IDOT 2002-2005 Count Data and representative of 2005 and future years

(Source: IDOT Office of Planning & Programming, Sept 2006)

Month

Normalized Month-long Count

Division Factors (MCDFs)

Days 

in 

Month

Monthly VMT Factors (MVFs)

= MCDF × days in month

Rural Urban Rural Urban

InterstatesOther 

FCs

InterstatesOther 

FCs

InterstatesOther 

FCs

InterstatesOther 

FCs

CHICAGO AREA (IDOT District 1)

January 0.8572 0.9643 0.9192 0.9267 31 26.57 29.89 28.50 28.73

February 0.8789 0.8560 0.9291 0.9379 28 24.61 23.97 26.01 26.26

March 0.9585 0.9461 0.9519 0.9736 31 29.71 29.33 29.51 30.18

April 0.9861 1.0107 0.9981 1.0177 30 29.58 30.32 29.94 30.53
39

May 1.0323 1.0114 1.0047 1.0280 31 32.00 31.35 31.15 31.87

June 1.1064 1.0688 1.0395 1.0417 30 33.19 32.06 31.19 31.25

July 1.1177 1.0619 1.0538 1.0114 31 34.65 32.92 32.67 31.35

August 1.1050 1.0509 1.0669 1.0183 31 34.26 32.58 33.07 31.57

September 1.0210 1.0192 1.0396 1.0143 30 30.63 30.58 31.19 30.43

October 0.9931 1.0124 1.0203 0.9923 31 30.79 31.38 31.63 30.76

November 0.9844 0.9899 1.0207 1.0195 30 29.53 29.70 30.62 30.59

December 0.9594 1.0084 0.9562 1.0186 31 29.74 31.26 29.64 31.58

Jun-Jul-Aug 

Sum 3.3291 3.1816 3.1602 3.0714 92 102.10 97.56 96.93 94.17

Emission factors by vehicle type representative of each month were obtained by 

running the MOBILE6.2 model twelve times, once for each month using average 

monthly temperature and fuel inputs as noted above. All twelve monthly runs for an 

area can be on a single input file. 

All-Facility-Type EFs were calculated assuming the default distribution of VMT 

among facility types; this is a reasonable because the Statewide M6 Facility Type 

fractions (Freeway 31%, Arterial 58%, Local 8%, Ramp 3%) are reasonably close to 

MOBILE6’s default fractions (Freeway 34%; Arterial 50%, Local 13%, Ramp 3%). 

For future-year estimates, one would use monthly climatological temperature and 

absolute humidity averages available from the National Weather Service’s National 

Climatic Data Center (NCDC) in the form of Local Climatological Data publications, 

as described above. Most of the other MOBILE inputs are “fixed”, that is, they don’t 

change from month to month. Examples are: Activity Inputs such as VMT by Hour, 

VMT by Speed Bin, and VMT by Facility Type, and VMT Fractions. One would use 

the same ones here as in the Summer Weekday EF calculations.

The MOBILE monthly inputs for Year and Month of Output EFs in a given year 

should be for evaluation months of January [Year], July [Year], or January [Year + 

1]. See the table below for 2008. U.S.EPA’s MOBILE6.2 Technical Guidance 

Document (August 2004), recommends that the resulting emission factor outputs be 

used as is (i.e., without interpolation) for the monthly EFs. 

Year and Month Input Settings for MOBILE6.2 

for Monthly 2008 Emission Factors

Months for Which

M6.2 EFs Are Desired

MOBILE Input Values for 

Evaluation Month 

& Calendar Year

January, February, or March 2008 1 (January) and 2008

April through September 2008 7 (July) and 2008

October, November, or December 2008 1 (January) and 2009

Emission factor results from the MOBILE runs are extracted from the MOBILE output 
40

files (*.OUT or *,TXT for VOC, CO, and NOx; *,PM for SO2, ammonia, and the 

particulate species) and placed in a page of an Excel spreadsheet. The “pivot table” 

commands in Excel allow the user to take those emission factors and put them into the 

tabular form used in the emission calculation spreadsheet, to which they are copied. 

At this point, the emission calculation spreadsheet has VMT by county and month on one 

page, and emission factors by vehicle type and month (and I/M status) on another. A 

third page contains All-Facility-Type Vehicle Mix by month and vehicle type. The same 

mix is used for all months. Subsequent pages contain the results of emission calculations 

by county, which are evaluated as follows. 

1. No-I/M County Emissions by vehicle type (VT) and month = (County ADVMT 

by month * (VMT Mix by VT and month) * No-I/M EF by pollutant, VT, and 

month) * 1.102 x 10-6 (grams-to-ton conversion factor). For areas without I/M, 

this is the only calculation.

2. I/M Credits by VT and month for counties with I/M = County VMT by month * 

VMT mix as above * I/M Credit EF by month (i.e., No-I/M EF – I/M EF by 

month, by pollutant and vehicle type) * I/M Coverage factor * 1.102 x 10-6). I/M 

Credits will exist for VOC, CO, and NOx, but not for any SO2, NH3, or any PM 

species. 

3. Net County Emissions by VT and month for counties with I/M = (No-I/M County 

Emissions by VT and month) – (I/M Credits by VT and month).

4. For Grundy and Kendall Counties, which are only partly in the NAA, No-I/M 

emissions were calculated for the NAA townships and Attainment townships 

separately using NAA-township VMT data and Attainment Township VMT data; 

then the I/M benefits for the NAA townships, then the Net Emissions for the 

NAA townships as in 3 above, and finally All-County emissions, which are the 

sum of the emissions for the Attainment townships and the Net Emissions for the 

NAA townships

Once each county’s or county subdivision’s emissions for all pollutants have been 

calculated, the spreadsheet can be commanded to aggregate them into NAA totals by 

pollutant. 

Motor Vehicle Emissions Budgets

Using the above VMT and control program assumptions and methodology, following are 

2008 and 2025 the proposed Chicago PM2.5 Maintenance Plan motor vehicle emissions 

budgets (rounded to the nearest ton/year) for use in determining transportation 

conformity.
41

Proposed 2008 and 2025 Motor Vehicle Emissions Budgets 

Chicago PM2.5 Maintenance Plan

(tons per year)

Year PM2.5 NOx

2008 1,816 99,627

2025 1,064 23,687
42

External MOBILE6.2 Inputs: 

In the examples of external files shown below, the actual command lines are boldfaced; 

the unbolded lines represent comments. The actual text files have no such distinction in 

typefaces. The unbolded lines have been “commented out” and have no effect on the 

MOBILE model. They may therefore be omitted, but it is suggested that they remain in 

the files for documentation, and to make the files easier for the user to read and 

understand. 

The comments and other text in the External Files have been shown in the Courier 

New typeface. Actual command lines—the inputs that MOBILE actually uses—are 

shown in Courier New Bold

Vehicle Inspection and Maintenance (I/M) Program 

The external I/M files giving the inputs used by the MOBILE6 model to generate year 

2008 emissions factors is described below. The first is the post-2007 I/M program that 

went into effect in early 2007. Since it is a biennial program, about 3⁄4 of vehicles subject 

to I/M had been tested under this program by mid 2008; but 1⁄4 of them had been tested 

under the pre-2007 program and were still generating benefits from the old program. 

Thus the actual I/M benefits in 2008 are the weighted average of the benefits of the two 

programs, the weighting factors being 75% for the post-’07 program and 25% for the pre-

’07 program.

Below is the post-’07 I/M program description, represented by the external input file 

IM07ON.D. This program is expected to continue into the foreseeable future. It 

represents an I/M program with four components, chief of which is an OBD (on-board 

diagnostics) test for vehicles of model year (MY) 1996 and newer. The order in which 

the components appear in the external file is not significant, but they must be numbered 

consecutively. Illinois EPA begins the external file with identifying comments and adds 

other comment lines or blank lines to make the file easier to read and understand. 

* ILLINOIS ENHANCED I/M DESCRIPTION 

* Filename: IM07ON.D

* External input file for Illinois' OBD-only I/M program 

* from 2007 on.

* OBD-only applies to light-duty vehicles only; HDVs still get 

* an Idle Test & Gas Cap Check.

* All program start years set to 1986 per U.S. EPA guidance in 

* "Frequently Asked Questions on MOBILE6" from U.S. EPA/OTAQ.

* This represents the NEW I/M program in which only 1996 & 

* newer vehicles are tested with an OBD test; and the OBD test 

* applies only to LDVs. 

* This program came into effect in February 2007.
43

*-------------------------------------------------

* Program description for post MY'96 LDV OBD I/M 

*=================================================

* FIRST I/M program--"Evaporative]" OBD for MY 1996+ LDVs 

*-------------------------------------------------

I/M PROGRAM : 1 1986 2050 2 T/O EVAP OBD

I/M MODEL YEARS : 1 1996 2050

I/M VEHICLES : 1 22222 11111111 1

I/M STRINGENCY : 1 20.0

I/M COMPLIANCE : 1 95.0

I/M WAIVER RATES : 1 0.5 2.2 '01 data

I/M EXEMPTION AGE : 1 25

I/M GRACE PERIOD : 1 4

In each case, the first number after the colon refers to the I/M program’s 

component number. 

I/M PROGRAM : 1 1986 2050 2 T/O EVAP OBD

Testing began in 1986 and runs into the indefinite future (2050). The program 

is a biennial test-only (2 T/O, here and in other program components) program, 

in this case an Evaporative OBD test. The vehicle engine computer records 

information from sensors in the engine and fuel system. Indications of 

malfunctions or out-of-specification operations of the engine or fuel and 

evaporative emission control systems are stored in the engine computer as “fault 

codes”. An OBD test consists of plugging a special scanner into an output jack 

from vehicle’s engine computer. The scanner queries the computer and records 

any fault codes that the computer’s OBD system has saved. OBD tests are 

quick, dependable, and clean, and, if a vehicle fails an OBD test, the fault codes 

that the scanner displays help mechanics diagnose the problem. 

I/M MODEL YEARS : 1 1996 2050

This program component covers only vehicles manufactured between model 

year (MY) 1996 (start year) and the indefinite future (MY 2050, the end year). 

An increasing percentage of vehicles are becoming subject to this test as new 

vehicles are purchased and older (pre-MY-1996) vehicles are retired. 

I/M VEHICLES : 1 22222 11111111 1

Only the five light-duty vehicle types only light-duty gasoline vehicles (LDGVs) 

and light-duty gasoline trucks (LDGTs 1, 2, 3, and 4) are covered by this 

program component (22222). Heavy-duty gasoline trucks (eight types) and 

gasoline buses are not covered by this program component (11111111 1), but 

rather by Programs 3 and 4, described below.

I/M STRINGENCY : 1 20.0

Stringency (exhaust inspection failure rate) is 20%. A Stringency entry is necessary for 

an exhaust test, but not an evaporative test, so this entry can be omitted or “commented 
44

out”. In this Evap test case, it will be ignored by the model, but is included for 

reference.

I/M COMPLIANCE : 1 95.0

Compliance rate (tested vehicles as percent of all vehicles subject to I/M) is 

95%

I/M WAIVER RATES : 1 0.5 2.2 '01 data

The Waiver Rate is the fraction of tested vehicles that get a waiver—i.e., do not 

pass the I/M test but, because repairs cost more than a specified amount, get a 

certificate of compliance. Waiver rate is 0.5% for MY 1980 and earlier vehicles 

(irrelevant now that pre-MY-96 vehicles are not tested), and 2.2% for MY 1981 

and later vehicles. These figures are from VIM’s actual 2001 waiver statistics, 

and have been representative of the last few years, so are deemed representative 

of 2009. In this case the comment stating that fact is allowed in the same line as 

the data.

I/M EXEMPTION AGE : 1 25

Vehicles older than 25 years are not subject to this program. This will not 

happen until at least 2021. The default is 25, and the model does not calculate 

benefits for vehicles older than 25 years, so in essence this command has no 

effect. It could be omitted, but is included for completeness. 

I/M GRACE PERIOD : 1 4

Vehicles less than 4 model years old—in this case MY2006, ’07, ’08, and ’09—

are exempt from I/M testing. 

Most of the inputs to the second and subsequent program components are the 

same as those for the first program, so the description of the components will be 

abbreviated and summarized as below, rather than after each command line as 

above.

* Second I/M program--"Exhaust" OBD for MY 1996+ LDVs

*----------------------------------------------------

I/M PROGRAM : 2 1986 2050 2 T/O OBD I/M

I/M MODEL YEARS : 2 1996 2050

I/M VEHICLES : 2 22222 11111111 1

I/M STRINGENCY : 2 20.0

I/M COMPLIANCE : 2 95.0

I/M WAIVER RATES : 2 0.5 2.2 '01 data

I/M EXEMPTION AGE : 2 25

I/M GRACE PERIOD : 2 4

*

The second program component is a biennial, test-only Exhaust OBD test for 

MY 1996 and later LDGVs and LDGTs. In this OBD test, the scanner queries 

the vehicle’s computer for fault codes concerning exhaust emissions. 

Stringency, Compliance, Waiver Rates, Exemption Age, and Grace Period are 
45

the same as in the first program. An entry for I/M STRINGENCY (20%) is 

required for an Exhaust I/M program.

*------------------------------------------------------

* Program description for post MY'96 HDV Idle & GC I/M

*======================================================

* Third I/M program--HDV IDLE for MY 1996+ HDVs

*------------------------------------------------

I/M PROGRAM : 3 1986 2050 2 T/O IDLE

I/M MODEL YEARS : 3 1996 2050

I/M VEHICLES : 3 11111 22222222 2

I/M STRINGENCY : 3 20.0

I/M COMPLIANCE : 3 95.0

I/M WAIVER RATES : 3 1.2 1.5 '01 data

I/M EXEMPTION AGE : 3 25

I/M GRACE PERIOD : 3 4

The third program component is a biennial, test-only Idle test for MY 1996 and 

later HDGVs and Gas Buses (22222222 2). Light-duty vehicles are not subject 

to this component (11111), but rather to components 1 and 2. Stringency, 

Compliance, Exemption Age, and Grace Period are the same as in component 1, 

but the pre- and post-MY 1981 Waiver Rates (1.2% and 1.5%, respectively), are 

slightly different from those in components 1 and 2. HDGVs are few in 

number, and most of them are commercial vehicles. 

* Fourth I/M program--Gas Cap Check for MY 1996+ HDVs

*----------------------------------------------------

I/M PROGRAM : 4 1986 2050 2 T/O GC

I/M MODEL YEARS : 4 1996 2050

I/M VEHICLES : 4 11111 22222222 2

I/M COMPLIANCE : 4 95.0

I/M WAIVER RATES : 4 1.2 1.5 '01 data

I/M EXEMPTION AGE : 4 25

I/M GRACE PERIOD : 4 4

The fourth program component is a biennial, test-only Gas Cap Check for MY 

1996 and later HDVs. Compliance, Waiver Rates, Exemption Age, and Grace 

Period are the same as in the third program. Since a Gas Cap Check is an 

evaporative I/M test, the I/M STRINGENCY command is not necessary and is 

not included here.

Below is the pre-’07 I/M program ILLOBDIM.D

* ILLINOIS ENHANCED I/M DESCRIPTION Filename: ILLOBDIM.D

* OBD EXH AND GAS CAP 1996+ BEGINNING IN 2002

* The Illinois I/M is Biennial Test Only (2 T/O) program

* that applies to LDGVs, LDGTs, and, in slightly different
46

* fashion, to HDGVs. Exhaust & Evaporative OBD is for 

* MY '96+ vehicles; IM240 and simple Idle tests remain for 

* pre-'96 LDVs pre-'81 LDVs respectively.

* Ref to MYCUTS in 2nd program changed to

F:\ONROAD\AREASPEC\MYCUTS.D

* by SL on 31.j.05 from F:\ONROAD\MOBILE62\RUN\EXAMPLES\MYCUTS.D

* -------------------------------------------------

* Program Description for older LDVs' I/M programs

* -------------------------------------------------

* First I/M program--IDLE test for MY 1968+ LDVs

I/M PROGRAM : 1 1986 2050 2 T/O IDLE

I/M MODEL YEARS : 1 1968 1980

I/M VEHICLES : 1 22222 11111111 1

I/M STRINGENCY : 1 20.0

I/M COMPLIANCE : 1 95.0

I/M WAIVER RATES : 1 0.5 2.2 '01 data

I/M GRACE PERIOD : 1 4

*

Program 1 is for vehicle of MY1968 to MY 1980. It consists of a biennial testonly Idle Test for light-duty cars and trucks (22222), with stringency of 20%, 

Compliance of 90%, and a 4-year grace period (which is irrelevant, since 1980 is 

long in the past. Waiver rates are 0.5% and 2.2% for pre-MY1981 and MY1981-

and-after The IM240 cutpoints are given by the MYCUTS.D file. See the 

MOBILE6 User’s Guide, Section 2.8.9.4.g..

* Second I/M program--IM240 for MY 1981 to 1995 LDVs

I/M PROGRAM : 2 1999 2050 2 T/O IM240

I/M MODEL YEARS : 2 1981 1995

I/M VEHICLES : 2 22222 11111111 1

I/M STRINGENCY : 2 20.0

I/M CUTPOINTS : 2 F:\ONROAD\AREASPEC\MYCUTS.D

I/M COMPLIANCE : 2 95.0

I/M WAIVER RATES : 2 0.5 2.2 '01 data

I/M GRACE PERIOD : 2 4

*

* Third I/M program Gas Cap Check for MY 1968 to 1995 LDVs

I/M PROGRAM : 3 1992 2050 2 T/O GC

I/M MODEL YEARS : 3 1968 1995

I/M VEHICLES : 3 22222 11111111 1

* I/M STRINGENCY not required in evaporative I/M program input

I/M COMPLIANCE : 3 95.0

I/M WAIVER RATES : 3 0.5 2.2 '01 data

I/M GRACE PERIOD : 3 4

The second and third I/M programs also apply to light-cars and trucks and 

consists of a biennial IM240 test and a Gas Cap Check for vehicles of MY1981 

through MY 1995. Stringency, Compliance, Waiver Rates, and Grace Period are 

as above,
47

The fourth and fifth I/M programs apply to light-duty vehicles (22222) of 

MY1996 on. Program 4 is a biennial Test-Only Evaporative OBD Test + Gas 

Cap Check; and Program 5 is a biennial Test-Only “Exhaust” OBD test, as 

described below. There is a 4-year grace period; thus in 2008 the OBD tests have 

been applied only to light-duty vehicles from MY1996 to MY2004,

* --------------------------------------------------------

* Program description for LDV Evaporative and Exhaust OBD

* --------------------------------------------------------

* Fourth I/M program--EVAP OBD & Gas Cap Check for 1996+ LDV

I/M PROGRAM : 4 2002 2050 2 T/O EVAP OBD & GC

I/M MODEL YEARS : 4 1996 2050

I/M VEHICLES : 4 22222 11111111 1

* I/M STRINGENCY not required in evaporative I/M program input

I/M COMPLIANCE : 4 95.0

I/M WAIVER RATES : 4 0.5 2.2 '01 data

I/M GRACE PERIOD : 4 4

* Fifth I/M program--"Exhaust" OBD for MY 1996+ LDVs

I/M PROGRAM : 5 2002 2050 2 T/O OBD I/M

I/M MODEL YEARS : 5 1996 2050

I/M VEHICLES : 5 22222 11111111 1

I/M STRINGENCY : 5 20.0

I/M COMPLIANCE : 5 95.0

I/M WAIVER RATES : 5 0.5 2.2 '01 data

I/M GRACE PERIOD : 5 4

The final two programs in the ILLOBDIM file apply to heavy-duty vehicles 

(HDVs) only (22222222 2), and consist of an Idle Test and a Gas Cap check for 

all HDVs of MY1968 and later, with a 4-year grace period

* -----------------------------------------------

* Program description for Heavy-Duty Vehicle I/M 

* -----------------------------------------------

* Sixth I/M program--HDV IDLE for MY 1968+ HDVs

I/M PROGRAM : 6 1986 2050 2 T/O IDLE

I/M MODEL YEARS : 6 1968 2050

I/M VEHICLES : 6 11111 22222222 2

I/M STRINGENCY : 6 20.0

I/M COMPLIANCE : 6 95.0

I/M WAIVER RATES : 6 1.2 1.5 '01 data

I/M GRACE PERIOD : 6 4

*

* Seventh I/M program--Gas Cap Check for MY 1968+ HDVs

I/M PROGRAM : 7 1992 2050 2 T/O GC

I/M MODEL YEARS : 7 1968 2050

I/M VEHICLES : 7 11111 22222222 2

* I/M STRINGENCY not required in evaporative I/M program input

I/M COMPLIANCE : 7 95.0

I/M WAIVER RATES : 7 1.2 1.5 '01 data

I/M GRACE PERIOD : 7 4

*

* ----------------
48

*

* NOTES:

* This is the standard Illinois I/M input, describing

* the I/M program with OBD as it exists after early 

* March 2002. 

The MYCUTS file mentioned above is as follows:

* This file was created automatically by a Mobile6 conversion utility.

* The same cutpoints are used for each model year and vehicle type.

I/M CUTPOINTS : CUTP015.D 

*

*

* Block 1 (LDGV, LDGT1)

 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800

 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800

 0.800 0.800 0.800 0.800 0.800

15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000

15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000

15.000 15.000 15.000 15.000 15.000

999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000

999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000

999.000 999.000 999.000 999.000 999.000

*

* Block 2 (LDGT2, LDGT3)

 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800

 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800

 0.800 0.800 0.800 0.800 0.800

15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000

15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000

15.000 15.000 15.000 15.000 15.000

999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000

999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000

999.000 999.000 999.000 999.000 999.000

*

* Block 3 (LDGT4)

 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800

 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800

 0.800 0.800 0.800 0.800 0.800

15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000

15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000

15.000 15.000 15.000 15.000 15.000

999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000

999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000

999.000 999.000 999.000 999.000 999.000

*

* Block 4 (HDGV)

 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800

 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800 0.800

 0.800 0.800 0.800 0.800 0.800

15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000

15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000 15.000

15.000 15.000 15.000 15.000 15.000

999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000

999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000 999.000

999.000 999.000 999.000 999.000 999.000

The Registration Distribution
49

The Registration Distribution (RD) for a vehicle type is an indication of the fraction of 

the vehicle fleet of that type that is made up of vehicles of a given age. The following is 

based on 2008 registration data from the Illinois Secretary of State’s office (ISOS). It 

and its contents are described below. The file is named CHRD08AA.D.

REGISTRATION DISTRIBUTION

* CNAA M6 LDV RD = SOSLDV (Light-duty Vehicles--passenger cars) RD from 

* 08VADbyCounty.xls for Chicago omitting '09 counts & '08 = 75% of '07

1 0.0550 0.0733 0.0675 0.0656 0.0649 0.0666 0.0698 0.0665 0.0680 

0.0598

 0.0524 0.0500 0.0415 0.0421 0.0325 0.0263 0.0218 0.0166 0.0134 

0.0103

 0.0074 0.0057 0.0043 0.0033 0.0154

* CNAA M6 LDT1 RD = SOSLDT1 (ISOS "light" or type 1 LD trucks) RD from

* 08VADbyCounty.xls for Chicago omitting '09 counts & '08 = 75% of '07

2 0.0526 0.0702 0.0769 0.0872 0.0796 0.0729 0.0835 0.0670 0.0669 

0.0586

 0.0583 0.0478 0.0385 0.0342 0.0294 0.0219 0.0148 0.0118 0.0076 

0.0065

 0.0051 0.0031 0.0020 0.0012 0.0024

 

* CNAA M6 LDT2 RD = Same as M6 LDT1 RD; see above. 

3 0.0526 0.0702 0.0769 0.0872 0.0796 0.0729 0.0835 0.0670 0.0669 

0.0586

 0.0583 0.0478 0.0385 0.0342 0.0294 0.0219 0.0148 0.0118 0.0076 

0.0065

 0.0051 0.0031 0.0020 0.0012 0.0024

 

* CNAA M6 LDT3 = SOSLDT21 (ISOS "heavy" or type 2 LD trucks) RD from

* 08VADbyCounty.xls for Chicago omitting '09 counts & '08 = 75% of '07

4 0.0457 0.0609 0.0635 0.0720 0.0854 0.0843 0.0729 0.0689 0.0705 

0.0800

 0.0517 0.0472 0.0349 0.0375 0.0294 0.0203 0.0162 0.0095 0.0104 

0.0099

 0.0075 0.0049 0.0041 0.003 0.0094

 

* CNAA M6 LDT4 = same as LDT3 RDs; see above.

5 0.0457 0.0609 0.0635 0.0720 0.0854 0.0843 0.0729 0.0689 0.0705 

0.0800

 0.0517 0.0472 0.0349 0.0375 0.0294 0.0203 0.0162 0.0095 0.0104 

0.0099

 0.0075 0.0049 0.0041 0.003 0.0094

* Heavy-Duty & MC RDs below are all assumed same as M6 default RD.

 

* HDV2B (Heavy-duty vehicles 2B--M6 Default RDs)

6 0.0503 0.0916 0.0833 0.0758 0.0690 0.0627 0.0571 0.0519 0.0472 0.0430

 0.0391 0.0356 0.0324 0.0294 0.0268 0.0244 0.0222 0.0202 0.0184 0.0167

 0.0152 0.0138 0.0126 0.0114 0.0499

* HDV3 (Heavy-duty vehicles3, same RD as HDV2B, M6 Default RDs)

7 0.0503 0.0916 0.0833 0.0758 0.0690 0.0627 0.0571 0.0519 0.0472 0.0430

 0.0391 0.0356 0.0324 0.0294 0.0268 0.0244 0.0222 0.0202 0.0184 0.0167

 0.0152 0.0138 0.0126 0.0114 0.0499
50

* HDV4 (Heavy-duty vehicles 4, M6 default RDs)

8 0.0388 0.0726 0.0679 0.0635 0.0594 0.0556 0.0520 0.0486 0.0455 0.0425

 0.0398 0.0372 0.0348 0.0326 0.0304 0.0285 0.0266 0.0249 0.0233 0.0218

 0.0204 0.0191 0.0178 0.0167 0.0797

* HDV5 (Heavy-duty vehicles 5, same RD as HDV4, M6 Default)

9 0.0388 0.0726 0.0679 0.0635 0.0594 0.0556 0.0520 0.0486 0.0455 0.0425

 0.0398 0.0372 0.0348 0.0326 0.0304 0.0285 0.0266 0.0249 0.0233 0.0218

 0.0204 0.0191 0.0178 0.0167 0.0797

* HDV6 (Heavy-duty vehicles 6, same RD as HDV4, M6 Default)

10 0.0388 0.0726 0.0679 0.0635 0.0594 0.0556 0.0520 0.0486 0.0455 0.0425

 0.0398 0.0372 0.0348 0.0326 0.0304 0.0285 0.0266 0.0249 0.0233 0.0218

 0.0204 0.0191 0.0178 0.0167 0.0797

* HDV7 (Heavy-duty vehicles 7, same RD as HDV4, M6 Default)

11 0.0388 0.0726 0.0679 0.0635 0.0594 0.0556 0.0520 0.0486 0.0455 0.0425

 0.0398 0.0372 0.0348 0.0326 0.0304 0.0285 0.0266 0.0249 0.0233 0.0218

 0.0204 0.0191 0.0178 0.0167 0.0797

* HDV8A (Heavy-duty vehicles 8A same RD as HDV4, M6 Default)

12 0.0388 0.0726 0.0679 0.0635 0.0594 0.0556 0.0520 0.0486 0.0455 0.0425

 0.0398 0.0372 0.0348 0.0326 0.0304 0.0285 0.0266 0.0249 0.0233 0.0218

 0.0204 0.0191 0.0178 0.0167 0.0797

* HDV8B (Heavy-duty vehicles 8B,same RD as HDV4, M6 Default)

13 0.0388 0.0726 0.0679 0.0635 0.0594 0.0556 0.0520 0.0486 0.0455 0.0425

 0.0398 0.0372 0.0348 0.0326 0.0304 0.0285 0.0266 0.0249 0.0233 0.0218

 0.0204 0.0191 0.0178 0.0167 0.0797

* HDBS (HDV School buses; this M6 RD default is assumed)

14 0.0393 0.0734 0.0686 0.0641 0.0599 0.0559 0.0522 0.0488 0.0456 0.0426

 0.0398 0.0372 0.0347 0.0324 0.0303 0.0283 0.0264 0.0247 0.0231 0.0216

 0.0201 0.0188 0.0176 0.0165 0.0781

* HDBT (HDV Transit buses; this M6 RD default is assumed)

15 0.0307 0.0614 0.0614 0.0614 0.0614 0.0614 0.0614 0.0614 0.0614 0.0613

 0.0611 0.0607 0.0595 0.0568 0.0511 0.0406 0.0254 0.0121 0.0099 0.0081

 0.0066 0.0054 0.0044 0.0037 0.0114

* MC (Motorcycles; this M6 default RD is assumed)

16 0.1440 0.1680 0.1350 0.1090 0.0880 0.0700 0.0560 0.0450 0.0360 0.0290

 0.0230 0.0970 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000

 0.0000 0.0000 0.0000 0.0000 0.0000

This Chicago area-specific data is derived from ISOS registration data for LDVs subject 

to I/M in the Chicago-area counties. Since more than 90% of the light-duty gasoline 

vehicles in the Chicago NAA are subject to I/M, we assume the RD for Chicago-area 

LDVs subject to I/M is representative of that for all Chicago-area LDVs.

The ISOS data were counts for what ISOS calls "LDVs", LDT1s", and "LDT2s" by 

model year (MY). Those appear below as SLDV, SLDT1, and SLDT2 to distinguish 

them from M6 vehicle types. 

• SLDVs correspond to passenger cars, so SLDVs = M6 LDVs.

• SLDT1s correspond to M6 LDT1s and LDT2s. ISOS data do not distinguish 

between the two M6 categories. For this reason, the RDs for M6 LDT1 and 

LDT2 are assumed to be the same. 

• Similarly, SLDT2s correspond to M6 LDT3s and LDT4s, and ISOS data don't 

distinguish between those two M6 categories either. Therefore, the RDs for M6 

LDT3 and LDT4 are also assumed to be the same. 

The age distribution fractions have been rounded to 4 decimal places, and where the 

rounded fractions do not add up to 1.0000 exactly, RD fractions for old (age 22 to 24 
51

years) have at times been modified by +/- 0.0001 so as to make the RDs add up to 

1.0000, a requirement of the MOBILE6.2 model. 

In this RD file, the first number in each distribution is an integer that indicates which of 

the 16 M6 vehicle classes are represented by the RD in question. That number is 

followed by 25 age fractions arranged in two rows of 10 values followed by a third row 

with the last 5 values. 

It is assumed that the RDs for diesel vehicles are the same as the RDs for the 

corresponding gasoline vehicles; in particular, LDDV and LDDT RDs are assumed the 

same as LDGV and LDGT RDs. Since the (default) HDV RDs are based more on diesel 

vehicles to start with, and HDGVs are many fewer than HDDVs, especially in the higher 

weight classes, we feel the default HDV RDs represent both HDGV and HDDV 

reasonably well.

Default RDs are assumed for the various HDV classes. Good area-specific HDV age 

distribution data are lacking—the ISOS data covered only light-duty vehicles subject to 

I/M—and besides, much Chicago-area HDV VMT is from vehicles registered outside the 

Chicago area and just passing through. The best choice, then, was to go with the HDV 

defaults. Similarly, accurate local-area registration data for motorcycles are lacking, so 

the default MC RD is used.

External MOBILE6.2 Activity File Inputs: VMT by Facility Type, VMT 

by Hour, VMT by Speed Bin. 

The following files were used in the 2002 base year and the 2009 future year estimates. 

VMT by Facility Type

The M6.2 default file is FVMT.D, provided with the MOBILE6 model. The Chicagoarea-specific VMT-by-facility-type file is FVMTCH07.D, shown below. It based on the 

most recent complete data from CMAP on VMT by hour by vehicle class. This is a very 

long file —about 750 lines—so for the purposes of this Attachment, only the data for 

vehicle types 1, 6, 11, 13, 24 (LDGV, HDGV2b, HDGV7, HDGV13, and MC) are 

shown; the others are omitted. See the second paragraph of the introduction to the file.

VMT BY FACILITY

*

* 

* VMT fractions are listed for 28 vehicle classes for each hour of 
52

* the day starting at 6AM, as follows 

* Classes 1-5 (LDGV, LDGT1, LDGT2, LDGT3, and LDGT4), and 

* Classes 14, 15, and 28 (LDDV, LDDT12, LDDT34) were all assumed 

* to have the "Light-duty Vehicle" distribution on page "SL VMT 

* by vtype reedited" of the MF13 file. 

* Classes 6-10 and 16-20 (HDGV2b-HDGV6 and HDDV2b-HDDV6) were assumed

* to have the "LTRK" (light HDV) distribution on that page.

* Classes 11 & 12 and 21 & 22 (HDGV7 & HDGV8a, and HDDV7 & HDDV8a) were

* assumed to have the "MTRK" (medium HDV) distribution on that page.

* Classes 13 and 23 (HDGV8b and HDDV8b) were assumed to have the 

* "HTRK" (heavy HDV) distribution on that page

* Classes 24 and 25-27 (Motorcycles and the three bus classes [HDGB,

* HDDBT and HDDBS]) were assumed to have the default distribution

* for those types in FVMT.DEF. 

*

* The four values in each line represent the VMT distribution on

* freeway, arterial, local and ramps--in that order--as shown.

*

* See M6UG 2.8.5.1.f., p. 49, or CLASLIST.TXT for further info.

* (The CLASLIST file describes the vehicle classes.)

* 

* Veh Int& Arts& Local

*Class Fwys Colls Rd/St Ramps

*----- ---- ----- ----- -----

* 

 1 0.3341 0.5393 0.1105 0.0161 

 0.2604 0.6106 0.1160 0.0130 

 0.2604 0.6106 0.1160 0.0130 

 0.2669 0.5831 0.1365 0.0135 

 0.2576 0.5823 0.1468 0.0133 

 0.2576 0.5823 0.1468 0.0133 

 0.2576 0.5823 0.1468 0.0133 

 0.2576 0.5823 0.1468 0.0133 

 0.2683 0.5830 0.1354 0.0133 

 0.2683 0.5830 0.1354 0.0133 

 0.2646 0.5911 0.1315 0.0128 

 0.2646 0.5911 0.1315 0.0128 

 0.2825 0.5568 0.1468 0.0139 

 0.2825 0.5568 0.1468 0.0139 

 0.3363 0.5122 0.1358 0.0157 

 0.3363 0.5122 0.1358 0.0157 

 0.3363 0.5122 0.1358 0.0157 

 0.3363 0.5122 0.1358 0.0157 

 0.3363 0.5122 0.1358 0.0157 

 0.3363 0.5122 0.1358 0.0157 

 0.3363 0.5122 0.1358 0.0157 

 0.3363 0.5122 0.1358 0.0157 

 0.3363 0.5122 0.1358 0.0157 

 0.3363 0.5122 0.1358 0.0157 

.

[Data for Vehicle Types 2 through 5 omitted]

.

 6 0.3836 0.5157 0.0827 0.0180

 0.3045 0.5985 0.0822 0.0148

 0.3045 0.5985 0.0822 0.0148

 0.3589 0.5412 0.0829 0.0170

 0.3791 0.5203 0.0826 0.0180

 0.3791 0.5203 0.0826 0.0180

 0.3791 0.5203 0.0826 0.0180

 0.3791 0.5203 0.0826 0.0180

 0.3606 0.5397 0.0827 0.0170

 0.3606 0.5397 0.0827 0.0170

 0.3581 0.5432 0.0816 0.0171
53

 0.3581 0.5432 0.0816 0.0171

 0.4101 0.4884 0.0815 0.0200

 0.4101 0.4884 0.0815 0.0200

 0.4312 0.4663 0.0818 0.0207

 0.4312 0.4663 0.0818 0.0207

 0.4312 0.4663 0.0818 0.0207

 0.4312 0.4663 0.0818 0.0207

 0.4312 0.4663 0.0818 0.0207

 0.4312 0.4663 0.0818 0.0207

 0.4312 0.4663 0.0818 0.0207

 0.4312 0.4663 0.0818 0.0207

 0.4312 0.4663 0.0818 0.0207

 0.4312 0.4663 0.0818 0.0207

.

[Data for Vehicle Types 7 through 11 omitted]

.

 11 0.4158 0.4904 0.0752 0.0186

 0.3337 0.5763 0.0749 0.0151

 0.3337 0.5763 0.0749 0.0151

 0.3905 0.5165 0.0755 0.0175

 0.4111 0.4952 0.0752 0.0185

 0.4111 0.4952 0.0752 0.0185

 0.4111 0.4952 0.0752 0.0185

 0.4111 0.4952 0.0752 0.0185

 0.3928 0.5144 0.0753 0.0175

 0.3928 0.5144 0.0753 0.0175

 0.3896 0.5185 0.0742 0.0177

 0.3896 0.5185 0.0742 0.0177

 0.4423 0.4630 0.0743 0.0204

 0.4423 0.4630 0.0743 0.0204

 0.4619 0.4425 0.0745 0.0211

 0.4619 0.4425 0.0745 0.0211

 0.4619 0.4425 0.0745 0.0211

 0.4619 0.4425 0.0745 0.0211

 0.4619 0.4425 0.0745 0.0211

 0.4619 0.4425 0.0745 0.0211

 0.4619 0.4425 0.0745 0.0211

 0.4619 0.4425 0.0745 0.0211

 0.4619 0.4425 0.0745 0.0211

 0.4619 0.4425 0.0745 0.0211

.

[Data for Vehicle Types 7 through 12 omitted]

.

 13 0.6106 0.3299 0.0430 0.0165

 0.5563 0.3937 0.0367 0.0133

 0.5563 0.3937 0.0367 0.0133

 0.6241 0.3235 0.0376 0.0148

 0.6260 0.3178 0.0403 0.0159

 0.6260 0.3178 0.0403 0.0159

 0.6260 0.3178 0.0403 0.0159

 0.6260 0.3178 0.0403 0.0159

 0.6561 0.2957 0.0340 0.0142

 0.6561 0.2957 0.0340 0.0142

 0.6029 0.3414 0.0401 0.0156

 0.6029 0.3414 0.0401 0.0156

 0.5776 0.3523 0.0508 0.0193

 0.5776 0.3523 0.0508 0.0193

 0.5737 0.3512 0.0547 0.0204

 0.5737 0.3512 0.0547 0.0204

 0.5737 0.3512 0.0547 0.0204

 0.5737 0.3512 0.0547 0.0204

 0.5737 0.3512 0.0547 0.0204
54

 0.5737 0.3512 0.0547 0.0204

 0.5737 0.3512 0.0547 0.0204

 0.5737 0.3512 0.0547 0.0204

 0.5737 0.3512 0.0547 0.0204

 0.5737 0.3512 0.0547 0.0204

.

[Data for Vehicle Types 14 through 23 omitted]

.

 24 0.392 0.457 0.117 0.034

 0.344 0.497 0.129 0.030

 0.338 0.497 0.135 0.029

 0.349 0.492 0.129 0.030

 0.346 0.497 0.127 0.030

 0.333 0.509 0.129 0.029

 0.324 0.516 0.132 0.028

 0.334 0.506 0.131 0.029

 0.334 0.506 0.131 0.029

 0.320 0.519 0.134 0.028

 0.330 0.506 0.135 0.029

 0.312 0.521 0.140 0.027

 0.295 0.538 0.141 0.026

 0.310 0.527 0.137 0.027

 0.329 0.510 0.133 0.029

 0.343 0.497 0.131 0.030

 0.381 0.460 0.126 0.033

 0.405 0.437 0.123 0.035

 0.426 0.418 0.118 0.037

 0.443 0.403 0.115 0.039

 0.457 0.394 0.110 0.040

 0.461 0.391 0.107 0.040

 0.453 0.400 0.108 0.039

 0.418 0.434 0.112 0.036

[Data for Vehicle Types 25 through 28 omitted; the file ends after Vehicle Type 28.]

VMT by Hour of the Day

The MOBILE6.2 default file is HVMT.D. The most current Chicago-area-specific file,

derived from 2007 modeling output from CMAP, is shown below. Again, this file 

contains “commented-out” data from previous files for comparison purposes. 

VMT BY HOUR

* Fraction of all vehicle miles traveled by hour of the day. 

* First hour is 6 a.m. These data are for the Chicago NAA for 

* 2007, derived from CMAP VbyHr07.def file based 

* upon his run iepa07 300_20070830, VMT for 2007.

*

* IEPA estimates are based on CMAP data, but assume VMT in multi-hour 

* modeling periods is distributed as the default is distributed across 

* the hours in question. Calculations made from VbyHr07.def 

* in accordance with USEPAU.S.EPA guidance on the subject. See M6 Technical 

Guidance 

* Document (Jan '02) Section 4.3.3 for details.
55

0.03358 0.07039 0.06240 0.07658 0.05870 0.06327

0.06609 0.06207 0.06693 0.07118 0.07991 0.07507

0.05924 0.04599 0.02160 0.01851 0.01360 0.01010

0.00757 0.00603 0.00568 0.00561 0.00687 0.01304

 

* Here are RP's original fractions from VbyHr07.def 

* 0.033579 0.066392 0.066392 0.076578 0.062532 0.062532

* 0.062532 0.062532 0.069056 0.069056 0.077490 0.077490

* 0.052616 0.052616 0.010861 0.010861 0.010861 0.010861

* 0.010861 0.010861 0.010861 0.010861 0.010861 0.010861

* These following are the default values from HVMT.DEF

* supplied for comparison.

* 0.0569 0.0740 0.0655 0.0555 0.0540 0.0582

* 0.0608 0.0571 0.0598 0.0636 0.0777 0.0730

* 0.0501 0.0389 0.0308 0.0264 0.0194 0.0144

* 0.0108 0.0086 0.0081 0.0080 0.0098 0.0186

*

* Following are SL's original HVMTCH07 fractions based upon DE's '07 model

* runs made in 2002 (for information).

* 0.0443 0.0851 0.0755 0.0577 0.0541 0.0583

* 0.0609 0.0572 0.0659 0.0701 0.0818 0.0769

* 0.0576 0.0447 0.0219 0.0188 0.0138 0.0102

* 0.0077 0.0061 0.0058 0.0057 0.0070 0.0132

All these Hourly-VMT files show similar profiles, with morning and afternoon peaks, a 

noontime dip, and a minimum about 3AM - 4AM.

VMT by Speed Bin

The MOBILE6.2 default file is SVMT.D. The Chicago-area-specific Speed-bin file is 

VbySpd07.DEF, shown below. It represents 2007 CMAP transportation model output, 

deemed representative for 2008 and 2009 as well. Since it is a “wide” file (at least 90 

columns), it is shown here in a smaller-than-usual typeface to make it easier to read 

SPEED VMT

 1 1 0.0001 0.0000 0.0050 0.0075 0.0043 0.0103 0.0253 0.0254 0.0452 0.0638 0.1040 0.3767 0.1943 

0.1383

 1 2 0.0001 0.0080 0.0148 0.0466 0.0625 0.0859 0.0908 0.1456 0.1013 0.1130 0.1416 0.1285 0.0299 

0.0316

 1 3 0.0001 0.0080 0.0148 0.0466 0.0625 0.0859 0.0908 0.1456 0.1013 0.1130 0.1416 0.1285 0.0299 

0.0316

 1 4 0.0001 0.0048 0.0307 0.0799 0.0662 0.0918 0.1283 0.1232 0.0962 0.1322 0.1209 0.0715 0.0286 

0.0256

 1 5 0.0000 0.0002 0.0012 0.0103 0.0282 0.0531 0.0824 0.0971 0.1819 0.1460 0.1768 0.1341 0.0358 

0.0529

 1 6 0.0000 0.0002 0.0012 0.0103 0.0282 0.0531 0.0824 0.0971 0.1819 0.1460 0.1768 0.1341 0.0358 

0.0529

 1 7 0.0000 0.0002 0.0012 0.0103 0.0282 0.0531 0.0824 0.0971 0.1819 0.1460 0.1768 0.1341 0.0358 

0.0529

 1 8 0.0000 0.0002 0.0012 0.0103 0.0282 0.0531 0.0824 0.0971 0.1819 0.1460 0.1768 0.1341 0.0358 

0.0529

 1 9 0.0000 0.0002 0.0044 0.0256 0.0476 0.0554 0.0941 0.1110 0.1631 0.1493 0.1555 0.1277 0.0264 

0.0395

 1 10 0.0000 0.0002 0.0044 0.0256 0.0476 0.0554 0.0941 0.1110 0.1631 0.1493 0.1555 0.1277 0.0264 

0.0395

 1 11 0.0000 0.0083 0.0147 0.0337 0.0587 0.0474 0.0728 0.1249 0.1122 0.1205 0.1318 0.1771 0.0449 

0.0530

 1 12 0.0000 0.0083 0.0147 0.0337 0.0587 0.0474 0.0728 0.1249 0.1122 0.1205 0.1318 0.1771 0.0449 

0.0530
56

 1 13 0.0000 0.0001 0.0044 0.0012 0.0133 0.0118 0.0238 0.0312 0.0561 0.0519 0.1358 0.3491 0.1903 

0.1310

 1 14 0.0000 0.0001 0.0044 0.0012 0.0133 0.0118 0.0238 0.0312 0.0561 0.0519 0.1358 0.3491 0.1903 

0.1310

 1 15 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0023 0.0201 0.0151 0.0416 0.0454 0.0992 0.6347 

0.1414

 1 16 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0023 0.0201 0.0151 0.0416 0.0454 0.0992 0.6347 

0.1414

 1 17 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0023 0.0201 0.0151 0.0416 0.0454 0.0992 0.6347 

0.1414

 1 18 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0023 0.0201 0.0151 0.0416 0.0454 0.0992 0.6347 

0.1414

 1 19 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0023 0.0201 0.0151 0.0416 0.0454 0.0992 0.6347 

0.1414

 1 20 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0023 0.0201 0.0151 0.0416 0.0454 0.0992 0.6347 

0.1414

 1 21 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0023 0.0201 0.0151 0.0416 0.0454 0.0992 0.6347 

0.1414

 1 22 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0023 0.0201 0.0151 0.0416 0.0454 0.0992 0.6347 

0.1414

 1 23 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0023 0.0201 0.0151 0.0416 0.0454 0.0992 0.6347 

0.1414

 1 24 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0023 0.0201 0.0151 0.0416 0.0454 0.0992 0.6347 

0.1414

 2 1 0.0000 0.0008 0.0034 0.0102 0.0177 0.0367 0.1027 0.1775 0.1839 0.2465 0.0867 0.1338 0.0000 

0.0000

 2 2 0.0017 0.0254 0.0689 0.0968 0.1127 0.1207 0.1452 0.1356 0.1088 0.0924 0.0445 0.0474 0.0000 

0.0000

 2 3 0.0017 0.0254 0.0689 0.0968 0.1127 0.1207 0.1452 0.1356 0.1088 0.0924 0.0445 0.0474 0.0000 

0.0000

 2 4 0.0050 0.0531 0.1042 0.1302 0.1335 0.1256 0.1265 0.1096 0.0819 0.0645 0.0314 0.0345 0.0000 

0.0000

 2 5 0.0003 0.0070 0.0329 0.0740 0.1233 0.1356 0.1577 0.1579 0.1184 0.0963 0.0417 0.0547 0.0000 

0.0000

 2 6 0.0003 0.0070 0.0329 0.0740 0.1233 0.1356 0.1577 0.1579 0.1184 0.0963 0.0417 0.0547 0.0000 

0.0000

 2 7 0.0003 0.0070 0.0329 0.0740 0.1233 0.1356 0.1577 0.1579 0.1184 0.0963 0.0417 0.0547 0.0000 

0.0000

 2 8 0.0003 0.0070 0.0329 0.0740 0.1233 0.1356 0.1577 0.1579 0.1184 0.0963 0.0417 0.0547 0.0000 

0.0000

 2 9 0.0008 0.0120 0.0470 0.0938 0.1316 0.1388 0.1523 0.1449 0.1091 0.0837 0.0382 0.0476 0.0000 

0.0000

 2 10 0.0008 0.0120 0.0470 0.0938 0.1316 0.1388 0.1523 0.1449 0.1091 0.0837 0.0382 0.0476 0.0000 

0.0000

 2 11 0.0032 0.0375 0.0866 0.1239 0.1277 0.1268 0.1365 0.1206 0.0909 0.0680 0.0356 0.0428 0.0000 

0.0000

 2 12 0.0032 0.0375 0.0866 0.1239 0.1277 0.1268 0.1365 0.1206 0.0909 0.0680 0.0356 0.0428 0.0000 

0.0000

 2 13 0.0000 0.0015 0.0097 0.0286 0.0596 0.0997 0.1556 0.1827 0.1639 0.1548 0.0635 0.0805 0.0000 

0.0000

 2 14 0.0000 0.0015 0.0097 0.0286 0.0596 0.0997 0.1556 0.1827 0.1639 0.1548 0.0635 0.0805 0.0000 

0.0000

 2 15 0.0000 0.0000 0.0000 0.0000 0.0000 0.0003 0.0615 0.1295 0.1536 0.3574 0.0745 0.2231 0.0000 

0.0000

 2 16 0.0000 0.0000 0.0000 0.0000 0.0000 0.0003 0.0615 0.1295 0.1536 0.3574 0.0745 0.2231 0.0000 

0.0000

 2 17 0.0000 0.0000 0.0000 0.0000 0.0000 0.0003 0.0615 0.1295 0.1536 0.3574 0.0745 0.2231 0.0000 

0.0000

 2 18 0.0000 0.0000 0.0000 0.0000 0.0000 0.0003 0.0615 0.1295 0.1536 0.3574 0.0745 0.2231 0.0000 

0.0000

 2 19 0.0000 0.0000 0.0000 0.0000 0.0000 0.0003 0.0615 0.1295 0.1536 0.3574 0.0745 0.2231 0.0000 

0.0000

 2 20 0.0000 0.0000 0.0000 0.0000 0.0000 0.0003 0.0615 0.1295 0.1536 0.3574 0.0745 0.2231 0.0000 

0.0000

 2 21 0.0000 0.0000 0.0000 0.0000 0.0000 0.0003 0.0615 0.1295 0.1536 0.3574 0.0745 0.2231 0.0000 

0.0000

 2 22 0.0000 0.0000 0.0000 0.0000 0.0000 0.0003 0.0615 0.1295 0.1536 0.3574 0.0745 0.2231 0.0000 

0.0000

 2 23 0.0000 0.0000 0.0000 0.0000 0.0000 0.0003 0.0615 0.1295 0.1536 0.3574 0.0745 0.2231 0.0000 

0.0000

 2 24 0.0000 0.0000 0.0000 0.0000 0.0000 0.0003 0.0615 0.1295 0.1536 0.3574 0.0745 0.2231 0.0000 

0.0000

*

* Comments are not allowed before the end of the data!

*

* Fraction of vehicle miles traveled within an hour within an average speed bins by hour of the day.

* The first hour is 6 a.m.

*

* Speed Bins:

* Hr 2.5 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 65.0+
57

*

* These values developed from run iepa07 300_20070830 by CMAP, and were calculated in December 2007. 

Speed bins extend 2.5 mph on either side of the bin name (i.e., the 30-mph speed bin 

encompasses speeds from 27.5 to 32.5 mph), except for the first (2.5 mph) bin (0 to 2.5

mph) and the last (65+ mph) bin (62.5 mph and above). 

The information in this file strictly speaking represents a speed distribution for 2007, but 

is assumed (after discussion with CMAP) to be reasonably valid throughout the 2000-

2010+ period.

The above data are for the Chicago NAA and for Freeways and Arterials only. See M6 

User's Guide Sec. 2.8.8.2.c and Appendix B, Table 5: "Average Speed Ranges for Speed 

Bins (SPEED VMT Command)" for further information about this file and its use. See 

also the default VMT-by-speed file SVMT.DEF for more information and comments.

The first number in each line is roadway type: 1 = Freeways; 2 = Arterials. Locals and 

Ramps have a fixed speed in built into the M6 model, and therefore are not affected by 

this file. The second number is the hour of the day, hour 1 being [hour beginning at] 6 

AM, and hour 24 being [hour beginning at] 5 AM the next day. The third and subsequent 

numbers are the fractions of VMT in that hour that occur within the specified speed bins. 

Note that, for Freeways, most VMT is in the 45-50-55-60-mph speed bins, with lower 

speeds more common during Peak hours. Much the same holds for Arterials, where most 

VMT is in the 30-35-40-45 mph speed bins.