Technical Support Document

Attainment Demonstration State Implementation Plan (SIP) and Related Regulations for the HoustonGalveston-Brazoria 1997 8-hour Ozone Nonattainment Area (HGB Area)

Docket ID EPA-R06-OAR-2013-0387

Table of Contents

I. Summary of Proposal

II. Background

A. The 1997 ozone NAAQS and the HGB Ozone Nonattainment Area

B. CAA and Regulatory Requirements for Ozone Nonattainment SIP

C. State SIP submittals

III. Evaluation of Components for the Attainment Demonstration

A. Attainment Demonstration Modeling and Weight of Evidence

B. Control Measures Relied Upon in the Attainment Demonstration

1. Mass Emissions Cap and Trade (MECT) program 

2. Highly Reactive Volatile Organic Compound (HRVOC) emissions cap and trade 

(HECT) program 

3. Voluntary Mobile Emissions Program (VMEP) Measures and Transportation Control 

Measures (TCMs)

4. Previously Approved State Measures and Federal Measures

5. Summary of Regarding Control Measures Relied Upon in the Attainment 

Demonstration

C. Reasonable Available Control Measures

D. Contingency Measures

E. Motor Vehicle Emission Budget (MVEB)

F. General Air Quality Definitions

IV. 110(l) Evaluation

V. EPA Guidance Documents

VI. Appendices

I. Summary 

This Technical Support Document (TSD) supports rulemaking to propose approval of the HGB area 

attainment demonstration SIP for the 1997 ozone National Ambient Air Quality Standards (NAAQS). 

Specifically, it supports proposed approval of the following Texas SIP submittals for the HGB area:

• Attainment demonstration for the 1997 ozone NAAQS

• Revisions to the MECT air pollution control program

• Revisions to the HECT air pollution control program

• VMEP measures and TCMs

• A 2018 year MVEB 

• Demonstration of Reasonable Available Control Measure (RACM) implementation

• Failure to attain contingency measures plan in the event of failure to attain the NAAQS by the 

applicable attainment date

Proposed approval is based on requirements of the Clean Air Act (CAA) for ozone nonattainment areas.
II. Background

A. The 1997 ozone NAAQS and the HGB Ozone Nonattainment Area

Ground level ozone is formed when NOx and volatile organic compounds (VOC) react in the presence 

of sunlight. These two pollutants, referred to as ozone precursors, are emitted by many types of pollution 

sources, including on-road and non-road motor vehicles and engines, power plants and industrial 

facilities, and smaller area sources such as lawn and garden equipment and paints. See 77 FR 30088 

30089 (May 21, 2012). Breathing ozone can trigger a variety of health problems including chest pain, 

coughing, throat irritation, and congestion. It can worsen bronchitis, emphysema, and asthma. Ground 

level ozone also can reduce lung function and inflame the linings of the lungs. Repeated exposure may 

permanently scar lung tissue. See 77 FR 30088 30089, May 21, 2012. For more information on ground 

level ozone please see htpp://epa.gov/airquality/ozonepollution. 

In 1979, under section 109 of the CAA, EPA established primary and secondary national ambient air 

quality standards (NAAQS or standard) for ozone at 0.12 parts per million (ppm) averaged over a 1-hour 

period. See 44 FR 8202 (February 8, 1979). Primary standards are set to protect human health while 

secondary standards are set to protect public welfare. On July 18, 1997, EPA revised the primary and 

secondary NAAQS for ozone to set the acceptable level of ozone in the ambient air at 0.08 ppm, 

averaged over an 8-hour period. See 62 FR 38856 (July 18, 1997). EPA set the 8-hour ozone standard 

based on scientific evidence demonstrating that ozone causes adverse health effects at lower 

concentrations and over longer periods of time than was understood when the pre-existing 1-hour ozone 

standard was set. EPA determined that the 8-hour standard would be more protective of human health, 

especially children and adults who are active outdoors, and individuals with a pre- existing respiratory 

disease, such as asthma.1

In 2004, we classified the HGB area (Brazoria, Chambers, Fort Bend, Galveston, Harris, Liberty, 

Montgomery and Waller counties) as a moderate ozone nonattainment area for the 1997 ozone NAAQS 

(69 FR 23858, April 30, 2004). In 2007, at the request of the State, and under CAA section 181(b)(3), 

we reclassified the HGB area to severe calling for attainment as expeditiously as practicable but no later 

than June 15, 2019 (73 FR 56983, October 1, 2008). Since 2018 is the first full year before the 

attainment deadline, we will judge attainment based on data through the end of 2018 and therefore, we 

refer to 2018 as the attainment year.

B. CAA and Regulatory Requirements for Ozone Nonattainment SIP

States must implement the 1997 8-hour ozone standard under Title 1, Part D of the CAA, which includes 

section 172, “Nonattainment plan provisions,” and subpart 2, “Additional Provisions for Ozone 

Nonattainment Areas” (sections 181–185). We promulgated a regulation to implement the 1997 ozone 

NAAQS at 40 CFR 51, subpart X (Provisions for Implementation of 8-hour Ozone National Ambient 

Air Quality Standard). The regulation addresses the requirements for modeling and attainment

demonstrations, reasonably available control technology and measures (RACT and RACM), reasonable 

further progress (RFP), contingency measures, and new source review. 

 

1

In 2008 we lowered the 8-hour ozone NAAQS to 0.075 ppm (73 FR 16436, March 27, 2008) and in 2012 we classified the 

Houston area as a marginal nonattainment area for the 2008 ozone NAAQS (77 FR 30088 30089, May 21, 2012). This 

rulemaking does not address the 2008 ozone NAAQS.
When we reclassified the HGB area, we also identified the SIP requirements for the area. The 

requirements being addressed in this notice are: (1) an attainment demonstration (40 CFR 51.908), (2) 

provisions for RACM (40 CFR 51.912), and (3) contingency measures to be implemented in the event of 

failure to attain the standard by the applicable attainment date (CAA 172(c)(9) and 182(c)(9)). In order 

to approve the attainment demonstration for the area we must also approve: (1) the measures relied on as 

necessary to demonstrate attainment, and (2) an attainment MVEB for transportation conformity 

purposes, and (3) the RFP plan and the RFP contingency measures. See Sierra Club v. EPA, 294 F.3d 

155, 163, (D.C. Cir. 2002). Some measures, relied upon as necessary for attainment, have been 

previously approved (section II.B.5). We are proposing to approve additional measures relied on as 

necessary to demonstrate attainment, and an attainment MVEB for 2018. In a separate proposal we are 

addressing the RFP and RFP contingency measures requirements (please see docket EPA-R06-OAR2010-0333 in www.regulations.gov). Current information on the status of HGB area SIP requirements 

for the 1997 ozone NAAQS can be found at: http://epa.gov/air/urbanair/sipstatus.

CAA section 172(c)(6) requires the attainment demonstration to include enforceable emission 

limitations, and such other control measures, means or techniques as well as schedules and timetables 

for compliance, as may be necessary to provide for attainment by the applicable attainment date. In 

order to be considered in the modeling, the measures must be permanent, enforceable and quantifiable. 

Please see 57 FR 13498, 13567, April 16, 1992. 

CAA sections 110(a)(1) and (2) and 110(l) require a state to provide reasonable public notice and 

opportunity for public hearing prior to the adoption and submission of a SIP or SIP revision. To meet 

this requirement, every SIP submittal should include evidence that adequate public notice was given and 

an opportunity for a public hearing was provided consistent with EPA’s implementing regulations in 40 

CFR 51.102.

Below is a table of the HGB SIP requirements for the 1997 ozone NAAQS. Some requirements have 

been previously implemented as Houston was classified as a severe ozone nonattainment area for the 

1979 1-hour ozone NAAQS.
Table 1. HGB SIP requirements for the 1997 ozone NAAQS

SIP Requirement (CAA section) Comments

Emissions Inventory (182(a)(1)) Approved April 22, 2009 (74 FR 18298)

Emissions Statement (182(a)(3)(B)) Approved August 26, 1994 (59 FR 44036)

Provisions for reasonably available control

technology (RACT) (182(b)(2))

Partially addressed with April 2, 2013 approval (78 

FR 19599). Remainder to be addressed in other 

rulemaking.

Enhanced Ambient monitoring (182(c)(1)) Approved October 4, 1994 (59 FR 50502)

Enhanced vehicle inspection and maintenance 

program (182(c)(3))

Approved August 22, 1994 (59 FR 43046)

Clean fuel vehicle program or an approved 

substitute (182(c)(4))

Substitute program approved 2001 (66 FR 9203). 

Repeal of a portion of the substitute program (Texas 

clean fuel vehicle program regulations) submitted 

May 15, 2006, to be addressed in future rulemaking. 

A Texas clean fuel vehicle program equivalency 

demonstration was approved for the Beaumont/Port 

Arthur SIP on October 20, 2010 (75 FR 64675).

Gasoline vapor recovery for motor vehicle 

refueling emissions (182(b)(3)) 

Approved April 15, 1994 (59 FR 17940)

Attainment demonstration (182(c)(2)) and 

failure to attain contingency measures 

(172(c)(9) and 182(c)(9))

Being proposed

Provisions for reasonably available control 

measures (RACM) (172(c)(1))

Being proposed

Reasonable Further Progress (RFP) to reduce 

emissions (182(c)(2)) and RFP milestone 

failure contingency measures (CAA 172(c)(9) 

and 182(c)(9))

Proposal (see docket EPA-R06-OAR-2010-0333 in 

www.regulations.gov)

Transportation controls to offset emissions 

from growth in vehicle miles traveled (CAA 

182(d)(1)(A))

Proposal (see docket EPA-R06-OAR-2010-0333 in 

www.regulations.gov)

Severe Area New Source Review emission 

offsets (182(d)(2))

Approved September 27, 1995 (60 FR 49781)

Severe/Extreme Area Failure to Attain Fee 

Program (Section 185)

At this time the required SIP element does not have a 

deadline for submittal. See 

http://epa.gov/air/urbanair/sipstatus/blankdates.html.

C. State SIP submittals

On April 6, 2010, Texas submitted for the HGB area: (1) an attainment demonstration, (2) revisions to 

the MECT program to protect the integrity of the oxides of nitrogen (NOx) cap in the HGB area, (3) 

revisions to the HECT program to reduce the HRVOC cap by 25% in Harris County and provide for a 

more equitable distribution of the HECT allowances, and (4) revisions to the General Air Quality 

definitions applicable to the entire Texas SIP. 
On May 6, 2013, Texas submitted an update to the attainment demonstration. The update included: (1) 

revised on-road mobile source emissions inventories and MVEBs using the more recent EPA MOVES 

mobile source emissions estimation model, (2) an update of the contingency measures analysis, and (3) 

updated discussions of emissions inventory, photochemical modeling, control strategies and required 

elements, and weight of evidence that the area will attain by its attainment date.

In addition to the revisions submitted on April 6, 2010, Texas previously submitted SIP revisions to the 

General Air Quality Definitions (30 TAC 101.1) on August 16, 2007. Texas later submitted additional 

revisions to 30 TAC 101.1 on March 11, 2011. 

Each of the above identified submittals was given proper hearing and public notice by Texas as required 

by 40 CFR 51.102. Evidence of this was provided in the SIP submittal and is summarized below:

• June 10, 2005 submittal: notices in Austin American-Statesman (February 11, 2005), Fort Worth 

Star-Telegram (February 14, 2005) and Houston Chronicle (February 12, 2005); hearing on 

March 17, 2005 (Austin)

• August 16, 2007 submittal: notices in Austin American-Statesman, Fort Worth Star-Telegram, 

and Houston Chronicle February (February 12, 2007); hearing on March 20,2007 (Austin)

• April 6, 2010 submittal: notices in Austin American-Statesman and Houston Chronicle 

(September 28, 2009); hearings on October 28, 2009 (Houston) and October 29, 2009 (Austin)

• March 11, 2011 submittal: notices in Austin American-Statesman, Fort Worth Star-Telegram, 

and Houston Chronicle (August 13, 2010); hearing on September 20, 2010 (Austin)

• May 6, 2013 submittal: notices in Austin American-Statesman and Houston Chronicle (October 

19, 2012); hearing on November 19, 2012 (Houston)

III. Evaluation of Components for the Attainment Demonstration

A. Attainment Demonstration Modeling and Weight of Evidence

Review of all the photochemical modeling and Weight of Evidence provide by TCEQ in support of this 

attainment demonstration is voluminous and covered in a separate document that is attached (Appendix 

A – Technical Support Document For Houston Galveston Brazoria Modeling and Other Analyses 

Attainment Demonstration (HGB-MOAAD), further referred to as “HGB-MOAAD”). EPA’s detailed 

review and conclusions of TCEQ’s modeling and WOE are included in the HGB-MOAAD document.

In summary, TCEQ’s modeling projects significant improvement in air quality and all but three of the 

monitors are projected to attain the standard and the three monitors not demonstrating attainment to the

standard are projected to be only slightly above the standard. 

TCEQ provided numerous pieces of evidence as part of the WOE in support of the attainment 

demonstration. Of these evidence items, the strongest parts of the WOE analysis are the most recent 8-

hour ozone monitoring trends and the continued reductions expected from vehicle fleet turnover. Ozone 

Design Value trends at most of the monitors in the HGB area show significant decreases over time and 

many of the monitors are currently attaining the 1997 8-hour ozone standard. Furthermore, the ozone 

precursor trends are mostly showing a decrease that supports the HGB area’s impact on ozone levels that 

exceed the standard are continuing to decrease. Houston’s most recent design value is 88 ppb through 

2012. With 6 more years of cleaner cars and off/non road equipment coming into the fleet, EPA believes 

that the additional 4 ppb of reduction necessary from 2012 monitored levels to reach attainment supports 

the proposed finding that HGB will attain by its attainment year
This modeling evidence taken together with the WOE, especially ambient data trends, demonstrates that 

HGB will reach attainment of the 1997 8-hour ozone NAAQS by the end of the ozone season of 2018. 

Our full evaluation of each modeling and WOE elements of the attainment demonstration submitted by 

TCEQ in this SIP revision is included in HGB-MOAAD (Appendix A of this document). 

Our review confirms that TCEQ’s modeling and WOE conform to 40 CFR §51.908, §51.112, Appendix 

W of Part 51, EPA’s guidance and methodologies. 

B. Control Measures Relied Upon in the Attainment Demonstration

1. Mass Emissions Cap and Trade (MECT) program 

The MECT is a portion of the SIP-approved control strategy for the HGB area stationary sources that 

caps NOx emissions beginning January 1, 2002, with a final reduction to the cap occurring in 2007. The 

cap represents a reduction in NOx emissions of 80% from the applicable stationary sources. Facilities 

are required to demonstrate compliance with the MECT on an annual basis by having sufficient 

allowances, or other credits as provided in the SIP, to equal the annual NOX emissions from the 

previous year. EPA published a final rule approving the MECT program on November 14, 2001 (66 FR 

57252). We have subsequently approved revisions to the MECT on September 6, 2006 and July 16, 

2009. See 71 FR 52698 and 74 FR 34503.

The April 6, 2010 submittal included revisions to the MECT program to protect the integrity of the NOX

cap in the HGB area. Appendix B discusses our review of the MECT program revisions.

2. Highly Reactive Volatile Organic Compound (HRVOC) emissions cap and trade (HECT) program

The HECT program is a mandatory cap and trade program of HRVOCs for covered facilities including 

vent gas streams, flares, and cooling tower heat exchange systems that emit HRVOCs, as defined in 30 

TAC Section 115.10, and that are located at a site subject to Chapter 115, Subchapter H. Facilities are 

required to meet HRVOC allowances on an annual basis. Facilities may purchase, bank or sell their 

allowances for use in the following control period. EPA published final approval of the HECT program 

on September 6, 2006, as an integral component of the HGB attainment demonstration. See 71 FR 

52659.

The April 6, 2010 submittal included revisions to the HECT program to reduce the HRVOC cap in 

Harris County by 25%, a step taken as a result of photochemical modeling in support of the HGB 8-hour 

ozone attainment demonstration. The revisions also change the allocation methodology to promote 

equitable distribution of allowances as a result of comment and add necessary definitions to implement 

the allocation methodology changes. The TCEQ also adopted non-substantive revisions throughout to 

correct typographical errors and Texas Register formatting requirements. Appendix B discusses our 

review of the HECT program revisions.
3. Voluntary Mobile Emissions Program (VMEP) Measures and Transportation Control Measures 

(TCMs)

VMEP Measures

What is EPA’s Voluntary Mobile Emission reduction Program (VMEP)?

A VMEP is an overall control strategy that attempts to complement existing regulatory programs 

through voluntary, non-regulatory changes in local transportation activities or changes in in-use vehicle 

and engine composition. EPA supports innovative methods in achieving air quality goals and the 

creation of viable voluntary mobile source air quality programs. The increasing cost of technological 

improvements to produce incrementally smaller reductions in grams per mile or grams per kilowatt-hour 

emission in the entire fleet of vehicles and engines suggests that supplemental or alternative approaches 

for reducing mobile source air pollution are necessary. 

The Clean Air Act (Act) allows State Implementation Plan (SIP) credit for new approaches to reducing 

mobile source emissions. This approach is primarily founded in section 110 of the Act, and the 

economic incentive provisions in sections 182(g)(4)(A) and 108 of the Act. In interpreting 110(a)(2) of 

the Act, EPA issued a guidance document entitled, “Guidance on Incorporating Voluntary Mobile 

Source Emission Reduction Programs in State Implementation Plans (SIPs)”, Memorandum from 

Richard D. Wilson, Acting Assistant Administrator for Air and Radiation, dated October 24, 1997, 

which allows for SIP credit for voluntary measures.2The Fifth Circuit Court of Appeals upheld, as a 

reasonable interpretation of the Act, EPA’s VMEP policy and allowed States to consider estimated 

emissions reductions from a VMEP in the attainment demonstration. See BCCA Appeal Group v. EPA, 

355 F.3d 817, 825 (5th Cir. 2003).

The EPA's VMEP Guidance provides a detailed framework for states to obtain SIP emissions reduction 

credit for such voluntary emissions reductions. EPA guidance allows a state to take credit for a 

maximum of 3% of the total future year emissions reductions required to attain the appropriate NAAQS. 

In addition, states must identify and describe the voluntary measures in a VMEP and include supportable 

projections of emissions reductions associated with the measures. The state must also make an 

enforceable commitment to monitor, assess, and report on the implementation and emissions effects of 

the VMEPs, as well as to remedy timely any shortfall in emissions reductions that do not meet the 

projected levels. More specifically, the guidance outlines the following criteria for approval of voluntary 

emissions reduction credits. The credits should be:

1. Quantifiable - VMEP emission reductions must be quantifiable. The level of uncertainty in achieving 

emission reductions must be quantified, and this uncertainty must be reflected in the projected emission 

reductions claimed by the VMEP. VMEPs must also contain procedures designed to both evaluate 

program implementation and to report program results as described in the “Technical Support for 

VMEPs” portion of the guidance.

2. Surplus - VMEP emission reductions may not be substituted for mandatory, required emission 

reductions. States may submit to EPA for approval any program that will result in emission reductions in 

 

2 While this guidance was later incorporated into another EPA guidance, “Implementing Bundled Measures into a State 

Implementation Plan (SIP),” the VMEP demonstration is based on the former and the mobile source portion of the latter.
addition to those already credited in a relevant attainment or maintenance plan, or used for purposes of 

SIP demonstrations such as conformity, rate of progress, or emission credit trading programs.

3. Enforceable - VMEPs must be enforceable at the State and Federal levels. A State can adopt a 

measure into the SIP such that the State is obligated only to track, assess and report on the 

implementation of voluntary actions and the emission reductions achieved from the voluntary actions. 

The State is not responsible, necessarily, for implementing a program depending on voluntary actions. 

The State must commit to conducting program evaluations and reporting the results to EPA within an 

appropriate time-frame.

4. Permanent - VMEP emission reductions must continue at least for as long as the time period in 

which they are used by the applicable SIP demonstration.

5. Adequately Supported - VMEPs must demonstrate adequate personnel and program resources to 

implement the program.

6. Consistent - VMEPs must be consistent with attainment of the standard and with and Rate of 

Progress requirements. Further, VMEPs cannot interfere with the other requirements of the Clean Air 

Act. 

What is the Background for the HGB VMEP Program?

The State first established the VMEP program in the December 2000 1-hour ozone attainment 

demonstration for the HGB nonattainment area approved by EPA on November 14, 2001, 66 FR 57160. 

In that initial action we approved VMEP emission reductions of 23 tons per day (tpd) of NOx (up to 3% 

of the total needed for attainment) because the state was able to demonstrate that the HGB area’s ozone 

SIP VMEP met the criteria for credit in the SIP. The State showed that the credits were quantifiable, 

surplus, enforceable, permanent, adequately supported, and consistent with the SIP and the Act. The 

State, through the Houston-Galveston Area Council (H-GAC) implemented the VMEP program in the 

HGB area, and committed to evaluate each program to validate estimated credits, and report the 

emission reductions to the TCEQ. The State continues to be responsible for verifying the reported 

emissions and timely remedy any shortfall. The Fifth Circuit found that while the state did not make a 

separate specific commitment to remedy any shortfall in the VMEPs, it believed that the existing 

enforceable commitment regarding adoption of additional NOx controls also applied to any shortfall in 

reductions from VMEPs. See Footnote 40 of BCCA Appeal Group v. EPA, 355 F.3d 817, 825 (5th Cir. 

2003). As part of reinforcing its commitment to VMEPs the state revised its SIP. EPA approved the 

state’s clarification of its enforceable commitment for VMEP. See Approval and Promulgation of 

Implementation Plans, 67 Fed. Reg. 68,941 (EPA Nov. 14, 2002) (final rule). 

The VMEP program has been revised with substitute measures or additional measures as SIP revisions. 

In the mid-course SIP review submitted December 1, 2004, we approved revisions to the VMEP 

program, which revised credit taken for this program to 7 tpd. In that revision, certain mobile emission 

credits were recalculated using MOBILE6. In the earlier SIP submittal these credits were calculated 

using MOBILE5a. EPA approved those VMEP measures. 71 FR 52670 (September 6, 2006). In a June 

13, 2007 SIP submittal, adopted May 23, 2007, the State revised it VMEP measures as part of the 

Houston-Galveston-Brazoria State Implementation Plan. This submittal built upon the VMEP program 

established in previous SIP revisions as noted above. The additional commitments reduced NOx by an 

estimated 2.82 tons per day. EPA approved those VMEP measures. 78 FR 19599 (April 2, 2013).

What did the State submit?

The state submitted several general program descriptions (Table 2) that projected reductions attributable 

to each specific program as part of the Houston-Galveston-Brazoria attainment demonstration State 

Implementation Plan submitted on March 10, 2010. This submittal builds upon the VMEP program 
established in previous SIP revisions as noted above. The H-GAC, as the regional metropolitan 

transportation planning agency for the HGA area, will implement these programs in the HGA area, 

commits to evaluating each program to validate estimated credits, and will report the emissions to 

TCEQ. All VMEP measures will be in place to be relied on for purposes of attainment by 2018. 

Table 2. Voluntary Mobile Emission Reduction Programs and Credits Claimed in Tons per Day

Program Type NOx Benefits (tons/day)

Alternative Commuting

- Bicycle and Pedestrian Actions

- Cleaner Diesel Fuel/Alternative Fuels

- Subscription Bus Service

- Public Transit Improvements

- Compressed Work Week

- Internet Ridematching Services

- Vanpooling

0.20

Regional Traffic Flow Improvements

- Local Intersection Signal Improvements

0.05

Vehicle Retrofit and Replacement

 - Public and Private Sector Clean Fuel Fleets

 - Dedicated Funding for School Bus Replacement

 - Electric Vehicles/Increased Use of Hybrid Buses

1.30

Off-road Measures

- Voluntary Non-road Replacement and Retrofit Programs

- Rail Efficiency Measures

0.70

Total Benefits 2.25

EPA’s Analysis

Consistent with EPA policy, the NOX benefits claimed and attributed to the VMEP program amount to 

less than 3% of the total future year emissions reductions required to attain the appropriate NAAQS. 

Overall the VMEP projects are consistent with the SIP. EPA’s detailed analysis below shows the VMEP 

measures are quantifiable. The reductions are surplus by not being substitutes for mandatory, required 

emissions reductions and they are not being counted in any other control strategy. The programs do not 

interfere with nor are they mandated by other Act requirements. As in past commitments, we interpret 

that the VMEP portion of the SIP to be enforceable because the State, through the H-GAC, has 

committed to fill any shortfall in credit, thus any enforcement will be against the State. The H-GAC, as 

the regional metropolitan transportation planning agency for the HGA area, has committed to implement 

the projects and/or programs outlined in the HGA VMEP submittal. The H-GAC will be responsible for 

monitoring and reporting the emissions reductions to the TCEQ. The State, through the H-GAC has 

committed to cover any VMEP shortfall (of the 2.25 tpd of NOx committed).The State, through the HGAC, will remedy any VMEP shortfall that might occur in the VMEP program. 

The emissions benefits for the measures are calculated for 2018 and are permanent as the H-GAC is 

responsible to monitor, assess, report on future emissions reductions from the measures and remedy any 

shortfall. All VMEP measure must be fully in place in order to be relied on for purposes of attainment 

by 2018. 
As detailed in the measures below, each measure will be adequately supported by personnel and 

program resources for implementation. 

Consistent with the State’s commitment in the December 2000 SIP and forward, that assures that any 

shortfall in VMEP credits would be made up with other measures not already in the SIP, the measures 

are enforceable. This SIP submittal reiterates the commitment “to remedy in a timely manner any SIP 

credit shortfall if the VMEP program does not achieve projected emission reductions.” 3The VMEP 

measures will be in place for the life of the SIP, until 2018, which makes them permanent. 

Our analysis below further shows that each program is also quantifiable and adequately supported. 

Therefore all criteria for the VMEP have been met. Descriptions of these measures are found in 

Appendix H of the April 10, 2010 submittal, Voluntary Mobile Emission Reduction Program for the 

HGB Attainment Demonstration SIP Revision for the 1997 Eight-Hour Ozone Standard. 

1. Alternative Commuting 

a. Bicycle and Pedestrian Actions

This measure encourages construction of new bicycle lanes, new bikeway plans, and greater use 

of existing lanes instead of vehicle use. H-GAC analysis shows that there is greater bicycle use in the 

Texas Medical Center area of Houston and at the University of Texas at Galveston than previously 

thought. It is anticipated that bicycle commuters would increase to 21,978 people per day by 2018 and 

reduce VMT by 153,845 miles of travel per day, if they were previously driving. Emission reductions 

were calculated using MOSERs methodology.4Total emission savings from NOx and VOC combined is 

25.6 tons per year (0.03 tpd of NOx and 0.04 tpd of VOC). Cost effectiveness is $390,625 per ton. Cost 

of the projects is covered by the H-GAC Transportation Improvement Plan (TIP) and local 

governments’ Capital Improvement Programs. This measure is quantifiable and adequately supported. 

b. Cleaner Diesel Fuel/Alternative Fuels

This measure would change TxLED diesel fuel to either cetane additive enhanced (CAE) or 

Fischer-Tropsch (FT) diesel fuel. This would not be a mandatory change but likely a demonstration 

project on specific Class 8b Heavy Duty Truck fleets or in a local area. Because of distribution 

challenges, this measure was evaluated as a targeted measure, consisting of replacing TxLED fuel in 

10% of the heavy-duty truck fleet with either FT or CAE fuel. MOBILE6 was used to estimate 

emissions from three classes of vehicles: HDD class 8a, HDD class 8b, and busses. In evaluating for 

only the HDD class 8b trucks, the emission reductions are expected to range from 1.3% for CAE to 12% 

for FT. This results in 0.02-0.25 tpd emission reductions of NOx for HDD class 8b trucks. If it were 

applied to all classes evaluated, the reductions would be 0.25-2.36 tpd of NOx. The cost of 

implementation would be borne by the fleet which is anticipated to obtain grant funding to offset some 

of the cost. Therefore, this measure is quantifiable and adequately supported.

c. Subscription Bus Service

This program would be designed to remove obstacles to transit use by providing more 

personalized services between underserved residential areas and underserved employment areas. This 

might include on-line transit planning, subscription bus service, and feeder shuttles from major transit 

 

3 Appendix F. Evaluation of mobile source control strategies for the Houston-Galveston-Brazoria

State Implementation Plan (With Detailed Strategies). Prepared for Houston-Galveston Area Council,

Prepared by ENVIRON International Corporation. Page F-1.

4 Mobile Source Emission Reduction Strategies. http://moser.tamu.edu/
stops to work centers. Buses and vans equipped with wireless Internet connections and accommodate 

working in transit with fold-down tables would attract white collar workers who commute from Katy to 

the Texas Medical Center, for example.

Calculation of emission reductions is by MOSERs methodology 5that relied on the following key 

variables:

• 100 buses seating 35 people operating four round trips (per person) per day; at 80% capacity this is 

equivalent to 11,200 people per work day;

• 100 shuttle buses seating 15 people operating 6 round trips (per person) per day; at 80% capacity this 

is equivalent to 7,200 people per work day.

• 100% of shuttle use is due to new transit users who did not previously use transit because it did not 

provide a viable way to their place of employment or their home.

• average work trip distance is 40 miles round trip 

• business buses travel 40 miles for each round trip, or 160 miles each day per bus; new emissions due to 

these buses is therefore based upon an average weekday mileage of 16,000 miles.

• shuttle buses are assumed to travel 10 miles per round trip, or 60 miles per day per shuttle; new 

emissions due to the shuttles is therefore based upon an average weekday shuttle mileage of 6,000 miles.

• Average light duty vehicle composite emission factor for NOx for same day is 0.471grams per mile

• Average light duty vehicle composite emission factor for VOC for same day is 0.489 grams per mile.

• Average shuttle bus emissions are represented by the MOBILE6 category LDDT12 and are 2.68 grams 

per mile of NOx and 2.56 grams per mile of VOC.

• Average transit bus emissions are represented by the MOBILE6 HDDBS category and are 9.83 grams 

per mile NOx and .57 grams per mile VOC.

The cost of the program is estimated at over $45.6 million/year (in 2005-2006 $) not including 

marketing and administration. Riders will pay $2 to $5 per round trip. Selling ad space inside the 

vehicles will also be considered as a way to help pay for the service. Combined NOx and VOC 

reduction benefits are 59.8 tons, with cost effectiveness at $456,500/ton. The analysis shows that this 

measure is quantifiable and could be adequately supported.

d. Public Transit Improvements

There are three measures related to transit options in the list of measures that could generate

measurable emissions reductions: Electrified buses, Light rail expansion, and Hybrid buses. The 

electrified buses or light rail require infrastructure improvements (overhead catenary or rail 

construction), but would result in an elimination of the engine emissions on those routes served. The 

planned and potential expansion of the current light rail network could be up to an order of magnitude 

increase by 2018, and could include commuter rail as well as light rail. Hybrid buses usually recover 

enough energy during braking and allow the engine to operate at peak efficiency to effect a 25% 

reduction in fuel consumption and emissions. It is not clear how the infrastructure for expanded rain and 

electric buses would be financed, but the hybrid buses, which seem more practical, could be partially 

funded by the savings in fuel expenditures. Electrification of rail and buses could provide 0.012-0.12 tpd 

of NOx reductions, while the hybrid buses could potentially provide 0.23 tpd of NOx reductions. These 

numbers were generated using known emission values of trips replaced by cleaner technologies. The 

 

5The MOSERs manual was issued in 2002. It was reviewed by EPA, TxDOT, TTI, TCEQ and FHWA. It was funded by 

TxDOT and largely authored by the transportation engineers at TTI. Its purpose is to standardize how emissions reductions 

credits for similar projects are calculated. FHWA cited it as an example of best practices used by the Texas transportation 

community; it has been used in transportation conformity since 2002.
TCEQ commitment for implementation by HGAC ensures adequate support for any portion of this 

project. Therefore, the measures are quantifiable and adequately supported.

e. Compressed Work Week

Compressed work weeks are already part of the Commute Solutions program utilized by many 

employers in the Houston area. A program specifically aimed at increasing the amount of compressed 

work weeks through a mandatory program is not currently in place but could be implemented as a part 

of the overall ozone attainment plan.

There are a number of variables important for evaluating the emission benefits of this

measure. These are as follows:

• Total employment projected by H-GAC for 2018 is 3,183,000. The above-cited figure of 20% would 

be 636,600 employees.

• The average round trip work distance for Houston area employees is 40 miles; therefore daily VMT 

reduction on a compressed work week day is 25,464,000 and on an average day (1/7th of the miles) 

would be 3,637,714 miles per day.

• Average light duty vehicle composite emission factor for NOx in 2018 is 0.171 grams per mile

• Average light duty vehicle composite emission factor for VOC in 2018 is 0.231 grams per mile

The emissions analysis utilized the basic process suggested by the MOSERs methodology,

Costs to employers are minimal with benefits due to employee retention possibly offsetting costs. The 

emission reductions are estimated at 0.93 tpd of VOC and 0.69 tpd of NOx. These measures are 

quantifiable and adequately supported.

f. Internet Ridematching Services

This program is described as an H-GAC ridesharing program that uses computer-based methods to 

match riders for carpooling. The consultant is NuRide. It was started in August 2005, and had a big 

expansion in 2007 and 2008. This program offers incentives to participate by offering gift cards and 

points redeemable at popular retailers to participants based on the number of times they sign up for a 

carpool. If the program increased in ridership at the same rate between 2005-2008, there would be 

376,757 regular riders in 2018. It is assumed carpools average 2.7 people per vehicle and those 

carpoolers rideshare an average of twice per week at an average trip distance of 15 miles. This program 

is available seven days a week, and so can provide additional reductions that other commuter programs 

would not ordinarily do. The VMT reductions are calculated with MOSERs methodology using the 

number of ridesharers, miles of carpooling, miles driven by the carpool driver, and frequency of 

ridesharing. It is expected that well before 2018 the costs of the program will be limited to reporting 

costs. Conservatively they estimate the combined reporting and administrative costs to H-GAC to be 

$100,000 in 2018. The benefits are 0.52 tpd of VOC and 0.38 tpd of NOx emissions reduced. The 

analysis shows that this measure is quantifiable and could be adequately supported.

g. Vanpooling

The ongoing vanpooling program is anchored by METRO (the local transit agency), and consists 

of standard vanpools and a newer effort called “miniPOOL”. This popular program is heavily 

subsidized, and whatever funding is provided for the program is assumed to go forward in the future. 

This measure calculates the benefit based on the current vanpool program as it would be in 2018. Total 

single driver emissions based on individual VMT are subtracted from vanpool emissions to show 
emission reductions. The program is projected to reduce NOx by 0.07 tpd and VOC by 0.1 tpd. The 

analysis shows that this measure is quantifiable and could be adequately supported.

2. Regional Traffic Flow Improvements

a. Local Intersection Signal Improvements

Local intersection signal improvements are part of the on-going H-GAC Plan and Transportation 

Improvement Plan (TIP) that are funded accordingly. This project shows the emission reduction benefit 

from improving signal synchronization or addition, and constructing other improvements to 

intersections, e.g., turn lanes. The primary measure of the benefit of the project is improvements in the 

average speeds. The default estimate is to use the assumption that the average speed will improve from 

30-MPH to 35-MPH on Freeways and 20-MPH to 25-MPH on Arterials. Moving traffic reduces idling 

time. The idling emissions were determined using the idling emission factor in kilo-grams/hour (The 

idling emission factor is determined using the grams/mile for 2.50-MPH idling speed multiplied by 2.50-

MPH.) and the delay reduction in vehicle-hours. The difference in emission factors (grams/mile) 

multiplied by vehicles-miles of travel (VMT) will give emission benefits in kilograms/day. For this 

summary, it was assumed that twice the money and benefit would be available during the period of 2015 

– 2017. Emission reduction benefits are 2.0 tpd for VOC and 1.8tpd of NOx. The analysis shows that

this measure is quantifiable and could be adequately supported.

3. Vehicle Retrofit and Replacement

a. Public and Private Sector Clean Fuel Fleets

This measure seeks to reduce on-road vehicle emissions by rapid turnover to newer lower

emitting engines, retrofit of existing engines with approved devices, or new lower emission 

technologies. These programs have been mandated or voluntarily implemented with federal incentives 

or state funding from programs like TERP. Congestion Mitigation and Air Quality (CMAQ) funds are 

distributed to replace and retrofit lower emitting heavy-duty vehicles. This measure would address 

heavy-duty diesel, heavy-duty gasoline vehicles, and buses. Replacing two thousand older vehicles 

expected to be in use in 2018 with those meeting 2010 or later emissions standards would result in about 

1 to 2.5 tpd emission reductions of NOx. These calculations were made using input files used in HGB 

MOBILE modeling. Program funding would come from TERP, and CMAQ through the Clean Cities 

program. This measure is quantifiable and adequately supported.

b. Dedicated Funding for School Bus Replacement

This measure accelerates the replacement of older buses in school district fleets through a fund 

dedicated to helping meet the costs of purchasing new buses to replace the older buses. Buses that are 

replaced should be scrapped. Funding would come from a TERP block grant. Assuming that normal 

turnover from 2010 onwards would remove almost all of the remainder of these buses by 2018 (each 

ISD replacing an average of 10.5 buses per year), a dedicated school bus fund could aim to accelerate 

the replacement of 25% of the fleet. Because of the TERP requirement to meet the $15,000/ton of NOx 

reduced threshold, schools could receive only about 1/3 the cost of a new bus. Calculation of emissions 

reduced relies on engine emission standards and known conversion factors for TxLED and engine 

conversions. The NOx emission reductions/day from replacing 665 buses (using a 250 day year) is 0.774 

tpd. This measure is quantifiable and adequately supported.

c. Electric Vehicles/Increased Use of Hybrid Buses

The electric vehicle control measure consists of the voluntary inclusion of a greater percentage of 

zero emission vehicles (ZEVs) or zero emitting travel through the use of plug-in hybrids or other 

vehicles. This could occur through new purchases or a replacement program for existing vehicles. 
Hybrid buses have an advantage over all-electric (catenary) buses because no new infrastructure is 

required to implement their use. Emission reductions from hybrid buses are 25% lower because the 

engines they use are low emission bus engines. Therefore fewer emission reductions are gained from 

switching to hybrid buses. 

This measure could affect about 40 tpd of VOC and 30 tpd of NOx 2018 on-road light-duty emissions in 

the eight-county HGB ozone nonattainment area. This is based on emission standards for the various 

model year vehicles and the estimated VMT for each during the time period being evaluated. The most 

likely vehicle types to be replaced by zero emitting activity are the smaller passenger cars. Therefore the 

emission reduction benefit is estimated to be 0.04 tpd of VOC and 0.02 tpd of NOx. There is an 

extensive discussion of the cost to implement, which is quite high. The program could target specific 

niches to partially achieve emission reductions. Options include targeting public or private sector fleets 

as demonstration programs for the implementation of ZEV technology and providing the infrastructure. 

Though the submittal indicates that H-GAC would be the implementer of the VMEP measures, there is 

no indication where the funding for vehicle replacements and charging infrastructure would come from. 

This measure is quantifiable, but it is questionable whether it would be adequately supported. Should it 

not be funded, the anticipated reductions would be mitigated by either substituting another measure in a 

SIP revision or perhaps from excess reductions from another measure. Both options are permissible.

4. Off-road Measures

This category makes use of the state’s TERP program to fund most of these eligible non-road 

projects. Although they suggest that additional funds could come from EPA’s DERA funds through the 

Blue Skyways Collaborative, the suggestion that this funding would be annually available through 2018 

is optimistic at best, but unlikely, considering the continuing economic slump and enormous national 

debt. To be funded by a TERP grant or a DERA grant, emission reductions must be demonstrated using 

acceptable methodologies recognized by the State and EPA and spelled out in their respective guidance 

documents. Therefore, all measures funded by TERP or DERA in this category are considered 

quantifiable. And if funded by TERP, DERA, or other similar funding mechanism, they are also 

considered adequately supported.

a. Voluntary Non-road Replacement and Retrofit Programs

This measure considers emission reductions from 10 categories of non-road equipment, some of 

which may be covered in other measures under Off-Road Measures. The main evaluation performed 

under this measure was replacement or retrofit of switcher locomotives. This evaluation was based on 

work funded by the Houston Advanced Research Center (HARC), ERG and Starcrest being the 

contractors. Data includes that collected by HARC and the major railroads operating in the HGB area. 

Emission estimates for short lines and switching yards is based on fuel consumption. From this analysis, 

emission reductions are estimated to be 2-3.5 tpd of NOx and VOC.

The TERP project for marine vessels has focused on harbor craft, which include tugs, excursion, and 

supply vessels because these vessel are more likely to spend most of their time within the area. Nearly 

all of the projects involve repowering propulsion and/or auxiliary engines with those meeting lower 

emission standards. Comparing the Tier 3 with the Tier 1 emission rates provides a potential 45% 

reduction is possible or 4 tons per day of NOx as an upper limit. Arbitrarily half of this maximum 

penetration rate was chosen as a lower limit of what could be achieved. Emission reduction values rely 

on emission standards for the various model year engines replaced or retrofitted. Emission reductions 

are projected to be 2-4 tpd of NOx and VOC in 2018.
The potential for construction and off-road engine replacement projects funded under TERP and/or other 

funding mechanisms is 2.5 tpd of NOx and VOC. This would include various types of non-road 

equipment including forklifts.

b. Government Construction Incentives

An incentive program or a requirement for publicly-funded (including just captive state, county, 

and municipal fleets of off-road equipment) or all construction projects could affect emission reductions 

by encouraging fleet turnover to those meeting lower emission standards. A TxDOT plan provides an 

example of an incentive program. There are two basic methods, a voluntary or incentive approach and a 

fixed requirement for clean equipment. The incentive approach raises the cost to the State or local 

government contracts by offering a monetary incentive, and the requirement raises the cost on the 

construction firm to maintain a clean fleet that would likely be passed on to the cost of the project. In the 

TxDOT example, the incentive was additional funds for using cleaner equipment based on the 

horsepower and the engine tier utilized. The incentive of Tier 4 engines is required to demonstrate 

significant emission reductions compared to the average fleet age distribution in 2018. By 2018, half of 

the equipment in use could meet Tier 4 final standards under normal turnover. The emission benefit for 

public and publicly funded contracts is limited to 1.4 tpd (with TxLED benefit applied) of NOx 

emissions.

c. Promote Cleaner Lawn and Garden Equipment

This program would use rebates or other incentives to replace the gasoline powered equipment 

with electric models. In many cases the gasoline equipment is exchanged for the rebate/incentive and so 

is taken out of service. Replacement of 6000 lawnmowers with electric models results in 0.04 tpd VOC 

benefit. Replacing leaf blowers would bring additional benefits. Unlike the previously discussed nonroad programs, this program would have to be funded by H-GAC because this equipment is not eligible 

for TERP funding. 

d. Reduced Idling

Idling is an inefficient operation that can produce unwanted air pollutants. Idling however also 

occurs during normal work and when work is performed intermittently. Restarting an engine may be 

considered an annoying delay. But idle reduction programs are interesting because the costs are typically 

low and may be a net savings to the owner/operator of the equipment while also reducing air emissions. 

Timed automatic shut-off devices are used widely in the on-road and parts of the non-road arenas. 

Savings in fuel would pay back the cost of the device in a relatively fast timeframe. An even less 

expensive (but potentially less reliable) method is operator training. Calculating emission reductions 

would be based on the amount of fuel saved. No estimates are given for this measure, although 

reductions in NOx would be expected.

e. Development of Clean Air Action Plans for Regional Port and Marine Operations

The focus of this project is larger ocean-going vessel (OGV) strategies because smaller 

commercial marine and shoreside (nonroad, locomotive, and trucking) port initiatives are described in 

another VMEP measure. Most OGV are foreign flagged creating potential legal obstacles, inter-port 

competition (higher fees may be a competitive disadvantage), and other concerns with operating a port 

under unique costs or operating restrictions. The administration of the program would fall to the ports or 

the state, and the methods used to enforce the program would still need to be defined. Overall 

enforcement of the VMEP Off-Road Measures in terms of obtaining emission reductions claimed falls to 

the State.
Examples of measures that could be applied to Large Ocean-Going Vessels (OGV):

o OGV Vessel Speed Reduction (VSR)

o Reduction of At-Berth OGV Emissions

o OGV Auxiliary Engine & Main Engine Fuel Standards

o OGV Main and Auxiliary Engine Emissions Improvements

The international standards include provisions for low sulfur fuel and engine emission controls 

worldwide with additional controls near regions defined by nations as sensitive to OGV pollution. The 

United States championed by EPA is applying to define the U.S. as a sensitive region requiring such 

emissions controls. The International Maritime Organization (IMO) has agreed to proposed amendments 

to the MARPOL Annex VI regulations to reduce NOx emissions from engines beginning in 2011 with a 

14.4 g/kW-hr and 3.4 g/kW-hr in an Emission Control Area (ECA) in 2016 compared with 17 g/kW-hr 

starting with vessels built in 2000. 

At very low engine loads, the emissions per mile is a function of the vessel speed squared, so slowing 

the vessel speeds by 30% will reduce emission by half. Unlike California ports that are on the shore, 

Galveston Bay vessels speeds are already low. Therefore the vessel speed reduction would affect 

emissions well out in the Gulf and may not affect local air quality as much as might be expected. (But 

considering the on-shore/off-shore meteorology of the Houston area, this may still have a worthy benefit 

in reducing ozone.)

At the dock, auxiliary engines are used for on-board power needs. These engines frequently are 

uncontrolled diesel engines. Solutions are to provide plug-in shore power, or use a hood or bonnet that 

routes the exhaust to a scrubber system that is either barge mounted or shore-based.

Switching to lighter, lower sulfur fuels has been suggested primarily to reduce sulfur and particulate 

matter emissions, but would have some benefit for NOx emissions as well.

A large NOx emission reduction benefit could be effectuated by using engine controls either designed 

into the engine or as an aftertreatment device that could be used only near sensitive air quality areas. 

This would result in about a 12.5% emission reduction in 2018. 

The projected emission reduction benefits for these measures range from 0.2 tpd of VOC to up to 4 tpd 

of NOx depending on the method utilized. Cost of funding these measures will fall to the shipping 

company and the Port of Houston and its tenants. The Port and its tenants could apply to TERP for 

possible funding for shore power electrification. Ocean-going vessels that come to the Port would not be 

eligible for TERP funds for modification of the ship’s engines, shore power conversion equipment, fuel 

switching or other modifications dedicated to the ship itself.

f. Rail Efficiency Measures

This strategy suggests projects that might improve rail efficiency requiring less activity from line-haul 

locomotives. Some measures to effect this improvement could be public/private partnerships while 

others might be implemented by the railroads. New technologies that have improved rail efficiency 

include wheel and rail lubrication, better bearings, more efficient engines, and perhaps other 

technologies yet to be identified. The operational changes include idle reduction, improved 

aerodynamics, longer trains, and improved training and evaluation of engineers to reduce braking, 

idling, and other inefficient operations. This measure was assumed to primarily affect the mainline rail 
operations and therefore the line-haul locomotives. Short line and switch engine efficiencies are covered 

by another VMEP program. Rail efficiency is measured in terms of freight moved per gallon of fuel 

consumed. Future changes could include rail network improvements to avoid congestion (such as 

double-tracking where locomotives would otherwise need to brake and idle while awaiting other trains), 

free flow operations to avoid closing local roadways (such as through grade separation projects), regrading or straightening routes (to reduce mileage and fuel consumption), or other projects. Emission 

reductions are projected to be 0.8 – 1.6 tpd of NOx. Project proponents would include the rail operators 

(railroads), and local, state, and federal transportation planners each of whom may provide funding and 

see benefits beyond air quality. Any project under this category would be adequately supported by the 

project partners.

Conclusion

The HGB 8-Hour Attainment Demonstration SIP revision VMEP meets the criteria for credit in the SIP. 

The State has shown that the credits are quantifiable, surplus, enforceable, permanent, adequately 

supported, and consistent with the SIP and the Act. We recommend to propose approval of the VMEP 

portion of the HGB 8-hour Attainment Demonstration SIP.

TCMs

TCMs are transportation related projects or activities designed to reduce on-road mobile source 

emissions. Section 108 of the CAA outlines allowable types of TCMs. Federal regulations at 40 CFR 

93.101 define a TCM as any measure that is specifically identified and committed to in the applicable 

implementation plan that is either one of the types listed in section 108 of the Act, or any other measure 

for the purposes of reducing emissions or concentrations of air pollutants from transportation sources by 

reducing vehicle use or changing traffic flow or congestion conditions. In September 1990 EPA issued 

“Transportation Control Measure: State Implementation Plan Guidance” 

(www.epa.gov/otaq/stateresources/policy/transp/tcms/state_plan_guidance.pdf). TCMs used as an 

emissions reductions control strategy must be specific, permanent, enforceable and quantifiable. TCMs 

in the SIP must include an identification of each project, location, length of each project (if applicable), 

a brief project description, implementation date, and emissions reductions for NOx and VOC. 

EPA approved the Texas TCM rule as a revision to the SIP on December 5, 2002 (67 FR 72379).

The SIP included 6 projects identified by the Houston-Galveston Area Council (H-GAC) to reduce 

mobile source emissions by enhancing pedestrian and bicycle pathways. The projects are listed in 

Appendix G of the April 6, 2010 SIP submittal and summarized in table 3. The emission reductions 

estimated from these projects are 0.015 tons/day of NOx. In an August 1, 2013 email, H-GAC stated 

that the projects are completed or are anticipated to be implemented by the end of 2013.

Because these projects are specific, permanent, enforceable and quantifiable and would reduce NOx 

emissions by facilitating non-automobile travel we propose to approve them. 
Table 3. Pedestrian and Bicycle TCM Projects in the HGB SIP

Project

# 

Description NOx 

Reductions

(tons/day)

Project Update from H-GAC 

0912-72-

145

Holman Street 

Pedestrian 

Improvements

0.0001862

TRANSIT ENHANCEMENTS (BUS). RFP/IFB Issued: 

9/30/2010.

Contract Award: 10/14/2010. Contract Complete: 

1/7/2013.

0912-72-

146

Pedestrian 

Improvements 

for Elgin, Ennis, 

and Alabama 

Streets

0.0004562

0912-72-

147

Pedestrian/Trans

it Improvement 

Program for 

Westheimer 

Road

0.0137628 Uptown Westheimer project, including streetscape

improvements. Pedestrian improvements have been

completed on Westheimer Ph1, Uptown Park Blvd and

Skylark. as of Dec 2012 Jerdon contract has started work 

on Westheimer Ph2 and it is about 40% complete. Work 

on Westheimer and Richmond approx. 50% complete for 

both streets (Jerdon Contract). Anticipated completion by 

end of 2013.

0912-71-

544

Columbia Tap 

Rail to Trail 

Bikeway

0.0002721 The Columbia Tap Trail now connects the area east of 

the George R. Brown Convention Center (Polk St) to the 

Third Ward (Dixie Drive). The completed portions of the 

bikeway project are over 4 miles in length. An additional 

segment (MacGregor to E of SH 288) is anticipated to be 

completed in 2013. 

http://offcite.org/2009/03/12/rail‐to‐trail‐celebratingcolu

mbia‐tap

0912-71-

801

Columbia Tap 

Union Station 

Trail Shared Use 

Path with Bike 

Lane

0.0005840 Completed. TxDOT completion date: Dec‐2008

0912-71-

655

Phase 2 W.

Houston OnStreet Bikeway 

Network (Terry 

Hershey Park)

0.0001653 Completed. TxDOT completion date: Aug‐2009

Total 0.0154266

4. Previously Approved State Measures and Federal Measures 

Texas also identified State ozone control measures which we have previously approved and Federal 

measures applicable to the HGB area (Table 4-1 of the April 6, 2010 submittal). These State control 

measures were approved by EPA for (1) the 1-hour ozone NAAQS (71 FR 52670, September 6, 2006) 
and (2) additional VOC emission control from storage tanks, transport vessels and marine vessels in the 

HGB area (75 FR 15348, March 29, 2010). Electronic dockets for the 2006 and 2010 approvals are 

available through www.egulations.gov (EPA- R06-OAR-2005-TX-0018 and EPA-R06-OAR-2007-

0526).

The Federal measures are regulations on vehicle emissions and fuel. 

As we have already approved the State measures and promulgated Federal measures to reduce ozone 

levels it is appropriate that they are relied upon in the attainment demonstration. 

5. Summary Regarding Control Measures Relied Upon in the Attainment Demonstration

We must approve the measures relied on as necessary to demonstrate attainment in order to approve the 

attainment demonstration. These measures must be permanent, enforceable, quantifiable, and surplus. 

Our review of the control measures not yet approved found that they meet these criteria. We propose to 

approve these measures and to find that the SIP has sufficient measures to attain the 1997 ozone 

NAAQS in the HGB area as expeditiously as practicable but no later than the end of 2018. Table 4

summarizes the measures relied upon for attainment.

Table 4. Summary of Measures Relied Upon in the Attainment Demonstration

Measure Comments

1-hour ozone NAAQS measures Approved (71 FR 52670, September 6, 2006)

VOC emission controls for storage tanks, 

transport vessels and marine vessels 

Approved (75 FR 15348, March 29, 2010)

Federal measures Federal regulations affecting vehicle emissions

Revisions to the MECT Proposed for approval

Revisions to the HECT Proposed for approval

VMEP and Transportation Control Measures Proposed for approval

C. Reasonable Available Control Measures

The RACM requirement applies to all nonattainment areas that are required to submit an attainment 

demonstration . Section 172(c)(1) of the Act requires SIPs to provide for the implementation of all 

RACM as “expeditiously as practicable” and for attainment of the standard. We interpreted the RACM 

requirements of 172(c)(1) in the “General Preamble for the Implementation of Title I of the CAA 

Amendments of 1990” (General Preamble) as imposing a duty on States to consider all available control 

measures and to adopt and implement such measures as are reasonably available for implementation in 

the particular nonattainment area (April 16, 1992, 57 FR 13498 13560). In addition, measures available 

for implementation in the nonattainment area that could not be implemented on a schedule that would 

advance the attainment date in the area would not be considered by us as reasonable to require for 

implementation. We indicated that a State could reject certain measures as not reasonably available for 

various reasons related to local conditions . A State could include area-specific reasons for rejecting a 

measure as RACM, such as the measure would not advance the attainment date, or was not 

technologically and economically feasible.
EPA also issued a memorandum reaffirming its position on this topic, “Guidance on the Reasonably 

Available Control Measures (RACM) Requirement and Attainment Demonstration Submissions for 

Ozone Nonattainment Areas,” John S. Seitz, Director, Office of Air Quality Planning and Standards, 

dated November 30, 1999.6In the memorandum, EPA states that in order to determine whether a state 

has adopted all RACM necessary for attainment and as expeditiously as practicable, the state will need 

to provide a justification as to why measures within the arena of potential reasonable measures have not 

been adopted . The justification would need to support that a measure was not reasonably available for 

that area and could be based on technological or economic grounds . If technologically or economically 

infeasible, the State does not need to consider it RACM.

To summarize our interpretation of the RACM requirement:

1) A control measure is necessary under the RACM requirement if it: 

• is technologically feasible

• is economically feasible

• does not cause “substantial widespread and long-term adverse impacts”

• is not absurd, unenforceable, or impracticable 

• can advance the attainment date

2) States need to: 

• consider all available control measures 

• provide justification to support that a measure was not reasonably available

• adopt and implement RACM measures

Texas submitted a RACM demonstration with the April 6, 2010 attainment demonstration (section 4.5 

and appendix E of the April 6, 2010 submittal). To meet the RACM requirement Texas: 

• identified potentially available control measures with input from stakeholders 

• analyzed whether the measure would be considered a RACM measure 

Tables E-1 and E-2 in Appendix E of the April 2010 submittal list the potential stationary and mobile 

source measures, respectively, and the RACM determination for each measure. Texas evaluated each 

potential control measure and determined that only one, reduction of the HRVOC cap for Harris County, 

should be adopted to meet the RACM requirement. Texas then adopted a rule to implement the measure. 

Texas determined that the other potential control measures did not meet the RACM criteria listed above.

We looked at tables E-1 and E-2 and did not identify any additional control measures we think are 

RACM . We agree that the other measures do not meet the RACM criteria listed above. Our review of 

the Texas’ RACM process and analysis found that they considered all available control measures, 

provided justification to support that a measure was not reasonably available and adopted and 

implemented the measure it identified as RACM.

D. Contingency Measures

CAA sections 172(c)(9) and 182(c)(9) require contingency measures to be implemented in the event of 

failure to attain the standard by the applicable attainment date. These contingency measures must be 

fully adopted rules or measures which are ready for implementation quickly upon failure to meet 

 

6

http://www.epa.gov/ttn/caaa/t1/memoranda/revracm.pdf
attainment. Implementation of the contingency measures would provide additional emissions reductions 

of up to three percent of the adjusted base year inventory.7

The 1992 General Preamble stated that: “States must show that their contingency measures can be

implemented with minimal further action on their part and with no additional rulemaking actions such as

public hearings or legislative review.” (57 FR 13498 13512). In our November 29, 2005 Phase 2 rule for 

implementing the 1997 ozone NAAQS we noted that we had approved numerous SIPs that use as 

contingency measures one or more Federal measures that are in place and provide reductions that are in 

excess to the attainment demonstration (70 FR 71612 71651). We further noted a court ruling which 

upheld contingency measures that were previously required and implemented where they were in excess

of the attainment demonstration and RFP SIP. See LEAN v. EPA, 382 F. 3d 575 5th Circuit, 2004.

In the May 6, 2013 SIP submittal Texas provided a demonstration that the contingency measures 

requirement would be met through Federal rules affecting mobile emissions. Table 5 summarizes the 

contingency measure analysis provided by Texas with a recalculation of the contingency excess for NOx 

emissions. 

Table 5. 2019 Contingency Demonstration for the HGB Area 

Description NOx Emissions

(tons per day)

VOC Emissions

(tons per day)

Adjusted 2018 Base Year Emissions Inventory 1003.92 935.59

Percent for Contingency Calculation (total of 3%) 2.00 1.00

2018 to 2019 Required Contingency Reductions 20.08 9.36

Federal On-Road Reformulated Gasoline (RFG) 6.80 -0.25

Federal On-Road Mobile 

New Vehicle Certification Standards

22.28 9.50

State Inspection and Maintenance 

and Anti-Tampering Programs

-0.67 -0.26

Texas Low Emission Diesel (TxLED)** -0.20 0

Federal Non-Road Mobile 

New Vehicle Certification Standards

3.56 1.78

Non-Road RFG Gasoline 0.00 0.03

Federal Tier I and II Locomotive Standards 0.68 0.01

Federal Tier 2 Marine Diesel Standard 0.55 0.02

Total Contingency Reductions 33.20 10.83

Contingency Excess (+) or Shortfall (-) +12.92 +1.47

* The reason for negative numbers for the RFG, Inspection and Maintenance/Anti-Tampering and 

TxLED programs is that there is a slightly higher benefit in 2018 than in 2019.

** Table 4-3 in the May 6, 2013 submittal included this measure in the calculation, but did not list it in 

the table.

The Texas analysis documents that Federal measures can serve as contingency measures and provide

additional emissions reductions that are in excess to those needed to satisfy the contingency requirement 

for the year 2019 in the event that the area fails to attain the 1997 ozone NAAQS at the end of 2018.

 

7 The adjusted base year inventory is that inventory specified by CAA section 182(b)(1)(B). 
EPA finds that the Federal measures identified above are fully in place and adopted and provide for 

reduction in excess to the attainment demonstration of at least 3% of the baseline year, therefore we 

approve into the SIP the contingency measures identified by Texas. 

E. Motor Vehicle Emission Budget (MVEB)

A MVEB is that portion of the total allowable emissions allocated to highway and transit vehicles in the 

SIP for a certain date for the purpose of meeting reasonable further progress milestones or 

demonstrating attainment or maintenance of the NAAQS (40 CFR 93.101). CAA section 176(c) and our 

transportation conformity rules at 40 CFR 93 require that transportation plans and related projects result 

in emissions that do not exceed the MVEB established in the SIP. This is to ensure that the effects of

emissions from all on-road sources are consistent with the SIP. The SIP included an attainment MVEB 

for 2018 (table 6). The MVEB represents the maximum level of on-road emissions of NOx and VOC 

that can be produced in 2018, when considered with emissions from all other sources, which 

demonstrate attainment of the 1997 8-hour ozone NAAQS. The attainment MVEB submitted on April 6, 

2010 was updated in the May 6, 2013 submittal using a more recent EPA mobile source emissions 

estimation model (MOVES). Previously we determined that the updated 2018 MVEB was “adequate” 

for transportation conformity purposes and must be used for future conformity determinations in the 

HGB area (August 2, 2013, 78 FR 46947). All future transportation improvement programs, projects and 

plans developed, funded, or approved under Title 23 U.S.C. or the Federal Transit Laws for the HGB 

area will need to show that they do not result in emissions which exceed the MVEB (40 CFR 93.118). 

Table 6. 2018 HGB Attainment MVEB

Pollutant Summer Weekday Emissions

(tons per day)

NOx 103.34

VOC 50.13

Our review of the MVEB for adequacy found that it met the criteria found in 40 CFR 93.118(e)(4), 

specifically that:

• The submitted plan revision was endorsed by the Governor’s designee and was subject to a State 

public hearing

• Before the plan was submitted to EPA, consultation among federal, State, and local agencies 

occurred; full implementation plan documentation was provided to EPA; and EPA's stated 

concerns, if any, were addressed

• The MVEB is clearly identified and precisely quantified

• The MVEB, when considered together with all other emissions sources, is consistent with 

applicable requirements for attainment

• The MVEB is consistent with and clearly related to the emissions inventory and the control 

measures in the submitted plan revision 

• Revisions to previously submitted 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

We incorporate our analysis in the above adequacy determination and based upon it we propose to 

approve the 2018 MVEB into the SIP.
F. General Air Quality Definitions

The General Air Quality definitions found in 30 TAC Section 101.1 are applicable to the entirety of the 

Texas SIP. Revisions to the General Air Quality Definitions were submitted on June 10, 2005, August 

16, 2007, April 6, 2010 and March 11, 2011. Our analysis of these revisions are found in Appendix C of 

the TSD. In summary, our analysis demonstrates that the revisions are consistent with the CAA and 

EPA’s regulations at 40 CFR Part 51, therefore we propose approval of the revisions to 30 TAC 101.1 

submitted on June 10, 2005, August 16, 2007, April 6, 2010 and March 11, 2011.

IV. 110(l) Evaluation

CAA section 110(l) prohibits EPA from approving any SIP revision that would interfere with any 

applicable requirement concerning attainment and reasonable further progress or any other applicable 

requirement of the CAA. Because the SIP revisions provide for the area to attain the 1997 ozone 

NAAQS as expeditiously as practicable and meet other CAA requirements, approval of the SIP 

revisions would not interfere with any applicable CAA requirement.

V. EPA Guidance Documents

Relevant EPA Guidance Documents for this rulemaking are as follows:

Transportation Control Measures: State Implementation Plan Guidance, September 1990 (EPA 450/2–

89–020), http://www.epa.gov/otaq/stateresources/policy/transp/tcms/state_plan_guidance.pdf

Early Implementation of Contingency Measures for Ozone and Carbon Monoxide (CO) Nonattainment 

Areas, Memorandum from G.T. Helms, Chief, Ozone/CO Programs Branch, August 13, 1993

http://www.epa.gov/ttn/caaa/t1/memoranda/20789continmeas.pdf

Clarification of Issues Regarding the Contingency Measures that are due on November 15, 1993 for 

Moderate and Above Ozone Nonattainment Areas, Memorandum from D. Kent Berry, Acting Director, 

Air Quality Management Division, November 8, 1993

Document number EPA-HQ-OAR-2003-0079-0839 in regulations.gov

Guidance on the Post 1996 Rate-of-Progress Plan (ROP) and Attainment Demonstration, (EPA-452/R93-015), January 1994

http://www.epa.gov/ttn/naaqs/aqmguide/collection/cp2_old/19940218_oaqps_post1996_rop_guidance_corrected.pdf

Document number EPA-HQ-OAR-2003-0079-0838 in www.regulations.gov

Guidance on the Reasonably Available Control Measures (RACM) Requirement and Attainment 

Demonstration Submissions for Ozone Nonattainment Areas, John S. Seitz, Director, Office of Air 

Quality Planning and Standards, November 30, 1999

http://www.epa.gov/ttn/caaa/t1/memoranda/revracm.pdf

Memorandum dated December 14, 2000, from John S. Seitz, Director, Office of Air Quality Planning 

and Standards, “Additional Submission on RACM From States With Severe One-Hour Ozone

Nonattainment Area SIPs.”

http://www.epa.gov/ttn/oarpg/t1/memoranda/121400_racmmemfin.pdf
Improving Air Quality with Economic Incentive Programs, January 2001, (EPA-452/R-01-001)

http://www.epa.gov/ttn/oarpg/t1/memoranda/eipfin.pdf

Guidance on Incorporating Voluntary Mobile Source Emission Reduction Programs in State 

Implementation Plans (SIPs)”, Memorandum from Richard D. Wilson, Acting Assistant Administrator 

for Air and Radiation, October 24, 1997

http://www.epa.gov/otaq/stateresources/policy/general/vmep-gud.pdf

Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals 

for Ozone, PM2.5, and Regional Haze, April 2007

http://www.epa.gov/scram001/guidance/guide/final-03-pm-rh-guidance.pdf

VI. Appendices

Appendix A. Technical Support Document For Houston Galveston Brazoria Modeling and Other 

Analyses Attainment Demonstration (HGB-MOAAD)

Appendix B. Evaluation of MECT and HECT Program Revisions

Appendix C. Evaluation of General Air Quality Definition Revisions