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Program for Generation of Emission Credit by Urban Buses






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PROGRAM FOR GENERATION OF EMISSION CREDITS BY URBAN BUSES



I. Foreword



   The Clean Air Act, as amended in 1990, mandates market-based 

approaches in certain Federal programs and encourages the use of

such approaches at the Federal, State, and local levels, as well as

by individual sources, to facilitate the attainment of the mandated

milestones and goals of Title I of the Clean Air Act Amendments. 

In response to the Act, the Agency has proposed and issued rules

and guidance that incorporate the use of market-based measures in

Federal program areas such as acid rain reduction and clean fuel

fleet vehicle purchases.



   To facilitate the development of market-based programs that go

beyond such Federal programs, the Agency is developing

comprehensive rules and guidance for States and individual sources

to follow in designing and adopting market-based programs in State

Implementation Plans (SIP's).  The pending Economic Incentive

Program (EIP) Rules draw upon the general principles found in the

1986 Emission Trading Policy Statement (see 51 FR 43631 December 4,

1986) while providing a broad framework for the development and use

of a wide variety of market-based control strategies.  For States

to take credit in their SIP's for emission reductions based upon

such strategies, reductions must be quantifiable, enforceable,

surplus to other Federal and State requirements, permanent within

the timeframe specified by the program, and consistent with all

other statutory and Federal regulatory requirements.  The proposed

EIP Rules are applicable to all types of sources including

stationary and mobile sources and define general regulatory

elements (e.g., program baseline, auditing procedures, enforcement

requirements) that should be included in the design of market-based

control strategies.



   In addition to these broadly applicable general rules, the

Agency is also developing a more narrowly focused document entitled

"Guidance on the Generation of Mobile Source Emission Reduction

Credits" specifically for the development of market-based programs

involving the use of emission reduction credits generated by mobile

sources.  Such mobile source emission reduction credits (MERC's)

can be generated from surplus emission reductions over and above

Federal mobile source program requirements and can potentially be

used to substitute for stationary emission reduction requirements. 

The general guidance on the generation of MERC's mentioned above

addresses issues unique to emission reduction credits generated by

mobile sources, including the calculation of emissions baselines

for participating sources, the projection of future emissions

levels, and the time-averaging of emission reduction credits that

vary over time.





   To exemplify how MERC's can be generated from a specific

category of mobile sources, the following guidance addresses clean

technology urban buses, and illustrates how surplus purchases

(i.e., beyond Federal program requirements) can be used to generate

emission credits in a mobile-stationary source trading program. 

While market-based mobile source programs must be consistent with

the Economic Incentive Program Rules and the Guidance on the

Generation of Mobile Source Emission Reduction Credits, EPA does

not intend to limit flexibility and innovation beyond the

requirements found in these documents.  The following guidance is

intended to identify key elements in the design of a clean

technology urban bus emission credit generation program, not to

limit state initiative, creativity, or flexibility in developing a

program which best meets the state's needs within the limits of

good environmental policy.



II.   Introduction



   EPA is developing innovative methods to encourage low emitting

and clean fuel technologies.  As part of this initiative, market-

based incentive programs are an effective means to promote this

technology and to achieve the accompanying emission reductions. 

The overall regulatory burden is reduced because participation by

industry is voluntary.  Furthermore, it is reasonable to believe

that in a broad sense the reductions are cost effective since

industry would not become involved in the program if participation

was not viewed as economically attractive.  Finally, by a voluntary

shifting of the compliance burden to the party with the lowest

cost, market based programs can reduce the cost of compliance for

the industry as a whole.



   Urban buses represent a significant source of ground level NOx

and PM emissions within cities.  To help address this problem EPA

has two programs to reduce the emissions from urban buses.  The

first, which applies to urban bus engine manufacturers, involves

stringent NOx and PM emission standards for new urban bus engines. 

These emission standards can be met on an every engine basis or in

combination with credit programs such as averaging, banking and

trading.  The second program, which is presently in the proposal

phase, applies to fleet operators and involves in-use urban bus

engines.  This program requires either application of retrofit

technology to reduce emissions of individual rebuilt urban bus

engines or a fleet emissions averaging program to reduce overall

fleet emissions from in-use urban bus engines through one or more

of several approaches.



   These emission standards and other program requirements can

potentially be met through the use of either improved engine and

aftertreatment technology or the use of clean fuels.  For ease of

reference in this document, these methods will collectively be

referred to as "clean technologies".  Both approaches show promise

for providing additional emission reductions, but as with most

emerging technologies they are somewhat more expensive than current

diesel-powered urban buses.  In order to provide urban bus

operators with incentive to purchase clean technology urban buses,

EPA has developed a program which will allow trading of excess

urban bus emission reductions (credits) with other sources. As

background, this document will describe the regulatory programs and

current credit exchange programs for urban buses as mentioned

above, and then develop a credit generation program for new urban

buses and bus fleets which exceed emission requirements using clean

technologies.





III.  Description of Current Programs



A. Averaging, Trading and Banking Programs for Certification



   The current averaging, banking and trading (AB&T) programs apply

to NOx and PM emissions from heavy duty engines (HDEs).  Under

these programs, credits may be generated and used only by

manufacturers of new engines.  Urban bus engines meet the same HC,

CO, and NOx emission standards as other HDEs and are considered the

same as any other HDE within their primary intended service class

for NOx AB&T purposes.  However, there is a unique PM standard for

urban bus engines and PM AB&T programs are thus restricted to that

specialized subgroup.  Cross-fuel credit exchanges (AB&T) are

allowed between petroleum and methanol-fueled urban bus engines and

EPA recently proposed to extend this program to the gaseous fuels

(CNG, LNG, and LPG). The trading and banking rule lists the

equation for calculation of credits:



   Cr =  (Std-FEL)(CF)(UL)(Prod),  where



      Cr =  total mass of emissions credit for family (grams)

      Std = NOx or PM emission standard in g/bhp-hr

      FEL = Family emission limit in g/bhp-hr

      CF =  Conversion factor for g/bhp-hr to g/mile;

      CF =  BSFC x Fuel Economy x Fuel Density

      UL =  useful life in miles

      Prod =   Number of engines of the particular family produced



   In summary, under this program urban bus engine manufacturers

can generate NOx and/or PM credits for use in current or future

certification or trading to other engine manufacturers.  However,

their use is currently limited to new engine certification.







B. Retrofit/Rebuild



   EPA has proposed an urban bus retrofit/rebuild program aimed at

reducing emissions from older urban buses (57 FR 33141, July 27,

1992).  As required by the Clean Air Act (CAA), the proposed urban

bus retrofit/rebuild program would apply to 1993 and earlier model

year urban buses whose engines are rebuilt or replaced beginning

January 1, 1995.  The CAA limits the program requirements to urban

buses operated in metropolitan areas with a 1980 population of

750,000 or more.  EPA estimates that nearly 80 percent of the

nation's urban buses in approximately 100 cities could be affected

by the program.  (See Table 1)



   As proposed by EPA, urban bus operators would be allowed to

choose between two different retrofit/rebuild options to

demonstrate compliance.



   Under the first option as proposed, a bus operator's engines

would have to meet a 0.10 grams per brake-horsepower (g/bhp-hr) PM

emission standard at time of rebuild or replacement, as long as

aftertreatment equipment certified to meet the standard can be

purchased for no more than $5,000.  If no aftertreatment equipment

is available that meets the 0.10 g/bhp-hr PM standard at the cost

limit requirements, a bus operator would be required to install

equipment that has been certified to achieve a 25 percent or

greater emission reduction on that engine as long as such equipment

can be purchased for no more than $2,000.  The 25 percent emission

reduction is based on the original certification emission standard

for the engine.  If not certified to a PM standard, then the engine

must be rebuilt to the original configuration.  If no equipment is

available that meets these requirements, a bus operator would be

required to rebuild an engine to its original configuration or a

configuration that has lower PM emissions than the original

configuration.



   The second retrofit/rebuild option would be a fleet average

program that is designed to yield an emission reduction equivalent

to that expected from the performance based (retrofit technology)

option described above.  Under the second option,  using the

approach spelled out by EPA in the aforementioned proposal, a bus

fleet operator would calculate an annual target level for his fleet

(TLF) for PM emissions based on the fleet makeup and the

availability of control options.  The fleet operator could then use

any combination of certified retrofit technology, replacement with

used lower emitting urban bus engines, and early retirement of

their urban buses such that the average fleet level attained (FLA)

for PM emissions is at or below the required target level (TLF)

noted above.



   The final rule will include these points, but may make changes

to provide for costs other than equipment which transit operators

must consider.



   These two programs serve as the starting basis for a program to

permit credit generation for urban buses.  This program is

discussed below.





IV.   Emission Credit Generation Program for Urban Buses



A. Overview



   Under this program, operators of urban buses may generate

credits in two ways.  The first stems from the averaging, trading

and banking regulations and applies to purchases of new urban

buses.  The second stems from the retrofit/rebuild requirements,

and applies to any retrofitted clean technology bus which is used

to meet either the performance based option or the TLF option for

complying with the retrofit/rebuild requirements.  The specifics of

these programs are discussed below.



B. Purchase of New Urban Buses



   Any clean technology urban bus which is purchased by a fleet

operator may receive NOx and/or PM emission credits in the amount

that the urban bus has lower emissions than the then applicable

NOx/PM urban bus emission standards.  As is discussed below, credit

calculations would be based on actual VMT for the clean technology

bus in any given year.  These emission credits would accrue over

the bus useful life (until retirement or rebuild).  If there are no

rebuilds involved, credit generation could not exceed the average

urban bus lifetime of fifteen years (see Table 2).  However, in

most cases the first rebuild occurs after 5 years of use (about

220,000 miles); after this the bus must qualify for credits under

the retrofit/rebuild program.  Regardless of when retirement or any

subsequent rebuild occurs, credit generation is based on the

presumption that the bus is meeting the emission standards at all

times prior to that point.



   An additional provision is suggested to promote the early

retirement of higher emitting urban buses.  Referring to the data

in Table 2, if a new clean technology urban bus is used to replace

an older urban bus which is retired early, the clean technology bus

could generate emission credits in the amount that the clean

technology bus NOx and PM emissions are lower than the retired bus

NOx and PM emissions.  These benefits would accrue for the years

that the old urban bus would have been in operation.



   Under this approach, credit generation would be calculated

differently for the years when the new bus life overlaps with the

presumed remaining life of the old bus than for the years afterward

when the old bus is presumed to have been retired.  This method

requires reliance on the expected VMT of the old urban bus as shown

in Table 2 and the credit calculation methodology as explained in

Section VII below.  For the overlapping years credit calculation

would involve two steps.  The first step would depend on the

difference between the emission standard applicable to the old bus

and the new bus for the overlapping miles of Table 2.  The second

step, if applicable, would depend on the difference between the

emission standard applicable to the new bus and the family emission

limit of the new bus and the actual mileage of the new bus. 

Credits for the remainder of the new bus life (after the old bus is

presumed to have been retired), would be calculated as in the first

paragraph of this section using actual new bus VMT.



   Of course, as is mentioned in element 9 below, credits cannot be

generated under this method if the retired bus is also used to

achieve compliance under the requirements of the retrofit/rebuild

program.





                               TABLE 2



             EXPECTED URBAN BUS VMT BY YEAR OF OPERATION



                  YEAR OF OPERATION   EXPECTED VMT

                       1                45,000

                       2                45,000

                       3                44,000

                       4                42,000

                       5*               41,000

                       6                38,000

                       7                36,000

                       8*               35,000

                       9                33,000

                      10                29,000

                      11*               25,000

                      12                25,000

                      13                25,000

                      14                25,000

                      15                25,000



                      * expected rebuild point





C. 1995 Retrofit/Rebuild Urban Buses



   As mentioned above, under the CAA 1995 urban bus

rebuild/retrofit programs, there are two options for compliance.



   The first, the retrofit/rebuild option, is a performance based

program which is implemented on a per bus basis.  Under this option

an urban bus operator may receive emission credits for retrofitting

an old urban bus using clean technology.  This program would apply

to both PM and NOx.  Emission credits would be the amount the

individual urban bus was below the 1995 retrofit/rebuild emission

PM standard and the original configuration NOx emission standard.

Credit calculations would use the actual VMT of the bus as it is

used, not Table 2.



   The second retrofit/rebuild option is an averaging program that

is set up to provide the bus fleet operators greater compliance

flexibility while still yielding an emission reduction equivalent

to that expected from the performance based option outlined above. 

Under the second option, a bus operator would calculate an annual

target level for a fleet (TLF) for PM emissions based on the makeup

of the operator's urban bus fleet.  The bus operator could use any

combination of certified retrofit equipment (clean fuel or low

emitting technology) and early retirement of their urban buses such

that the average fleet level attained (FLA) for PM emissions is at

or below the target level (TLF) noted above.



   Under this option, it is possible that a company may elect to

surpass their TLF requirement by retrofitting/rebuilding additional

urban bus engines using clean technology or other means.  If this

is the case, and the company is below its TLE then any clean

technology urban buses in the fleet, after the fleet meets the TLF

emission level, may be used for credit generation by declaring that

the extra clean technology buses are not to be included in the TLF

calculation (a TLF opt-out bus).  However, the fleet must meet its

TLF with the remainder of the buses in the fleet.  This is

equivalent to allocating credits on a per engine basis as under the

performance based option above and credits for opt-out buses will

be calculated similarly.  As was the case for that option, this

program would only apply to PM and NOx emissions.



   Under either option, credits are calculated using the

appropriate actual VMT and emission differences.  Table 2 values

will not be used.



   In summary, there are three ways in which urban bus engines can

potentially generate NOx and PM emission credits:



-  purchase of new, clean technology urban bus engines certified to

   levels below the emission standards.



-  retrofit of in-use urban bus engines with clean technology kits

   certified to levels below the applicable retrofit/rebuild PM

   emission standards and the original configuration NOx standard.



-  TLF opt-out urban bus engines using retrofit clean technology

   certified to below applicable standards as above for PM and NOx.



V. Program Elements



   In an overall sense, credits for urban bus NOx and PM emissions

will be generated as discussed above.  Suggested elements of a

program that would allow clean technology urban buses to generate

emission credits are described below.  It will be up to the states

to develop a proposal to integrate the overall concepts described

above and these general elements into a specific program.



ELEMENT 1.  Credit-generating urban buses must be in addition to

            those required to be purchased by statute or must be

            certified to lower emission standards.



   Clean technology urban bus engines may generate emission credits

under one of the three  options listed above.  Emission reductions

must be beyond those required by the new bus emission standards or

those of the retrofit/rebuild program.  This element is necessary

to ensure that credits reflect actual excess emission reductions.



ELEMENT 2.  Clean technology buses may operate on clean alternative

            fuels or on petroleum-based fuels



   Since the focus of this program is on allowing the use of clean

technology urban buses to generate emission credits, it is not

necessary to require that the affected urban buses run on any

particular fuel.  It is only necessary that the urban bus emit at a

level lower than the then applicable urban bus PM and/or NOx

emission standard or that required in the retrofit/rebuild program. 

At the same time, it should be noted that urban buses which run on

clean alternative fuels (e.g., electricity, gaseous fuels, and neat

alcohol) will tend to be inherently cleaner and thus potentially

generate more emission credits than those that run on conventional

petroleum-based fuels or fuel blends relying more on advanced

emission control technology.



ELEMENT 3.  Clean alternative fuel vehicles need not be dedicated

            fuel vehicles.



   EPA is not averse to including dual-fuel, flexible-fuel, or

hybrid electric urban bus engines in a credit generating program. 

However, urban buses which operate on more than one fuel complicate

the calculation of tradeable credits.  Since different fuels

produce different emission rates, it is necessary to verify how

much time the urban bus operates on each fuel in order to calculate

the correct amount of emission reduction.



   Therefore, any program that includes dual-fuel, flexible-fuel,

or hybrid electric vehicles must include a provision to ensure that

vehicle miles on each fuel can be calculated reliably.  This will

ensure that the calculation of the credit more closely reflects the

actual reduction in emissions from operation on both fuels.  One

way to ensure accurate reporting is by equipping urban bus

refueling facilities with "fuel keys," which act to track, by

computer, the fuel type dispensed to each urban bus.   Such a

system can be expanded to permit coding of appropriate mileage

records, to enable accurate calculation of vehicle miles traveled

on each fuel.  Any system which accurately distinguishes between

the different fuels used and vehicle miles travelled would be

acceptable.  The ideal system would have minimal reliance on human

factors.  Fuel and/or additive purchase receipts adequate to cover

the mileage claimed may also be required.



ELEMENT 4.  Urban buses can be new or converted.



   New converted urban buses/engines are eligible to generate

credits as long as they comply with the same provisions and

emission standards which apply to new urban buses. 

Retrofit/rebuild conversions must be certified in accordance with

the provisions of the urban bus retrofit/rebuild program and meet

the appropriate emission standards and durability requirements.



ELEMENT 5.  Urban buses should pass an annual I/M test.



   A test is desirable to insure the vehicle is running correctly

in use.  Urban buses should pass an annual emissions performance

check where available.  States may require a decentralized testing

program if they desire, or require other means, such as in house

testing, to insure compliance.



ELEMENT 6.  Credits will be calculated annually, preferably on a

            calendar year basis.



   This element is necessary to ensure that the generation of

credits coincides on a time period basis with the purchase, use,

and compliance decisions which normally occur.  The normal model

year for heavy-duty engines is the calendar year and credits for

trading can easily be determined on a yearly basis.  Furthermore,

the parameters for that year should be the same as used in credit

use programs to simplify enforcement, ensure consistency, and

discourage gaming.  Therefore, for the purpose of calculating

emission reduction credits, vehicle miles traveled will be measured

from January 1 through December 31 of each year for each credit

generating vehicle in service, and the credit will be calculated

for that period.  However, other annual periods would probably be

acceptable depending on state preference.



ELEMENT 7.  Credits shall be calculated on a pollutant specific

            basis.



   This program will focus on reductions in emissions from NOx, and

PM.  Testing must be conducted to show that no other regulated

pollutant emission rates increase; in cases of pollutants for which

there is no standard, emissions must not be worse than those of

urban bus engines of the model year not in the program.  Credits

may not be generated for urban bus HC and CO emissions due to the

fact that HC and CO emissions from current diesel urban bus engines

(the dominant technology now in use) are already significantly

below the respective standards.





ELEMENT 8.  Credits can only be generated by urban buses which

            states choose to include in the program.



   Urban buses are a special sub-category of heavy-duty engines. 

The federal emission standards apply to all urban buses while the

retrofit/rebuild program applies only to urban bus fleets in the

larger metropolitan areas.  States have the option of choosing

whether to participate in the program and whether to extend the

credit program to all urban buses used within their state

regardless of whether or not they are in an area covered by the

retrofit/rebuild program.  This potentially increases the pool of

credits available.



ELEMENT 9.  Urban bus engines used in the certification AB&T

            programs or in TLF calculations cannot also generate

            credits for trading.



   The AB&T credit exchange programs are designed to be used by

engine manufacturers during certification.  To avoid double-

counting, new clean technology urban bus engines which generate

credits for certification cannot also be claimed by the bus fleet

operators to generate credits for this trading program.  The

ownership of these credits must be determined between the engine

manufacturer and the bus fleet owner and records kept.



Retrofit clean fuel technology urban bus engines cannot be used in

the TLF calculation and also generate credits under this program. 

To generate credits they must be declared as TLF opt-out engines.



VI.   Conversion Factor Requirements



   Credit generation and transactions will likely be based on mass

emissions.  However, heavy-duty engine testing produces emission

rates in terms of g/bhp-hr.  These emission rates in g/bhp-hr need

to be converted into g/mile figures to facilitate calculating the

equivalent mass of emission reductions for purposes of trading with

other sources.  Thus bhp-hr/mile conversion factors need to be

developed for vehicle/engine configurations which are to be used to

generate credits.  Because the bhp-hr/mile conversion factor is

engine specific, it must be developed experimentally by testing. 

For new or retrofit/rebuild urban bus engines using clean

technology, this calculation may be done using the information

developed as part of the certification process as is prescribed in

the heavy-duty AB&T programs.



VII.  Credit Calculation



   Credits will be calculated based on the number of miles traveled

by each vehicle each year, adjusted by the degree to which the

vehicle is cleaner than a conventional vehicle.  States may

calculate credits in one of two ways:  projected or year-end, as

described below.  A state's choice of method will depend on the

needs of its program.  However, under either method, the state must

have a method to verify that credits given reflect actual emissions

savings.



   The projection method of credit calculation ensures that credits

are used during the same year they are generated.  According to

this method, credits are estimated and allocated at the beginning

of the year they are generated, based on an estimate of how many

miles the vehicle will travel that year.  Then, at the end of the

year, the states must follow up with a verification procedure based

on actual vehicle miles traveled, to verify that estimated emission

reductions are the same actual emission reductions.  States using

this method must provide a remedy to correct estimation errors



   The year-end method of credit calculation can be used to avoid

the extra burden and paperwork associated with the verification

procedure required by the first method.  In the year-end method,

states calculate and allocate credits at the end of the year, based

on actual vehicle miles traveled.  Under this method, emission

credits are used during the year after they are generated.



   Under either program, credits are to be calculated according to

the following formula, in grams per year of each pollutant.  For

the two different methods of calculation, VMT represents either

estimated or actual mileage, depending on which method is used and,

if the first method is used, whether the calculation is the

beginning of the year estimate or the year-end verification.



   To calculate the credits generated by the purchase of a new

urban bus or retrofit/rebuild of an old urban bus, the following

formula will be applied for each pollutant.



   IU x [(engine imp) x CF þ VMT] = credit [grams/year]



      where



(engine imp) = (applicable NOx/PM standard) - (Family Emission

               Limit to which the urban bus is actually certified)

               applicable standard depends on the model year and

               whether the engine is generating credits as a new or

               retrofit/rebuild model



         VMT = vehicle miles traveled in one year (actual or

               estimated, depending on the method of credit

               calculation adopted)



          CF = conversion factor (BSFC x Fuel Econ x Fuel Density),

               where



         BSFC = brake specific fuel consumption



          IU = adjustment to account for the emissions difference 

               caused by calculating credits based on standards or

               FELs rather than in use performance



   The heavy-duty engine AB&T program uses the concept of Family

Emission Limit (FEL) as a surrogate for the emission standard for

credit generating/using engine families.  A similar concept will be

applied here; credits will be calculated based on the difference

between the emission standard and the FEL not the difference

between the emission standard and the engine certification level. 

Presumably, the FEL will be greater than the certification level to

account for deterioration, variability, etc.



   In these calculations it is necessary to take into account the

emissions performance of buses in use relative to the performance

predicted by the emission standards/FELs alone.  Changes can occur

for several reasons.  These include differences in low mileage

targets with more stringent standards/FELs, unexpected

deterioration in the emission control system efficiency,

malmaintenance, hardware defects, and tampering.  The credits

calculation includes a term (IU) to adjust for the effects of these

factors.  Present best estimates are that IU should have a value of

0.79 for NOx and 0.6 for PM.  However, it should be noted that

there are only a few certified urban bus engine families and

identifying one NOx and PM value to apply to the entire group is

problematic especially if the potential exists for a broad range in

values depending on the fuel or technology used. As more data

becomes available these values are subject to change.



   When electric vehicles are used, the credit calculation may need

to be adjusted to account for additional NOx and PM emissions

related to generating electricity.  Such a calculation will need to

take into consideration how electricity is generated in that area. 

It will be up to the affected states to determine the size of the

offset, depending on local electricity generating factors.



VIII. Special Issues



   A trading program such as the one described in this document

poses at least two special problems.  The first is that credits

could be given for an urban bus that does not actually have reduced

emissions.  The second is the case when urban buses are driven

additional miles to generate extra credits.



   The first case, when an urban bus is given credits even though

it does not have reduced emissions, is the more serious problem. 

This may occur if the bus is not properly maintained and/or it is

defective.  Since it is proposed that credits be calculated based

on the projected in-use emission levels derived in part from the

standards to which the engine is certified, and not on actual

emissions from an emission test on each engine, this problem would

be discovered only as a result of emission tests/inspections of

that urban bus configuration.



   While urban bus emission failures would seriously undermine the

credit program, EPA does not believe it will occur at such a rate

that more than annual tests should be required.  All new 1994 and

later bus engine families will be part of an EPA in use testing

program as required by the Clean Air Act.  Since urban buses will

ideally be subject to some in use test, EPA believes that it is

unlikely that credits would be allocated for urban buses that fail

to reduce emissions.  Credits are calculated annually and most

emission failures would be brought to the attention of the owner

during that year through the test programs.  In cases where an

urban bus configuration fails an emission test/inspection, those

urban buses would either not be allocated credits for that year, or

would be allocated a prorated share of credits based on actual

emissions.  In cases where a formal state I\M program is not

available, a substitute program may be acceptable.  Similarly

emission credits would need to be adjusted if the engine is

involved in an emission recall program.



   EPA believes that the second case, where a bus is driven

additional miles to generate credits, is unlikely to occur.  The

additional costs of generating those credits, in both fuel and

time, may not be worth the extra credits generated.  Furthermore,

if urban bus operators allocate more miles to their credit

generating bases and fewer to their other buses for the purpose of

generating more credits, this is in keeping with the spirit of both

programs, which is to generate fewer emissions.  Urban bus

operators that adopt this strategy are entitled to the extra

credits they generate.



   However, to ensure against misrepresentations, states may

consider comparing miles traveled on a year-to-year basis, to

detect unlikely increases in number of miles traveled.  Audits of

mileage and fuel use records may also be used as a check against

tampered odometers on vehicles.



IX.   Administration of the Program



   As noted above, states would be required to design and

administer their own programs.  However, EPA advises that all state

programs contain elements and methods of calculation similar to

those described above to ensure that emission reductions are being

achieved.  If a state does not follow this guidance, it must

demonstrate that the emission reductions are achieved.



   Finally, it should be noted that the states in which the program

will be run have the ultimate responsibility of ensuring that both

the urban bus credit generating provisions and trading programs are

implemented in accordance with their respective requirements.





                              TABLE - 1



      Areas Affected by the Urban Bus Retrofit/Rebuild Program



                                                             1980

 Area                                                  Population



Albany-Schenectady-Troy NY                                835,880



Atlanta (Marietta), Ga                                  2,138,231



Baltimore, MD                                           2,199,531



Birmingham (Bessemer), AL                                 883,946



Boston-Lawrence-Salem MA-NH CMSA

 -  Boston (Cambridge, Framingham, Lynn, Waltham) PMSA

 -  Brockton PMSA

 -  Lawrence-Haverhill PMSA

 -  Lowell PMSA

 -  Nashua N.H. PMSA

 -  Salem-Glouchester PMSA                              3,971,376



Buffalo-Niagra Falls, NY CMSA

 -  Buffalo PMSA

 -  Niagra Falls PMSA                                   1,242,826



Charlotte-Gastonia-Rock Hill NC-SC                        971,391



Chicago-Gary-Lake IL-IN-WS CMSA

 -  Aurora-Elgin IL PMSA

 -  Chicago (Evanston, Chicago Heights) IL PMSA

 -  Gary-Hammond (East Chicago), IN PMSA

 -  Joliet IL PMSA

 -  Kenosha, WI PMSA

 -  Lake County (North Chicago, Waukegan only)          7,937,326



Cincinnati, OH-KY-IN CMSA

 -  Cincinnati, OH-KY-IN PMSA

 -  Hamilton-Middletown, OH PMSA                        1,401,491



Cleveland-Akron-Lorraine, OH CMSA

 -  Akron (Barberton, Kent) PMSA

 -  Cleveland PMSA

 -  Lorain-Elyria, PMSA                                 2,834,062



Columbus, OH                                            1,243,833



Dallas-Forth Worth TX CMSA

 -  Dallas (Denton, Irving) PMSA

 -  Fort Worth-Arlington PMSA                           2,930,516

Dayton-Springfield OH                                     942,083



Denver-Boulder, CO CMSA

 -  Coulder-Longmont PMSA

 -  Denver PMSA                                         1,618,461



Detroit-Ann Arbor, MI CMSA

 -  Ann Arbor PMSA

 -  Detroit (Dearborn, Pontiac, Port Huron) PMSA        4,752,820



Greensboro-Winston-Salem-High Point, NC                   851,851



Hartford-New Britain-Middletown CT CMSA

 -  Bristol PMSA

 -  Hartford PMSA

 -  Middletown PMSA

 -  New Britain PMSA                                    1,013,508



Honolulu, Hawaii                                          762,565



Houston-Galveston-Brazoria, TX CMSA

 -  Brazoria PMSA

 -  Galveston-Texas City PMSA

 -  Houston (Baytown) PMSA                              3,101,293



Indianapolis, IN                                        1,166,575



Kansas City, MO-KS CMSA

 -  Kansas City (Leavenworth, Olathe), KS PMSA

 -  Kansas City, MO PMSA                                1,433,458



Los Angeles-Anaheim-Riverside, CA CMSA

 -  Anaheim-Santa Ana PMSA

 -  Los Angeles-Long Beach (Burbank, Pasedena, Pomona, Palm

    Springs) PMSA

 -  Oxnard-Ventura PMSA

 -  Riverside-San Bernardino PMSA                      11,497,568



Louisville, KY-IN                                         956,756



Memphis, TN-AR-MS                                         913,472



Miami-Fort Lauderdale, FL CMSA

 -  Fort Lauderdale-Hollywood-Pompano Beach PMSA

 -  Miami-Haileah (Miami Beach) PMSA                    2,643,981



Milwaukee-Facine (Waukesha), WI CMSA

 -  Milwaukee PMSA

 -  Racine PMSA                                         1,570,275



Minneapolis-St. Paul, MN-WI                             2,137,133



Nashville, TN                                             850,505



New Haven-Waterbury-Meriden, CT                           761,337



New Orleans (Slidell), LA                               1,256,256



New York-Northern New Jersey-Long Island, NY-NJ-CT

 -  Bergen-Passaic, NJ PMSA

 -  Bridgeport-Milford, CT PMSA

 -  Danbury, CT PMSA

 -  Jersey City (Hoboken), NJ PMSA

 -  Middlesex-Somerset-Hunterdon (New Bruswick, Perth Amboy), NJ

    PMSA

 -  Monmouth-Ocean, NJ PMSA

 -  Nassau-Suffolk, NJ PMSA

 -  New York, NY PMSA

 -  Newark, NJ PMSA

 -  Norwalk, CT PMSA

 -  Orange County, PMSA

 -  Stamford, CT PMSA                                  17,539,324



Norfolk-Virginia Beach-Newport News

 (Hampton, Portsmouth, Suffolk), VA                     1,160,311



Oklahoma City (Norman, Shawnee), OK                       860,969



Philadelphia-Wilmington-Trenton, PA-NJ-DE-MD CMSA

 -  Philadelphia (Norristown), PA-NJ PMSA

 -  Trenton (Camden), NJ PMSA

 -  Vineland-Milville-Bridgeport, NJ PMSA

 -  Wilmington, DE-NJ-MD PMSA                           5,680,768



Pheonix (Mesa-Scottsdale-Tempe), AZ                     1,509,052



Pittsburg-Beaver Valley, PA CMSA

 -  Beaver County PMSA

 -  Pittsburg (McKeesport) PMSA                         2,423,311



Portland-Vancouver, OR-WA CMSA

 -  Portland, OR PMSA

 -  Vancouver, WA PMSA                                  1,297,926



Providence-Pawtucket-Fall River, RI-MA CMSA

 -  Fall River, RI-MA PMSA

 -  Pawtucket-Woonsocket-Attleboro, RI-MA PMSA

 -  Providence, R.I. PMSA                               1,083,139



Richmond-Petersburg, VA                                   761,311



Rochester, NY                                             971,230



Sacremento, CA                                          1,099,814



St. Louis-East St. Louis-Alton, MO-IL CMSA

 -  Alton-Granite City, IL PMSA

 -  East St. Louis-Belleville, IL PMSA

 -  St. Louis (St. Charles), MO-IL PMSA                 2,346,998



Salt Lake City-Ogden, Utah                                910,220



San Antonio, TX                                         1,071,954



San Diego (Escondido), CA                               1,861,840



San Francisco-Oakland-San Jose, CA CMSA

 -  Oakland (Berkely, Livermore) PMSA

 -  San Francisco PMSA

 -  San Jose (Palo Alto) PMSA

 -  Santa Cruz PMSA

 -  Santa Rose-Petaluma PMSA

 -  Vallejo-Fairfield-Napa PMSA                         3,606,100



Seattle-Tacoma, WA CMSA

 -  Seattle (Auburn, Everett) PMSA

 -  Tacoma PMSA                                         2,093,112



Tampa-St.-Petersburg-Clearwater FL                      1,613,603



Washington, DC-MD-VA

 -  Washington DC

 -  Frederick MD

 -  Arlington VA                                        3

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