# Presentation: 270957

## Preparation of Fine Particulate Emissions Inventories 

***Preparation of Fine Particulate Emissions Inventories ***

**Chapter 4 – Nonroad Mobile Sources**

**Notes:**
After this lesson, participants will be able to:
describe EPA’s NONROAD model 
explain the approaches for estimating PM emissions from aircraft, commercial marine vessels, and locomotives

The discussion of EPA’s National Mobile Inventory Model presented in Chapter 3 is also applicable to the nonroad category, but will not be repeated.  

## What Sources are Included?

- SCCs (4-digit SCC denotes engine type)
- 	2260xxxxxx	2-Stroke Gasoline
- 	2265xxxxxx	4-Stroke Gasoline
- 	2267xxxxxx	Liquefied Petroleum Gasoline (LPG)
- 	2268xxxxxx	Compressed Natural Gas (CNG)
- 	2270xxxxxx	Diesel
- Two exceptions:
- 	2282xxxxxx	Recreational Marine
- 	2285xxxxxx	Railroad Maintenance

**Notes:**
This slide lists the source categories that are included in the NONROAD model.  
The four-digit source classification code generally denotes the engine type, or fuel that is used in the nonroad equipment.  
The four-digit SCC denotes the equipment type instead of engine type in two categories: 
 recreational marine, and 
 railroad maintenance. 

## What Sources are Included? (cont.)

- Logging
- Recreational marine vessels
- Recreational equipment
- Oil field
- Underground mining
- Railway maintenance

- Equipment Category (7-digit SCC denotes equipment)

- 10-digit SCC generally denotes specific application within equipment category

- Airport ground support
- Agricultural
- Construction
- Industrial
- Commercial
- Residential/commercial
- 	Lawn and garden

**Notes:**
There are 12 different equipment categories denoted by the seven-digit SCC in the NONROAD model.  

Each category may have multiple applications that are specified at the 10-digit SCC level. 

## What Sources are Included? (cont.)

- Pollutants
- PM10-PRI, PM2.5-PRI, CO, NOx, VOC, SO2, and CO2
- PM10 and PM2.5 emission factors represent Primary PM
- NH3 not a direct output of NONROAD, can be estimated based on fuel consumption and EPA emission factors derived from light-duty onroad vehicle emission measurements
- Model estimates exhaust and evaporative VOC components

**Notes:**
The pollutants included in the NONROAD model are PM10 and PM2.5 (representing  primary PM ), CO, NOx, VOC, SO2 and CO2.  

Although ammonia is not a direct output of the NONROAD model, it can be estimated from fuel consumption estimates.

These fuel consumption estimates come from the model and the EPA emission factors are derived from light-duty onroad vehicle emission measurements.  

In addition to exhaust pollutants, the NONROAD model estimates evaporative VOC components from crankcase emissions, spillage, and vapor displacement. 

## NONROAD Model Emission Equation

- Iexh = Eexh * A * L * P * N
- where:	*I*exh	=	Exhaust emissions, (ton/year)
- 		*E*exh	=	Exhaust emission factor, (ton/hp-hr)
- 		*A*	=	Equipment activity, (hours/year)
- 		*L**	*=	Load factor, (proportion of rated power 				used on average basis)
- 		*P**	*=	Average rated power for modeled engines, (hp)
- 		*N*	=	Equipment population

**Notes:**
The NONROAD model calculates exhaust emissions by assuming that they are dependent on equipment activity.

Measures of equipment activity used in the model include: 
number of hours per year the equipment is used, 
the load factor at which the engine is operating, 
the average rate of horse power of the engine, and 
the equipment population (i.e., how many pieces of equipment are in use).  

These equipment activity measures are multiplied by emissions factors in tons per horsepower-hour to obtain emission estimates as shown by the equation on the slide. 

## NONROAD ModelEmission Equation (cont.)

- Emission Factors
- Dependent on engine type and engine size (horsepower)
- Future year emission controls or standards reflected in emission factor value
- SO2, CO2, and evaporative VOC emissions based on fuel consumption
- PM10 assumed to be equivalent to total PM
- For gasoline and diesel-fueled engines, PM2.5 = 0.92 * PM10
- For LPG and CNG-fueled engines, PM2.5 = PM10

**Notes:**
The emission factors are dependent on the engine type as well as the engine size, or horsepower.  

Future year emission controls or standards are reflected in revised emission rates, so that as older engines are scrapped and new engines replace them, revised emission rates are applied to the new engines to reflect the standards that they need to meet. 

SO2, CO2 and evaporative VOC emissions are based on fuel consumption.  

In the NONROAD model:
PM10 is assumed to be equivalent to total PM and for gasoline and diesel engines
PM2.5 is assumed to be 0.92 times PM10.  
all PM is assumed to be less than PM2.5 for liquefied petroleum gas and compressed natural gas engines

## Geographic Allocation

- County-level allocation of equipment population
- National or state-level equipment populations from PSR or alternate sources, reported by equipment type (SCC) and horsepower range
- Allocates populations to counties using surrogate indicators that correlate with nonroad activity for specific equipment types

**Notes:**
Because there are no estimates of county level populations, the NONROAD model estimates those populations using surrogate indicators.

Using national or state level equipment populations (either by equipment type or horsepower range), the model allocates them to the county level by using surrogate indicators.

These indicators correlate with nonroad activity for a specific equipment type.  

##  Temporal Allocation 

- NONROAD accounts for temporal variations in activity
- Monthly activity profiles by equipment category according to 10 geographic regions
- Typical weekday and weekend day activity profiles by equipment category; do not vary by region

**Notes:**
The NONROAD model also accounts for temporal variations in activity.  

The temporal profiles vary by month and depend on the equipment category and the geographic region of the country.  

The model contains typical weekday and weekend day activity profiles by equipment category, however, those do not vary by region. 

## Improving Inputs

- Specify local fuel characteristics and ambient temperatures
- Replace NONROAD model default activity inputs with State or local inputs
- Perform local survey
- Obtain local information to improve geographic allocation indicators and temporal profiles

**Notes:**
Suggested methods for improving EPA’s latest 2002 model results: 
specify local fuel characteristics and the ambient temperatures specific to the area being modeled.  
replace the NONROAD default activity inputs with state or local data, if possible.

It can be resource intensive to obtain reasonable estimates to replace the default values.  To obtain this data, it would be necessary to perform a local survey of equipment owners and users.

Another way to improve the model results is to obtain local information to improve the geographic allocation (i.e., going from state to county).  Obtaining local data used for the temporal profiles can also improve the model results. 

## Improving Inputs (cont.)

- Significant PM Fine Equipment Categories include:
- Diesel construction
- Diesel farm
- Diesel industrial
- Gasoline lawn and garden
- Gasoline recreational marine

**Notes:**
Another approach to improve the model results is to focus on priority categories and obtain better data for those categories.  

For example, for fine PM, priority categories would be diesel construction, diesel farm, diesel industrial, gasoline lawn and garden, and gasoline recreational marine. 

## Resources

- http://www.epa.gov/otaq/nonrdmdl.htm
- From this web site, there are links to:
- Downloadable version of NONROAD2002a model
- Documentation
- User’s Guide
- Technical Reports to describe the sources and development of all model default input values

**Notes:**
The latest version of EPA’s NONROAD model can be accessed at the web address listed here. 

This web site contains documentation, a user’s guide, as well as technical reports to describe the sources and development of all the default input values (e.g., equipment populations, geographic allocations, growth factors, and emission rates). 

## AIRCRAFT - Overview

- SCCs
- 2275020000 – Commercial Aircraft
- 2275050000 – General Aviation
- 2275060000 – Air Taxis
- 2275001000 – Military Aircraft
- Activity Data – landing and take-off operations (LTOs)
- Emission Factors – aircraft/engine-specific or fleet average

**Notes:**
The SCCs representing the aircraft categories that have been historically reported in the NEI are listed here.  

The activity data used for aircraft are known as a landing and takeoff operations, or LTO.  

Emissions are estimated by applying emission factors to the LTO data that are either specific to an aircraft or engine type.  

If the make-up of the aircraft fleet is unknown, fleet averages can be applied to the emission factors. 

## AIRCRAFT - Overview (cont.)

- Definitions of Aircraft Categories:
- Commercial - Aircraft used for scheduled service to transport passengers, freight, or both
- Air taxis - Smaller aircraft operating on a more limited basis to transport passengers and freight
- General aviation - aircraft used on an unscheduled basis for recreational flying, personal transportation, and other activities, including business travel
- Military aircraft - aircraft used to support military operations

**Notes:**
This slide lists the definitions of the aircraft categories that have been historically reported in the NEI. 

## AIRCRAFT - Overview (cont.)

- Aircraft operations are defined by landing and take-off operation (LTO) cycles, consisting of five specific modes:
- Approach
- Taxi/idle‐in
- Taxi/idle‐out
- Take-off
- Climb-out
- The operation time in each of these modes (TIM) is dependent on the aircraft category, local meteorological conditions, and airport operational considerations

**Notes:**
The LTO cycle consists of different modes including: the approach, taxi idle in, taxi idle out, take off, and climb out.  

Operation time in each of these modes is dependent on the aircraft category, meteorological conditions, as well as how the airport is operating (e.g., the length of time waiting to take off).  

There can be substantial variations in these modes from airport to airport.  Because different emission rates result when the aircraft are operating in each of these modes, it is important to consider all of these factors in estimating emissions from aircraft. 

## COMMERCIAL AIRCRAFTNEI Method

- Activity/Emissions Developed at National Level
- Commercial Aircraft Emissions
- Calculated using national-level FAA LTO data by aircraft type and emission rates from Emissions and Dispersion Modeling System (EDMS) Version 4.0.
- Used default engines for each aircraft type and default time-in-mode values.

**Notes:**
The NEI estimated emissions for commercial aircraft by using national-level FAA LTO data by aircraft type and emission rates from the Emissions and Dispersion Modeling System version 4.0.  

## General Aviation, Air Taxi and Military Aircraft – NEI Method

- National Emissions for General Aviation, Air Taxi, and Military Aircraft calculated using equation:
*National Emissions**c,p** = National LTOs**c** * EF**c,p*
- 	where:	*LTOs*	=	landing and take-off operations;
*	**	**	**EF*	=	emission factor;
*	**	**	**c*	=	aircraft category; and
*	**	**	**p*	=	criteria pollutant.

**Notes:**
The NEI estimated emissions from the general aviation, air taxi, and military aircraft categories by also using national LTO data; however, data was not available for specific aircraft types within each of the aircraft categories.  

Consequently, emissions for these three categories were estimated by multiplying total LTO by an emission factor as shown in the equation on this slide.   

## General Aviation, Air Taxi and Military Aircraft – NEI Method (cont.)

- LTO-based PM Emission Factors
- General Aviation
- PM10-PRI:	0.2367 lbs/LTO
- Air Taxi and Military Aircraft
- PM10-PRI:	0.60333 lbs/LTO
- PM2.5-PRI Emissions
- Estimated by applying particle size multiplier developed for related engines to PM10 emissions estimate
- PM2.5-PRI = 0.92 * PM10-PRI

**Notes:**
Using PM as an example, the emission factors are LTO-based and represent a fleet average emission factor for the general aviation, air taxi, and military aircraft categories.  This slide lists these PM emission factors.  

The PM2.5 primary emissions are estimated, as they are for many combustion sources, by applying a particle-sized multiplier of 0.92 to the PM10. 

## AIRCRAFT - NEI Method

- National Emissions Allocation for Each Aircraft Category
*Airport Emissions**c,p,x** = National Emissions**c,p** * AF**c,p,x*
- where:	*AF*	=		allocation factor; and
*	**	**x*	=		airport (e.g. La Guardia) *	*
*	**	**c*	=		aircraft category; and
*	**	**p*	=		criteria pollutant.
*AF**c,x** = LTOs**c,x**/National LTOs**c*

**Notes:**
Once national emissions are calculated for the four aircraft categories, the NEI allocates them to the county level based on airport level LTO data as shown by this equation.  

Using La Guardia airport as an example, the NEI assumes that a fraction of the total LTO is assigned to La Guardia, and the emissions calculated from this allocation are assigned to the corresponding county. 

## AIRCRAFT - NEI Method (cont.)

- Documentation on the procedures used to develop criteria pollutant (as well as HAP) aircraft emission estimates is available at:
- ftp://ftp.epa.gov/EmisInventory/finalnei99ver3/ criteria/documentation/nonroad/ 99nonroad_voli_oct2003.pdf

**Notes:**
More information on the NEI methodology for estimating emissions from aircraft categories can be found at the web address listed here.   

## AIRCRAFT - General Approach

- Determine the mixing height to be used to define the LTO cycle
- Define the fleet make‐up for each airport
- Determine airport activity in terms of the number of LTOs by aircraft/engine type
- Select emission factors for each engine model associated with the aircraft fleet

**Notes:**
Although it may be acceptable to rely upon the NEI data for smaller airports in an area, a bottom up inventory should be developed for the larger airports.  

There are seven steps for developing an aircraft inventory for a specific airport:
Step 1 - Determine the mixing height to be used to define the LTO cycle.  The mixing height is important because above the mixing height, emissions are not expected to contribute much to ground level pollutant concentrations. 
Step 2 - Define the fleet make-up for the airport.  
Step 3 - Determine airport activity in terms of the number of LTO by aircraft and their associated engine-type.  
Step 4 - Select emission factors for each engine model that is associated with the aircraft fleet at the airport being inventoried (Instead of using defaults that EDMS may apply for a specific aircraft type). 

## AIRCRAFT - General Approach (cont.)

- Estimate the time-in-mode (TIM) for the aircraft fleet at each airport
- Calculate emissions based on aircraft LTOs, emission factors for each aircraft engine model, and estimated aircraft TIM
- Aggregate the emissions across aircraft

**Notes:**
Step 5 – Estimate the time-in-mode for the aircraft fleet at the airport. 
Step 6 – Calculate the emissions (based on the aircraft LTO data, the emission rates for each aircraft engine model, and the time-in-mode data).   
Step 7 – Aggregate the emissions across aircraft to obtain a total for the airport. 

## COMMERCIAL AIRCRAFTImprovements to NEI

- Determine engine types associated with local aircraft types, to replace default aircraft/engine assignments in EDMS
- Obtain information on climb-out, takeoff, approach times, as well as taxi/idle times

**Notes:**
Developing an emissions inventory for a local airport involves determining the engine types associated with the local aircraft types.  
This data is an improvement over the assumptions used in the NEI for the commercial aircraft category.  
In addition, developing information on climb-out, take-off, approach time, and taxi idle times will be an improvement over the defaults used in the NEI. 

## COMMERCIAL AIRCRAFT Improvements to NEI (cont.)

- For PM10 and PM2.5, match few emission factors from EPA’s 1992 Volume IV, Mobile Sources Procedures document, to the aircraft engines in their fleet as best as possible
- EPA OTAQ working with FAA to develop updated aircraft PM emission factors
- Regional inventories have used PM-10/NOx emission factor ratios for air taxi applied to commercial aircraft NOx emissions

**Notes:**
Because the current version of EDMS does not include PM emission rates, EPA recommends that the few PM emission factors available in the 1992 Mobile Sources Procedures document be matched to the aircraft engines in the local fleet as best as possible.  

EPA is aware of this limitation and work is underway to try to get better data on PM emission factors for commercial aircraft.  

Some regional inventories have looked at using emission factor ratios to develop the PM emission rates for commercial aircraft.  Specifically, the ratio based on the PM10 and NOX emission factor ratios for air toxics was applied to the commercial aircraft NOX emissions. 

## GA, AT and Military Aircraft Improvements to NEI 

- Obtain local estimates of LTOs for these categories (to obtain LTOs not covered by FAA data)
- Obtain information on the aircraft/engine types that comprise the aircraft fleet for these categories.  Apply EPA engine-specific emission factors or EDMS, if available

**Notes:**
For the other categories (general aviation, air taxis, and military aircraft) the NEI can be improved by obtaining local LTO estimates, such as: 
data from smaller airports that may not be reporting to the FAA
military bases (although heightened security measures have made it harder to obtain data from military operations) 

Another improvement is to obtain information on the aircraft/engine types that comprise the fleet for these other categories.  If data on the mix of aircraft types in a fleet are available, engine specific emission factors or EDMS could be used to estimate emissions.  

Finally, the NEI can be improved by maintaining the latitude/longitude of the airport so the emissions are not “smeared” across the entire county. 

## COMMERCIAL MARINE VESSELSOverview

- Commercial Marine Vessel SCCs
- 2280002100 – Diesel, In Port
- 2280002200 – Diesel, Underway
- 2280003100 – Residual, In Port
- 2280003200 – Residual, Underway

**Notes:**
The SCCs representing the commercial marine vessel categories that are currently used in the NEI are listed on this slide.  

This includes diesel activity for ships in port and underway, as well as residual or steamships for those two categories. 

## COMMERCIAL MARINE VESSELS NEI Method

- National Diesel and Residual Emissions split into port and underway components
- Port and underway activity allocated separately, assigned to counties
- Port emissions assigned to a single county in port area

**Notes:**
The NEI methodology for commercial marine vessels is a top down method that splits national diesel and residual emissions into port and underway components.  

The methodology makes assumptions about what portion of the activity for both diesel and residual ships takes place in ports and what portion takes place underway (i.e., away from ports or on their way between ports).  

These are allocated separately since port activity surrounds a port area, while underway covers a larger area such as along a river system.  Both port and underway emissions are assigned to counties, however, port emissions are assigned to a single county in a port area. 

## COMMERCIAL MARINE VESSELS NEI Method (cont.)

- Documentation on the procedures used to develop criteria pollutant (as well as HAP) commercial marine emission estimates is available at:
- ftp://ftp.epa.gov/EmisInventory/finalnei99ver3/ criteria/documentation/nonroad/99nonroadvoli_oct2003.pdf

**Notes:**
More information on the NEI methodology for estimating emissions from the commercial marine vessel categories can be found at the web address listed here.   

## COMMERCIAL MARINE VESSELS Improvements to NEI

- Review 1999 NEI emission estimates for representativeness
- Allocate port emissions to ports other than 150 largest
- Allocate port emissions to appropriate counties, since port emissions assigned to a single county in port area

**Notes:**
One approach to improving NEI emission estimates for the commercial marine vessel category is to review the spatial allocation of commercial marine emissions included in the NEI. 
Note that: 
NEI examines port traffic for the 150 largest ports in the United States and only allocates those emissions.  
Additional ports are not accounted for in the allocation method.  Identifying smaller ports that are not accounted for in the NEI would be an improvement. 

Another approach to improving the NEI method is to allocate port emissions to the appropriate counties.  
Port emissions in the NEI are being assigned to a single county in the port area. 
Some ports along the Mississippi and the Ohio Rivers that span multiple counties and even state boundaries.  Assigning these port emissions to the appropriate counties and states is another way to improve the NEI results. 

## COMMERCIAL MARINE VESSELS Improvements to NEI (cont.)

- Obtain activity estimates at the local or State-level from Department of Transportation, Port Authority
- Fuel consumption
- Categories of vessels
- Number and size (hp) of vessels in each category
- Number of hours at each time-in-mode
- Cruising
- Reduced speed zone
- Maneuvering
- Hotelling

**Notes:**
Another approach to improving the NEI results is to conduct a bottom-up inventory by obtaining activity estimates at the state or local level from the DOT or Port Authority.  
This can include: 
data on fuel consumption
data to define categories and characteristics of the vessels (number, size and horsepower in each category) 

Similar to aircraft, there are different emission rates depending on the operating mode of the vessels, so data on the fraction of the time engines are spent in those modes would also be an improvement. 

## COMMERCIAL MARINE VESSELS Emission Calculation

- Emissions = Pop * HP * LF * ACT * EF
- where:
- Pop	= Vessel Population or Ship Calls
- HP	= Average Power (hp)
- LF		= Load Factor (fraction of available power)
- ACT	= Activity (hrs)
- EF	= Emission Factor (g/hp-hr)

**Notes:**
This slide lists the equation for calculating emissions from commercial marine vessels.  

It requires data on vessel populations, horsepower, load factor, and the time-in-mode operation.  

Applying this emission equation with this data will produce a better inventory. 

## COMMERCIAL MARINE VESSELS Activity

- 1999 EPA studies:
*Commercial Marine Activity for Deep Sea Ports in the United States*
*Commercial Marine Activity for Great Lake and Inland River Ports in the United States*
- Studies provide activity profiles for select ports, and present method for an inventory preparer to allocate detailed time-in-mode activity data from a typical port to another similar port

**Notes:**
In 1999 EPA completed the two studies shown here.  

The content of these studies:
provides commercial marine activity profiles for select ports, and 
presents a method for allocating detailed time-in-mode activity data from a typical port to another similar port.  

## COMMERCIAL MARINE VESSELS Activity (cont.)

- Activity profiles for typical port include:
- Number of vessels in each category
- Vessel Characterization, including propulsion size (horsepower), capacity tonnage, and engine age
- Number of hours at each time-in-mode associated with cruising, reduced speed zone, maneuvering, and hotelling

**Notes:**
The specific variables that are collected for the typical ports in these studies include:

 the number of vessels in each category, 
 the vessel characterization, including propulsion size, capacity tonnage, and engine age, and 
 the number of hours at each time-in-mode associated with cruising, reduced speed zone, maneuvering, and hotelling.

## COMMERCIAL MARINE VESSELS  Activity (cont.)

- Data on the number of trips and the tons of cargo handled by vessel type are provided for the top 95 Deep Sea Ports and top 60 Great Lake and Inland River Ports
- More detailed activity for these ports can then be estimated based on the data calculated for a typical port

**Notes:**
These studies also contain data on the number of trips and the tons of cargo handled by vessel type for the top 95 deep-sea ports and the top 60 Great Lake and inland river ports.  

Based on the data calculated for a typical port, more detailed activity can be estimated for these ports.  

These reports also describe how the typical port inventories were developed and how they can be scaled for the port activity in a specific area.  

## COMMERCIAL MARINE VESSELS  Emission Factors

- Depending on activity data obtained:
- Horsepower-based emission factors
- Fuel-based emission factors
- EPA performing studies to develop updated emission rates
- Category 3 Engine Final Rulemaking, January 2003

**Notes:**
Horsepower-based emission factors are available for use with activity data on the number and size of engines.  

There are also fuel-based emission factors available for use with activity data on fuel consumption.  

EPA has been performing studies to develop updated emission factors as part of their rulemaking activities, such as the Category 3 engine final rulemaking that was published in 2003. 

## COMMERCIAL MARINE VESSELS  Emission Factors (cont.)

- PM10-PRI EFs for Category 1 and Category 2 Engines:

| Engine Category | PM10 [g/kW-hr] |
| --- | --- |
| Category 1:  37-75 kW | 0.90 |
| Category 1:  75-225 kW | 0.40 |
| Category 1:  225+ kW | 0.30 |
| Category 2 (5-30 l/cylinder) | 0.32 |

**Notes:**
This table presents EPA recommended PM10 emission factors for specific categories of commercial marine engines, on a gram per kilowatt-hour basis for Category 1 and Category 2 engines (i.e., small commercial marine vessel engines). 

## COMMERCIAL MARINE VESSELS  Emission Factors (cont.)

- PM10-PRI EFs for Category 3 Engines (> 30 l/cylinder):

| Mode: Engine | PM10 [g/kW-hr] |
| --- | --- |
| Cruise and Reduced Speed Zone: 2-stroke | 1.73 |
| Cruise and Reduced Speed Zone: 4-stroke | 1.76 |
| Maneuvering: 2-stroke | 2.91 |
| Maneuvering: 4-stroke | 2.98 |
| Hotelling: 2-stroke | 0.32 |
| Hotelling: 4-stroke | 0.32	 |
| All Modes: Steam Generators | 2.49 |

**Notes:**
EPA recommended PM10 emission factors for the larger engines are listed in this table.  

These factors are listed by the different modes of operation. 

## COMMERCIAL MARINE VESSELS Emission Factors (cont.)

- Emission factors in grams per gallon fuel consumed also available from *Procedures for Emission Inventory Preparation, Volume IV:  Mobile Sources*, EPA-450/4-81-026d (Revised), U.S. EPA, OAQPS, July 1989
- PM2.5-PRI = 0.92 * PM10-PRI emissions

**Notes:**
Emission factors in grams per gallon of fuel consumed are also available from the document listed on this slide.   

As with aircraft category,  PM2.5 emissions from commercial marine vessels are estimated to be 92% of the PM10 emissions. 

## LOCOMOTIVES Overview

- SCCs:
- 2285002006 – Diesel Class I Line Haul
- 2285002007 – Diesel Class II/III Line Haul
- 2285002008 – Diesel Passenger (Amtrak)
- 2285002009 – Diesel Commuter
- 2285002010 – Diesel Switchyard Locomotives

**Notes:**
The SCCs representing the locomotive categories that are currently used in the NEI are listed on this slide.    

This includes larger Class I line haul locomotives that travel through many states, as well as the smaller Class II and III line haul locomotives that tend to operate in a smaller area.  

The NEI also has information on passenger Amtrak trains, commuter trains, and switchyard operations. 

## LOCOMOTIVES NEI Methods 

- PM Emission Factors (represent Primary PM)
- Line-Haul
- PM10:		6.7 g/gallon
- PM2.5:	6.03 g/gallon
- Yard
- PM10:		9.2 g/gallon
- PM2.5:	8.28 g/gallon

**Notes:**
The PM emission factors in that are used in the NEI for the line haul and yard operations are listed on this slide.  

## LOCOMOTIVES NEI Methods (cont.)

- Activity Data (Gallons of distillate fuel oil consumed)
- National Activity
- 1999 year U.S. distillate consumption by railroads
- Class I
- Class II/III
- Passenger
- Commuter
- Class I Line-Haul versus Yard (Switch) Operation Activity
- Multiplied National Class I consumption by estimated line-haul percentage of total fuel consumption

**Notes:**
The activity data are based on a national estimate of the gallons of distillate fuel oil consumed.  
This national fuel consumption is allocated among four of the five categories of railroads to develop a national activity value for these four categories.  

Switchyard operation activity is estimated by multiplying the national Class I fuel consumption by the estimated line-haul percentage of the total fuel consumption.  It is assumed that fuel consumption estimates for Class I line-haul locomotives include switchyard fuel consumption.  

This assumption is based on the fact that the larger line-haul railroads are the ones that tend to operate in a switchyard. 

## LOCOMOTIVESNEI Methods (cont.)

- County-level emissions allocation
- National emissions allocated to counties based on ratio of county to national rail activity
- Rail activity measured as product of density (gross ton miles per mile) on each rail line and mileage for the associated rail line in county determined through GIS analysis

**Notes:**
The allocation of the activity data to the county level is based on a ratio of county to national rail activity.  

This rail activity is measured as a product of density (gross tons per mile) for each rail line and mileage for the associated rail line in the county.  

Mileage for each rail line in the county is measured using a GIS database that is available from the Bureau of Transportation Statistics. 

## LOCOMOTIVES NEI Methods (cont.)

- Detailed documentation on the procedures used to develop criteria pollutant locomotive emission estimates for the 1999 NEI are available at:
- ftp://ftp.epa.gov/EmisInventory/finalnei99ver3/ criteria/documentation/nonroad/ 99nonroad_voli_oct2003.pdf

**Notes:**
Detailed documentation on the procedures used to develop criteria and HAP pollutant locomotive emission estimates for the 1999 NEI can be found at the web address listed here.

## LOCOMOTIVES Improving the NEI

- Review NEI emission estimates for representativeness
- Obtain more representative fuel consumption estimates at the local or State-level
- Determine relative contribution of line-haul versus yard activity at local or State-level

**Notes:**
The first step in improving the NEI locomotive emission estimates is to examine the NEI data for reasonableness.  
If the NEI data does not represent emissions in a specific area, more representative fuel consumption at the local or state level should be obtained.  

Also, because the NEI makes an assumption to estimate switchyard emissions, an improvement could be made by obtaining information on the actual switchyard activity in the study area. 

## LOCOMOTIVES Case Study - Overview 

- Case Study:  County-level Locomotive Inventory for Sedgwick County, KS
- See Case Study Number 4-1

**Notes:**
This case study describes the development of a county level locomotive inventory for Sedgwick County, Kansas.  

Direct student to Case Study Number 4-1 and discuss it with the students.

## LOCOMOTIVES Case Study – Solution

- Case Study:  County-level Locomotive Inventory for Sedgwick County, KS
- See Handout 4-1

**Notes:**
Distribute the solutions (Handout 4-1) to the case study.  Review each question with the students.  Encourage discussion among the class.  Ask each group to report on the questions that were assigned to them.  Ask the other groups to critique their responses.