1) The document summarizes the development of on-road mobile emissions estimates for the 2011 National Emissions Inventory (NEI), which relied solely on the EPA's MOVES model for the first time. 2) Key aspects included a state submission process of MOVES County Databases, quality assurance checks on the submitted data, and improvements to default data informed by research projects including new datasets for vehicle age distributions and long-haul truck vehicle miles traveled. 3) Large-scale MOVES modeling runs were performed in a cloud computing environment to generate emission factor lookup tables needed for nationwide estimates in the SMOVES emissions modeling system.

1. Development of On-Road Emissions
for the 2011 NEI
Emissions Inventory Conference, San Diego, CA
April 16, 2015
Allison DenBleyker, John Koupal, Jeanette Alvis, Scott Fincher, Tim DeFries,
Cindy Palacios, Heather Perez, Richard Billings
Eastern Research Group, Inc.
Alexis Zubrow, Dave Brzezinski, Harvey Michaels, Alison Eyth, Laurel Driver
EPA Office of Air and Radiation

2. Acknowledgments
• States
• Coordinating Research Council (CRC)
Atmospheric Impacts Committee
– Project Leads: Susan Collet (Toyota), Mark Janssen (LADCO)
• Fluid and Reason
– Wes Faler
• ERG
– Meredith Weatherby, Anita White, Sandeep Kishan

3. National Emissions Inventory (NEI)
Overview
• NEI is compiled by EPA every 3 years, covering
major pollutants for all sectors and U.S. counties
• Final 2011 estimates published March 2015
• 2011 is the first NEI relying solely on MOVES for
on-road sources (outside CA)
• States given option to submit their own emissions,
or MOVES County Database (CDB) inputs

4. SMOKE-MOVES
Cloud MOVES Runs
SMOKE
On-road
NEI
State
Submitted
Data
QA Review
CRC Updates
MOVES
Input
Databases
all 3,224
counties
VMT
VPOP
HOT
Speeds
Activity
Emission Factors
Default
Data
“Representative”
County
Databases
284 counties
NEI On-road Flow Diagram

5. Submittal Process
• States submitted data through the EIS
(Emission Inventory System)
• County Databases (CDBs) of MOVES inputs
• Documentation
• QA check script results

6. What is Submitted?
MOVES County Data Manager
• County Data Manager (CDM) allows custom input for
following parameters, through MS Excel tables
Data entered through CDM “Best Practice” Sources
Vehicle Miles Travelled HPMS, Travel models
Temperature & Humidity Meteorology data
Vehicle Population Registration data, fleets
Average Speed Distribution Travel models
Vehicle Age Distribution Registration data, fleets
Fuel Properties/Market Shares Fuel surveys, fuel regulations
Road Type Distribution HPMS, Travel models (VMT source)
Fuel Technology Mix Registration data, fleets
I/M Compliance/Waiver Rates Operating program data & history
CDM interface

7. MOVES CDBs Submitted (Dark Blue)
33 states provided
data
(~1,400 counties)

8. Quality Checks on Submitted Data

9. Quality Assurance (QA) Checks
• Reviewed each table in the CDBs
• EPA’s “Completeness” QA script
• ERG’s “Reasonableness” QA script
– Flags unusual patterns for further review
– For example, gaps in model year coverage for I/M
programs or unusually “old” age distribution
• In some cases, EPA asked states for
revised data
• Updated the CDBs with corrections

10. Improvements to Default Data

11. Coordinating Research Council
– Supplemental Projects
• CRC sponsored two projects to evaluate state-submitted
data, and improve MOVES defaults used in the NEI
• CRC A-84 (also published as TRB14-2989)
– Analysis of MOVES data submitted by states vs. defaults
– MOVES sensitivity analysis to determine most influential state inputs
• CRC A-88 (also published as TRB 15-5129)
– Identify reliable national datasets to improve default MOVES NEI
inputs at the county level
– Task 1: Identify promising inputs to update
• Car/Light Truck Age Distribution, Population
• Long-Haul Truck VMT
• Passenger trip activity
• Truck idle locations
• Temporal VMT distributions
– Task 2: Make updates for NEI
• Age distribution, population; Long Haul VMT

12. CRC A-84 Results:
Most influential MOVES
inputs by pollutant
Source Type/Cluster Input Varied Total Increase
Passenger Car Age Distribution 24%
Passenger Truck Age Distribution 22%
Passenger Truck Population Fraction 16%
Passenger Truck VMT Fraction 14%
Passenger Car Population Fraction 12%
Source Type/Cluster Input Varied Total Increase
Passenger Truck VMT Fraction 30%
Passenger Truck Age Distribution 25%
Passenger Car VMT Fraction 22%
Passenger Car Age Distribution 21%
Light Commercial Truck Population Fraction 11%
Source Type/Cluster Input Varied Total Increase
Combination Long Haul Truck VMT Fraction 39%
Passenger Truck VMT Fraction 22%
Combination Short Haul Truck VMT Fraction 20%
Urban Unrestricted_Day Average Speed
Distribution
18%
Passenger Car VMT Fraction 12%
Source Type/Cluster Input Varied Total Increase
Combination Long Haul Truck VMT Fraction 79%
Combination Short Haul Truck VMT Fraction 35%
Urban Unrestricted_Day Average Speed
Distribution
18%
Rural Unrestricted_Day Average Speed
Distribution
14%
Combination Long Haul Truck Age Distribution 13%
HC
CO
NOx
PM
Percent change in total
emissions when input
was changed from 10th
to 90th percentile of
state-supplied data

13. Average Passenger Car age
by county, 2011
IHS average age ranges
from 4 – 17 years
NEI default is 9.8 years,
for all counties
IHS Automotive Data

14. Freight Analysis Framework 1 of 2
• Estimates long-
haul VMT for all
major road
segments
• Joins several
datasets
– VMT
– Commodity Flow
– Network Capacity
– Truck Trip Lengths

15. Freight Analysis Framework 2 of 2
0.27 0.29 0.27 0.28
0.48
0.44
0.35
0.39
0.57 0.59
0.53
0.62
0.90 0.88
0.70
0.84
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
A-88 Update
MOVES default
Urban
Unrestricted
Rural RestrictedCombination Unit Trucks
Fractions are ratio of VMT:
long-haul/ (long-haul + short-haul)
NEI default is 59% for combination
unit trucks
(12% for single unit trucks, not shown)

16. Use of CRC A-88
to update the NEI defaults
IHS Data
• Age distribution
• Population
• More
representative
counties
ID Source Use Type
11 Motorcycle
21 Passenger Car
31 Passenger Truck
32 Light Commercial Truck
41 Intercity Bus
42 Transit Bus
43 School Bus
51 Refuse Truck
52 Single Unit Short-haul Truck
53 Single Unit Long-haul Truck
54 Motor Home
61 Combination Short-haul Truck
62 Combination Long-haul Truck
FAF Data
• Long-Haul VMT
fractions
• Updated
hotelling hours
(source type 62)
Datasets (posted on www.crcao.org)
• Populations & Age Distribution for every U.S. County
• Long-Haul / Short-Haul VMT Fractions
• Truck idle locations – national GIS database

17. Creating SMOKE activity files

18. SMOKE Activity Files
• NEI on-road emissions are calculated
inside SMOKE
• SMOKE requires FF10-formatted activity
– VMT, Population, Hoteling, Speeds
– By county and SCC
• OTAQ and ERG developed scripts take
inputs from submitted CDB tables and
output FF10 tables ready for SMOKE

19. Adding Representative Counties

20. What is a representative county?
• A representative county is one that shares
similar emission factor-determining
properties as other counties
• Representative county emission factors
mapped to similar counties for the
inventory calculation
• NEI uses MOVES runs results for 284
counties to represent all 3,224 counties

21. Why add more representative
counties?
• CRC A-88 project brought new default
light-duty age distributions to NEI
– Average age ranges 4 to 17 years old
– New variation at the county level
• Ramp Fraction data added to criteria for
grouping “similar” counties
– Ramp Fraction is the fraction of highway driving time
spent on ramps
– Variation in submitted county data ranges 0 to 0.15,
plus some outliers with higher fractions

22. Adding Representative Counties
1 of 2
Light-duty age distributions
Average 10.8 years old
N 2,082 counties
Bin
Description (Mean age in
number of years old in 2011)
Number of
Counties
1 0.0 ≤ Mean Age < 7.0 1
2 7.0 ≤ Mean Age < 9.0 140
3 9.0 ≤ Mean Age < 11.0 994
4 11.0 ≤ Mean Age < 13.0 920
5 13.0 ≤ Mean Age < 15.0 25
6 15.0 ≤ Mean Age 2

23. Adding Representative Counties
2 of 2
Ramp fractions in the submitted data
N = 716 counties
Ramp fraction
= 0.08 (default)
Ramp fraction
~ 0.15
Ramp fraction
= 0
Bin
Description
(Fractions from 0 to 1)
Number of
Counties
1 0 ≤ ramp fraction < 0.05 244
2 0.05 ≤ ramp fraction < 0.09 336
3 0.09 ≤ ramp fraction < 0.13 120
4 0.13 ≤ ramp fraction < 0.17 7
5 0.17 ≤ ramp fraction 9

24. NEI 2011 v2
284 Representative Counties
Reference counties
are outlined in black.
Number of counties
assigned to each
reference county are
labeled.

25. Executing MOVES runs in the Cloud

26. MOVES in the Cloud
• Generated the lookup tables needed for
nationwide emission inventory in SMOKE
– Emission factor lookup tables
– Range of temperature/humidity conditions
• Cloud CPUs rented by processing time
– 568 instances in parallel (284 representative counties, 2
months)
• Computing Time
– Execution time 48-60 hours
– Total processing time 30,000 hours
– ~3.5 years on a single machine

27. Summary of on-road emissions
development for NEI
• NEI 2011 is the first to solely use MOVES
• Submittal process invites states to provide CDB(s)
• QA checks rely on EPA and ERG scripts
• CRC A-88 data was introduced to improve default
data in the NEI
• FF10 activity files for SMOKE are consistent with
state submitted activity and MOVES internal
calculators
• Cloud environment critical to support large-scale
MOVES modeling