EmiLink: Mobile Source Air Toxic Analysis Tool

17th International Emission Inventory Conference

Session 11: Mobile Sources

Madhusudhan VenugopalNorth Central Texas Council of Governments

June 5, 2008

MSAT BACKGROUNDMobile Source Air Toxics

Mobile source air toxics are compounds emittedfrom highway vehicles and non-roadequipment which are known, or suspected, tocause cancer or other serious health andenvironmental effects.

The Clean Air Act identified 188 air toxics, alsoknown as hazardous air pollutants (HAPs). Mobile Sources are a significant contributor.

MSAT BACKGROUNDMobile Source Air Toxics

The Environmental Protection Agency (EPA) hasidentified a group of 21 as mobile source airtoxics (MSAT) in its Final Rule (66 FR 17235).

EPA Has Extracted Six Priority MSATs:Benzene, FormaldehydeAcetaldehydeDiesel Particulate Matter/Diesel Exhaust Organic GasesAcrolein1,3-Butadiene

The Federal Highway Administration (FHWA) hasdeveloped a tiered approach for analyzingMSATs in the NEPA documents.

No Analysis For Projects With No Potential ForMeaningful MSAT Effects

Qualitative Analysis For Projects With LowPotential MSAT Effects Or

Quantitative Analysis To DifferentiateAlternatives For Projects With HigherPotential MSAT Effects

MSAT BACKGROUNDMobile Source Air Toxics

Emissions Factors Estimation - MOBILE6.2

MSAT Emissions Estimation Including EstimationOf Vehicle Miles Of Travel - EmiLink Module

Identifying Affected Transportation NetworkComparing Build Versus No-Build

MSAT ANALYSISProcedure

Estimation Of Annual Emission Factors Rates,Calculated By Combining Monthly Emissions Factors Using Weighting Factors CorrespondingTo Each Month

Local Inputs include

Vehicle Age Distribution

Diesel Fraction

Trip Length Distribution

Hourly VMT Distribution

Inspection And Maintenance, Etc.

MSAT ANALYSISEmissions Factors Estimation

MSAT ANALYSISEmissions Factors Estimation

MSAT ANALYSISEmissions Factors Estimation

EmiLink Uses Vehicle Miles Of Travel (VMT)Calculation Consistent With TheTransportation Conformity Process

Travel Demand Modeling Four-Step Process

Non-Recurring Congestion Factor

HPMS Adjustment Factor

Seasonal Adjustment Factor

MSAT ANALYSISEmiLink - Vehicle Miles of Travel Estimation

MSAT ANALYSISEmiLink Features

Capable Of Estimating Link-Level EmissionsThat Can Be Used Easily For MSAT Analysis

Capable Of Estimating Hourly Emissions

Capable Of producing Emissions Files ThatCan Be Used In EPS3 (Emissions Processing System) For PhotochemicalModeling

Eliminates Writing Job Control Files (JCF)

Has Run Time Of Three Hours For DFWNetwork With Approximately 40,000 Links

MSAT ANALYSISEmilink Module

TOD = Time of day

VMT-MIX FILEROADWAY

CORRESPONDENCE FILE

AIR QUALITY-LINK FILE

MOBILE6.2 EMISSIONS FACTORS FILE

EMISSIONS = VMT * VMT-MIX * MOBILE6.2 EMISSIONS FACTORS

POLLUTANT EMISSIONS

FILE

COUNTY EMISSIONS FILE

COUNTYTOD

FUNCTIONAL CLASS

TOD SPEED

ROADWAY TYPE

POLLUTANT ANDEMISSION TYPE

FUNCTIONAL CLASS

LINK IDVMT

LINK IDFUNCTIONAL CLASS

VOLUMEPOLLUTANT

EMISSION TYPEEMISSIONS FOR 28 EPA VEHICLE TYPES

POLLUTANTEMISSION TYPE

MOBILE6.2 EMISSION FACTORSVMT MIX FRACTIONS FOR

28 EPA VEHICLE TYPE

MSAT ANALYSISEmilink Module – Stage 2

MSAT ANALYSISEmiLink Interface

MSAT ANALYSISEmiLink Output Files

Tab-Delimited Hourly Emission Summary ByCounty, Roadway Type And Vehicle Type

Database Format File With Daily And AnnualLink Level Emissions, VMT And Volume

Hourly Emissions By Link In EPS3 Format

MSAT ANALYSISEmiLink Output: Link-Emissions File

Quantitative MSAT Analysis Should Include:

Estimation Of Total Emissions For Build AndNo Build Scenarios

Identification Of Affected TransportationNetwork

Estimation Of Change In Emission And VMT InThe Affected Area/Links From A No-Build ToA Build Alternative

MSAT ANALYSISQuantitative MSAT Procedure

MSAT ANALYSISLoop 12 Roadway Case Study

MSAT ANALYSISFHWA Recommended Five-Percent Volume Change

MSAT ANALYSISTraffic Survey Zone Analysis

MSAT ANALYSISLink Level Emissions

15848.65

19318.41

25601.6225614.65

19338.59

0

5000

10000

15000

20000

25000

30000

2007 Base 2015-Build 2015 No-Build 2030 Build 2030 No Build

MODEL SCENARIOS

EMIS

SIO

NS

(LB

S) a

nd V

MT

( 10^

4 M

iles)

Total_MSATsVMT (10 4̂ miles)

MSAT EMISSIONSTotal MSAT Emissions and VMT Growth

MSAT EMISSIONSBuild And No-Build Analysis

0.00

2,000.00

4,000.00

6,000.00

8,000.00

10,000.00

12,000.00

14,000.00

Acrolei

n (lbs

)Ace

talde

hyde

(lbs)

Formald

ehyd

e (lbs

)

Butadie

ne (lb

s)

Benze

ne (lb

s)Dies

el PM10

(lbs)

TOTAL MSATs

VMT (10^

5 mile

s)

POLLUTANTS AND VMT

EMIS

SIO

NS(

LBS)

AN

D V

MT

(MIL

ES)

20072015-Build2015 No-Build2030 Build2030 No Build

EmiLink Has Been Used Successfully On Projects In DFW And Has Shown The Following Advantages:

Reduces The Calculation Time For The MSATAnalysis

Significantly Decreases The Cost Of The WorkFrom Initial Estimates

Provides Consistency Of Results By ItsConsistent VMT Estimation

Provides A Stream-Lined Process To Get FromThe Mobile 6.2 Emission Factor Files To TheEmissions Output

Provides User-Friendly Interface For SpecifyingInputs

MSAT ANALYSISConclusions

EmiLink can be modified to be used by other metropolitan planning areas.

Improvements are needed in the process of finding affected roadways links.

A recommendation for EPA and FHWA would be to develop a process for quantitative MSAT analysis that targets only the affected roadway links.

Applying an emission threshold yields better results than percent volume or VMT change.

MSAT ANALYSISFuture Directions

MSAT ANALYSISContact Information

Madhusudhan VenugopalSenior Transportation Planner

(817) 608-2333mvenugopal@nctcog.org

Kathleen YuSenior Transportation System Modeler

(817) 608-2343 kyu@nctcog.org