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Implementing Soak-Time Distribution Models in a GIS Framework Aruna Sivakumar Department of Civil Engineering (Transportation) University of Texas at Austin.

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Presentation on theme: "Implementing Soak-Time Distribution Models in a GIS Framework Aruna Sivakumar Department of Civil Engineering (Transportation) University of Texas at Austin."— Presentation transcript:

1 Implementing Soak-Time Distribution Models in a GIS Framework Aruna Sivakumar Department of Civil Engineering (Transportation) University of Texas at Austin November 21 st 2000 TERM PROJECT GIS in Water Resources (CE 394K.3) Fall 2000

2 CE 394K.3 Fall 2000 Overview / Background – air quality modeling / Objective and Scope / TransCAD – GIS application / Modeling Background / Data & sources / Procedure / Results / Further work CE 394K.3 Fall 2000

3 / Non-Attainment and Conformity State Implementation Plan (SIP) Dallas-Fort Worth, TXBeaumont-Port Arthur Ozone Houston-Galveston-Brazoria El Paso Ozone, CO, PM10 CE 394K.3 Fall 2000 Air Quality Modeling / Sources of air pollution – “criteria pollutants” CO, NO 2, Pb, Ozone, SO 2, PM10 / Clean Air Act (OAQPS) National Ambient Air Quality Standards (NAAQS)

4 CE 394K.3 Fall 2000 / MOBILE – Highway vehicle emissions factor model / VOC (ozone), CO, NO x / 8 vehicle categories / 1952 to 2050 / ambient temp, avg traffic speeds, gasoline volatility CE 394K.3 Fall 2000 Mobile Emissions / Tailpipe Emissions a third of the air pollution in the country. / Office of Transportation & Air Quality Vehicle & Engine Emissions Modeling Software MOBILE, PART5, Fuels Models, Non-Road models… TRAQ

5 CE 394K.3 Fall 2000 / Emission type classes running, start, hot-soak, diurnal, resting, run loss, crankcase, refueling CE 394K.3 Fall 2000 MOBILE6 (2000) / Inputs trip length estimates, trip start and trip ends, diurnal soak time, engine start soak time distributions, VMT by hour of day, facility, speed etc. / Outputs / “emission factors” expressed as grams of pollutant per vehicle mile traveled (g/mi). / Can be combined with estimates of total VMT

6 CE 394K.3 Fall 2000 To implement the soak time distribution models in a GIS framework with the following features - user interactive input - output format suitable for MOBILE6 Objective TransCAD + GISDK

7 CE 394K.3 Fall 2000 TransCAD & GISDK Transportation GIS Software -better suited to application of statistical models -comprehensive sets of transportation, geographic and demographic data CE 394K.3 Fall 2000

8 Compile Execute -includes Caliper Script TM a macroprogramming language -powerful development language (GISDK) for creating macros, add-ins, server applications, and custom front-ends CE 394K.3 Fall 2000

9 Soak-time / Duration of time in which the vehicle’s engine is not operating and which precedes a successful vehicle start (i.e. one that does not result in a stall) / soak time < 12 hoursHOT START / 70 soak time bins 1 – 30 min (1 min intervals) 30 – 60 min (2 min intervals) min (30 min intervals) CE 394K.3 Fall 2000

10 Soak-time Models 1.Binary logit model – to estimate the fraction of first trip starts. 2.Log-linear soak-time models for first and non- first trip starts – to estimate the fraction of trip starts in each soak-time bin Soak Time depends on Time-of-day of trip start, activity purpose preceding the trip start, land use and demographic characteristics of the zone of trip start, trip characteristics CE 394K.3 Fall 2000

11 Inputs to MOBILE6  fraction of trips in each of 70 soak-time bins by time- of-day and origin activity purpose (for each zone). Time Periods Morning AM Peak AM Off Peak PM Off Peak PM Peak Evening Origin Activity Purpose Home Work School Social/Recreational Shopping Personal Business Other

12 CE 394K.3 Fall 2000 Data Dallas-Fort Worth 919 TAP Zones Source: NCTCOG (North Central Texas Council of Govts.) GIS datafiles CE 394K.3 Fall 2000 Zonal land use and Demographic characteristics

13 CE 394K.3 Fall 2000 Procedure / Import the D-FW shapefile into TransCAD Tap Zones: tap919.shp Attribute table for the TAP Zones

14 CE 394K.3 Fall 2000 / With the land- use and demographic data (from the attributes table) apply the soak time models in Excel / Create dataviews from the results in Excel, one for each time-period and link these to the corresponding zones. The soak-time distribution is now an attribute of the zone.

15 CE 394K.3 Fall 2000 Map Attributes of selected zone Soak time distribution in the selected zone during the Morning period and by Origin activity purpose Soak time distributions by activity purpose

16 CE 394K.3 Fall 2000 Results / A visual representation of the soak time distribution for each zone in the study area by time-of-day and origin activity purpose / Soak time distribution output data as inputs to MOBILE6 / First step in the development of a GIS- based user interface for emissions modeling

17 CE 394K.3 Fall 2000 Further Work / Developing macros and add-ins using GISDK – user input interface, computation of soak time distribution, output files into MOBILE6

18 CE 394K.3 Fall 2000 Thank You!


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