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

Implementing Soak-Time Distribution Models in a GIS Framework

Aruna Sivakumar

Department of Civil Engineering (Transportation)

University of Texas at Austin

November 21st 2000

TERM PROJECT

GIS in Water Resources (CE 394K.3)

Fall 2000

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

CE 394K.3 Fall 2000

Non-Attainment and Conformity

State Implementation Plan (SIP)Dallas-Fort Worth,

TX Beaumont-Port Arthur Ozone

Houston-Galveston-BrazoriaEl Paso Ozone, CO, PM10

CE 394K.3 Fall 2000

Air Quality Modeling Sources of air pollution – “criteria pollutants”

CO, NO2, Pb, Ozone, SO2, PM10

Clean Air Act (OAQPS)

National Ambient Air Quality Standards (NAAQS)

CE 394K.3 Fall 2000

MOBILE –Highway vehicle emissions factor model

VOC (ozone), CO, NOx

8 vehicle categories

1952 to 2050

ambient temp, avg traffic speeds, gasoline volatilityCE 394K.3 Fall 2000

Mobile Emissions Tailpipe Emissions

a third of the air pollution in the country.

Office of Transportation & Air QualityVehicle & Engine Emissions Modeling Software

MOBILE, PART5, Fuels Models, Non-Road models…

TRAQ

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

CE 394K.3 Fall 2000CE 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

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

CE 394K.3 Fall 2000

Compile Execute

-includes Caliper ScriptTM a macroprogramming language

-powerful development language (GISDK) for creating macros, add-ins, server applications, and custom front-ends

CE 394K.3 Fall 2000

CE 394K.3 Fall 2000

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 hours HOT START

70 soak time bins

1 – 30 min (1 min intervals)

30 – 60 min (2 min intervals)

60-720 min (30 min intervals)

CE 394K.3 Fall 2000

CE 394K.3 Fall 2000

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

CE 394K.3 Fall 2000

Inputs to MOBILE6fraction 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

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

CE 394K.3 Fall 2000

Procedure Import the D-FW shapefile into TransCAD

Tap Zones: tap919.shp

Attribute table for the TAP Zones

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.

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 Origin Activity Purpose

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1 4 7 10 13 16 19 22 25 28 32 38 44 50 56 90 180

270

360

450

540

630

720

Soak Time (min) ->

Fra

ctio

n o

f tr

ips

->

Home

Work

School

Social/Rec

Shopping

Pers. Bus.

Other

Soak time distributions by activity purpose

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

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

CE 394K.3 Fall 2000

Thank You!