Lexington Area TransCADTravel Demand Model

July 22, 2003

Kentucky Traffic Model Users Group Meeting

Kyeil Kim, Ph.D.

Bernardin, Lochmueller & Associates, Inc.

Main Features

Consists of separate time-of-day (TOD) models Realistic free-flow speed based on a speed survey and

HCM-based signal delays Varying capacities by TOD for reversible lanes Model parameters are based on recent travel survey and

KYTC’s HIS database. 2-stage assignments: Initial and Feedback User-friendly model GUI

Model Area

Roadway Network

Incorporation of KYTC’s HIS and geometric/operations data

All MINUTP network attributes

FHWA functional class, posted speeds, etc.

Number of lanes, reversible lanes & bike lanes

Area type, shoulder widths, median type, etc.

Traffic signals & multi-way stops (signal priority, multiple signals)

Turn prohibitors

TAZ DB

Total 489 zones Internal zones = 445 zones External zones = 44 zones

51 data attributes Date related to population and household Employment by SIC code Student population, group quarters & school enrollment Vehicle ownership

Key data for estimating trip productions and attractions

Speed/Capacity Estimation

Free-flow speed, peak-hour capacity & daily capacity

A special GIS-dk program to estimate directional capacities by TOD & free-flow speed

Consideration of changes in reversible lanes by TOD

Free-flow speed = f (functional class, posted speed, number of lanes, facility type, delays on interrupted facilities)

Daily capacity = f (functional class, number of lanes, facility type)

Peak-hour capacity = max. service flow * adjustment factors

where, Adjustment factors = f (geometric data, functional class, facility type, area type, delays on

interrupted facilities)

Speed/Capacity Estimation (Cont’d)

Delays on interrupted facilities

HCM 2000 procedure

delay/veh = uniform delay * PF + incremental delay + initial queue delay

where, PF = progression factor = f (arrival type, g/C)

uniform delay =

Varying g/C’s and PF’s by signal priority and multiple signals

Cgcv,1min1

Cg1C5.0 2

Lexington ModelGUI

Lexington ModelGUI

Trip Generation

Six internal trip purposes: - HBW, HBK12, HBU, HBO, NHBW & NHBO

Trip production

- Cross-classification technique

- Data: The 2000 Knoxville Household Travel Behavior Study, The 1999 Indiana University Travel Demand Survey

- Analysis of Variance (ANOVA) and non-parametric correlations techniques to identify the predictor variables for various trip

purposes

- Stratification curve: distribution of households in a zone over various

levels of the predictor variables

Trip Generation (Cont’d)

Trip production model

Trip Purpose 1st Predictor 2nd Predictor Overall Trip Rate

HBW Workers/H.H. Vehicles/H.H. 1.30

HBK12 Students/H.H. None 0.64

HBU University Student/TAZ

None 0.48

HBO Household Size Vehicles/H.H. 3.72

NHBW Workers/H.H. Household Income

0.84

NHBO Household Size Vehicles/H.H. 2.02

Total 9.00

Trip Generation (Cont’d)

Trip attraction model: the Atlanta regression model

Trip Purpose Independent Variable Parameter

HBW Total Employment 1

HBK12 K-12 Enrollment 1

HBU University Enrollment 1

HBO

Population .1168Retail Employment .8257

Commercial & Gov’t Employment .0408Other Employment .0137

NHBW & NHBO

Population .0575Retail Employment .7593

Commercial & Gov’t Employment .0846Other Employment .1053

Trip Distribution

Doubly-constrained Gravity model for the 6 internal trip purposes & E-I trips

Friction factors

- Initial factors from the old MINUTP model

- Fitting to Gamma function for smoothing the factors

- Adjustment of Gamma parameters to arrive at correct trip lengths by trip purpose

Socioeconomic (or K) factors

Vehicle Occupancy

Vehicle occupancy rates by trip purpose

HBW 1.09 persons/vehicle

HBK12 1.96 persons/vehicle

HBU 1.20 persons/vehicle

HBO 1.83 persons/vehicle

NHBW 1.17 persons/vehicle

NHBO 1.75 persons/vehicle

(Source: The 2000 Knoxville Household Travel Behavior Study)

Time-of-Day

AM peak (06:30~09:00); Midday peak (12:00~13:30); PM peak (15:30~18:00) and Off-peak

TOD factors

- Split the 24-hr trip table into tables by TOD

- by trip purpose

Directional factors

- Convert trip tables in a production-attraction format to origin-destination tables

- by trip purpose and by TOD

Data Source: the 2000 Knoxville Household Travel Behavior Study

External Trips

44 external stations

E-E trips The 1994 O-D survey by Wilbur Smith Associates Most of E-E trip interchanges except for the interstate and US60 exchanges

Kentucky Statewide Travel Model via critical link analysis E-E trip interchanges for the interstate and US60 external stations

Modlin Equations A check of reasonableness

E-I trips = ADT’s - E-E trips at each external station

27 stations of the 44 stations carry through trips

Traffic Assignment

Time-of-day user equilibrium assignments

- separate AM-peak, Midday-peak, PM-peak & Off-peak assignments

Improved free-flow speeds and varying capacities by TOD by reversible lanes

Separate volume-delay functions (defaults)

Unsignalized facilities = 0.20; = 10.0

Signalized facilities = 0.05; = 10.0

Feedback assignment

Feedback Loop24-Hour

Average SpeedGravity Model

TOD Trip TableFactoring

AM-peakAssignment

Midday-peakAssignment

PM-peak Assignment

Off-peakAssignment

24-Hour Weighted Average

Congested Link Speed

CAL_REP

Assignment post-processor written in GIS-dk and incorporated in the GUI

Various error statistics by functional classification, volume group, screenline, cutline and specific corridors

Error statistics

total counts, average counts, counts standard deviation total loadings, average loadings, loadings standard deviation % root mean square error mean error, % error total counts VMT, total loadings VMT, % VMT error

Assignment Results

CAL_REP Report

Loading % error = -1 % Loading VMT error = 0.9% % RMSE = 25% Interstate =

0.03% (% error); -2.6% (VMT error) Urban Principal Arterial =

-1.3%; -3.1% Urban Minor Arterial =

-3.8%; 3.7%

In Progress

Model runs for future years and post-processing 2030 with committed projects only

2010 with committed plus Plan projects scheduled for completion by 2010

2020 with committed plus Plan projects scheduled for completion by 2020

2030 with all projects in the current LRP

“Multinet” feature in GUI for efficient network data handling

THANK YOU!