Presentation is loading. Please wait.

Presentation is loading. Please wait.

Lexington Area TransCAD Travel Demand Model July 22, 2003 Kentucky Traffic Model Users Group Meeting Kyeil Kim, Ph.D. Bernardin, Lochmueller & Associates,

Similar presentations


Presentation on theme: "Lexington Area TransCAD Travel Demand Model July 22, 2003 Kentucky Traffic Model Users Group Meeting Kyeil Kim, Ph.D. Bernardin, Lochmueller & Associates,"— Presentation transcript:

1

2 Lexington Area TransCAD Travel Demand Model July 22, 2003 Kentucky Traffic Model Users Group Meeting Kyeil Kim, Ph.D. Bernardin, Lochmueller & Associates, Inc.

3 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 KYTCs HIS database. 2-stage assignments: Initial and Feedback User-friendly model GUI

4 Model Area

5 Roadway Network Incorporation of KYTCs 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

6 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

7 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)

8 Speed/Capacity Estimation (Contd) 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/Cs and PFs by signal priority and multiple signals

9 Lexington Model GUI

10

11 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

12 Trip Generation (Contd) Trip production model Trip Purpose1 st Predictor2 nd PredictorOverall Trip Rate HBWWorkers/H.H.Vehicles/H.H.1.30 HBK12Students/H.H.None0.64 HBUUniversity Student/TAZ None0.48 HBOHousehold SizeVehicles/H.H.3.72 NHBWWorkers/H.H.Household Income 0.84 NHBOHousehold SizeVehicles/H.H.2.02 Total9.00

13 Trip Generation (Contd) Trip attraction model: the Atlanta regression model Trip PurposeIndependent VariableParameter HBWTotal Employment1 HBK12K-12 Enrollment1 HBUUniversity Enrollment1 HBO Population.1168 Retail Employment.8257 Commercial & Govt Employment.0408 Other Employment.0137 NHBW & NHBO Population.0575 Retail Employment.7593 Commercial & Govt Employment.0846 Other Employment.1053

14 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

15 Vehicle Occupancy Vehicle occupancy rates by trip purpose HBW 1.09 persons/vehicle HBK 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)

16 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

17 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 = ADTs - E-E trips at each external station 27 stations of the 44 stations carry through trips

18 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

19 Feedback Loop 24-Hour Average Speed Gravity Model TOD Trip Table Factoring AM-peak Assignment Midday-peak Assignment PM-peak Assignment Off-peak Assignment 24-Hour Weighted Average Congested Link Speed

20 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

21 Assignment Results

22 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%

23 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 with committed plus Plan projects scheduled for completion by with all projects in the current LRP Multinet feature in GUI for efficient network data handling

24 THANK YOU!


Download ppt "Lexington Area TransCAD Travel Demand Model July 22, 2003 Kentucky Traffic Model Users Group Meeting Kyeil Kim, Ph.D. Bernardin, Lochmueller & Associates,"

Similar presentations


Ads by Google