Simpson County Travel Demand Model

1
Simpson County Travel Demand Model
July 22, 2003
2
BACKGROUND

• WSA started working on KY 1008 Pre-Design Scoping
  Study in November 2002
• Currently, there is ¾ of a Bypass (KY 1008)
  around Franklin, Kentucky
• Planning project aimed to determine need (if any)
  for full bypass
• Traffic would be important in justification of
  new segment
• As a result, the KYTC made the decision to
  develop travel demand model to coincide with study

3
BACKGROUND (CONT.)

• Project coordinated through the Divisions of
  Planning and Multimodal Programs
• KYTC decided to build full travel demand model
  for Simpson County for future uses
• Air quality analysis (non-attainment)
• Other transportation improvements

4
BACKGROUND (CONT.)
5
STUDY AREA
6
MODEL DEVELOPMENT

• Roadway Coverage / Network
• Traffic Analysis Zones
• Model Development
• Trip Generation
• Trip Distribution
• Traffic Assignment

7
ROADWAY COVERAGE

• Roadway Coverage includes
• All state-maintained roads in Simpson County
• I-65 (North / South)
• US 31W (North / South)
• KY 100 (West / East)
• Many local roads
• County Roads
• City Streets

8
ROADWAY COVERAGE
9
TRAFFIC ANALYSIS ZONES

• Traffic Analysis Zones were based upon
• Census Blocks / Census TAZs
• The highway network
• Socioeconomic Data included
• Census Bureau
• Dun Bradstreet Employment Data
• Franklin-Simpson Industrial Board
• KYTC District 3

10
(No Transcript)
11
3-STEP MODEL

• Automated using GISDK User Interface
• Trip Generation (Quick Response Method)
• Trip Distribution (Gravity Model with Gamma
  Function)
• Traffic Assignment (User Equilibrium)

12
GISDK USER INTERFACE

• Originally developed for the Madisonville UATS
• Easily moved from model to model
• Simplified each model run
• Included Error-Prevention Strategies

13
RESULTS

• Very good initial runs
• Particular consideration given to calibration in
  Franklin and areas near bypass
• Met FHWA calibration requirements
• Overall RMSE lt 30
• RMSE requirements achieved for all functional
  classifications
• Also, met RMSE requirements for volume groups

14
FRANKLIN BYPASS EXTENSION

• The calibrated base year model was used to
  forecast traffic patterns for the Future Year
  2025
• As mentioned, the number of vehicles expected to
  utilize new bypass extension was very important
• Result ranged from 6,500 7,000 vehicles per day
  on the bypass (Year 2025)

15
TRUCK COMPONENT

• E-E truck trips are a major source of truck trips
  in the study area along major north/south routes
  (I-65/US 31W)

• External-External (E-E) truck trips were
  simulated for this project based on existing
  truck counts
• Internal truck trips is currently being developed

16
BPR CURVE

• Speed Estimation has been important topic
  recently for the KYTC
• KYTC asked to use updated BPR function
  parameters
• a 0.05 (signalized) 0.2 (other)
• b 10
• Currently, conducting sensitivity analyses to
  study the difference between default BPR (a0.15
  b4) parameters and updated BPR parameters

17
MOBILITY ANALYSIS

• Another important topic for KYTC is Mobility
  Analysis
• Currently, researching TTI methodology for
  computing congestion using
• Travel Time Index
• Travel Rate Index
• Result will be an overall value (or index) for
  quantifying congestions for an urban area (or
  other specified area)

18
Questions?