Roosbeh Nowrouzian, Siva Srinivasan University of Florida. March 4 th, 2011

Transcription

1 Roosbeh Nowrouzian, Siva Srinivasan University of Florida March 4 th,

2 Overview Introduction and Motivation Objective Data and Data Manipulation Process Methodology Spatial Transferability Conclusions and Implications 2

3 Travel Demand Models: The state of the practice approach: Introduction and Motivation o uses individual trips as the unit of analysis o usually includes four sequential steps o each trip is considered as independent of other trips o each person is considered independent of other household members Short comings: o The trip-based approach ignores the linkages among trips over o o o space time different persons within a household. State of the practice approach 3

4 4

5 Activity Based Modeling o o a tour as fundamental unit of analysis maintain consistency of the modeled choice attribute across, the trips of the same tour 5

6 Simple Tour Tour Classification Fully Joint Tour Complex Tour 6

7 Objective Identifying tours and modeling tour generation with particular focus on intra-household inter-dependency such as Fully Joint tours Evaluating transferability of estimated model in each region to other regions 7

8 Data The 2000 Northeast Florida (NE) Household Travel Survey North East(NE) Tampa Bay (TB) The 1996 Tampa Bay (TB) Area Household Travel Survey South East (SE) The 1999 Southeast Florida (SE) Household Travel Survey 8

9 Data Manipulation Process Creating tours from trip file for each region Explicitly Capturing Intra Household Interactions Determining the purpose of each tour based on the most important activity taken place in the tour Splitting the data for estimation and verification 85 percent of data is randomly selected for estimation and 15 percent of data is left for verification and evaluating spatial transferability 9

10 Structure of the Choice Alternatives Only for 2 or more household members Only for 2 or more household members 10

11 Determining Tour Purposes 11

12 Continued 12

13 NE SE TB Work Tours No work tour Simple work tour Complex work tour w/o P/D Complex work tour with P/D Pick Up Drop Off tours No P/D tour Simple P/D tour Complex P/D tour Joint Other Tours No joint tours One simple joint tour One complex joint tour Two or more joint tours Independent Other Tours No independent tours One simple independent tour One complex independent tour Two or more independent tours

14 NE SE TB Age Age Age Employed Full Time Employed Worker in a single-worker household Worker in a multi-worker household Non worker in a 0-worker household Non worker in a single-worker household Non worker in a multi-worker household No children in household One child in household Multiple children in household No car household Car sharing houesehold (cars < adults) Non-car sharing (cars >= adults)

15 Evaluating Spatial Transferability of Estimated Models Spatial transferability can reduce or eliminate the need for o o a large data collection model development effort in the application context Spatial transferability is investigated using three methods o o o aggregate disaggregate sensitivity analysis (elasticity) 15

16 Spatial Transferability 85% for model estimation 85% for model estimation North East(NE) 15% for spatial transferability 15%for spatial transferability Based Model Tampa Bay (TB) Based Model South East (SE) 85% for model estimation 15%for spatial transferability 16

17 Examining spatial transferability of estimated models 17

18 Elasticity Aggregate(WRMSE) Disaggregate Work Tour Scenario1 Scenario2 NE SE SE,TB TB SE SE NE,TB NE,TB NE,TB TB TB NE,SE SE,NE NE,SE SE P/D Tours NE SE SE TB SE NE TB,NE TB TB NE,SE SE Joint Other Tours NE TB,SE TB,SE TB,SE TB,SE SE NE NE NE TB TB NE,SE NE,SE SE,NE SE Independent Other NE SE,TB SE,TB TB,SE SE NE,TB NE,TB TB TB NE,SE NE,SE NE,SE 18

19 Conclusions and Implications In order to capture trip changing behavior, existing models are inadequate Intra household inter dependencies should be incorporated in the existing models A single representative model system appears not to be adequate for Florida Not all model components are equally transferable and not all measures of transferability lead to the same results Additional empirical research is necessary to identify the appropriate measures of transferability 19

20 Thank you 20