1. Activity-Travel Trends
An Exploratory Approach Utilizing Multiyear NHTS/NPTS Data and Sequence Alignment Technique
Jingyue Zhang
Department of Civil & Environmental Engineering
University of Connecticut
Karthik Konduri
Prepared for NEITE
12/4/2017

2. Outline Motivation and objectives Sequence alignment method Data
Result
Conclusion and future studies

3. Motivation Activity-travel behaviors changed over last two decades
An increasing portion of households choose to live without a car and use alternative modes for traveling
Passenger travel in the United States slightly less reliant on private cars
Limitations of current studies
Focus on univariate dimension of travel
Focus on certain group of people
Ignore the temporal dimension of activity-travel behavior

4. Objectives
Identify representative activity-travel patterns by considering multiple attributes of travel
Explore how the patterns vary over time

5. Categorizing Activity-Travel Pattern
Individual’s daily activity-travel pattern is represented as an alphabetical sequence
Each one or more alphabets represent a certain activity in a certain time interval
Temporal dimension of activity-travel is embedded in the sequence
Talks about how people describe activity-travel pattern: used sequence to describe it.

6. Sequence Alignment Method
Three steps of sequence alignment approach:
Pairwise alignment
Exact match of all three attributes: 10 points
Match of activity type: 6 points
Match of mode/accompaniment: 2 points
Mismatch: 0 point
Multiple sequence alignment
Taxonomic Tree

7. Data
Four waves of National Person Travel Survey (NPTS) and National Household Travel Survey (NHTS)
1990, 1995, 2001, 2009
Samples are selected from New York Metropolitan area
Diverse of activity-travel patterns can be observed
Experienced the impact of various technological, economic and cultural disruptions over the last 20 years
A weighted random sample of 300 individuals was drawn from each of the chosen waves of data

8. Attributes for Defining Activity-Travel Sequence
Example:
AAAAAAAAAAGGGGGSSSSSSSSSSSSSSS
A: Traveled alone to conduct a discretionary activity by car
G: Traveled with others to conduct a maintenance activity by public transit
S: Traveled alone home by car
Attributes
Categories
Activity Type
Mandatory
Maintenance
Discretionary
Home
Travel mode
Car
Non-motorized mode
Public transit
Accompaniment
Travel alone
Travel with others

9. Taxonomic Tree
Talks about ClustalG

10. Travel Characteristics
Pattern 3 has lower average trip rate
Greatest proportion of activities in pattern 1 is home activities followed by maintenance activities
36% of activities in pattern 2 are maintenance activities
32% of activities in pattern 3 are mandatory activities

11. Travel Characteristics
Majority of trips in pattern 1 were made by car
Majority of trips in pattern 3 were made by taking public transit
Majority of trips in pattern 1 and 3 were made alone
63% of trips in pattern 2 were made with others

12. Demographic Characteristics
Pattern 1 has slightly fewer young adults but more persons from 55 to 64 years old
Pattern 2 has more persons 65 years old or above
Pattern 3 has more young adults and fewer elders
Pattern 1 has more males
Pattern 2 and 3 have more females

13. Demographic Characteristics
Majority of people in Pattern 1 and 3 are workers
44% of workers in Pattern 2 did not conduct mandatory activity

14. Representative Travel Patterns
There are three types of activity-travel patterns:
Pattern 1: Auto Oriented Employed Individuals with a Work Episode (AOE)
Pattern 2: Other Employed and Unemployed Individuals (OEU)
Pattern 3: Non-Auto Oriented Employed Individuals with a Work Episode (NOE)

15. Variations within Pattern
Number of Sampled Persons
1990
1995
2001
2009
AOE
152
127
138
137
OEU
101
115
118
111
NOE 47 58 44 52
Change pattern 1,2,3 to acronym
Number of sampled people who fall into AOE decreased from 1990 to 1995
Number of sampled people who fall into OEU increased from 1990 to 2001

16. Variations in Average Trip Rate
Average trip rate dropped for all three patterns since 2001

17. Variations in Activity Type
Percentage of home activity decreased for AOE and OEU
Percentage of discretionary activity increased for AOE and OEU
Percentage of mandatory activities decreased for OEU and NOE

18. Variations in Travel Mode
Automobile remains as the predominant mode for AOE
Percentage of vehicle trips increased from 2001 to 2009 for OEU
For NOE, percentage of transit trips increased from 1990 to 2009

19. Conclusion & Future Studies
Three activity-travel patterns are identified over last 20 years
The number of persons fall into each pattern varied over time but not in a large magnitude
For each pattern, some variations of travel characteristics are observed over time
Limitation and future studies:
Computational intensive
Apply other sequential data clustering algorithms
Incorporate other attributes (i.e. generational cohorts)
Talks about that there are so many stuffs going on over last 20 years, we observed three activity-travel patterns. The number of persons fall into each pattern varies over time(number) because of the changes.
This is kind of the first step that we predict how the travel pattern changes in the unknown future. We thought that the travel patterns will remain, especially the number of trips that people make everyday for certain types of activity, but how they executed for example the mode might be changed.

20. Questions?

21. Appendix: Household Characteristics
Persons fall into pattern 3 have smaller household size
Persons fall into pattern 2 have fewer workers in household
Persons fall into pattern 1 have more drivers and vehicles in household

22. Appendix: Variations in Household Level Characteristics
Household size decreased since 1990
Number of drivers increased from 2001 to 2009
Number of vehicles increased from 2001 to 2009 in pattern 1 and 2, but decreased in pattern 3

23. Appendix: Variations in Gender Distribution
Percentage of female fall into OEU decreased since 1990

24. Appendix: Variations in Employment Distribution
Show both female and male distribution, show workers and non-workers
Percentage of employed persons in AOE and OEU increased from 1995 to 2001 and then decreased from 2001 to 2009