ACTIVITY CHOICE ANALYSIS TIME ALLOC\TION
AND DISAGGREGATE TRAVEL DEMAND MODELINC
by
JOSEPH HENRY BAIN
B.ARCH., University of Illinois
(1967)
M.ARCH., University of Nebraska
(1969)
Submitted in partial fulfillment
of the requirements for the degree of
Master of Science in Civil Engineering
at the
Massachusetts Institute of Technology
June, 1976
Signature redacted
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2
ABSTRACT
ACTIVITY CHOICE ANALYSIS TIME ALLOCATION
AND DISAGGREGATE TRAVEL DEMAND MODELING by
JOSEPH HENRY RAIN
Submitted to the Department of Civil Engineering on June 15, 1976, in partial fulfillment of the requirements for the degree of Master of Science in Civil Engineering.
This study is an analysis of individual human activity behavior and time budget allocation specifically related to transportation demand analysis. By investigating the influences and constraints which give
order to sequences of activities, activity choice and time allocation, models can be developed to provide insight into the independence and dependence of different activity travel purposes, better definitions of travel demand choice sets, the use of activity duration as an exo-genous variable of travel choice models, the relationship among weekday and weekend activity and travel behavior patterns, and the use of
ac-tivity choice analysis to answer policy questions which cannot be answered
by existing travel demand models.
The study first identifies the position of activity choice in a hier-archy of mobility, activity and travel choice models. Then the character-istics of activities and traditional economic choice theory are considered in order to develop the theoretical model of activity choice, a time share model, and the activity choice duration models. Based upon available data and explanatory variables four models of activity choice duration for week-day and weekend shopping-personal business and social-recreation activities
are estimated using single equation Tobit model procedures. Finally travel
time to total activity duration distributions are estimated to analyze the net travel time savings of a policy change of a five day work week versus a four day work week.
Estimations of weekday and weekend choice duration models prove to be
feasible and generally result in behaviorally and statistically acceptable
parameter values. The travel time to total activity duration distributions and activity choice duration models indicate that shopping-personal busi-ness activity behavior may be quite different for the weekday as compared
to the weekend. The social-recreation activity remains rather consistent for the weekday and weekend with natural increases in choice and duration for the weekend. Further investigation of activity choice and duration
3
for weekday and weekend activity pnxedures should be undertaken. using a simultaneous tobit model
Thesis Supervisor:
behavior using single equation tobit More complex estimation procedures would also be appropriate research.
Moshe E. Ben-Akiva Assistant Professor Title:
4
ACKNOWLEDGEMENTS
A great number of people have provided assistance to me in the course
of this research. Professor Moshe Ben-Akiva as thesis supervisor gave
valuable advice on various aspects of the work. In addition Professors
Steven Lerman and Marvin Manheim provided useful ideas and suggestions.
A number of fellow students provided advice during the course of
this research. In particular, I would like to thank Thawat Watanatada
and Tom Adler, who were sources of information and ideas at various times.
The data for this study was obtained through the cooperation of
F. Stuart Chapin, Jr. Professor, University of North Carolina at Chapel
Hill, Center for Urban and Regional Studies and the transportation staff
of the Metropolitan Washington Council of Governments. The single
equa-tion tobit estimaequa-tion program was obtained through the cooperaequa-tion of
Forrest D. Nelson, Professor, California Institute of Technology and the
National Bureau of Economic Research, Inc.
I would like to thank Ellen Shepherd for typing the preliminary
draft and Rebecca Muller and Merilyn Williams for typing the final draft
of the research.
Finally, I wish to dedicate this thesis to my mother Pauline and in
5
TABLE OF CONTENTSPage
TITLE PAGE ABSTRACT ACKNOWLEDGEMENTS TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES CHAPTER 1: INTRODUCTION1.1 Motivation, Objective and Purpose of Activity
Choice Analysis Research
1.2 Heirarchy of Choice Models: Mobility, Activity and Travel
1.3 Overview of This Activity Choice Analysis
Research
CHAPTER 2: FREQJENCY; SOCIAL, TEMPORAL, SPATIAL DIMENSIONS;
AND DOMINANCE: CHARACTERISTICS OF ACTIVITIES
2.1 Three Kinds of Activities Based on Frequency
2.2 Social, Temporal and Spatial Dimensions of
Activity Choice
2.3 Out-of-home Activity Dominance by Purpose
2.4 Activity Dominance in Trip Tours
1
2 45
9
11 1212
14
1719
19
20
23 282.5 Mean Duration of Out-of-home Activities by
Day-of-the-week
2.6 The Importance of Activity Characteristics
in Model Development
CHAPTER 3: THEORETICAL DEVELOPMENT OF A MICROECONOMIC
ACTIVITY CHOICE MODEL
3.1 Four Decisions Related to Out-of-home
Activities
3.2 Traditional Economic Choice Theory
3.3 Basic Concept of Activity Choice Theory
3.4 Two Time Constraint Categories: Time
Resource and Time Consumption
3.5 Lagrange Function of Activity Coice Model 3.6 Three Major Categories of Activities
3.7 Practical Use of the Microeconomic Activity
Choice Model
CHAPTER 4: ACTIVITY CHOICE TIME SHARE AND TIME DURATION
MODELS
4.1 Activity Time Share Model Formulation
4.2 Activity Choice Duration Models Using Single
Equation Tobit
4.3 Activity Choice Duration Model Using
Simultaneous Tobit
4.4 Activity Time Share and Activity Choice
Duration Model Summary
CHAPTER 5: EXPLANATORY VARIABLES OF ACTIVITY CHOICE DURATION MODELS AND DATA
5.1 Four Categories of Explanatory Variables
6
Page
34 36 37 37 39 40 43 46 50 53 55 55 58 62 64 6565
7
Page
67
695.2 Activity Characteristics Variables
5.3 Travel Mode and Trip Characteristics
Variables
5.4 Socioeconomic Variables
5.5 Environmental Location Characteristics:
Zone Attributes
CHAPTER 6: WEEKDAY AND WEEKEND SHOPPING-PERSONAL BUSINESS
AND SOCIAL-RECREATION ACTIVITY CHOICE DURATION
MODEL ESTIMATES
6.1 Variables Specification of the Time Duration
Models
6.2 Weekday and Weekend Variable Correlation
Matrixes
6.3 Weekday Shopping-Personal Choice Duration Model
6.4 Weekend Shopping-Personal Choise Duration Model
6.5 Weekday Social-Recreation Duration Model 6.6 Weekend Social-Recreation Duration Model Business Activity Business Activity Activity Choice Activity Choice 71 77 78 80 84 87 89 91 93
6.7 Comparison of the Weekday and Weekend
Shopping-Personal Business Choice Duration Models
6.8 Comparison of the Weekday and Weekend
Social-Recreation Acitivity Choice Duration
Models
6.9 Weekday Shopping-Personal Business Travel
Time to Total Duration Distributions
6.10 Weekday Socia1-Recreation Travel Time to
Total Duration Distributions
95
96
8
Page
6.11 Weekend Shopping-Personal Business Travel 100
Time to Total Duration Distributions
6.12 Weekend Social-Recreation Travel Time to Total 102
Duration Distributions
6.13 Summary of Activity Choice Duration Models, 104
Time Share and Travel Time to Total
Duration Distributions
CHAPTER 7: ACTIVITY CHOICE ANALYSIS AND NET TRAVEL TIME 107
SAVINGS: FOUR DAY WORK WEEK VERSUS FIVE DAY
WORK WEEK
7.1 Use of Activity Choice Analysis in the 107
Determination of Travel Time Savings
7.2 Changes in Leisure Activity Duration Given 108
Changes in Work Duration
7.3 Net Travel Time Savings for the Four Day 111
Work Week
7.4 Model Limitations in Determining Travel 113
Time Savings
CHAPTER 8: CONCLUSIONS AND RECOMMENDATIONS 114
8.1 Summary of This Activity Choice Time 114
Allocation Research
8.2 Future Activity Choice Duration and Travel 116
Demand Modeling
9
LIST OF TABLES
Table Title Page
2.1 Weekday Out-of-home Activity Participation 24
2.2 Saturday Out-of-home Activity Participation 25
2.3 Sunday Out-of-home Activity Participation 26
2.4 Weekday Out-of-home Activities and Trip Tours 29
2.5 Weekend Out-of-home Activities and Trip Tours 30
2.6 Sunday Out-of-home Activities and Trip Tours 32
2.7 Saturday Out-of-home Activities and Trip Tours 33
2.8 Out-of-home Activity Duration by Day-of-the-week 35
6.1 Weekday Correlation Matrix 81
6.2 Weekend Correlation Matrix 82
6.3 Weekday Shopping-Personal Business Activity Choice 85
Duration Model Estimates
6.4 Weekend Shopping-Personal Business Activity Choice 88
Duration Model Estimates
6.5 Weekday Social-Recreation Activity Choice Duration 90
Model Estimates
6.6 Weekend Social-Recreation Activity Choice Duration 92
Model Estimates
6.7 Summary Comparison of the Weekday and Weekend 94
Shopping-Personal Business and Social-Recreation Activity Choice Duration Models
6.8 Summary Activity Time Duration and Activity Time 105
Share Statistics
7.1 Expected Changes in Shopping-Personal Business and 110
Social-Recreation Durations Given Changes in Work Duration
10
Table Title Page
7.2 Two Approaches to Calculatine Net Travel Time Savings: 112 Four Day Work Week Versus Five Day Work Week
11
LIST OF FIGURES
Fi&gre Title Page
1.1 HIerarchy of Choice Models 15
2.1 A Typical Activity Sequence 22
6.1 Weekday Shopping-Personal Business Travel Time to 97
Total Activity Duration Distributions
6.2 Weekday Social-Recreation Travel Time to Total 99
Activity Duration Distributions
6.3 Weekend Shopping-Personal Business Travel Time to 101
Total Activity Duration Distributions
6.4 Weekend Social-Recreation Travel Time to Total 103
12
CHAPTER 1
INTRODUCTION
1.1 Motivation, Objective and Purpose of Activity Choice Analysis
Research
This study represents a theory of individual human activity
beha-vior of time budget allocation specifically related to transportation
demand analysis wherein a time dimension constraint and budget constraint
are relevant. Over the years there have been a number of attempts to
modify neoclassical consumer theory and time budget analysis to deal
with problems of transportation demand, but none of the attempts have
explained the interdependence of travel for different purposes.
Currently, existing disaggregate behavioral travel demand models
are estimated for a specific non-work trip purpose category independent
of other non-work trip purpose categories. They generally consider
only the attributes of travel and the socioeconomic characteristics of
the individual as exogenous variables giving little, if any,
considera-tion to the attributes of the activity for which the trip is made.
Likewise the travel choice set of trip frequency, destination, time of
day, mode and route specified in the models are not generally well
de-fined because we know little about how individuals perceive their
travel choice alternatives.
Consequently, it is the objective of this research to use an
activity choice analysis approach in order to improve existing
13
allocate time to activities and how they organize sequences of
acti-vities; second, what influences and constraints give order to the
time allocation and activity sequencing processes; third, how activity
sequencing and time allocation affect the travel behavior of individuals.
In this research particular attention is given to the individual's
participation in out-of-home activities as they relate to individual
travel behavior.
Through activity choice analysis, knowledge can be advanced in five
areas of travel demand modeling:
* the independence and dependence of different out-of-home
activity travel purposes considering both direct substitution
effects within a purpose and cross substitution effects among
purposes;
* better definitions of the travel choice set by developing
criteria which will eliminate irrelevant alternatives and
in-clude relevant alternatives in the choice set;
* use of the duration of the activity at the destination as in
an exogenous variable of the travel choice model;
* determine the relationship or dependency among weekday and
weekend travel patterns;
* the use of activity choice analysis to answer policy questions
and issues which cannot be answered through present travel
14
1.2 Heirarchy of Choice Models: Mobility, Activity and Travel
In Figure 1.1, one can see how activity choice interacts with the
mobility and travel decisions in a heirarchical choice structure. This
set of three models can be termed block conditional as defined by
Lerman (1975) and Ben-Akiva (1972), where the blocks of mobility,
acti-vity and travel choices as interelated single units have a conditional
choice structure, while each block within itself has a joint choice
structure.
The mobility choice can be viewed as a long range set of decisions
which establishes one's employment location, residential location,
housing type, auto ownership, and work trip mode. The mobility choice
determines the environmental supply system in which the individual may
select to locate the activities in which they participate. In general
the supply system may be viewed as taking place in one of two categories:
at home (in-home) or away from one's residential location (out-of-home).
The activity choice is viewed as an intermediate decision; it is
a simultaneous choice of activity participation, duration and general
location (in-home or out-of-home). If the activity location is in one's
home, then no travel is involved. However, if the activity location
is out-of-home, then the travel choice decision must also be made. For
the out-of-home activity the travel decisions of frequence, destination,
mode, route, and time of day are viewed as simultaneous choices.
The hierarchy of the three choice models is not a simplistic
15
FIGURE 1.1
HIERARCHY OF CHOICE MODELS
MOBILITY CHOICE
RL: RESIDENTIAL LOCATION WL: WORK LOCATION
HT: HOUSING TYPE
AO: AUTO OWNERSHIP
WM: WORK TRIP MODE
ACTIVITY CHOICE
AP: ACTIVITY PARTICIPATION
AD: ACTIVITY DURATION
IF IN-HOME IF OUT-OF-HOME TRAVEL CHOICE F: FREQUENCY D: DESTINATION M: MODE R: ROUTE H: TIME OF DAY 4-' +--OUT-OF-HOME ACTIVITY SUPPLY N E N T 0 W D 0 E K S IN-HOME ACTIVITY SUPPLY
16
prior mobility choice, but also upon the expected travel level of
service variables which are dependent upon the travel choice sets that
are perceived as being available to the individual decision maker.
Likewise, the mobility choices are influenced by the perceived
avail-ability or expected level of activity and expected travel level of
service that a specific mobility choice will afford to the individual mobility decision maker.
17
1.3 Overview of This Activity Choice Analysis Research
This chapter has introduced the role of activity choice in
ad-vancing knowledge in travel demand modeling and the heirarchical
posi-tion of activity choice between the mobility and travel choice decisions
in a block conditional structure. The chapters which follow describe
and develop a theory of activity choice behavior, estimates four
activity time duration models, and shows how such models may be used
to determine travel time savings resulting from a policy change of going
from a five day work week to a four day work week.
Chapter 2 presents the characteristics of activities in descriptive
terms in order to present criteria for developing a theoretical
micro-economic activity choice model in Chapter 3 and the activity time share
and time duration models of Chapter 4. The study recognizes the
inde-pendence and deinde-pendence of different activity categories but focuses
its attention only to the interaction of the out-of-home
shopping-personal business, social-recreation, and work activity categories in
discussing single equation Tobit estimation procedure in Chapter 4.
The possible estimation of simultaneous activity choice is discussed
in Chapter 4, but no simultaneous models are estimated in this research
effort. Single equation estimates for the shopping-personal business,
and social-recreation weekday and weekend choice duration models are
presented in Chapter 6 after a discussion of the data sources and pos-sible choice of explanatory variables in Chapter 5. Chapter 7 shows
18
a four day work week. Finally, Chapter 8 recommends directions for
ac-tivity choice duration model research based on the theoretical and
em-pirical evidence accumulated in this study.
The use of activity choice analysis in the development of better
criteria for determining travel choice sets is not considered in detail.
Likewise, the use of activity duration at the destination as an exogenous
variable of travel choice is also left for future research.
19
CHAPTER 2
FREQUENCY; SOCIAL, TEMPORAL, SPATIAL DIMENSIONS; AND DOMINANCE: CHARACTERISTICS OF ACTIVITIES
2.1 Three Kinds of Activities Based on Frequency
Before developing a theoretical model of activity participation it
is necessary to discuss some general descriptive characteristics of
ac-tivities. These characteristics influence the choice of activities,
their location, and the mode of travel used to reach the activity
lo-cation. In general, there are three kinds of activities based upon
fre-quency: first, activities which occur with a predetermined frequency,
e.g., work and group meetings; second, activities where the frequency
can vary despite a constant demand, e.g., shopping and laundering; and
third, activities not based on a constant demand, e.g., visiting friends,
going to the movies, or going for a walk. The frequency of need or
de-mand is a prime factor influencing an individual's sequence (or order)
20
2.2 Social, Temporal and Spatial Dimensions of Activity Choice
Besides frequency, an individual's sequence of nctivities can be viewed as being related to the social, temporal, and spatial organization of the urban environment. Both the social and temporal dimensions of
ac-tivities are closely related to frequency. The idea behind the social
dimension is that because of the social organization of society and in-dividual social contacts, activities are imposed upon people in varying
degrees dependent upon the specific activity. Thus activities can be related to:
e Physiological needs, e.g., eating, sleeping;
* Social duties, e.g., school attendance, jury duty;
* Agreements, e.g., working, meeting attendance; * Sudden urgent needs, e.g., repairs, dental visit;
e Services, e.g., shopping, banking services;
e Leisure, e.g., social visits, recreation, walking.
The temporal dimension is based on the fact that society generally
organizes activities according to a time schedule which provides an
op-portunity for performing different activities at different hours of the
day. Activities, then, may be regarded as taking place:
e Over a number of consecutive and predetermined hours, e.g.,
working, attending school;
* Any time between any two activities, e.g., waiting for an event
to begin;
* A fixed hour, e.g., an appointment;
21
e Any time but unrelated to other persons, e.g., walking alone.
The spatial dimension reflects an established set of constraints, i.e., the tendency for activities to be more or less at fixed points (or locations) in space. Changes in location require travel. An activity can take place:
* At fixed locations, e.g., most work, family visits;
* Within administrative borders, e.g., social services, visits to the doctor;
e In a purpose related facility, e.g., shopping, the movies; * At any place, e.g., socializing with others;
e Movement between points, e.g., any travel.
An example of a typical activity sequence is shown in Figure 2.1.
It can be assumed that this pattern is influenced to various degrees by the social, temporal and spatial organization of the urban environment. For example, it may be necessary for the individual to shop near work if shops close shortly after work. The behavioral pattern may be condition-ed by the supplementary or complementary nature of activities. Cashing a check before going shopping is a supplementary situation; whereas going for a late night snack may be complimentary to going to a movie
or the theatre. Likewise, dependent upon the day of the week certain activities may dominate other activities.
8:
AUTO DR (24 Mi
8:39 AMI
FIGURE 2.1
A TYPICAL ACTIVITY SEQUENCE
HOME 15 AM 6:30 PM AUTO DRIVER (10 Min.) 6:20 PM SHOPPING (25 Min.) IVER 5:55 PM ni.) AUTO DRIVER (20 Min.) 5:35 PM WORK WORK (190 Min.) (271 Min.) 11:54 AM 1:04 Pm WALK WALK (6 Min.) (5 Min.) 11:59 AM SHOPPINGWALK Mi) 12:48 PM SHOPPING ( i. (5 Min.) 12:04 PM 12:07 PM EAT (41 Min.) 22
23
2.3 Out-of-Home Activity Dominance by Purpose
From the viewpoint of participation and mean duration of out-of-home
activities in a survey of human time allocation in Washington D.C. in
1968, and the presentation of the study by F. Stuart Chapin, Jr. of the
University of North Carolina Center for Urban and Regional Studies in
1974, one can see in Table 2.1 that the work activity dominates all of
the other out-of-home activities for the weekday. Of the 1667 persons
surveyed, 58 percent or 967 work; their per participant mean duration is 7.77 destination hours or 0.97 travel hours. The per capita mean destination hours are 4.49 and the travel mean hours are 0.57 per capita.
For 67 or 4 percent of the individuals the education activity is
impor-tant with 4.84 mean destination hours and 0.57 mean travel hours. It is
significant to note that 36 percent of the individuals participate in the
shopping activity. Of all the activity categories only the household
business has a destination time of less than one hour per participant.
Comparisons between weekday and weekend out-of-home activity
par-ticipation can be made by analyzing the data of Table 2.2 and Table 2.3 in contrast to Table 2.1. On Saturday the shopping participation rate
dominates other activity choices; 48 percent of those surveyed shop on
Saturday compared to 15 percent on Sunday and 36 percent for the weekday. Only 12 percent of those surveyed work on Saturday; on Sunday 12 percent work. These compare with 58 percent on the weekday. The shopping travel
time of 0.72 hours is a significant part of the 2.27 hours of total shop-ping activity duration (destination plus travel time); it is 32 percent.
24 TABLE 2.1
WEEKDAY OUT-OF-HOME ACTIVITY PARTICIPATION
PERCENT MEAN HOURS SPENT MEAN HOURS SPENT ENGAGING PER,'PARTICIPANT PER CAPITA IN ACTIVITY
ACTIVITY CATEGORY (n=1,667) DESTINATION TRAVEL DESTINATION TRAVEL
WORK
58
7.77
0.97
4.49
0.57
SHOPPING 36 1.02 0.57 0.36 0.21
HOUSEHOLD BUSINESS 24 0.80 0.14 0.19 0.03
HEALTH CARE SERVICES 6 2.03 0.34 0.12 0.02
EDUCATION 4 4.84 0.57 0.18 0.02 VISITING NEIGHBORS 4 1.43 0.03 0.06 0.00 VISITING OTHERS 14 1.64 0.25 0.22 0.04 OTHER SOCIAL 4 1.95 0.50 0.09 0.02 CULTURAL EVENTS 6 1.61 0.19 0.10 0.01 MOVIES 2 2.28 0.64 0.04 0.01
WALKING & CYCLING 3 0.00 0.98 0.00 0.03
FAMILY DRIVES & 1 2.26 0.11 0.03 0.00
OUTINGS NON-FAMILY DRIVES 1 0.00 0.90 0.00 0.01 PARTICIPANT SPORTS 6 1.50 0.21 0.09 0.01 SPECTATOR SPORTS 1 1.90 0.51 0.01 0.01 OTHER RECREATION 2 1.18 0.03 0.03 0.00 RELIGIOUS ACTIVITIES 4 1.66 0.26 0.07 0.01
Source: Chapin, F. Stuart, Jr. Human Activity Patterns in the City,
25 TABLE 2.2
SATURDAY OUT-OF-HOME ACTIVITY PARTICIPATION
PERCENT MEAN HOURS SPENT .MEAN HOURS SPENT
ENGAGING PER PARTICIPANT PER CAPITA
IN ACTIVITY
ACTIVITY CATEGORY (n-807) DESTINATION TRAVEL DESTINATION TRAVEL
WORK 18 6.64 0.73 1.20 0.13
SHOPPING 48 1.55 0.72 0.75 0.34
HOUSEHOLD BUSINESS 21 1.00 0.20 0.21 0.04
HEALTH CARE SERVICES 5 3.36 0.54 0.15 0.03
EDUCATION 1 5.77 0.57 0.07 0.01 VISITING NEIGHBORS 4 1.95 0.03 0.08 0.00 VISITING OTHERS 12 2.82 0.52 0.33 0.06 OTHER SOCIAL 8 2.99 0.69 0.24 0.06 CULTURAL EVENTS 5 1.84 0.42 0.10 0.02 MOVIES 4 2.89 0.67 0.11 0.02
WALKING & CYCLING 2 0.00 1.61 0.00 0.04
FAMILY DRIVES & 2 1.62 0.38 0.03 0.01
OUTINGS NON-FAMILY DRIVES 1 0.00 1.18 0.00 0.02 PARTICIPANT SPORTS 5 2.13 0.27 0.11 0.02 SPECTATOR SPORTS 2 3.22 0.61 0.08 0.01 OTHER RECREATION 3 1.56 0.07 0.04 0.00 RELIGIOUS ACTIVITIES 5 2.16 0.21 0.12 0.01
Source: Chapin, F. Stuart, Jr., Human Activity Patterns in the City, (New York: John Wiley and Son), 1974, page 254.
26 TABLE 2.3
SUNDAY ,OUT-OF-HOME ACTIVITY PARTICIPATION
PERCENT MEAN HOURS SPENT MEAN HOURS SPENT . ENGAGING PER PARTICIPANT PER CAPITA
IN ACTIVITY
ACTIVITY CATEGORY (n=802) DESTINATION TRAVEL DESTINATION TRAVEL
WORK 12 6.23 0.54 0.73 0.06
SHOPPING 15 0.50 0.44 0.07 0.07
HOUSEHOLD BUSINESS 17 1.49 0.24 0.25 0.04
HEALTH CARE SERVICES 3 4.79 0.38 0.17 0.01
EDUCATION 2 3.93 0.00 0.09 0.00 VISITING NEIGHBORS 4 2.03 0.12 0.09 0.01 VISITING OTHERS 14 1.84 0.38 0.26 0.05 OTHER SOCIAL 5 2.36 0.75 0.13 0.04 CULTURAL EVENTS 6 1.80 0.26 0.12 0.02 MOVIES 1 2.93 0.75 0.03 0.01
WALKING & CYCLING 5 0.00 1.49 0.00 0.08
FAMILY DRIVES & 6 1.69 0.08 0.05 0.00
OUTINGS NON-FAMILY DRIVES 2 0.00 2.64 0.00 0.06 PARTICIPANT SPORTS 6 1.89 0.29 0.12 0.02 SPECTATOR SPORTS 1 2.50 0.25 0.03 0.00 OTHER RECREATION 3 1.78 0.16 0.05 0.01 RELIGIOUS ACTIVITIES 32 1.87 0.50 0.60 0.16
Source: Chapin, F.Stuart, Jr. Human Activity Patterns in the City, (New York: John Wiley and Son), 1974, page 255.
27
On Sunday travel time is 47 percent of the total shopping duration.
Simi-lar comparison can be made for the other activity categories. It is
par-ticularly important to note that 32 percent of the individuals surveyed
participate in religious activities. Religion dominates the activity
choice on Sunday. The destination durations and participation rate also
increase for the social and recreational activity categories for Saturday
28
2.4 Activity Dominance in Trip Tours
The dominance of different activity categories can also be seen in
the trip tours or sojourns of individuals. In Table 2.4, of all trip
tours for weekday travel, 24.4 percent of the tours are work round trips
as compared to 8.0 percent for weekend work trips. Likewise, 43.5 percent
of all trip tours have work as the dominant activity on the tour for the
weekday compared to 13.0 percnt for the weekend. Of all weekday trip
tours 64.3 percent are round trip (or two link) tours as compared to
68.0 percent for all weekend tours. For all weekend trip tours in Table 2.5, the shopping activity dominates most trip tours with 23.2 percent;
the social activity follows a close second with 22.1 percent of all tours.
For weekday trip tours the shopping activity is the second most dominant
activity with 18.3 percent of all tours following behind the work activity
with 43.5 percent of all tours. In analyzing multiple stop trip tours,
travel time is assigned to each activity based upon the travel time from
the previous activity to the destination of the activity under
consider-ation. The travel time from the last activity destination to home link
is then assigned to each activity based upon a ratio equivalent to the
destination time of each activity to the total destination time of all
activities for the complete tour.
In examining the dominance of different activity categories for the
weekday it is not important to examine each day separately; the tour pat-terns of the five weekdays Monday, Tuesday, Wednesday, Thursday, and
Friday are rather consistent. Friday evening may be an exception to this
TABLE 2.4
WEEKDAY OUT-OF-HOME ACTIVITIES AND TRIP TOURS (350 Trip Tours)
(228 Individuals)
# OF LINKS IN TOUR
ACTIVITY OF LONGEST DURATION ON TRIP TOUR (SOJOURN)
WORK SHOP PB&S SOC REC EDUC EEL EAT WALK SPAX DRIV MISC
I. I Z FOR # OF LINKS IN TOUR
1.4
.7
.3
24.4
11.5
4.5 5.2
1.7
1.0
.7 7.7 2.8 2.4 1.4 1.05.9
3.8
1.0 2.1
.7
.3
.3
.3
5.9
1.0
.7
2.8 1.0 .7S
1.4
.3
.3
.7
.3 .3.3
.3
.3 --I
I
43.518.3
6.1 9.7
3.0
1.3
1.7
8.0
2.8
3.0
1.4 1.0Activities: Work w Work; Shop - Shopping; PB&S w Personal Business & Service; Soc = Social;
Rec -
Recreation;
Educ = Education; Rel = Religious; Eat = Eating; Walk = Walk;SPAX - Driver to Serve Passenger; Driv = Family Drive; Misc = Miscellaneous. Source: Author's analysis of 285 individuals of University of North Carolina at Chapel Hill,
Center for Urban and Regional Studies Survey of Human Time Allocation in Washington,
D.C. (1968). See Chapter 5 for data discussion. %0
1
23
4
5
6
7
8
9
2.4
TOTAL 2.464.3
14.3 9.33.7
4.1
0.7
0.30.3
99.8%
1. wTABLE 2.5
# OF LINKS IN TOUR
WEEKEND OUT-OF-HOME ACTIVITIES AND TRIP TOURS (319 Trip Tours)
(203 Individuals)
ACTIVITY OF LONGEST DURATION ON TRIP TOUR (SOJOURN)
WORK SHOP PB&S SOC REC EDUC REL EAT WALK SPAX DRIV MISCI
% FOR # OF LINKS IN TOUR 1 .8 3.8 1.5 .4 .4 1.1 8.0 2 8.0 17.6 4.2 11.8 5.7 11.1 .8 4.2 2.7 .8 1.1 68.0 3 3.0 3.0 .8 3.8 1.5 .8 12.9 4 .8 1.5 .8 .8 1.5 .4 5.8
5
.4
.8
.8
2.0
6 1.1 1.1 2.2 13.0 23.2 5.0 22.1 9.5 0.0 14.6 1.2 4.2 3.1 1.9 1.1Activities: Work = Work; Shop = Shopping; PB&S = Personal Business & Service; Soc = Social; Rec = Recreation; Educ = Education; Rel = Religious; Eat = Eating; Walk = Walk; SPAX = Driver to Serve Passenger; Driv = Family Drive; Misc = Miscellaneous;
Source: Author's analysis of 285 individuals of the University of North Carolina at Chapel Hill, Center for Urban and Regional Studies Survey of Human Time Allocation in Washington,
D.C. (1968). See Chapter 5 for data discussion.
0
31
weekdays. However, for the weekend sojourns or trip tours, it may be
im-portant to examine the Saturday and Sunday sojourns separately.
The strong dominance of the Sunday religious activity does not appear
to be significant with Saturday and Sunday aggregated into a weekend group
as in Table 2.5. However, as shown in Table 2.6, the religious activity
dominates 25.9 percent of all Sunday trip tours with the social activity
dominating only 20.3 percent of the trip tours. On Saturday shown in
Table 2.7, the shopping activity dominates 32.6 percent and the social
activity dominates 23.1 percent of all tours. This is a different
domin-ance pattern compared to the weekend aggregate analysis of the trip tours
where 23.2 percent of the tours are dominated by the shopping activity
TABLE 2.6
# OF LINKS IN TOUR
SUNDAY OUT-OF-HOE-ACTIVITIES AND TRIP TOURS (166 Trip Tours)
(106 Individuals)
ACTIVITY OF LONGEST DURATION ON TRIP TOUR (SOJOURN)
WORK SHOP PB&S SOC REC EDUC REL EAT WALK SPAX DRIV MISC
% FORi OF LINKS IN TOUR 1 1.4 4.9 1.4 0.7 0.7 2.8 11.9 2 5.6 10.5 2.8 9.1 6.3 19.6 1.4 4.9 2.8 1.4 1.4 65.8 3 2.1 2.1 4.2 1.4 1.4 11.2
4
0.7
1.4
2.8
1.4
6.3
5 0.7 0.7 1.4 2.86
0.7
.7
2.8 20.3 10.50.0
25.9
2.1 4.9 4.2 1.4Activities: Work = Work; Shop = Shopping; PB&S = Personal Business & Service; Soc = Social; Rec = Recreation; Educ = Education; Rel = Religious; Eat = Eating; Walk = Walking;
SPAX = Driver to Serve Passenger; Driv = Family Drive; Misc = Miscellaneous. Source: Author's analysis of 285 individuals of University of North Carolina at Chapel Hill,
Center for Urban and Regional Studies Survey of Human Time Allocation in Washington,
D.C. (1968). See Chapter 5 for data discussion.
TABLE 2.7
SATURDAY OUT-OF-HOME ACTIVITIES (153 Trip Tours)
(96 Individuals)
# OF LINKS IN TOUR
ACTIVITY OF LONGEST DURATION ON TRIP TOUR (SOJOURN)
WORK SHOP PB&S SOC REC EDUC REL EAT WALK SPAX DRIV MISCI
% FOR # LINKS IN TOUR 1 2.4 1.6 0.8 4.8 2 9.5 25.4 5.6 14.3 6.3 1.6 3.2 2.4 1.6 0.8 70.7 3 4.0 4.0 1.6 3.2 1.6 14.4 4 1.6 3.2 0.8 5.6 5 0.8 0.8 6 1.6 1.6 15.1 32.6 7.2 23.1 9.5 0.0 1.6 0.0 3.2 2.4 1.6 1.6
Activities: Work = Work; Shop = Shopping; PB&S = Personal Business & Service; Soc = Social;
Rec = Recreation; Educ = Education; Rel = Religious; Eat = Eating; Walk = Walking;
SPAX - Driver to Serve Passenger; Driv = Family Drive; Misc = Miscellaneous.
Source: Author 's analysis of 285 individuals of University of North Carolina at Chapel Hill,
Center for Urban and Regional Studies Survey of Human Time Allocation in Washington,
D.C. (1968). See Chapter 5 for data discussion.
34
2.5 Mean Duration of Out-of-Home Activities by Day-of-the-Week
It is also interesting to compare the total mean amount of time
indi-viduals spend in out-of-home activities at the destination.and in travel to and from the activity locations. The data in Table 2.8 indicates that
total out-of-home activity time (destination time plus travel time)
de-creases for the weekend (Saturday and Sunday) as compared to the weekdays.
This is not surprising since during the weekend the relative importance
of work, usually the single largest out-of-home time allocation, decreases
accounting for substantially less total out-of-home activity time.
Like-wise, the non-work (leisure) out-of-home activity shows an increase
dur-ation for Saturday and Sunday as compared to the weekdays. Among the
weekdays, the out-of-home activity time is significantly higher on
Fri-day because of the combination of the work activity and FriFri-day evening out-of-home social activities. Thursday is the weekday with the lowest amount of time devoted to out-of-home activities. Leisure activity
(non-work activity) duration does not seem to vary significantly for the other weekdays Monday, Tuesday and Wednesday.
35 TABLE 2.8
OUT-OF-HOME ACTIVITY DURATION BY DAY-OF-TiE-WEEK
MEAN
NUMBER OF DURATIONS
DAY OF WEEK SAMPLES IN HOURS
MONDAY 292 8.48 TUESDAY 290 8.17 WEDNESDAY 252 8.80 THURSDAY 317 7.85 FRIDAY 516 10.64 WEEKDAYS 1667 8.89 SATURDAY 807 7.49 SUNDAY 802 6.33 WEEKEND 1609 6.91
Source: Chapin, F. Stuart, Jr. Human Activity Patterns in the City, (New York: John Wiley and Son) , 1974, pages 101 and 121.
36
2.6 The Importance of Activity Characteristics in Model Development
The material in this chapter has focussed on the descriptive
charac-teristics of activity choice.
Work as a frequent, predetermined dominant
activity strongly influences the remaining time that the individual worker
can spend in in-home activities and out-of-home leisure activities,
speci-fically the shopping-personal business, and social-recreation activities.
The shopping-personal business activity, where frequency can vary despite
a constant demand, can be expected to influence the time remaining for the
social-recreation activities, which are less frequent and not based on
con--stant demand, particularly for the weekday. On the weekend, the
shopping-personal business activity may have little, if any, effect on the
social-recreation activity. The social-social-recreation activities are more dominant
than shopping-personal business on Sundays.
These patterns of dominance and the other characteristics are
impor-tant in the development of the models, data sources, and explanatory
vari-able selection presented in the following chapters. With these
character-istics in mind, the theoretical model of microeconomic activity choice is
developed in the next chapter.
'17
CHAPTER 3
THEORETICAL DEVELOPMENT OF A MICROECONOMIC ACTIVITY CHOICE MODEL
3.1 Four Decisions Related to Out-of-Home Activities
The aim of this chapter is to develop a microeconomic model of
con-sumer behavior which will contribute to the understanding of the
funda-mental nature of activity choice decisions and travel decisions of
indi-viduals and of the interactions of these decisions with each other and
other activities. Particular attention is given to out-of-home
activi-ties as primary goods while travel is viewed as an intermediate good --the means of getting from one activity location to ano--ther.
The main decisions of the individual are:
* Whether or not to participate in activity,
e If one participates how long to participate, * If one participates where to participate,
e If one particIpates out-of-home how to travel to the activity location.
The models developed in this chapter provide information on these four
types of decisions.
The primary activity and its intermediate travel require both the
consumption of goods and/or services and of time. The decision to par-ticipate in an out-of-home activity and to travel to a particular
destin-ation is not only a function of the cost of the activity and cost of the
trip, but also of the value the individual attaches to the activity time
38
model developed in this chapter explicitly takes into account the problems
of time allocation among the various activities and time allocation among
their related travel; both enter the utIlity function of the individual
consumer.
An important objective of this chapter is to determine the possible
contribution of microeconomic theory to our knowledge of the determinants
of the value individuals place on different activities and their related
travel and the direct and indirect substitution effects among activities
and related travel.
The theoretical relationship between the marginal
value of time savings in activities and travel and the wage rate will be
considered. Also derived from these models will be the theoretical
foun-dations of empirical research into the value of activity time savings,
3.2 Traditional Economic Choice Theory
In traditional consumer behavior theory individuals maximize their
utility:
U = U (XyX2''''' n
subject to one resource constraint:
Ep X =Y = W + V
where:
X= goods purchased,
P,= market price of goods,
Y = money income,
W
- earnings,V
- other income.However, a few authors have emphasized the fact that consumers are
also subject to a time constraint. These authors include Lesourne (1964),
Becker (1965), Oort (1969), Klaassen (1970), Watson and Mansfield (1970),
40
3.3 Basic Concept of Activity Choice Theory
In this reserach the activity choice and travel choice models
in-clude the cost of time on the same footing as the cost of market goods
and services. Individuals are considered both as producing units and
utility maximizers. They are assumed to combine time and market goods
and/or services to produce more basic commodities called activities.
Each activity, A, is a function of goods and/or services, time, and the
socioeconomic characteristic of the individual consumer:
A
i, fiq
- f (Xiit
TA S)where:
f W the production function of activity Ai,
X - the vector of goods or service attributes
of activity Au,
T
- the vector of time inputs used inpro-ducing activity A,
S = the vector of socioeconomic
character-t istics of consumer t.
In this formulation each individual or household chooses the best
combination of these activities in the conventional way by maximizing
their utility function:
41
subject to both the budget constraint:
n
E pX, Y -V+ T x W
1
w
where:
P, unit price vector,
X- good or service attribute vector,
Y
- money income,V
- other income,T - hours spent at work,
w
W - earnings per unit of Tw
and the time constraint:
n
E =T -T -T - t
where:
TA - total time spent in the ith activity
(TA - TD + T )
i i i
Tz= total time spent in all leisure activities
(non-work activities),
T1 - ta-nl t4ma avaiSla, tme rnounrrn fnrA
J6 t A. L~M.I- a ".- _ A
0 given period,
T - total time spent in the work activity,
42
tW
-total time required for the work trip,
T - total destination time spent in the ith i activity,
T - total travel times spent in the ith activity.
i
The individual is not able to adjust the length of his work time
within the given time resource period (day, week, month ... ) according to his preferences. In other words, the work time, T , is an exogenous
variable for the individuals in the short run, but should probably be
re-laxed for long-run models. Likewise, for simplicity's sake, the total
work travel time is assumed to be fixed for each individual. In this
research effort we are only interested in the interaction of non-work
ac-tivities. Thus, constant work travel time is a realistic assumption,
particularly for individuals whose home and job location are given and
43
3.4 Two Time Constraint Categories: Time Resource and Time Consumption
Basically there are two classes of time constraints: the time
re-source or fixed time endowment and a time consumption constraint for a
given activity.
The individual has a fixed time resource, T, equal to the length of
the decision period. The time resource constraint requires that the
amounts of time allocated to each specific activity add up to the time
available:
T
= T + ET
0 w i
This relationship follows directly from the assumption that activities
are consumed one at a time and that all available time is allocated to
activity participation. It is important to note that both the budget and
time resource constraints, as specified, are independent of each other.
Each represents a resource constraint, but unlike most descriptions of
consumer time allocation, parametric time prices of goods and/or
ser-vices are absent from the time constraint. This is important for the
's are specified as decision variables distinct from the X's. The
use of time prices would reduce the number of decision variables by
one-half, for the choice of any X would determine, by means of the time
price, the corresponding TA. Time prices are excessively rigid and
un-i.
necessary.44
activity is partly a matter of choice and partly a matter of necessity.
The fact that activity consumption generally requires some interactive
expenditure of time and money places both an upper bound and lower bound
upon the amount of time an individual may spend in a particular activity.
For simplicity these relationships are assumed to be linear. Also
be-cause of interest in the interrelationship among time spent at a
destin-ation and the travel time to a destindestin-ation TA may be divided into T the
i
T
time spent in the activity at the destinations and Ti the travel time
spent in getting to and from the activity. Mathematically, then the time
consumption constraints may be given by imposing maximum and minimum
pos-sible values for Ti and TD. for each unit of i consumed:
Si
T
T > c X ,i
-ixi
T T < d X, i - i il T > e X,i
-ixi,
TD < f X, i-where c and e may be interpreted as technologically or institutionally
determined minimum amounts of time, while d and f are determined
maxi-mum amounts one may devote to consuming one unit of X .
The constraints are specified as inequalities because the individual
is free to allocate more than the minimum and less than the maximum time
45
individual preference, although common sense suggests that the constraints
will be binding for nearly all individuals in certain activities because
of the nature of the activity. Examples of such technological or
physi-cal constraints are the length of or amount of movies, meals, traffic
con-gestion, books, games, sporting events, etc. Examples of the institutional
type of constraints are business hours, speed limits, rigid work weeks,
meeting schedules, etc. The time consumption constraints, be they
tech-nical, physical or institutional, must be made explicit in the
maximiza-tion model along with the budget constraint and time resource constraint,
46
3.5 Lagrange
Function of Activity Choice Model
The individual's problem of efficiently allocating his time and money
resources and constraints may be expressed as the maximization of the
Lagrange function assuming U to be a concave function:
L U(X DT T max U( . n;T9,..,n;TS...tn 1**'''Sn) + PP0nTDnT P(T-Tw iI i -l + n X(Y - E
P
x
)
+
n E 1k (T
-eX)
+ n T E 1 m1(fX -T nii o (T
-c Xi) +
n i r (d X T -T
where p,
A
> 0 and kim.e
1,r >0, i=l,...,n.47 ax P + k e +oc - mf - rId
QUJ
-
k +m
a -o + r cl T D TD T T-e X
ii
X
-fcX
=iiX
ork
=0
orm
=0
or o =0
or r =0
Thus if it is assumed that individuals spend the minimum possible time on
an activity at the destination, the money value of saving destination time
on an activity is: DT i
A
A
TD
~-
~
i
where k 00and m -0. where:48
Likewise if it is assumed that individuals spend the minimum possible time
on travel, the money value of saving time on travel for the activity is:
TT U
=a
savings AX Ti
where o 00and r, = 0.
If an individual values his travel time and destination time at the
same rate than o = k, and the money value of saving destination time
would equal the money value of saving travel time. However, this is
generally unlikely since the time spent in an activity at the destination
generally provides a positive utility while the travel time has a
dis-utility; travel service is an intermediate good which is not consumed for
its own purpose, except in the case of the family drive, recreational
cycling, pleasure walks, etc.
From this model the value of time savings for an activity and its
associated travel is the resource cost offset by the enjoyment derived
from activity participation and travel. The idea of leistLre activities
fixed in terms of the money and time required, but with the time input
able to vary within defined upper and lower limits, seems reasonable in
relation to activities such as visits to friends or to the theater. In
the short run, even shopping trips may fit into this classification;
the individual is likely, when considering making a shopping trip to a
49
the shopping trip (or even personal business trip) decision is more one
of deciding whether tb do the activity in the minimum possible time or
to devote time to careful selection of the required goods or services,
the maximum possible shopping time or service time on any one trip being
50
3.6 Three Major Categories of Activities
In this theoretical model one may distinguish between three
cate-gories of activities. The first two categories have the common
char-acteristic that time and goods and/or services are consumed simultaneously
in the performance of an activity. In the third category only time is
consumed.
The first category of activities covers those which can be consumed
with reveral combinations of goods and/or services and time. In other
words goods or services can be substituted for time and vice versa in the
performance of a given activity level. The level (quality or satisfaction)
or an activity may be achieved with the money purchase of different
com-binations of services and/or goods and time allocation to the activity.
Examples of this category of activities are: the journey to the grocery
store, cleaning the house. The individual can walk, or drive or take
public transit to go marketing. The individual can clean the house
with or without different household appliances or the service of others.
In each case, the same level of activity may be achieved with different
combinations of goods (money) and time.
The second category consists of activities whose level can only be
increased by using more time and goods in a fixed proportion. Watching
television is an example of this activity category.
The third category of activities consists of those activities which
do not require the simultaneous consumption of time and the purchase of
goods or services. In other words, there are activities which involve
51
are "environmental goods" which have no direct cost but may have indirect
cost which cannot be determined. Examples are. a free beach, the
cultur-al characteristics and environment of the people living in one's
neigh-borhood, etc. Environmental goods may affect the time budget of the
individual in three ways: first, the travel time and cost of reaching
the free activity, the free beach; second, the amount of social and
cultural interaction with one's neighbors; and third, the quality of
certain environmental goods is a function of the location of one's living
place in a given city or in a given region. The degree of air pollution,
the scenery, the social environment varies from neighborhood to
neigh-borhood within a given area. Hence the acquisition of certain
environ-mental goods implies the choice of specific locations of one's
activi-ties in space (the choice of location of one's residence, one's
profes-sional activities, etc.). These choices of mobility and environmental
quality have a significant influence on several trip purpose travel times.
Thus, temporal space is not homogeneous with respect to the quality of the
living environment.
The model of consumer behavior developed in this chapter assumes
that the consumer only produces consumption activities of the first
type, i.e., activities that can be produced with different combinations
of goods and/or services and time. Most activities and travel fall
in-to this category of consumption activities. However, the family drive and
the walk in the park involve the second and third activity categories.
Travel activities in the second and third categories can be assumed to
con-52
sumed for pleasure as primary activities rather than as intermediate
53
3.7 Practical Use of the Microeconomic Activity Choice Model
The preceding model enlightens the fundamental nature of activity choice and travel choice in the consumption sphere. The activity choice and its related travel choice is basically equivalent to choosing a given combination of goods or aervices (money) and time required to participate
in the activity and to get to and from the activity. In real life
indi-viduals are not faced with continuous production functions and their
utility functions are not measurable or quantifiable. All that can be
assumed from utility is that individuals rank activities in some
consis-tent way. To say that the utility of activity B is greater than that of
another activity C only means that B is preferred to C. From the concept
of duration or time allocation one might say that if an individual spendr more time in activity B than activity C then activity B is preferred to C. Thus the research directs its focus to the development of a time share model and choice duration models in order to determine the preference
that an individual has for one activity as compared to another.
Conse-TD
tae
ieTT
quently the destination time and travel time T of the utility
fune-i
i
tion or their summation the total activity T
(T
= 1? + TT) for aspeci-i speci-i
i
i
fic activity becomes the means of determining activity choice preference. From the theoretical model one can develop more practical models where TA becomes a function of an individuals income Y, the unit prices
i
P 's of the goods and service attributes X 's consumed in the
participa-tion of each activity, the individuals other socioeconomic characteristics,
and the amount of time spent in other activities. The duration models
54
money (goods and services) and socioeconomic characteristics.
When choosing among activities and modes of travel the individual
will compare cost at the destination and travel costs, the time required
at each destination and travel time, and the quality of service and goods
at destination and by each mode. The activity choice is quite complex.
It may be based upon prior commitments, chance encounters with different
individuals and spur of the moment whim. However, within a specific
ac-tivity category a shorter, cheaper high quality service acac-tivity may be
preferred to longer, more expensive less quality of service activity,
i.e., if the activity is shopping. Likewise, for the travel choice if
one mode is faster, cheaper, and more comfortable than the other modes,
it will be chosen. If one is faster and more comfortable but also more
expensive than the other modes, it will be chosen only if the value of
the time savings plus the value of the added comfort during the remaining
55
CHAPTER 4
ACTIVITY CHOICE TIME SHARE AND TIME DURATION MODELS
4.1 Activity Time Share Model Formulation
In theory one can view the allocation of time over a given period
as a share model. In this study the time period is one day or 24 hours.
S
Thus any activity's share of a 24-hour period, Ti, may be expressed as:
TA TA _ _ _ Ti n #rA TA 24 i-l i +Th
w
where:4
- f(X2,XP,PI,YtSITA) TnTh =24-
TA-
TA
-in-home activity time,h
w 1-1i
TA
= summation of both work time and work trip time,XD - vector of destination goods or service attributes of activity AV,
T
X = vector of travel service attributes associated with activity Ai,
D
P = unit price of destination goods or service consumed
for activity Ai,
T
56
Y t Mthe money income of individual t,
St -other socioeconomic characteristics of individual t.
This study uses the actual values of the explanatory variables associated
with each individuals participation in a specific activity. However, in
theory expected values associated with anticipated activity participation
should be used as exogenous explanatory variables because activity choice
is really based on expected goods or service consumption; the activity
has not yet taken place when the activity participation decision is made.
Composite variables of travel time, travel cost, and destination
attri-butes may be determined by the following:
D M Xtt - S S ttdmx P(m,d:MD)
d1 m~l
d
D M Xtc d SE tcx P(m,d:MD)d1 m-l
dm
D Xat - S at x P(d:D)d1 d
where: Xtt - expected travel time,
Xtc - expected travel cost, Xat - expected attribute,
ttdm - total travel time to destination d by mode m,
tCdm - total travel cost to destination d by mode m,
atd - attribute of destination d, e.g., total retail employment,
