Domestic telephone habits and daily mobility

Trmspn. Res:A, Vol. 2lA. Printed in Great Britain.

No. 4, pp. 277-290.

0965~8564/93 M.00 + .oo 0 1993 Pergamon Press Ltd.

195’3

DOMESTIC TELEPHONE

HABITS AND DAILY MOBILITY

GERARDCLAISSE Laboratoire d’Economie des Transports, E.N.T.P.E.-Universite Lumiere Lyon II, Unite Mixte du C.N.R.S., Rue M. Audin, 69518-Vauix en Veiin, France and FRANTZROWE Maitre de Conferences, Ecole Nationale Superieure des Telecommunications, Departement Economic et Management, 46, Rue Barrauit, 75634-Paris, France (Received 25 January 1990; in revisedform 7 November 1992) Abstract-Based on an analysis of the present French domestic telephone habits, this paper puts forward an original approach for the evaluation of telephone and mobility interactions. A survey carried out on a sample of 663 French people, which recorded the characteristics of 7252 domestic telephone calls, has enabled us to identify, evaluate and characterize these impacts by distinguishing 4 types of telephone traffic: specific traffic, management traffic, substitution traffic and induction traffic. The main finding is that nearly two thirds of domestic telephone activity is linked to daily mobility, whether it replaces, generates or-manages trips or activities.

I. INTRODUCTION technologies were developed in the 1970s at a time when the world was going through a series of crises-energy, economy and urbanization. This led to a certain amount of prospective thinking being done as to what economic alternatives (Pye, 1976), energy alternatives (Tyler et al., 1974, 1976) and organizational alternatives (Harkness, 1973; Meier, 1968) for transport could be provided by telecommunications. Salomon (1986) and Claisse (1983), amongst others, have examined this literature in detail. Until the beginning of the 1980s priority was given to the prospective evaluation of the substitution of new communication systems for travel. If we focus the analysis of telecommunicationtransportation relationships on substitution prospective, we are taking a double risk: (a) that of reducing the diversity and the complexity of the effects of the development of new communication technologies on transport; (b) and consequently, that of overestimating the possibilities of substituting telecommunications for transport (Mitchell, 1969; BCEOMDATAR, 1970; Lathey, 1975). The aim of this paper is to present a new analysis of the influence of individuals’ telephone activity on their daily mobility. However, before we can describe the methodology we have chosen, and the data used to carry out this analysis, we must first review

New communication

the complexity and the diversity of the interactions between transportation and telecommunications. 1. I. Transportation and telecommunications: Complex relationships

To illustrate the diversity of the interactions between transportation and telecommunications, we must go back two centuries before the invention of

the telephone. At that time, communication needs could partially be satisfied in one of the following three ways: an unexpected meeting, a letter or a trip. The communication market was then suddenly revolutionized by the introduction of the telephone. The results were considerable. These results can be classified into the following three categories: (a) the development of a new communication market; (b) the direct and (c) the indirect effects on the pre-existing means of communication. The first consequence, that of the development of a specific market for the telephone call, is often overlooked. The real goal of any major technical innovation is to develop its own market, to respond to latent needs and to create new ones. In fact both transportation and telecommunications systems enable us to respond to specific communication needs that are not transferable from one system to the other. 1. First, the technologies studied are often new communication technologies, or more specifically the so-called advanced telecommunication techniques. 2. Second, and in consequence, these studies have often been prospective; historical approaches are virtually non-existent (de Sola Pool, 1977); empirical studies on the effects of telecommunications on transportation at present are frequently carried out as part of technical or social experimentations that are used as a basis for a prospective generalization. 3. Third, and logically, this work is often based on an in-depth analysis of the demand for transport; few studies start off from an analysis of the demand for and the use of telecommunications in order to evaluate their influence on transport. 277

G. CLAISSE~~~

278

4. Finally, the communications market studied is often that of trips linked to professional activities: commuting (Libby, 1968; Jones, 1973), and business trips (Kollen and Gardwood, 1973), company communications (Gensollen, 1978), and electronic mail. The analysis of the influence of individuals’ telephone activity on their daily mobility that we proposed in this paper is relatively new. This empirical approach is not prospective; it is based on a technology more than one hundred years old and in use all over the world, with well-established habits. It is based on the analysis of telephone consumption and habits and tries to underline the direct effects of these practices on the daily mobility of individuals. Finally, it deals with residential and not with professional communications. The telephone activity of an individual is defined by the set of telephone calls, both given and received, at home. Each call is described by its main characteristics (day, time, duration, location, action and aim, correspondent, etc). Daily mobility is defined by the set of trips made during an ordinary week day. Each trip is described by its main characteristics (day, time, duration, origin-destination, mode, motive, etc.). The central question we have tried to answer is the following: Does the analysis of residential telephone habits enable us to find, identify and evaluate what we will go on to call (according to the general typology carried out in most of the research works on telecommunication-transportation interactions): Management telephone traffic, i.e. telephone communications rhar enable individuals to manage their actlvltles and their daily mobility. Substitution

telephone

traffic,

i.e. telephone

com-

trip,. Induction traffic. made up of all the telephone communications that lead to unplanned trips. This effect i\ somerImes referred to as the generamunications

tion

effect

to avoid

rhar replace

(3loore

and .lo\anis,

this evprewon

1984); Me prefer

Inwfar

as it could

be con-

fused with rhc creation of communication needs that are specific to the telephone. Finally, speclflc or auronomous telephone traffic, that groups

together

all those communications

directly

connected

viduals.

For esample,

iar voice,

to spend

some news about specific

New

with

rhe daily to chat,

bomr

time

a relative’s

or autonomous

communication

mobility

to listen together,

health,

not

of indito a familor to get

belong

to this

traffic.

hablts

stern

from

the tele-

phone; without it, some communication events could not have occurred. We name specific or autonomous traffic, those calls that do not directly manage, induce or replace trips. Of course, should we view the communication space in a more dynamic way, each

F.ROWE

communication event (a trip, a call) is linked to others or forthcoming events. Therefore, each call is related to a more or less distant trip, and in the last resort each call, each trip is an event of the same set: the individual’s daily life. In order to analyze the choices among the various modes in the communication market, the traditional approaches consist of observing the effective behavior patterns of individuals through a survey that lists all means of communication. Such work has just been undertaken by France Telecom and should lead to a modelling of the preferences brought out by the use of the model referred to as LOGIT. The cost of such surveys is, however, considerable. Other approaches have been used more recently in transportation analysis and they have enabled this cost to be reduced. These approaches are not based on the observation of real behavior but on individuals’ stated preferences. The person questioned is placed in a hypothetical situation and can then express his or her preferences (by grading, classification or choice) among a given number of alternatives (Louviere, 1985; Bradley and Kroes, 1990). This approach was used, for example, in order to model the choices among various mail and telecommunication services for professional communications (Moore and Jovanis, 1988). The survey we have carried out does not enable this type of investigation to be made. Moreover, the evaluation of the influence of the development of the telephone on the communication market (creation of specific communication needs) and more specifically on individuals’ daily mobility (induction, substitution, management) is not posed in terms of modal choice in this article. I .3. The data In order to carry out this investigation, we have used the results of survey that we made on individuals’ telephone habits (Claisse, Vergnaud, and Rowe, 1985). This survey was carried out in 1984 on a representative sample of the subscribers of the Lyons conurbation. Its main objective was to analyze the determining reasons for telephone consumption and to construct a typology for individuals’ telephone habits. This survey is one of the first quantitative studies in the world on the domestic use of the telephone that makes it possible to identify the content of calls in detail. The results of this survey were presented to the international scientific community dealing with the sociology of telecommunications on the occasion of several international conferences (Claisse and Rowe, 1987; 1989; 1990). The methods for this research are to be used again in the very near future for an international comparative analysis of the telephone habits of individuals, which will bring together research institutes in France, Germany, the United States, Japan, Australia and the United Kingdom. This survey was carried out on a sample of 663

Telephone habits and daily mobility people and enabled us to get information on 7252 telephone calls. The sample was selected on the basis of dwelling units, according to quotas based on age and on the socio-professional category of the head of the household. The telephone traffic recorded is only representative of the telephone calls made or received by the individuals in their home, and does not take into account calls they may have made outside their dwelling (from call boxes or at work, for example). The survey material included three questionnaires: 1. A household questionnaire dealing with traditional socioeconomic characteristics of the household and the individuals within the household, the residential mobility of the household, the telephone equipment, how the telephone was considered and how much it cost. 2. A diary to be filled in by the members of the household (13 years of age or older), in which they recorded all the calls made or received by all the individuals in the household during the week selected for the survey, and enabling the calls to be classified according to twenty-odd basic variables. In particular, the respondents were given the set of “actions” and “aims” listed in Table 1 and asked to choose the first item appearing in the ranking of this table applicable to their call. 3. A relationship network questionnaire filled out by the surveyor when he or she came to collect the diary, and which enabled us to identify all the correspondents contacted by phone during the survey week (telephone relationship network) as well as the main characteristics of the relationship network of the household (family, professional, friends, neighborhood, etc.).

279

Thus, in the survey which we have just reviewed, the individual was asked to answer, in the telephone diary, the two following questions: 1. “Has this call led you or your correspondent to make an unplanned trip?” The answers proposed were “yes” or “no” both for the surveyed person and the correspondent. 2. “If the whole French telephone network was suffering from a long-lasting breakdown, what would you have done, or what would your correspondent have done, if it were he or she who was calling?” The six alternatives proposed were the following: “undertaken a trip,” “sent a messenger, ” “a letter, ” “a telegram, ” “waited for an opportunity, ” “or done nothing.” The answer to the first question gives a first evaluation of what we refer to as induced telephone traffic. The answer to the second question gives a first evaluation of the effect of substitution (trips or mail) and of specific telephone traffic (waited for an opportunity or done nothing). In the following paragraph we will see how we can evaluate what we refer to as daily mobility management telephone traffic. The replies obtained to these two questions are not of the same nature. On the one hand we can see the possible induction of a trip based on the individual’s objectivising the result of his telephone call; on the other hand we can record the preferences declared among several alternatives in the relatively theoretical case of the individual’s not being able to telephone for some considerable time. Thus, rather than giving us a perfect reconstruction of reality, the data we use can enable us to propose a heuristic representation of the telephone and mobility direct interactions.

Table I. Call motives Action 1. 2. 3. 4.

Number of Calls

%

63 50 455 717

1.0 0.8 7.3 II.5

5. 6. 7. 8. 9. 10.

Emergency call Place or respond to an advertisement Ask for or give help Make an appointment, announce a visit Confirm an appointment, a visit Modify an appointment, a visit Cancel an appointment, a visit Make a reservation, order Organize an activity Discuss a problem

427 171 127 82 436 602

6.9 2.7 2.0 1.3 7.0 9.7

I 1. 12. 13. 14. IS. 16. 17.

Solve a problem Inform, get information Give notice of a change of schedule Spent some time with someone Inquire after, given, exchange news Other action No answer

184 858 160 336 1287 143 127

3.0 13.8 2.6 5.4 20.7 2.3 2.0

Total

6225

100

Aim

1. Professional activities 2. Group, Union or political activity 3. Health problem 4. Buying, Selling, Renting 5. 6. 7. 8. 9. 10.

Studies, Scholarship Marriage, Birth, Death Invitation, Visit Leisure, entertainment, going out Personal or affective problems Family intendance, daily household life 1I. Other aim 12. No answer

Number of Calls

%

752 221 592 259

12.1 3.6 9.5 4.2

197 75 634 778 798 727

3.2 1.2 10.2 12.5 12.8 11.7

665 527

10.7 8.5

6225

100

280

G.

CLAISSE and

The methodological limitations The methodological limitations of this study arise from the design of the survey, which principally aims at analysing residential telephone habits and consumption. The analysis of telephone habits and daily mobility interactions was only a subset of this research. Besides the fact that this survey does not enable us to identify the indirect effects of the telephone on the daily mobility (changes in ways of life), the recorded data are also incomplete. On the one hand, the assessment method of the telephone activity-mobility interactions relies on a call-based analysis. Given the available data, we are bound to this type of approach and are facing the same limits as in modal split transportation surveys based on trip analysis. It would be more satisfying and relevant to link each communication event (a call, a trip) to the communications events chain it belongs to. It would allow a more dynamic analysis of the telephone activity-mobility interactions. This is a serious methodological problem and the Achilles’ heel of telecommunication-transportation tradeoffs, which are often derived from trip-based analysis. This limitation does not prevent us from carrying out an, albeit imperfect, assessment from a call-based analysis. On the other hand, this call-based assessment might have been completed with a trip-based assessment in order to identify the way in which daily mobility of the individuals is linked with their telephone activity. This would have required the diary to record not only the telephone calls but also the different trips of the persons surveyed. Finally, the evaluation method we have chosen may seem somewhat precarious because of: (a) the importance given to the declared attitudes of the persons surveyed; and (b) the very hypothetical situation of a long lasting breakdown of the telephone network. However, three comments enable this first judgment to be tempered. First, the surveyed persons who are asked to express their preferences, do so in real situations, as a result of there being a perfect identification of the various characteristics of their telephone communication in the diary. We can therefore consider that these characteristics are taken into account at least implicitly. Second, it so happens that this survey was carried out six months after the breakdown of the LyonsSevigne telephone switch, which blocked telephone traffic in the Lyons conurbation for several days and led to disruptions over a period of two weeks. By placing the surveyed persons in the situation of a generalized telephone breakdown, it was therefore possible to call upon their experience of something that had really happened and that they could refer back to in order to reply to the questions posed. We recall the Wurtzle and Turner (1978) survey, based on a sample of 190 persons. This survey followed a fire in the New York switching on February 27, 1975, which disrupted the communication of 90,399 tele1.4.

F. ROWE

phone customers for 23 days. The main results of this study show that these people were deeply affected by feelings of frustration and loneliness during this period. Forty-four % of the individuals surveyed made more trips to visit relatives and friends than usual. Third, the method and the content of the survey enabled us to avoid some of the common pitfalls of the stated preference methods as identified by Bonsall(1985). When we are dealing with a survey where the surveyed person has to fill in the replies himself or herself, the major pitfall is for the respondent to want to “please” the interviewer (affirmation bias)this is considerably reduced here. Furthermore, since we offer the pollee the hypothesis of a degraded situation (network breakdown), the bias linked to the overvalorization of the alternatives (policy response bias) is avoided. In spite of those limitations, it is on the basis of an in-depth knowledge of the telephone habits of individuals that we can analyze their influence on people’s daily mobility. In the coming section we will present the main characteristics of the use of the telephone by individuals (Section 2). We will then evaluate and characterize the influence of their telephone activity on their daily mobility (Section 3). We will then be in a position to propose a summary evaluation for the effects on urban motor traffic of a lasting and generalized breakdown in the telephone network (Section 4). 2. INL~I~IDUALS’TELEPHD~E

HABITS

This section will be given over to a succinct presentation of the principal results obtained regarding the content of the telephone calls, and to the points that determined the individuals’ telephone consumption and habits. As far as the transportation-telecommunication tradeoff if concerned, we cannot use the results of other telephone surveys such as those referred to in Saunders and Wellenius (1984), for they do not tackle this problem and the methods differ drastically from ours (Claisse and Rowe, 1992). 2. I. A typolog_~~Jortelephone rraffiic As soon as we accept the infimte diversity and complexity of telephone calls, we are inevitably confronted with the problem of creating a typology of communications enabling us to specify the functions, uses and practices linked with the household phone. In order to do so we specially weighted the answers to the following questions: Who are we calling? And why? Who are we calling? As far as the first question is concerned, theanswer is clear. Forty percent of household telephone traffic is with members of the family; 36% with friends and acquaintances. Calls to or from firms, the civil service, shops, etc. only represent 12% of the total. Finally we come to business relations (8070). neighbours (2oio), and clubs (2oio).

Telephone habits and daily mobility Therefore, four-fifths of household telephone traffic is with socio-affective correspondents. It is then only too easy to conclude that the telephone call is fundamentally relational and convivial, since the nature of the correspondents tells us nothing about the nature of the call. Why do we telephone? An important effort was made to create a pertinent matrix for the reasons for telephoning. The principle finally adopted was that of a matrix, which was ranked according to the main reason for calling, in the form of a combination of an action to be carried out in a given field or aim. Sixteen actions and eleven aims were thus chosen (see Table 1). This matrix therefore enabled 176 principal reasons for phone calls to be defined. From the 6225 calls recorded, the three most commonly quoted actions are exchange of news (21%), obtaining information (14%) and making an appointment (12%). Obtaining information means, for instance, asking for an address, while exchanging news is much closer to the French meaning of keeping in touch and asking, “what’s up?” The three aims concern personal or affective problems (13%). leisure or outings (12.5%), and professional activities (12%). On the basis of these first results, we chose to draw up a typology for the actions, then for the aims, in order to obtain a synthetic classification for the reasons for telephoning. The analysis of the results obtained by the techniques of multidimensional data analysis formally confirmed the primary tendencies observed. Telephone conversations, then, concern the following three actions: management (actions 4, 5, 6, 7, 8, 9 and 13). information (actions 10, 11, 12, 3 and 2), and discussion (actions 14 and 15). We can also distinguish three aims or main fields which tally with three parts of daily life: private life (aims 3, 4, 9 and IO), social life (aims 2, 6, 7 and 8), and working life (aims 1 and 5). It is thus possible to distinguish eight main reasons for telephoning (see Table 2). Household telephone calls seem to be structured by four main functions: discussion concerning private life, management of activities linked with social life, the ex-

Table

2. Traffic typology

281

change of information concerning private life, and finally, information relative to working’ life. We now know the correspondent and the reason for the call. It is therefore possible to work out a synthetic classification for the calls. Two main poles appear: functional communication and relational communication. Functional communication is accompanied by an objective to be attained. This objective can refer either to the management of activities or to service enterprises. For instance, we classified the motive “To make an appointment with a friend to go to the movie” as a functional call. Conversely, the only real aim of relational communication is to keep in touch with relatives or friends. For example, to chat or spend some time with a friend or a relative is classified as a relational call. Between those two pure types we can distinguish two categories: The functional and incidentally relational calls; for example to ask for some help (e.g. babysitting or shopping) from a relative or a friend. The aim is clearly functional but the relationship is relational. The relational and incidentally functional calls; for example, to discuss personal problems with a fellow worker. This call is relational (discussion, personal problems) and the relationship is mainly functional. In order to bring out these categories, we decided to give each type of correspondent, action and aim, a describer (functional, relational or mixed) which, by adding the describers thus obtained, would enable us to classify each call in one of the four chosen types. The typology for household telephone traffic thus obtained is more stimulating (see Table 3), since it does away with the myth of the convivial telephone. It appears more clearly that telephone traffic is principally functional (56.5%) rather than relational (43.5%). Thus the image of the telephone as a convivial tool structured around a relational use is too

by call motives

(number

of calls)

Aim

Action Discussion Information Management

Total

Exchange

Working Life

Social Life

Private Life

Total

514 (10%) 410 (8%)

284 (5%) 359 (7%) 1075 (21 ore)

1109 (22%) 932 (18%) 455 (9%)

1393 (27%) 1805 (35%) 1940 (38%)

924 (18%)

1718 (33%)

24% (49%)

5138 (100%)

G. CLAISSEand F. ROWE

282 Table 3. Traffic typology

% of the Time Spent

Number of Calls

%

Relational traffic Rather relational traffic Rather functional traffic Functional traffic

1950 566 612 2668

33.5 10 11 45.5

Total

5796

100

46 11 10 33 100

limiting. Only one third of the traffic is strictly relational. We thus rediscover the very important place of the telephone as a tool for the management of daily life. Should we use the time spent over the telephone instead of the number of calls as an indicator, the relational traffic (46%) becomes the most common type.

2.2. Telephone consumption On average, the weekly telephone consumption of individuals amounts to nine calls, viz. more than one hour and a quarter spent on the phone for a budgetary cost of 2 dollars. This average, however, hides considerable deviations. Thus the question is whether we can explain these differences with the socioeconomic characteristics of the individuals. With a synthetic aim, we will start off from the final result of the analysis of the determinants for individual telephone consumption, i.e. the typology of the individuals which we carried out in relation to their consumption (see Table 4). To simplify matters, let us say that we can distinguish two prime determinants: the size of the household to which the individual belongs, and the individual’s gender; and three secondary determinants: age, activity and socioprofessional category. We can first see that single people living alone telephone, on average, twice as much as individuals belonging to households of two or more. Two explanations can be put forward. First, single people living alone have to see to all the external relations (family, friends, etc.) concerning their household. Second, for singles, their telephone no doubt enables them to compensate for their relative isolation at home. With the exception of single people, women use the telephone twice as much as men. Of course this result is linked

with the activity

status:

nonworking

women at home use the telephone more than working women. However, women who work outside of the home also use telephone twice as much as working men. The division of roles within the household can be another reason. In more than 55% of the households, there is one person who usually answers the telephone. In more than 80% of the cases, this is a woman. This brings us to the third explanation. Women still have, in France, a central place, within the household, in the management of daily life.

Gender and marital status have such an influence on telephone consumption that it is difficult to discover the effects of other determinants without having first neutralized the effects of these first two characteristics. When this has been done, we can use the age, activity and socioeconomic activity to go further. The oldest and youngest people telephone somewhat less than the others. For the youngest, there are several possible explanations: draining of telephone calls towards other places (call boxes for example); a certain amount of autocensorship as far as the filling out of the diary is concerned since it is under parental control; and of course a relational context that is less diversified and limited to friends and acquaintances. As is true for younger generations, the older generation certainly have fewer reasons for telephoning. The circle of family and friends has been eroded by the years which go by, the telephone is costly for old people and finally for security or emergency reasons, the presence of the telephone is more important than its use. The social role is of course important. Bosses, executives and professional people spend more time on the phone than employees and shopfloor workers. The social position of the individual can be seen as a somewhat complex network of relationships and sociability. However, gender is still an overwhelming determinant. Female shopfloor workers, for example, telephone just as much as executives. To summarize, an individual’s telephone consumption fundamentally depends on the interrelationships between personal resources and constraints: the division of roles within the household, free time or time at home and the degree of concern with working life. If we can so easily interpret the variations in telephone consumption of individuals (30% of the variance can be explained by this typology) what can we say about their habits? 2.3. Telephone habits An in-depth analysis of telephone habits was carried out with regard to the calls placed and received, the different correspondents contacted, the action taken, the aims, the reasons, the space and time characteristics for each call. Here, we will only present the results obtained very synthetically. Women, first, do not use the phone in the same way as men. Their behaviors are more relational, and more conversations take place, mainly with family and friends. For women, functional calls are often of collective interest, since they deal with the management of the daily life of the household (daily life of their young children, shopping, domestic business, etc.). For men, functional calls dominate (6075%); they primarily manage their own professional and private life. Second, working people and nonworking people (excluding students and schoolchildren) have different telephone habits. Calls are functional for work-

Telephone habits and daily mobility

283

Table 4. Telephone consumption by individual categories

Individual Categories

Numberof calls

Weekly Time

Number

Per Week

Budget

Weekly Cost (F.P.)

Single Living Alone (S)

1. Working 2. Nonworking

29 39

14 19

lh48 2h55

11 26

Working Men (NS)

3. Manager operators 4. Manager non-operators 5. Worker

57 41 79

9 4 5

lh 27’ 25’

17 4 4

Nonworking men (NS)

6. Re:ired 7. Student more than 18 years 8. Scholar more than 13 years

42 38 31

5 5

3

26’ 38’ 25’

12 5 3

45 73

13 11

lh40 lh35

14 14

35 32 33 58 31

21 14 9 9 4

23148 2h lhl0 Ih30 35’

38 18 14 9 2

1hlS

12.27

32%

13%

Working women (NS)

9. Manager 10. Worker

Nonworking women (NS)

11. 12. 13. 14. IS.

Less than 60 well-off (manager) (a) Less than 60 well-off (worker) (a) More than 60 Student more than 18 Scholars more than 13

Total

663

Explained variance

9.36 30%

(a) Husband’s profession S = Single living alone, NS = Non Single

ing people and more relational for nonworking ones. Their professional activities, the constraints upon their timetable and their many and varied activities explain the more functional habits of working people. Moreover, executives and professional people’s telephone traffic is always more functional than that of blue- and white-collar workers. Third, young people are differentiated from their elders by their mixed habits, which are both relational and functional. Thus, for boys between 13 and 18 years of age mixed traffic represents two thirds of their calls. To explain this, we must point out that the boundary between work and friendly relationships is not very clearcut. Classmates are both chums and “professional” relations. The result is doublecontent calls; functional since school problems are often dealt with, and relational since the same discussion often concerns socioaffective domains. Finally, we can consider the effect of life cycle. Whether male or female, schoolchildren’s habits are relatively similar: their telephone habits are principally mixed. Their paths separate when they become students. Male students more typically parallel the functional behavior of “middle-aged” men. Female students approximate the relational behavior of older women. Once they enter the workforce, male executives primarily use the phone to manage their own activities while their female counterparts have much more diversified communications. At retirement, their phone habits become closer and grow more and more relational.

Thus we can distinguish habits:

five types of telephone

1. The telephone

2.

3.

4.

5.

“compensator” or the single person’s telephone; compensation for relative isolation and search for an equilibrium. The telephone as a “tool” for the male worker; these individuals spend little time on the phone and generally use it lo save time or manage the time constraints linked to their professional activities. The “mixed” telephone or the young people’s telephone; boy-girl conversations are much more frequent; working and social life are present; conversations are both relational and functional. The “umbilical cord” or the telephone of nonworking women; these calls provide a link with parents and children and conversations are often related to private life. The “polyvalent” telephone of the working women. Their habits are highly diversified; here we fundamentally find the behavior of doublyactive people (household tasks and professional tasks) when the division of roles, within the household, between men and women still remains significant.

Now that we have presented the principal characteristics of individuals’ telephone habits we can go on to examine the consequences of their telephone activity on their daily mobility.

G. CLAISSEand

284

F. ROWE

Table 5. Telephone-mobility interactions: Primary results If the telephone had been out of order, what would you have done?

-a trip -sent someone

Does this call engender an unexpected trip?

1783 163

(29%) (3%)

742

(12%)

-sent a telegram -waited for an opportunity -nothing

103 1174 2094

(2%) (19%) (35%)

Total (Number of calls)

6062

(100%)

-sent

mail

-for you -for your correspondent -for you and your correspondent -no

(8%) (8%)

244 4310

(4%) (80%)

5438

3. TELEPHONE ACTIVITY AND DAILY MOBILITY

3. I. Evaluation

459 425

(100%)

the caller if we want to be in a position to add and compare the results obtained on these two questions. 2. When the caller is the surveyed person’s correspondent, the supposed behavior of the caller is identified thanks to the pollee’s replies. The pollee’s perception of his or her own behavior would seem to be more reliable than how he or she perceives the correspondent’s behavior.

of influences

If we start off from the gross results obtained from the two questions asked of the surveyed persons and presented in section 1.3 (cf. Table S), the first three comments which can be made are as follows: (a) the communication needs created by the telephone, and which could not lead to the use of any other means of communication if the person were unable to telephone (waited for an opportunity or nothing), represent more than half the telephone calls; (b) with the same hypothesis, one third of the communications would be replaced by a trip and 14% by mail; and (c) 20% would lead to an unplanned trip made either by the pollee or the correspondent or by both of them. These first results give a somewhat naive representation of the influence of individuals’ telephone activity on their daily mobility. Two main boundaries limit the scope of this primary evaluation:

Despite the fact that this may have caused us to lose a certain amount of data, we have preferred to concentrate on the telephone traffic of the surveyed person only. The results obtained from calls made by the pollee have enabled us to make a more rigorous evaluation of the relationships between individuals’ telephone activity and their daily mobility, as well as a first measurement of so-called mobility management telephone traffic (cf. Table 6). Specific telephone traffic, which groups together all the calls that at first sight have nothing to do with daily mobility, represents 40% of traffic. Substitution for trips telephone traffic represents more than 25% of communications. Induction traffic accounts for 5% of communications. Finally, we see that 10% of calls lead to an unplanned trip and would have

1. Only the stated behavior

of the person who telephones is known in the hypothesis of a telephone network breakdown. The behavior of the person called is not known and therefore we must limit the evaluation to the influence on the behavior of

Table 6. Telephone mobility interactions: Primary evaluation (number of outgoing calls) Does This Call Lead IO an Unexpected

Withour the Telephone What Would You Have Done? -trip

or sent someone

No

Management

Trip Substitution

283

(10%)

Induction -mail

or telegram

41

(1%)

Induction

778

Trip?

Total

Yes

(27%)

1061

(37%)

426

(15%)

Mail Substitution 385

(14%)

Specific

-waited for an opportunity, or nothing

123

(470)

1227

(44%)

1350

(48%)

Total

447

(15%)

2390

(85%)

2837

(100%)

285

Telephone habits and daily mobility

Illducdon

2525 calls

unexpected

No unexpected

’

Fig. 1. Telephone and mobility interactions.

been replaced by a trip if there had been a telephone network breakdown. In this specific case, the substitution and induction effects cancel each other out. We propose the hypothesis that this type of telephone call is often used to manage activities; in this case telephone activity is a perfect complement to daily mobility, which it helps to program and organize. In fact, it is worth noting that more than 60% of these calls (which would have been replaced by a trip and induced an unforeseen trip) are motived either by an appointment, by the organizing of an activity, by urgency or by a change of schedule, i.e. communications related to the management of daily life. We thus obtain a primary evaluation of telephone traffic used for daily mobility management (10%). The difference between substitution traffic and induction traffic thus gives a first measurement of the net theoretical rate of substitution of individuals’ telephone activity for their daily mobility: viz. 22% of telephone calls made by the surveyed persons. Finally, according to the persons surveyed, 14% of the telephone calls would have been replaced by mail, if the telephone had been out. We cannot, however, say that the net rate of substitution of telephone for mail is 14%, because we do not know if this call leads to an unplanned mail between the

Table 7. Telephone-mobility

pollee and his correspondent or not. We have, therefore, chosen to eliminate from this evaluation the telephone calls which would have been replaced by mail so as to work on the sole impacts between the telephone and individuals’ mobility. On the basis of this second evaluation, we can work out an even more relevant evaluation by taking into account the motives of the telephone calls. More than a third of the telephone calls are motivated by making, cancelling, confirming or changing an appointment. These telephone calls aim mainly at the management of upcoming trips. Therefore, they have systematically been placed in the category of telephone traffic managing the individuals’ daily mobility. A new evaluation of the impacts of the individuals’ telephone activity on their daily mobility can thus be obtained (see Fig. 1). Before making any comment upon these results, which were obtained from the domestic telephone traffic of the pollees, we now need to take into account the spatial distribution of the telephone traffic (see Table 7). As for daily mobility, the telephone traffic of Lyons is mainly made up of local calls (about 80070). As for daily trips, telephone calls are mainly nearby ones. Hence, the impacts of the individuals’ telephone activity on their daily mobility ought to vary

interactions and the spatial distribution of the traffic (number of calls)

Impacts on Mobility Substitution

induction

Management

Specific

Total

Local: Conurbation of Lyons

385 (20.5%)

757 (40.3%)

672 (35.8slo)

1878 (100%)

Regional: Rhone-Alpes area

10 (8Q) (8V:)

64 (3.4%) 2 (2%) 0 -

Trunk: Other in France or Abroad

45 (39%) 35 (32%)

51 (50%) 65 (59%)

114 (100%) 109 (100%)

CL CLAISSEand

286

depending on whether we consider the local, trunk or regional telephone traffic. By thus splitting up the domestic telephone traffic, the results obtained amply confirm this hypothesis. Table 7 clearly shows that the main stake of the telephone on the individual’s mobility concerns urban mobility. Regional or trunk calls represent a rather limited percentage of the telephone traffic (20%) and, overall, either have no impact on mobility (specific traffic) or are complementary to the individuals’ mobility. If in this same table, we had ‘included cases where the telephone replaces mail, we would have noticed the importance of this fact at the regional and trunk levels: 30% of the regional telephone calls and 49% of the trunk calls would have been replaced by mail. For local calls, we must underscore the following main characteristics: 1. Individuals’ telephone activity is closely linked to their daily mobility; nearly two thirds of the calls manage, prepare or lead to a local trip. 2. Telephone traffic is primarily a complementary activity of daily mobility; about 40% of the telephone calls aim at preparing, managing and organizing activities and trips associated with them. 3. Telephone activity is also a specific activity organized around communications needs that do not seem to be transferable to transportation means. 4. Finally, the telephone can sometimes be a substitute for 20.5%), or lead to (3.4%) trips; the net rate of telephone substitution for daily mobility represents Having to identify

17010of the telephone

traffic.

worked out an indicator which enables us and to measure part of the direct effects

F. ROWE

of the individuals’ telephone activity on their daily mobility, we will now concentrate on local calls. 3.2. Characterization of telephone and mobility interactions Before starting to analyze the impact of the telephone on urban traffic, we must try to characterize each type of communication thus identified (see Table 8). The specific traffic. Specific traffic is chiefly divided into discussion and exchange of information. Conversations with friends and relatives deal with both private and social lives, and, secondarily, with working life. Two thirds of this traffic is mainly relational and more than one half purely relational; most of this traffic involves women. However, this independent traffic can also be functional. This means that the specific needs of communication created by the development of the telephone do not only amount to chatting. The telephone also enables individuals to solve problems and to exchange information without having to wait for a future meeting. It is, therefore, easier to choose when we want to deal with certain matters independent of space and time constraints. Communications that have no direct link, in the perspective of a call-based analysis, with individuals’ mobility are less urgent than others, but are considered as urgent in 13% of cases. The telephone now enables people to deal with certain urgent situations that could not be dealt with before. The traffic of management. The telephone is also a management tool for activities; therefore, for the individuals’ mobility. Forty-two Qo of the activities relating to this traffic are linked to the individuals’ social life (invitations, leisure, outings, calls, etc.)

Table 8. Main characteristics of telephone-mobility Substitution 1. Correspondents

Relatives Friends

100 27.5 35

Induction loo 33 51

interactions (in ‘To) Management 100 23 34

Specific 100 44

41

Others

37.5

16

43

15

2. ActIons

Discussion Information Management 3. Aim

100 21 65 14 100

loo 29 49 22 100

loo 3 9 88

100 40 51 9

Working life Social life Private life

24 26 50

10 48 42

100 21 42 37

100 I5 26 59

4. Nature Relational Rather rela. Rather func. Functional

100 28 I5 17 40

100 31 32 14 23

100 4 2 3 91

100 50 15 15 20

5. Urgency Urgent Not urgent

100 45 55

100 10 90

100 40 60

100 13 87

6. Sex Men Women

100 36 64

100 27 73

100 35 65

100 26 74

Telephone habits and daily mobihty and 24% to their working life. Functional correspondents (tradespeople, executives, managers, firms, professional relations, etc.) take up most of the time. Thus, the traffic of management is almost exclusively functional. Management traffic involves men more frequently than does specific traffic. Working men in professional positions use the telephone 50% of the time as a tool for the management of their mobility. The specific and management traffic present characteristics that are perfectly contrasted. Representing more than three quarters of the telephone traffic, their weight and their differences make it difficult to identify the particularities of other traffic. The traffic of substitution and induction can be seen as being, respectively, rather close to the management traffic and the specific traffic. The traffic of substitution. Like management traffic, substitution traffic corresponds with communicational needs, and activities that would have existed in the absence of the telephone. Substitution traffic should, therefore, have certain characteristics in common with the traffic of management. Calls and correspondents are mainly functional. Men are over-represented in the traffic of substitution. However, telephone calls that replace a trip are rather linked to an exchange of information as regards the private or working life. The point is no longer to manage activities but to carry out activities that in the absence of the telephone would have led to one or more trips. The traffic of induction. Very few telephone calls induce an unplanned trip (about 3%). We can, however, confirm the intuition we had that the induced traffic is rather close to specific traffic. Sixty-three percent of this traffic is relational and consists of telephone calls that are not very urgent, mainly with family and friends. Like specific traffic, almost three quarters of this traffic is made by women. On the other hand, unlike specific traffic, telephone calls that induce an unplanned trip concern social life rather than private life and friends rather than relatives. After having dealt with the identification of the impact of the telephone on individuals’ daily mobility, the measurement of these impacts on telephone activity, and the characterization of these impacts, we can now go on to evaluate the impact of the domestic use of the telephone on urban traffic, viz. on local travel demand. 4. IMPACTS ON URBAN TRAFFIC AND MOBILITY

The literature on the transportation-telecommunication tradeoff usually focuses on quantitative estimates of the telecommunication impacts on traffic, social costs, energy consumption, etc. So, we want to make clear that we are reaching the limits of the scientific approach and are bordering on speculation. In fact, to set up a truly scientific assessment method on the impact of individuals’ telephone activity on urban traffic, it would have been necessary to

281

overcome the limits of call-based analysis and take into account the indirect effects. However, we do think that such speculation offers sometimes heuristic virtues, brings about some interesting questions and stimulates scientific inquiry. Surveys on telecommunication-transportation substitution have often been condemned for this reason. In this spirit, let us imagine what urban travel demand would be if there were a long-lasting telephone network breakdown. We will therefore consider only the influence of domestic telephone activity of individuals on their level of urban mobility, viz.: 20.5% of calls would lead to trips if there were no telephone (substitution traffic) and 3.4% of calls would no longer lead to a trip if the telephone was out (induction traffic). This evaluation will not therefore take into account the improvement in efficiency of the use of transportation systems that the telephone brings, thanks to the remote management and preparation of economic and social activities. 4.1. General impact The Lyons conurbation has approximately one million inhabitants. What would be the impact of a sustained and general breakdown of the telephone on this conurbation? To estimate this, we began with the results of a household survey, carried out in 1986, concerning individuals’ mobility. The household car ownership rate in the Lyons conurbation is 75%. Daily mobility, all modes included, corresponds to 3.24 trips, among which 2.13 are motorized and divided according to the following purposes: work (28qo), school (Ilqo), social, shopping, recreation and business trips (43%) and nonhome based trips (18%). In France, individual urban mobility is defined as the number of trips made during a weekday within an urban transport area. The data collection method for this assessment is the activity pattern. When we know the number of trips per day, and the number of telephone calls that act as a substitute for trips or that lead to unplanned trips, it is easy to calculate the telephone impact on daily mobility according to the limitation of our methodology, viz.: S = (s -

r) x c/d,

where:

s= S=

i

=

c=

d=

growth rate of the urban mobility in the absence of the telephone; percentage of the domestic telephone calls that replace a trip; percentage of the domestic telephone traffic that leads to unplanned trip; average number of telephone calls per day and per person; and average number of trips per day and per person.

However, before calculating the growth rate S, we must define the referential situation and formulate, viz.: considering the very low percentage of

G. CLAESE and F. ROWE

288

neighborhood telephone traffic (2%), we assume that induced trips and trips replaced by domestic telephone use would have been achieved thanks to motorized modes. The daily mobility reference that we will, therefore, take into account will be the number of trips per day with a motorized mode; that is, 2.13 trips

per workday, which leads us to exclude the weekend telephone traffic in order to retain only an average of the number of telephone calls made per individual per workday: that is, 0.57. Finally, we will exclude from this evaluation nonhome-based trips (the origin of which and the destination of which are not the home). The survey that we carried out on domestic telephone use identifies only the telephone calls that were made or received at home, with the exclusion of private telephone calls that were made or received out of home (at work, from phone boxes, etc.). With the exception of nonhome-based trips, the average number of trips per day per inhabitant of Lyons is 1.68. Given the following data: (a) 21% of the domestic telephone calls made per workday replace a trip; (b) 3.26% lead to an unplanned trip; (c) the average number of telephone calls made per day per person is 0.57; and (d) the average number of motorized trips per day per person, excluding nonhome-based trips, is 1.68. The growth rate of the urban daily mobility would then be: S = (21 -

3.26) x 0.57/1.68

= 6%.

Thus, in the absence of the domestic telephone, the growth rate of urban motorized traffic would be around 6Qo. If we v,ere making the same evaluation on the basis of the Indicators as identified in Fig. 1, the groivth rare of urban motorized traffic would then be 9ro. Trips caused or replaced b!, rhe telephone are usually trips Mhlch tall Into the “business and other” category. The sro\\(h of this type of travel, which represents 0.9 IrIp> per da! uith a motorized mode, would then be around 11 Ob. Let us emphajlzc that \\e ha\e underevaluated so as to avoid on

the u\ual

overe\aluation

traps

telecommunlcarlan-transportation

First, timates

the sur\ e! carried the average

out In

number

in studies

substitution.

t 983 slightly

of telephone

underescalls made

by the individual. Second. the effects of substitution and induction are identified only for the surveyed caller, which mean< that rhis evaluation does not consider the poctihle impact5 in terms of mobility on persons called. FInall!, we must emphasize that this evaluation onl! rakes into account domestic telephone traffic, and thus tells us nothing about business telephone traffic, which represents most of the telephone traffic on workdays, and which is almost exclusively functional. If we did take the professional telephone traffic into account, there is little

doubt that, in the absence of the telephone, the growth rate of the urban motorized traffic would be much higher. However, if we keep to the impacts of domestic telephone traffic only, the motorized traffic growth rate, which is around 6% in the Lyons conurbation, does not mean much. During off-peak periods, such additional traffic would be perfectly bearable; peak hours, matter. 4.2.

however,

would

be

an

entirely

different

The impacts on traffic during peak hours

If we divide up telephone traffic and individuals’ mobility into periods of time, we can calculate the growth rate of urban mobility per period of time. However, we do not know when the induced trips or those replaced by the telephone would have been made. Due to the lack of this information, we have made two hypotheses corresponding to two tests (see Table 9): Trips that are generated or replaced by a telephone call would have been made at the very time of the telephone call; we thus obtain a first measure of the traffic increase “Sl”. Trips that are induced or replaced by the telephone traffic would have the same time distribution as the mobility due to “business and other.” We thus obtain a second indicator, “S2,” calculated thanks to the mean rate of substitution and of induction (21% and 3.3%). Whatever pattern we use, urban traffic growth would be around 7% during evening peak hours; 3.5oio to 5oio between 12 and 2 pm; and 2% to 3.6% during morning peak hours, viz. rather close results. Whar then would be the consequences of an increase in the urban motorized traffic of around 7% during the evening peak hours (5:30-6:30 pm)? To answer this question, a simulation carried out using a model of traffic assignment in the Lyons conurbation (the DAVIS Model), enabled us to compare the actual situation to one in which urban traffic would increase by 6.6% between 5:30 and 6:30 pm. The major changes that occurred were as follows: (a) an increase in the average level of traffic saturation superior of 7%; (b) a decrease in the average speed of the motorized vehicles of 12%; (c) an increase of urban traffic cost during peak hours of 21%; and (d) an increase of the waiting time or time lost in traffic jams of 75%. Beyond these general results, it is interesting to note that the number of road segments suffering from chronic congestion increases noticeably, doubling the number of road sections with a saturation rate between 1 and 1.2 and tripling the number of road sections with a saturation rate more than 1.2. This is a considerably worse situation for urban

traffic.

289

Telephone habits and daily mobility Table 9. Impact on the urban traffic per time period am

pm

Time Periods

o-7

7-9

9-12

12-2

2-5

5-7

7-12

Total

1. mobility without nonhome based 2. in % 3. time distribution “for business and other motives” (in olo) 4. telephone traffic emitted per individual 5. in Qio 6. rate of substitution (in W) 7. rate of induction

0.10 5.90 2.40

0.27 16.10 9.70

0.20 11.90 15.90

0.25 14.90 8.80

0.29 17.30 20.70

0.34 20.20 22.50

0.23 13.70 19.80

1.68 100 100

0.01

0.03

0.13

0.06

0.10

0.11

0.14

0.57

6 20.22 2.60

23 14.80 3.10

10 19.40 5.00

17 22.70 3.70

19 23.20 2.10

24 14.60 4.30

100 21 3.30

2.00 3.6

14.10 8.00

3.50 3.60

6.60 7.20

6.80 6.70

6.30 8.70

6.00 6.00

1 16.7

1.00 2.40

Sl* in % S2* in % S1 = I(6) s2 = (21 -

(7)l 3.3)

x (4)/(l) x 0.57 x (3)/[(l)

x

1001

CONCLUSION

Before reviewing the main results of this analysis on the relationships between the use of the telephone and daily mobility of individuals, it is necessary to underscore its limits. 1. The validity of our results is limited to the specific environment studied, i.e. that of urban households’ telephone communications. 2. Each communication event (a call, a trip) is considered independently from the communication chain to which it belongs. Again, call-based analysis faces the same limits as trip-based analysis. 3. The transportation-telecommunication interaction is subjected to so many variables that it is extremely difficult to reason in terms of “all things being equal.” Thus, the evaluation of a longlasting telephone network breakdown on urban motor traffic does not take into account the improvement of trips and their distribution thanks to the remote management of activities. How many unnecessary trips can be avoided thanks to the telephone? How many trips can be managed better or planned better? 4. Finally, the conclusions of our analysis suffer from the same limitations as any other inductive analysis, viz. those of the measurement and the replication of the phenomenon observed, and therefore of the generalization of the results. Nevertheless, over and above the limitations which are inherent to the method used, this analysis enables us to arrive at three basic conclusions. 1. Only one third of telephone traffic, specific traffic, has no direct connection with individuals’ daily mobility. On the other hand, this specific traffic can be analyzed as a good indicator for the effects of the residential mobility of households and the distance constraints which it leads to.

The rest of the traffic is principally a means of managing activities and mobility. The results show that numerous reasons for calling accompany trips and thus enable people to master their activities and trips better in time. Finally, the results of a hypothetical telephone network breakdown on urban motor traffic are significant. Such a breakdown would lead to a peak-hour urban traffic increase of 79’0, with all the inherent consequences in terms of social costs. This indicates that if we only take into account the secondary effects of individuals’ telephone activity on their daily mobility, the telephone enables people to avoid more trips than it obliges them to make.

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