An analysis of the relationships between motorization and housing planning

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1 An analysis of the relationships between motorization and housing planning R. Ando/*> N. Aoshima,^ M. Ito^ ^ Katahira & Engineers Inc, Nagoya Branch, West Point 1413, Tsubakicho 14-13, Nakamura-ku, Nagoya , Japan ando-ryo@katahira.co.jp ^Department of Civil Engineering, Gunma University ^Department of Public Works, Saitama Prefecture Abstract This study is to search for the answer of the question of what have made people own more cars in Japan assuming that housing location and conditions affect the car ownership. In this study, a survey was made using the questionnaire replies from families whose housing conditions changed. The contents of questionnaire include indices of houses, indices of home location, household characteristics and number of cars. Then the relationships among the car ownership and the above-considered factors were analyzed. The analysis showed that there are close relations among the number of cars per household and home location, housing conditions and the life stage of the family (which is defined by the number, ages, etc. of the family members). Furthermore, several ownership models were proposed and estimated by using the disaggregate logit model based on the results of the above analysis. The estimated results showed that these models could be applied for the analysis of the structure of car ownership as well as the forecasting of the number of cars holding. 1 Introduction Motorization has spread quickly in Japan since 1960s. The typical problem caused by the motorization is the traffic jam, which causes economic inefficiency and environmental pollution. In Japan, Gunma and Tochigi prefectures have the highest rank of the cars'

2 428 Urban Transport and the Environment for the 21st Century number per household. What have made people own more cars? Someone may say that high income is the main reason. However, this is correct in the developing countries, but not in the developed countries. In this study, analysis was made to search for the answers. Considering the characteristics, differing from that in the other prefectures, of Gunma and Tochigi prefectures, the analysis was made on the relations among the ownership of cars and the conditions of housing, living and household characteristics. A survey was made by using the questionnaire mails from the families whose housing conditions changed in the capitals and surrounding areas of Gunma and Tochigi prefectures. Answers were obtained from 305 families in Takasaki-Maebashi Region of Gunma Prefecture and 252 families in Utsunomiya Region of Tochigi Prefecture (Table 1). The contents of questionnaire include indices of houses, indices of home location, household characteristics and number of cars (Table 2). Region Objective household Survey method Number left Number received Percentage Table 1. Questionnaire survey Takasaki-Maebashi Utsunomiya Households located there during Visiting Leave - Mailing Back % 28.0% Then the relations among the ownership of cars and the considered factors that affect on the ownership of cars were analyzed. Housing Location Household Car ownership Table 2. Items of questionnaire survey Rooms' number, premises,floorspace etc. access time to station, bus stop etc. number of persons, age, driving license etc. number of cars Further, the ownership models were proposed and estimated using the logit disaggregate model based on the results of the above analysis. The ownership models include the multinomial logit model with the choices of [more cars], [no change] and [less cars], and the multinomial logit model with the choices of [one car], [two cars] and [three or more cars]. 2 Characteristics by regions 2.1 Change of number of cars Comparing the number of cars holding, about 20% of households in Takasaki- Maebashi Region had increased their cars' number comparing that before moving. In Utsunomiya Region, the percentage was up to about 25%.

3 Urban Transport and the Environment for the 21st Century 429 Takasaki-Maebashi More 0 D No change Less S Q Unknown Utsunomiya Region Region % Figure 1. Change of number of cars 2.2 Change of housing conditions Generally, people think that it is more convenient to live in the urban area than in the suburb. However, as shown in Figure 2, moving to the suburb means only being farther from the central station. In fact, it may make people nearer to another station or bus stops and make nothing inconvenient for their lives (refer to Figure 3: CD from center to suburb, nearer to station and shopping area, (D from center to suburb, nearer to shopping area but farther from station, (3)same center zone, farther from station and shopping area, same suburb zone, farther Railway A Shopping Area Station Central Station Station Figure 2. Depiction of home location Railway

4 430 Urban Transport and the Environment for the 21st Century from station and shopping area, same suburb zone, nearer to station and shopping area, same suburb zone, farther from station and nearer to shopping area, from suburb to center, farther from station and shopping area). Then what have made people change their home locations and number of cars? 14 Minutes 12 Takasaki-Maebashi Region Q before present 10.0 Station Bus Stop Shopping Area 14 Minutes 12.7 Utsunomiya Region before present Station Bus Stop Shopping Area Figure 3. Access time to certain places Here we compared the housing conditions obtained from the survey. From the survey, we know that more than 60% of all households are the first time homeowners. So it may be natural result that number of rooms, floor space and premises became more/larger in both Takasaki-Maebashi Region and Utsunomiya Region as shown in Figure 4-6(1 Tsubo=3.3m^).

5 Urban Transport and the Environment for the 21st Century 431 Takasaki-Macbashi Region I I 7 8 «I0~ rooms' number rooms' number known Figure 4. Change of rooms' number, SO SO 70- unknowii I" SO «, 70 W (Tsubo) (Tsubo) DO w TO-unknown '«20 30 <o so w M (Tsubo) (Tsubo) Figure 5. Change of floor space Figure 6. Change of premises

6 432 Urban Transport and the Environment for the 21st Century 2.3 Number of cars by LCS (Life Cycle Stage of Households) All households were classified into 13 groups as defined in Notation & definition. Then the numbers of cars by LCS were depicted in Figure 7. From the figure, we can see that one-car households generally become less with the increase of the number of LCS. ft means that households with more generations and more members tend to have more cars. Takasaki-Maebashi Region Utsunomiya Region ^ unknown 0 5 cars and more H 4 cars D 3 cars 0 2 cars 1 car Figure 7. Present number of cars by present LCS Households of LCS 7 & 8 are same to that of LCS 9 &10 and have two generations, but the former tend to have 1-2 cars and the latter tend to have 3 ~ 4 cars. This can be easily understood because the first child is able to have driving license. Further, the same thing can be said about households of LCS

7 Urban Transport and the Environment for the 21st Century Number of cars by area where home located When we classify the households by the area where their home is located compared with the area of the previous home (see Table 3), we found that 22.4% in Takasaki-Maebashi Region and 25.2% in Utsunomiya Region moved from the downtown area to the suburb area. That is quite greater than the households from the suburb area to the downtown area, which are 7.7% in Takasaki-Maebashi Region and 7.5% in Utsunomiya Region respectively. Table 3. Change of home location downk >wii su burb unknown Taka- Mae Region Uisunomiya Region i: 4 j 50.5%?:?% 1: 40.9% 22. 4% 25. 2% 7J5% t 18.4% % 1.0% 5.7% 3 What caused the increase in the number of cars? To answer what had made the cars' number increased, we estimated a multinomial logit model (see Table 4) with the linear utility function by using the disaggregate data. The basic viewpoints are hinted by the analysis of the survey. The first is that cars' number changed because of the change in location factors such as accessibility to the transit system and shopping mall. The second is that cars' number changed because of the change in household's factors such as LCS. The third is that that the cars' number changed because of the change in house's factors such as rooms' number, floor space and so on. The fourth is that the decision is made in the unit of household. However, as we saw in Figure 1, the increase did not occur in all households. Thus we made the model have three choices: [more cars], [no change], and [less cars]. Since the main purpose here is to understand the reasons of owning more cars, all explanatory variables except "choice 2 constant" were subject to the choice of [more cars]. Table 4 showed the estimated results which were proofed by the satisfactory statistical indices of s, p * value, hit-ratio. According to the estimated results, in both of Takasaki-Maebashi and Utsunomiya regions, people generally tend to have no change when they moved. However, "the present number of persons in household", "the dummy of increasing of access time for shopping", "the dummy of grading up of LCS", and

8 434 Urban Transport and the Environment for the 21st Century "the dummy of coming from a different prefecture" make the household have more cars. This reflects that the two regions have similar features being near Tokyo. On the other hand, "the dummy of being at high grade of LCS" is significant at 1% level in Utsunomiya Region but not in Takasaki-Maebashi Region. Furthermore, "the present age of head of household" showed a negative in Utsunomiya Region but a positive one in Takasaki-Maebashi Region although it is not statistically significant. Table 4. Estimations of multinomial logit model of car numbers' change Choice 1 constant Choice 2 constant Taka-Mae Utsunomiya Present number of persons in household Present age of head of household Dummy: access time for shopping increases Dummy: grading up of LCS Dummy: coming from a different prefecture Dummy: being at high grade of LCS ,203 p * value hit-ratio (%) Choices 1: more cars 2: no change 3: less cars Sample Size Taka- Mae: 294 Utsunomiya: Car ownership model On the basis of the above analysis, a general car ownership model is proposed here. The dependent variable is the car number in the present house and the choices are defined as [1], [2] and [3 or more]. As a multinomial logit model, the explanatory variables are subject to the choices of [2] and [3 or more] so as to represent the ownership of multiple cars. Table 5 summaries the estimated results. For the Takasaki-Maebashi region, the "premise" and the "floor space" showed the significant s. It means that the number of vehicles holding is proportional with the "size" of present house. Further, the households of two generations tend to have 2 vehicles and the households in which the first child is elder than 18 tend to have 3 vehicle. Whereas the household in which the head commutes by train tend to have 1 vehicle.

9 Urban Transport and the Environment for the 21st Century 435 Constant (subject to (=S.T.) choice 2) Constant (S.T. choice 3) Present premise (Tsubo, S.T. choice 2) Present premise (Tsubo, S.T. choice 3) Present floor space (Tsubo, S.T. choice 3) Dummy (=D): locating suburb district (S.T. 3) Present access time for shopping (min. S.T. 3) D: 2 generations households (S.T. 2) D: households in which the first child is elder than 18 (S.T 3) D: head of households commutes by train (S.T. 1) D: access time for shopping increases (S.T 2) Table 5. Estimations of multinomial logit model of car ownership Taka-Mae Utsunomiya p * value hit-ratio (%) Choices 1: one car 2: two cars 3: three or more cars Sample Size Taka- Mae: 300 Utsunomiya: 245 On the other hand, for the Utsunomiya region, although the s do not show the results as significant as the ones for the Takasaki-Maebashi region, it can be generally said that the car ownership model is quite good with some variables being really significant. In a word, the models show that the car ownership is dependent on the location conditions including access time for shopping, the LCS, the household factors and so on. 5 Conclusions In the study, we carried out the analysis on the relationships between motorization and housing planning by using the data collected from two different but similar regions which are about 100 km far from the center of Tokyo. The aggregate analysis and the estimated results of the multinomial logit model with

10 436 Urban Transport and the Environment for the 21st Century choices of [more cars], [no change] and [less cars] made us able to give some very significant conclusions: 1) people generally tend to have no change even when they moved; 2) the reasons that make people have more cars include that "present number of persons in household", "increasing of access time for shopping", "grading up of LCS" and "moving to a different prefecture"; 3) people in the different places have their own reasons. Furthermore, the car ownership choice model was proposed by using the multinomial logit model. The model was shown with the satisfactory estimated results, especially the model estimated by the Takasaki-Maebashi data. One example of the applications of the model is to predict the cars' number and to decide the scale of parking lot when doing the housing planning. Notation & definition LCS1 Single and under 35 LCS2 Single, age between 35 and 65 LCS3 Single and 65 or over LCS4 Couple and head is under 35 LCS5 Couple and head is between 35 and 65 LCS6 Couple and head is 65 or over LCS7 2 generations andfirstchild is under 6 LCS8 2 generations,firstchild is between 6 & 18 LCS9 2 generations,firstchild is not married & between 18 and 35 LCS10 2 generations,firstchild is married or over 35 LCS11 3 generations,firstchild is under 6 LCS12 3 generations,firstchild is between 6 and 18 LCS13 3 generations,firstchild is not married and between 18 and 35

January 2008 Finance Bureau of the City of Nagoya

January 2008 Finance Bureau of the City of Nagoya Contact: Funds Division, Finance Department, Finance Bureau of the City of Nagoya TEL: 052-972-2309 FAX: 052-972-4107 E-mail: a2309@zaisei.city.nagoya.lg.jp