6. Group F (4 sites)

Although the ratio of villa lots having areas ranging between 1000 and 1400 m<sup>2</sup> is high, the average land price is low. Nevertheless, vacant lots are evident. However, the total length of roads is very short, and parks are located very far from mosques. Evidently, some of these areas are unsuitable as residential environments. Therefore, special district planning is necessary for this type of neighborhood to increase the length of the roads and reduce the areas of villa lots.

#### **6. Conclusions**

Between 2007 and 2029, the estimated population growth of Jeddah, which is one of the most traditional and rapidly growing cities in Saudi Arabia, is expected to be around 2.25 million people. Faced with a serious housing shortage, the government proposed the provision of adequate new houses in response to the projected housing demand. Furthermore, within the SAR, villa-type housing is a historical and prestigious housing type compared with apartment-type housing. However, the proportion of villas is lower in Jeddah compared with these proportions in other cities. According to the PMPRLS, the characteristics of villa-type housing are a low population density and a minimum land lot area of 300 m2. In this situation, we aimed to clarify the characteristics of 103 sites according to the development trend by applying several indicators derived from the articles of the PMPRLS. In light of our analysis and typology, we proposed desirable developmental directions for each type of site.

In Section 2 of this paper, we discussed the extent of and reasons for the housing shortage in the city and projected future needs in relation to population growth. Moreover, we described the population density in relation to the presence of parks in all of the districts in Jeddah. The low population density associated with villa size is an outcome of Jeddah's ongoing structural planning, and it is clear that middle- and low-income individuals will find it difficult to own villa-type housing. Assaf [25] noted that inadequate labor, availability, material standards, design quality, and design changes have affected affordable housing costs, and that development policies that can improve these conditions are needed to address the housing shortage problem in Saudi Arabia. In addition, this study also noted that urban development in Jeddah, which is sprawling at low densities due to residents' preference for villa-type housing, does not solve the housing shortage problem, and that the housing costs associated with ensuring the necessary villa size do not lead to housing affordability for middle- and low-income individuals.

In Section 3, we discussed legislation for new residential area development with the PMPRLS, showing how contemporary neighborhoods were created. We also simulated population density, total street area and length, and numbers of parks and villas in relation to this legislation. Evidently, the MoMaRAaH did not consider the direct correlation between the average villa lot area and the total areas of streets and public facilities. The ratio of the total area of public facilities is fixed, even though there are variations in population density related to villa size. As highlighted by Hegazy (2021), there is a lack of planning tools for managing the urban planning system in Jeddah; thus, it is necessary to review the PPMPRLS of Jeddah to consider more diversity in lot areas, population density, street ratio, and park layout. This diversity is an important element of the solution to the housing shortage problem.

In Section 4, we analyzed the extent to which the legislation on new development of residential areas is applied in contemporary neighborhoods. In addition, we clarified the extent to which neighborhoods can respond to the housing shortage problem in terms of the quantity of housing provided. Based on the trend, which was calculated by the number of villas added to the total vacant area in the same development pattern and lot size, only 3.5% of the total shortage of housing problem would be solved. Alqahtany [26], based on the Saudi vision 2030 plan, discussed the problem of shortage of affordable housing in terms of housing cost, population change, etc. It is necessary to develop a solid strategy for the next 10 years to deal with the serious housing shortage problem projected in Jeddah.

A correlation analysis and multiple regression analysis were also presented to identify several factors that were correlated with each other. The results of the multiple regression analysis showed that the increase in the number of villas was related to the ratio of lots with areas ranging between 300 and 400 m<sup>2</sup> and the average land price; this means that an optimal size of villa lots for villa development and for reducing land prices is between 300 and 400 m2. Our findings also revealed that the ratio of vacant lots is related to the distance between mosques and parks, the total road length, and the ratio of lots sized between 1000 and 1400 m2. Therefore, future planning should accommodate the construction of parks near mosques and the extension of road length, as opposed to the total area of roads, and also reduce the sizes of villa lots within a range of 1000 and 1400 m2. Finally, all of the contemporary villa-type neighborhoods were categorized into six groups and suggestions were provided for each group with the aim of addressing an aspect of the housing shortage problem using six criteria derived from the multiple regression analysis.

In the PMPRLS, the area of roads, public facilities, etc., is fixed and does not flexibly respond to changes in population density. As a result, the PMPRLS has not been able to introduce flexible lot sizes. The development trend shows that, as housing prices are expected to increase, the current custom of preferring large lot sizes will not solve the housing shortage problem, because middle- and low-income buyers will not be able to afford to purchase houses. It is important to ensure the diversity of housing supply, such as by dividing large lots into smaller ones.

To conclude, we analyzed neighborhoods in Jeddah from economic and policy perspectives, and proposed different recommendations for each group. However, the contents of the recommendations were limited to the total area and length of streets, the minimum area of villa lots, and land prices. Although we proposed improvement measures for each group, we did not simulate the actual quantitative numbers to determine the size of the increase in the number of housing units. Therefore, quantitative support to determine the extent to which the housing shortage can be improved is a subject for future study. Future research also should consider other important factors, such as pedestrianization and its relation to motorization within planned neighborhoods.

**Author Contributions:** Conceptualization, R.M. and A.D.; methodology, R.M. and J.S.; software, R.M.; validation, R.M., J.S. and A.D.; formal analysis, R.M.; investigation, R.M.; resources, R.M.; data curation, R.M. and J.S.; writing—original draft preparation, R.M.; writing—review and editing, R.M. and J.S.; visualization, R.M. and J.S.; supervision, A.D.; project administration, R.M. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Data Availability Statement:** Data sharing not applicable.

**Acknowledgments:** The authors would like to thank the editors and reviewers for their time on the publication of this paper. The experimental participants and member of The University of Tokyo for their contribution to the study.

**Conflicts of Interest:** The authors declare no conflict of interest.
