1. Introduction
Transportation land is a crucial component of China’s construction land, designated for the construction of transportation infrastructure, including highways, railways, airports, ports, etc. [
1]. The transportation network serves as a vital foundation for regional economic development, and the amount of transportation land to some extent reflects the level of development of the transportation network [
2]. Since the late 1970s, when the Chinese central government implemented the reform and opening-up policy, China has experienced rapid economic growth, with urban construction land continuously expanding and the construction of transportation infrastructure accelerating. The development of transportation infrastructure is considered an important experience for China’s rapid economic growth [
3]. In particular, in regions of China where economic development has been relatively rapid, transportation systems have been continuously optimized and expanded, and the rapid expansion of transportation land has become a prominent feature of land use change in China [
4]. The 2022 Chinese Natural Resources Statistical Bulletin indicated that China’s total transportation land area has reached 101,800 square kilometers, an increase of 3.89 times compared to 2002, with an average annual growth rate of 8.26% [
5].
While the construction of transportation systems holds positive significance for regional economic development and sustainable growth, the substantial increase in transportation-related land use is a noteworthy concern. If the proportion of land occupied by transportation infrastructure construction is disproportionately large, it can significantly affect the rational use of existing land resources, potentially leading to a waste of land resources. On the one hand, the large-scale increase in transportation land consumes substantial land resources, resulting in the fragmentation of land use and negative ecological impacts [
6]. On the other hand, the investment required for transportation construction is substantial, but the economic returns are slow [
7]. Low utilization rates of transportation facilities not only lead to the significant waste of land resources but also increase the financial burden on cities [
8]. Thus, a reasonable scale for transportation land is crucial for promoting regional coordination and sustainable development.
In China, the adage “If you want to get rich, build roads first” has been a pivotal strategy for local governments in economic development. The concept of balanced transportation has been viewed as an important method to strengthen economic connections between developed and underdeveloped regions and to narrow the disparities in regional development. Consequently, over the past few decades, Chinese local governments have dedicated themselves to transportation infrastructure construction, laying the foundation for economic growth [
4,
9]. Moreover, influenced by the concept of coordinated regional development, a significant amount of public investment by the government has been skewed towards underdeveloped areas, leading to the extensive construction of transportation systems in many underdeveloped regions [
10,
11]. While transportation development can indeed improve conditions in underdeveloped areas to some extent, excessive transportation infrastructure construction is a cause for caution. Especially in recent years, profound changes have occurred in China’s regional economic structure and demographic structure. The population in underdeveloped regions is accelerating its shift towards developed areas [
12], and the imbalance between population and transportation development has become increasingly severe [
13]. Faced with the dual contradictions of regional balanced development and the waste of transportation resources, research on the relationship between transportation land and the population scale offers new perspectives to address this issue.
There is a relatively limited amount of research directly addressing the relationship between transportation land and the population. From the perspective of literature relevance, current researchers tend to focus on analyzing the coupled relationship between population and land use changes, as well as the impact of transportation land. In existing research on the coupled relationship between population and land changes, quantitative analysis methods have been primarily employed. Common analytical techniques include the MCCA model, the coupling coordination model, the Tapio decoupling model, econometric models, etc. [
14,
15,
16,
17]. For instance, Feng Qiu et al. utilized spatial econometric methods to analyze the Edmonton–Calgary Corridor (ECC) region of Alberta, Canada. Their findings indicated a significant spatial interaction between population growth and urban land development, with population growth promoting land development, which in turn attracted suburban and rural residents to migrate to urban areas, thereby driving population growth [
16]. Hung Chak Ho et al., based on a combined comparison of spatial multicriteria analysis, zonal statistics, and spatiotemporal modeling, examined population growth and land development in the continental United States from 2001 to 2011 to identify regions of population pressure. They discovered that the Midwest and Southern states in the United States will face less population pressure in future land development, while the southeast coast, Washington state, northern Texas, and the Southwest will face greater pressure due to faster population growth compared to suitable land loss [
17]. Leonardo Bianchini et al. used principal component analysis to assess the spatial changes in per capita land use change indicators at five time points in Rome from 1949 to 2016. The results indicate that the mismatch between Rome’s urban expansion and population growth is increasing, highlighting the unsustainable characteristics of the current development pattern [
18]. In China, there is also a wealth of research on the relationship between population and land changes. For example, Yongsheng Wang et al. used the Tapio decoupling model to study the relationship between the area of rural residential land and the resident population in the Yellow River Basin. The results indicated that the rural man–land relationship in the Yellow River Basin is not harmonious, characterized by a loss of the resident population in rural areas and an expansion of rural residential land areas [
19]. Congmou Zhu et al., using the urban–rural construction land structure transformation index, established a theoretical model to reveal the relationship between urban–rural construction land transformation and urban–rural population flow. They found that the relationship between construction land and population flow in the Yangtze River Delta city group transitioned from a coupled state from 2000 to 2005 to a weak decoupling state from 2005 to 2015, with significant regional differences [
20].
The academic community has conducted extensive research on transportation land. The construction of transportation land has been widely demonstrated to have a very positive significance in promoting regional economic development [
21,
22,
23]. For instance, Eva Ivanova et al. employed time series and correlation analysis to study the transportation network of Czechoslovakia from 2000 to 2011, discovering a strong correlation between GDP development and the construction of transportation infrastructure. High-quality transportation facilities contribute to the direct inflow of external capital, thereby enhancing regional competitiveness [
23]. C. P. Ng et al. analyzed time-series cross-sectional data from 60 countries over a period of 3 decades from 1980 to 2010 using fixed-effects panel linear regression, finding that the increase in road length per thousand people led to an increase in export volume, contributing to economic growth [
22]. However, in terms of the relationship between transportation land construction and rural development, the promotion effect of transportation land construction shows significant regional differences. For instance, Sam Asher et al. used fuzzy regression discontinuity designs, and comprehensive household and firm census microdata to assess the impact of India’s USD 40 billion national rural road construction program, discovering that the main effect of transportation land growth is to facilitate the movement of workers out of agriculture. Even with better market connections, remote areas still lack economic opportunities [
24]. John Gibson et al., based on the cross-sectional data of 4000 rural households in Indonesia from 1993 to 2000, proved that improving the accessibility and quality of rural road facilities would bring benefits to rural development [
25]. Even though there are differences in the research of different scholars, it is undeniable that transportation land is a very important entry point for studying regional development. Research on the relationship between transportation land and population changes can provide a basis for addressing regional coordinated development.
Overall, the current study has its clear limitations. Firstly, there are relatively few studies on the analysis of the spatiotemporal and structural characteristics of transportation land in China. Moreover, the few existing studies use national-scale sample data, and there is a lack of research on provincial-scale transportation land. Secondly, scholars often analyze construction land as a whole in relation to the population, with limited research on the specific types of construction land and their relationship with population size. Based on the aforementioned considerations, this study takes Guangdong Province as a case study to analyze the dynamic relationship between transportation land and the population, aiming to unveil the equilibrium predicaments faced during the process of regional development in China. Guangdong, situated in the southern part of the Chinese Mainland, is one of the most economically developed provinces in China, with an urbanization rate reaching 74.79%. However, Guangdong is also one of the most unequally developed provinces in China, with significant disparities on the population and economic scale across regions within the province, and it presents an evident “center-periphery” structure (Pearl River Delta vs. peripheral areas surrounding the Pearl River Delta). The most economically developed center of Guangdong is the nine-city cluster of the Pearl River Delta, which includes Guangzhou, Foshan, Zhaoqing, Shenzhen, Dongguan, Huizhou, Zhuhai, Zhongshan, and Jiangmen. In 2023, the PRD economy surpassed CNY 11 trillion, accounting for 81% of the province’s GDP. Regionally balanced development has been a persistent policy direction for the Guangdong Provincial Government, which has also invested heavily in transportation infrastructure in recent years in pursuit of balanced development and to narrow the gap between the center and the periphery [
26]. Therefore, it is imperative to focus on Guangdong Province as a case study to conduct specialized research on the regional balance issues faced by China’s most developed provinces and to assess the relationship between changes in transportation land and population structure. This study attempts to answer the following two questions: (1) What is the spatiotemporal pattern of transportation land use in Guangdong province, China, from 2010 onwards, and what are its characteristics? (2) What is the relationship between transportation land and population growth in Guangdong province from 2010 onwards? Are there features of mismatch between population and transportation land?
4. Discussion and Conclusions
This study focuses on 121 counties (cities and districts) in Guangdong Province as the research area, analyzing the temporal and spatial changes and structural features of transportation land. This study employs exploratory spatial data analysis (ESDA) and decoupling models to explore the relationship between transportation land and population growth. The findings indicated the following: (1) From 2010 to 2020, the per capita transportation land in various districts and counties of Guangdong Province showed a hierarchical structure of “low center and high periphery”. Conversely, the proportion of transportation land to construction land displayed a “high center and low periphery” characteristic. (2) During the same period, the total amount of transportation land in the peripheral areas of the Pearl River Delta was higher than that in the PRD (the Pearl River Delta) and the gap widened each year. Meanwhile, the proportion of transportation land to construction land in the peripheral areas of the Pearl River Delta was consistently higher than that in the PRD. (3) There were significant spatial differences between the per capita transportation land hotspots and population distribution hotspots in Guangdong Province, exhibiting characteristics of a misalignment between human and transportation land. (4) According to the results of the Tapio decoupling model, from 2010 to 2015, the relationship between transportation land and population growth exhibited a layered pattern; from 2015 to 2020, the pattern of this relationship became more complex, with increased regional imbalances. The decoupling results for the PRD during 2010–2020 were dominated by weak decoupling and expansionary negative decoupling; for Ps-PRD, they were primarily strong negative decoupling and expansionary negative decoupling.
The relationship between transportation land and population distribution provides new insights for understanding regional balanced development. For developing countries like China, the construction of transportation systems is considered an important means to narrow regional development gaps. Particularly, increasing transportation infrastructure investment in underdeveloped areas to enhance transportation connections between underdeveloped and developed areas has long been regarded as an effective development strategy for achieving regional balance. However, this study found that with the changes in population distribution patterns, the mismatch between transportation land use and population size in economically disadvantaged areas has become more severe, and the decoupling phenomenon between the transportation land and population is very apparent. Looking at the transportation land structure of the peripheral area surrounding the Pearl River Delta (PRD) of Guangdong Province, rural road land accounted for the highest proportion before 2015. On the one hand, this is due to natural conditions, such as the rugged hilly terrain in these areas, combined with low socio-economic levels and low population agglomeration, leading to a large amount of rural infrastructure consuming valuable land resources and funds. On the other hand, this also forces us to reflect on the issue of transportation waste. Therefore, further sustainable development strategies are needed to address the problem of transportation land waste. It is worth noting that during the period 2015–2020, the highway land in the peripheral area surrounding the PRD of Guangdong Province grew rapidly. Combining recent news reports and published data, it can be seen that Guangdong Province has conducted a large amount of road construction in underdeveloped areas in recent years in order to radiate the economy of the Pearl River Delta region to the surrounding areas and drive the development of the peripheral area surrounding the PRD. Additionally, it cannot be ignored that as the area surrounding the PRD, the transportation roads connecting the PRD region with the outside world must pass through the peripheral area surrounding the PRD of Guangdong Province. These transportation lands, to some extent, also occupy the transportation land development indicators of the peripheral area surrounding the PRD of Guangdong Province and cause certain damage to its ecological environment. Balancing the sacrifices of underdeveloped areas with the gains of developed areas has always been a recognized global challenge. Currently, there have been some achievements in existing research on similar contradictions or problems, such as development and ecological protection or carbon emissions, but there is still little research on the fairness of transportation land development. In China, the layout of transportation land is greatly influenced by the higher-level government, especially in the construction of national strategic channels, where the multi-level government game is very complex.
In terms of policy recommendations, this study suggests that Guangdong Province should adopt differentiated policies to address diverse regional types and regional development disparities. For areas experiencing decoupling or connecting decline, urban cores that are in a shrinking stage should aim for intensive development to avoid the extensive construction of new transportation projects. This can be achieved by conducting transportation surveys and demand forecasts to develop reasonable transportation plans that balance transportation demand and resource supply. Additionally, optimizing urban industrial structures, providing more employment opportunities, and implementing preferential policies to attract the population can improve the efficiency of transportation infrastructure utilization.
For areas experiencing strong negative decoupling and expansionary negative decoupling, it is recommended to cautiously adjust the current expansion-oriented construction mode and promote high-quality transportation construction that is compatible with economic and social development, while considering efficiency and being within the range of fiscal affordability. Additionally, strategies may include leveraging existing transportation advantages, strengthening the construction of industrial supporting facilities to improve the business environment, enhancing cooperation between regions, leveraging regional comparative advantages, actively undertaking enterprise relocation and economic radiation from the Pearl River Delta region, and jointly promoting regional economic development. In addition, fully utilizing existing transportation infrastructure, nurturing new economic growth points, increasing investment in agriculture, services, and other fields to promote economic structural adjustment, transformation, and upgrade, may also be useful. Weak decoupling areas are mostly located in the central districts of cities with relatively good economic development. For these areas, it is necessary to strengthen the role of transportation in supporting populations and industries, and to fully leverage the population advantages.
Secondly, there is an urgent need to comprehensively improve the quality of transportation infrastructure supply. In the context of uneven regional development, it is necessary to address the regional differences in the supply structure of transportation infrastructure and achieve the optimal allocation of transportation elements. Aligning transportation development with regional population mobility trends to avoid blind investment and inefficient construction is crucial. Special attention should be given to areas where transportation construction is excessively large, the population is shrinking rapidly, and resource and environmental-carrying capacity are weak.
Lastly, regarding regional transportation infrastructure, its construction benefits have both temporal medium-to-long-term characteristics and spatial spillover effects. In terms of time, the multiplier effects of transportation infrastructure, such as improving productivity, driving employment, and enhancing market conditions, take time to accumulate. In terms of space, the construction of a cross-regional transportation corridor drives development over a larger geographical area and serves multidimensional comprehensive goals such as promoting economic, social, cultural, and national security. The investment in the peripheral area surrounding the Pearl River Delta (PRD) of Guangdong Province may not yield immediate results in the short term, which has, to some extent, led to the current mismatch between population and transportation land. However, from a long-term perspective, the investment in transportation land plays a role in driving the development of these economically backward areas. Evaluating transportation development from a land-use perspective requires a multidimensional global perspective that considers both short-term and long-term effects.
This study explores the spatiotemporal pattern and structural characteristics of transportation land in Guangdong Province, China, as well as its relationship with the spatial distribution of the population. It enriches the exploration of the spatiotemporal pattern of transportation land in China and the study of the relationship between specific land types and population sizes. The research results are beneficial for deepening our understanding of regional development differences and balancing resource supply, providing a theoretical basis for achieving regional sustainable development. However, the current study still has certain limitations that require further exploration. Firstly, the factors influencing the expansion of transportation land have not been further explored. Future research should increase the analysis of driving factors by adding more time series data, which may provide more policy insights. Secondly, the interaction between transportation land and the population has not been deeply analyzed, and future research should supplement and improve the relevant analysis. Finally, due to data limitations, this study did not distinguish between transportation infrastructure serving local communities and large corridors serving nationally important cities, neglecting the background differences caused by the characteristics of the two. Future research could differentiate between them and provide a detailed comparison of the results.
From the perspective of the “center-periphery” theory, this study links the research results with theoretical concepts. It analyzes the differences in transportation infrastructure supply and its relationship with the population in the center-periphery zone of Guangdong, China, under the background of regional imbalance development. This study uses the results to provide reference suggestions for regional policies and facility allocation, aiming to enhance our understanding of China’s changes, promote the connection between theory and empirical evidence, and provide a reference value for future research.