Research on the Synergistic Evolution of Comprehensive Transportation Network System in the Yellow River Basin Aimed at High-Quality Development

Abstract

The high-quality development of the Yellow River Basin is still facing the issue of imbalance and inadequacy, and it urgently requires the backing and assistance of a well-coordinated and efficient comprehensive transportation network system. Based on this purpose, this study uses a composite system synergy degree model incorporating “mode dimension + regional dimension” to analyze the evolution of this network. The results indicate the following: (1) Railway and air transportation surpass highway transportation in growth and synergy, though overall system synergy is still low. (2) Downstream areas are gradually taking the lead, and the orderliness of each subsystem is gradually becoming consistent. The complexity and variability of the composite system’s synergy are high, with an overall low level of synergy. Overall, despite improvements in service capacity and quality, better integration of different transport modes and enhanced cross-regional cooperation are needed. This study reveals and analyzes in depth the complexity of the comprehensive transportation network system in the Yellow River Basin and its spatiotemporal characteristics of synergistic evolution. We propose suggestions for high-quality development at national, regional, and industry levels, fostering the continuous improvement of the system structure, which aids in overcoming the tangible obstacles faced by the high-quality development of the Yellow River Basin.

1. Introduction

The Yellow River Basin covers a vast geographical area in China and serves as an essential cultural source and a crucial support for economic development. In recent years, China has placed ecological protection and high-quality development of the Yellow River Basin in a strategic position of importance. However, the Yellow River Basin spans multiple natural zones, with varying regional resource endowments and development conditions [1]. Due to the unique characteristics of the Yellow River channel, lacking intrinsic and holistic connectivity, it faces issues of imbalance and inadequacy [2], hindering resource flow and allocation, and the formation of market size advantages. This constrains the high-quality development of the Yellow River Basin. Therefore, to achieve high-quality development in the Yellow River Basin, it is necessary to overcome geographical constraints, strengthen regional connectivity and cooperation, facilitate the free flow of resource elements and efficient allocation, and promote coordinated development within the basin [3,4].

Including China, many countries attach great importance to the significance of transportation in economic development. Governments worldwide have successively introduced policies to promote the construction of transportation networks to ensure economic transformation, upgrading, and sustainable development. In 2007, the National Development and Reform Commission of China, together with relevant departments, issued the country’s first “Comprehensive Transportation Network Medium and Long-Term Development Plan”, which explicitly stated that the comprehensive transportation network is the foundation of the integrated transportation system. It covers various modes of transport and, through an organic combination and connection in geographical units and functions, forms a network layout that emphasizes rational planning, division of labor, and collaboration. It highlights optimization, connection, and coordination, conducive to leveraging overall advantages and intensifying efficiency [5]. According to the guidance issued jointly by the CPC Central Committee and the State Council in 2021, by 2035, China’s transportation network should be convenient, economical, green, intelligent, and safe [6]. Furthermore, the “National Comprehensive Three-dimensional Transportation Network Planning Outline” in China regards the Yellow River Basin as a key area for promoting the coordinated development of transportation [7].

Current studies indicate that transportation, especially transportation networks, can expand market demand, accelerate resource flow, enhance resource allocation efficiency and regional economic interconnectedness, drive overall economic growth, and help address issues of imbalance and inadequacy [8,9]. The new economic geography model points out the impact of transportation on spatial economic structure [10]. Pokharel et al. [11] demonstrated through a systematic literature review the close relationship between transportation infrastructure and regional economic development from the perspectives of infrastructure investment and policies. They highlighted that inter-regional transportation links can dictate urban spatial layout and subsequent urbanization, while urban transportation infrastructure determines the size and population scale of cities. Jiang et al. [12] used the SOLOW model to analyze the spillover effects of transportation endowment in Chinese provincial regions, finding that the improvement of the transportation network is beneficial in generating positive externalities, especially for the western regions with low transport costs. Jiao et al. [13] found that different modes of transportation have varying impacts on economic growth, highlighting the consideration of synergy in comprehensive transportation system planning. In conclusion, we have reason to believe that the improvement and upgrading of the comprehensive transportation network will help to utilize its externalities to promote economic growth and deepen regional economic connections, optimizing spatial economic structure. However, existing studies mostly consider the impact mechanism of transportation networks on regional spatial structure and regional economic development from the perspectives of accessibility and infrastructure construction [14,15], paying little attention to the complex system of regional transportation networks and their evolution processes, which makes it difficult to leverage network effects effectively. This study argues that the comprehensive transportation network is a complex system with self-organizing properties, where its synergies imply a rational, efficient, and stable system structure, generating overall advantages greater than the sum of its parts, which are crucial for regional connections and transportation mode integration, determining whether efficient flow and exchange of resources between regions can be achieved, thus better supporting and serving the basin economic system. Therefore, it is necessary to focus on the role of the comprehensive transport network and its synergy in the high-quality development of the Yellow River Basin. Based on theoretical analysis, this study empirically analyzes the orderliness within the system and the synergy of the overall system using a composite system synergy model, revealing the synergistic evolutionary laws and spatiotemporal characteristics of a comprehensive transportation network system in depth. Through result analysis, pathways for achieving high-quality development relying on comprehensive transportation networks are proposed from various perspectives. This study provides a certain basis and policy implications for constructing an interconnected, deeply integrated, and structurally improved comprehensive three-dimensional transport network to serve the high-quality development of the Yellow River Basin. At the same time, it also holds certain theoretical significance, further expanding the research on the transportation and high-quality development of the basin from the perspective of complex systems, deepening the cross-fusion of multidisciplinary knowledge.

2. The Synergistic Evolution of the Comprehensive Transportation Network System and the High-Quality Development of the Yellow River Basin

Specifically, the Yellow River runs through nine provinces with significant geographical variations in natural resources. Different regions have diverse economic development foundations. Hence, it is necessary to adapt measures to local conditions, fully exploit regional comparative advantages, establish a comprehensive division of labor system, and achieve coordinated regional development [4]. Classical economics posits that differences in factor returns between regions will tend towards equilibrium through factor mobility. The movement of tangible capital and population may explain the convergence between regions [16]. Therefore, achieving high-quality development in the Yellow River Basin and addressing the current imbalance requires not a pursuit of absolute regional equality, but breaking through geographical barriers, strengthening regional connectivity, promoting complementary advantages and rational division of labor among regions, and reducing development gaps. The networked nature of the comprehensive transportation system plays a prominent role in regional connectivity and integration, significantly reducing spatial–temporal distances through the effective combination of functionality and space, facilitating the flow and exchange of production factors such as labor, information, capital, and land, altering the spatial distribution of economic activities [17].

The transportation modes involve complex competitive and cooperative relationships, where different modes can both substitute and cooperate with each other in the transportation service process. With a broad geographic scope, diverse covered elements, emphasis on integration and connectivity, complex structure, and diverse functions, it is evident that a comprehensive transportation network is a complex system composed of various elements interwoven and interacting with each other.

Although the integrated construction and development of the comprehensive transportation network are designed and guided by organizers such as national and local governments, transportation departments, and other organizations, absolute comprehensive and precise interventions still cannot be carried out. The evolution of the overall system still relies on the relationships among various elements and entities within the system. As a theory of complexity science management, self-organization theory reveals the autonomous evolution process of systems from disorder to order, emphasizing the internal ordering of the system rather than relying on external commands [18,19].

First, the comprehensive transportation network continuously exchanges energy with the external environment based on its characteristics, functioning as an open complex system characterized by the multi-factor intersection; second, the system includes different modes of transportation and regions, with competition, cooperation, and nonlinear interactions among them. On one hand, it disrupts the equilibrium of the overall system, while on the other hand, it promotes the generation and fluctuation of order parameters, providing the driving force for self-organization and collectively promoting the system to evolve into a new stable structure. In practical terms, systems passively receive external instructions, but under the interactions of various components, they exhibit self-organizing behaviors, dynamically adapting to environmental changes. In the construction and development of comprehensive transportation networks, due to different interests and situational changes faced by various departments and regions, there may be significant flexibility and uncontrollability. Simultaneously, the complex interaction mechanisms among various subsystems within the comprehensive transportation network may result in intertwined management authority and scope of responsibilities. Without effective alignment and overall coordination, issues such as blind competition, fragmented development, redundant construction, and mutual blame may arise, constraining the network economic effects of the comprehensive transportation structure and hindering the realization of development goals involving complementary advantages and synergistic linkage, thereby impeding the high-quality development of the Yellow River Basin. Therefore, for the management of the system, it is necessary to respect its integrity and synergy, requiring not only unified efforts from its organizers but also coordinated cooperation within the system.

Synergistics is at the core of the self-organization theory, revealing the synergistic effects when a system interacts with its environment. It considers a system as composed of multiple subsystems and elements, with competitive and cooperative relationships between subsystems driving the emergence of macroscopic ordered structures [20]. The synergistic evolution of the comprehensive transportation network continually reinforces the openness of the system, prompting the system and its subsystem to engage in constant energy exchange with the external environment, leading to learning and adaptation of the structure, accelerating the flow of resource elements, leveraging spillover effects, and thereby driving high-quality development in the Yellow River Basin. Simultaneously, it will break through geographical constraints, connecting various modes of transport, fostering voluntary equality and cooperation among stakeholders under common governance rules, pursuing mutual benefits, and better integrating various modes and comparative advantages of different regions to generate a “1 + 1 > 2” synergistic effect.

Therefore, it is essential to emphasize the functionality and role of the comprehensive transportation network. Exploring its synergistic evolution laws can ensure that the system structure evolves into a more rational, efficient, and stable new structure, serving the flow, exchange, and efficient allocation of production factors. Otherwise, it will not be possible to improve the imbalanced and insufficient current situation in the Yellow River Basin, supporting the basin’s economy to enter an advanced stage of development.

3. Methods and Materials

3.1. Study Area

The Yellow River Basin is the birthplace of Chinese civilization, rich in energy resources, developed in agriculture, with a solid industrial base. It is a key area for population and economic development [3], as well as an important component of China’s ecological security framework, playing a crucial role in promoting regional economic integration and ecological balance [21]. As shown in Figure 1, The Yellow River Basin is divided into three parts: the upper reaches, the middle reaches, and the lower reaches, spanning nine provincial-level administrative regions including Qinghai, Sichuan, Gansu, Ningxia, Inner Mongolia, Shaanxi, Shanxi, Henan, and Shandong provinces [22]. There are significant differences among the regions within the basin. Due to serious sediment deposition, the Yellow River has gradually lost its water transport function, failing to provide innate transportation links to various regions [23]. The overall economic development level in the basin is relatively lagging, with severe imbalances and inadequate development [24].

3.2. Framework and Data

The synergistic evolution level of a system often depends on its order parameters, which can describe its macroscopic order and patterns [25]. Due to the lack of inherent transportation connections in the Yellow River Basin, the integration of other modes of transportation becomes even more important. Therefore, based on the comprehensive transportation network characteristics mentioned earlier, we construct a composite system of highway transportation, railway transportation, and air transportation based on the mode dimension. Additionally, according to the Yellow River Conservancy Commission of the Ministry of Water Resources of the People’s Republic of China and existing research on the natural river basin range division, considering regional integrity and connectivity, we divide the Yellow River Basin into three regions: the upper reaches (Qinghai, Sichuan, Gansu, Ningxia, Inner Mongolia), the middle reaches (Shaanxi, Shanxi), and the lower reaches (Henan, Shandong) at the provincial level to build a composite system of interactions among regions. Based on the calculation of the ordered degree of subsystems, combined with indicator weights, we further obtain the synergy of the composite system.

3.2.1. Order Parameters Selection

The order parameters dictate the direction and speed of change in the subsystem, playing a dominant and decisive role in the overall system evolution [26]. We start from the purpose of promoting high-quality economic development in the Yellow River Basin through the development and improvement of comprehensive transportation network services and follow principles such as effectiveness, appropriateness, and availability for order parameter selection. As a crucial component of the socio-economic system, freight and passenger transportation directly reflect the aggregation and transmission intensity of energy on transportation axes [27]. Referring to studies by Lai et al. [28] and Jia et al. [29], the freight transport volume and passenger transport volume are selected as the order parameters of the highway transportation and railway transportation subsystems within the modal compound system. Building on research by Wu et al. [30] and Cao et al. [31], airport cargo and mail throughput and airport passenger throughput are selected as the order parameters of the air transport subsystem in the modal compound system. Drawing from studies by Li et al. [32], Jin [33], and Zong et al. [34], we select highway freight transport volume, railway freight transport volume, highway passenger transport volume, railway passenger transport volume, airport cargo and mail throughput, and airport passenger throughput as order parameters within the regional composite systems.

3.2.2. Data Source

We collected relevant data on the Yellow River Basin in nine provinces between 2009 and 2020, but due to changes in the statistical caliber of road transport volume in 2013, a discontinuity in the orderliness of the road transport subsystem was found during the analysis. Coupled with the severe impact of the COVID-19 pandemic on the transportation industry, abnormal values of significant decrease have been seen in all data since 2020, which are insufficient to reflect the coordinated evolutionary laws of the comprehensive transportation network and draw robust conclusions.

Therefore, considering the stability, scientific validity, and timeliness of the conclusions to support future decisions, we ultimately narrow down the data scope to the period between 2013 and 2019. Data on highway freight transport volume, highway passenger transport volume, railway freight transport volume, and railway passenger transport volume from 2013 to 2019 are sourced from the “China Statistical Yearbook” and “China Transport Statistical Yearbook”, while data on airport cargo and mail throughput and passenger throughput from 2013 to 2019 are obtained from the annual production statistical reports of civil aviation airports. The original data of each airport in different regions were aggregated in the earlier stage to derive the cargo and mail throughput and passenger throughput of airports in each province. The specific research framework is illustrated in Figure 2.

3.3. Methods

3.3.1. The Ordered Degree of the Subsystem’s Order Parameter Components

Define the composite system as $S$, and the order parameter of the subsystem $E_i$ as $e_i=\left(e_{i1},e_{i2},\dots ,e_{in}\right)$, $n\ge 1$. The order parameters have an upper critical point and a lower critical point: $a_{ij}$ and $b_{ij}$. $e_{i1},e_{i2},\dots ,e_{in}$ is the slow-relaxation variable, and its value positively correlates with the system’s ordered nature, while $e_{in+1},e_{in+2},\dots ,e_{im}$ is the fast-relaxation variable, and its value negatively correlates with the system’s ordered nature. The ordered degree of the subsystem’s order parameter components $e_{ij}$ is as follows [35,36]:

$$u_i\left(e_{ij}\right)=\{\begin{array}{l}{\displaystyle \frac{e_{ij}-b_{ij}}{a_{ij}-b_{ij}}},\left(j=1,2,\cdots ,n\right)\hfill \\ {\displaystyle \frac{a_{ij}-e_{ij}}{a_{ij}-b_{ij}}},\left(j=n+1,n+2,\cdots ,m\right)\hfill \end{array}$$

(1)

3.3.2. The Model of the Subsystem’s Ordered Degree

Based on the ordered degree of the subsystem’s order parameter components, the order degree of the subsystem can be derived as follows [37]:

$$u_i\left(e_i\right)={\displaystyle \sum _{i=1}^n{Q}_i\times u_i}\left(e_{ij}\right),Q_i\ge 0\mathrm{and}{\displaystyle \sum _{i=1}^n{Q}_i=1}$$

(2)

Among them, $Q_i$ represents the weight of each order parameter and also signifies the position and role of them in the system operation.

3.3.3. The Composite System Synergy Degree Model

Assume $u_i^0\left(e_i\right)$ represents the ordered degree of the subsystem at the initial year $t_0$, and $u_i^1\left(e_i\right)$ represents the ordered degree of the subsystem evolving to the year $t_1$; the synergy degree of the system is shown in Equation (3) [36,37,38]:

$$C=\phi \times \sqrt[i]{\left|u_1^1\left(e_1\right)-u_1^0\left(e_1\right)\right|\times \cdots \times \left|u_i^1\left(e_i\right)-u_i^0\left(e_i\right)\right|}$$

(3)

$\phi$ takes on values of 1 or −1, representing the direction of synergistic development among subsystems. When the ordered degree of subsystems in year $t_1$ is greater than that in year $t_0$, $\phi$ takes the value 1, indicating that the compound system is in a state of synergistic evolution with a positive value; conversely, if $\phi$ takes the value of −1, it signifies that the compound system is in a state of non-synergistic evolution, operating at a negative synergy level. When calculating the synergy degree of systems such as “highway transportation–railway transportation” or “upstream–downstream”, $i$ is set to 2. However, for evaluating the overall synergy degree between systems like “upstream–midstream–downstream” or “highway transportation–railway transportation–air transportation”, the value of $i$ is set to 3.

3.3.4. The Indicator Weighting Model

We use the correlation matrix weighting method to determine the weights. It is assumed that the $P_i$ denotes the total impact of the $i$-th order parameter indicator on the other $n-1$ order parameter indicators. The formulas for calculating the indicator weights are illustrated in Equations (4) and (5) [39,40]:

$$Q_i={\displaystyle \frac{P_i}{{\displaystyle \sum _{i=1}^n{P}_i}}},\left(i=1,2,\cdots ,n\right)$$

(4)

$$P_i={\displaystyle \sum _{i=1}^n\left|p_{ij}\right|}-1,\left(i=1,2,\cdots ,n\right)$$

(5)

Determine the weights of the order parameter indicators in each subsystem, as shown in

Table 1. The weights of the order parameter indicators in the subsystem.

Dimension	Subsystem	Order Parameter	Weight
Mode dimension	Highway transportation	Highway freight transport volume	0.5
		Highway passenger transport volume	0.5
	Railway transportation	Railway freight transport volume	0.5
		Railway passenger transport volume	0.5
	Air transportation	Airport cargo and mail throughput	0.5
		Airport passenger throughput	0.5
Regional dimension	Upstream	Highway freight transport volume	0.138
		Highway passenger transport volume	0.195
		Railway freight transport volume	0.094
		Railway passenger transport volume	0.194
		Airport cargo and mail throughput	0.188
		Airport passenger throughput	0.191
	Midstream	Highway freight transport volume	0.128
		Highway passenger transport volume	0.169
		Railway freight transport volume	0.144
		Railway passenger transport volume	0.187
		Airport cargo and mail throughput	0.181
		Airport passenger throughput	0.190
	Downstream	Highway freight transport volume	0.166
		Highway passenger transport volume	0.179
		Railway freight transport volume	0.052
		Railway passenger transport volume	0.204
		Airport cargo and mail throughput	0.192
		Airport passenger throughput	0.207

.

4. Results

4.1. Mode Dimensional Analysis

4.1.1. The Ordered Degree of Subsystem

We normalize the data according to Formula (1), then calculate the ordered degree of the highway transportation, railway transportation, and air transportation subsystems according to Formula (2), and the data results are shown in

Table 2. The ordered degree of the transportation mode subsystem in the Yellow River Basin.

Year	Highway Transportation	Railway Transportation	Air Transportation
2013	0.476	0.234	0.000
2014	0.602	0.278	0.169
2015	0.400	0.134	0.284
2016	0.425	0.213	0.476
2017	0.487	0.490	0.648
2018	0.564	0.775	0.810
2019	0.196	1.000	1.000

.

As shown in Figure 3, the results indicate that (1) the ordered degree of highway transportation shows a trend of fluctuating decline, with a significant drop in 2019. (2) Railway transportation ordered degree fluctuated and rose, with a notable decrease in 2015, followed by consecutive annual increases from 2016 to 2019, with an accelerated growth rate. (3) The ordered degree of air transportation increased year by year, maintaining overall stability. (4) Generally, in terms of subsystem orderliness, before 2014, highway transportation surpassed railway and air transportation. Between 2014 and 2017, air and railway transportation gradually overtook, and from 2017 to 2019, the ordered degree was air transportation > railway transportation > highway transportation.

The empirical results indicate the following: (1) Highway transportation is gradually undergoing transformation and upgrading. In line with national policies, the State Council of China issued the “Three-Year Action Plan for Promoting the Adjustment of Transportation Structure (2018—2020)” in 2018. We believe this plan mandates the strategic shift of bulk goods transport from highways to railways and waterways, aiming to optimize the national freight transport structure. This shift partly explains the reduction in highway freight volumes since 2018, leading to a decrease in systematic orderliness. (2) Railway transportation has increasingly assumed a leading role, supporting the adjustment of industrial structures. The rising fluctuations in the ordered degree of the railway transportation subsystem further verify changes in the transport structure, with railways drawing some traffic away from highway transportation. In 2015, the Chinese government first proposed supply-side reform, demanding the elimination of backward capacities in industries like steel, coal, and coal-powered electricity to enhance the quality of economic development. The resource-intensive industrial structure of the Yellow River Basin was particularly impacted. Transportation reflects the needs of economic development [41], and the decline in the ordered degree of the railway transportation subsystem reflects a decrease in bulk goods transportation demand, indicating significant effects of capacity reduction initiatives. With the evolving landscape of the industry, there has been an increase in sector concentration and, coupled with the expanded pricing autonomy of various railway bureaus, transportation costs have been reduced, leading to a recovery in subsystem orderliness. Additionally, based on original data, the contribution of passenger rail traffic to system orderliness has gradually increased since 2015. This suggests that improvements in railway infrastructure, especially high-speed railways, have had spillover effects that accelerate population mobility and stimulate potential consumer demand within the regions served. (3) The advantages of air transportation are increasingly prominent, with rising transportation demands from emerging industries. We hold the opinion that high-quality, efficient air services are crucial in attracting modern industries like high-tech. The systematic escalation in the ordered degree of the air transportation subsystem illustrates the ongoing enhancement in the transportation service levels of the Yellow River Basin, meeting an expanding array of transportation needs. This also reflects the transformation and upgrading of the consumption and industrial structures, with rapid growth in high-tech industries, equipment manufacturing, and e-commerce services, and a growing demand for the transportation of technology-intensive and perishable products, and air transportation, with its accessibility and safety advantages, has become a crucial support for all of the above. Particularly since Zhengzhou, Qingdao, and Xi’an were approved as airport economic demonstration zones, leveraging hub airports to develop airport-linked economies has further leveraged the advantages of air transportation, stimulating the development of emerging industries. Moreover, changes in the air transportation subsystem of the Yellow River Basin also indicate, to some extent, enhanced regional economic openness and the accelerated circulation of resource elements over a broader area, with continuous increases in airport cargo and mail throughput and passenger throughput, leading to the subsystem’s ordered degree progression.

Overall, since 2013, the comprehensive transportation network system in the Yellow River Basin has begun to develop in a more sustainable, efficient, and open direction. The transportation structure is continuously optimized, and infrastructure is constantly improved, facilitating the flow of people, goods, and information, and supporting industrial transformation and upgrading.

4.1.2. Synergy Degree of Composite System

We calculate the degree of synergy among the composite systems of highway transportation, railway transportation, and air transportation based on Formula (3), as shown in

Table 3. The degree of synergy among the composite systems of transportation mode in the Yellow River Basin.

Year	Highway–Railway	Highway–Air	Railway–Air	Highway–Railway–Air
2013	-	-	-	-
2014	0.074	0.146	0.086	0.098
2015	−0.171	−0.152	−0.129	−0.150
2016	0.044	0.068	0.123	0.072
2017	0.131	0.103	0.219	0.144
2018	0.149	0.112	0.215	0.153
2019	−0.288	−0.265	0.207	−0.251

.

The results indicate the following: (1) The degree of synergy between “highway transportation–railway transportation” and “highway transportation–air transportation” has been on the rise annually since 2016, with synergy levels entering negative values in 2015 and 2019, generally reflecting a low level of synergy. (2) The synergy between “railway transportation–air transportation” showed negative values in 2015, but has increased generally since 2016, with a relatively higher overall level of synergy. (3) Overall, the synergy among “highway transportation–railway transportation–air transportation” has been low, but it has similarly shown an annual increase since 2016, with negative values recorded in 2015 and 2019.

Empirical results indicate the following: (1) The synergy of the composite system is influenced by the fluctuations in the ordered degree of its subsystems. The fluctuation in the highway transportation subsystem, contrasting with trends in other transportation subsystems, leads to a lower synergy level and exhibits negative synergy in the composite system. We believe this reflects the gradually emerging effects of transportation structural adjustments, with transportation volumes increasingly shifting from highways to railways. As previously mentioned, the industrial homogeneity in the Yellow River Basin is quite pronounced, with various regions prioritizing the energy, chemical and steel industries as leading sectors [42]. This has resulted in a considerable reliance on both highway and railway transportation modes. The year 2015 signified the onset of supply-side reforms, with government measures aimed at reducing capacity in traditional sectors, which subsequently led to a decline in cargo transportation demand throughout the Yellow River Basin. Consequently, the ordered degree of the subsystem experienced a drop, and the synergy within the composite system remained relatively low, culminating in negative synergies. However, with the economy’s smooth transition and ongoing enhancements to infrastructure, the orderliness of the highway and railway transportation subsystems experienced a positive rebound, while the synergy of the composite system was on a path to gradual recovery. Nonetheless, due to interventions stemming from transportation structure adjustments, highway transportation volumes fell in 2019, resulting in a detrimental shift in the subsystem’s ordered degree, which once again adversely affected the synergy level of the composite system. (2) The synergy of the compound system between railway and air transportation is relatively higher and maintains an overall upward trend. This shows some success in exploring and implementing combined air–rail transportation methods in the Yellow River Basin, although the synergy level remains around 0.2, indicating a low level of synergy. There remains a significant gap in achieving highly efficient linkage and interconnected synergy. (3) Overall, we hold the view that the comprehensive transportation network system of the Yellow River Basin is undergoing adjustments and optimizations in its transportation structure. However, the individual transportation subsystems have not yet achieved benign synergistic development, with the overall synergy level fluctuating between [−0.3,0.2]. The Yellow River Basin largely encompasses the interior regions of central and western China, where economic development is notably behind that of the eastern coastal areas and is presently undergoing a developmental transformation. Due to regional policies, economic strength, and resource constraints, the basin’s industrial transformation process is lengthy and slow [43], leading to fluctuations in transportation demand. These fluctuations result in instability in the orderliness of various transportation systems and consequently affect the synergy degree of the composite system. Furthermore, the basin lacks a unified multimodal transport policy, resulting in disparate management and development approaches across regions, which hampers effective collaboration. Additionally, macro-level adjustments are also factors contributing to the variability in the coordination of this complex system.

4.2. Regional Dimensional Analysis

4.2.1. The Ordered Degree of the Subsystem

The data were normalized according to Equation (1), then the ordered degree of the upstream, midstream, and downstream subsystems was calculated as per Equation (2), with the results shown in

Table 4. The ordered degree of the regional subsystem in the Yellow River Basin.

Year	Upstream	Midstream	Downstream
2013	0.250	0.190	0.222
2014	0.363	0.329	0.334
2015	0.357	0.266	0.255
2016	0.459	0.322	0.411
2017	0.581	0.475	0.567
2018	0.705	0.709	0.708
2019	0.720	0.745	0.726

.

As shown in Figure 4, The results indicate the following: (1) The ordered degree in the upstream sector increased through twists and turns, showing significant growth during 2016–2018, with a reduced rate of increase in 2019. (2) The ordered degree in the midstream sector exhibited fluctuating growth, with a minor decline in 2015 followed by a continuous rise from 2015 to 2018, where the rate of increase accelerated, then slowed down between 2018 and 2019. (3) The ordered degree in the downstream sector demonstrated a fluctuating upward trend, with a decline in 2015 followed by successive annual increases, yet with a slower rate of growth in 2019. (4) Overall, the ordered degree of the upstream subsystem was greater than that of the downstream subsystem, which was in turn greater than that of the midstream subsystem before 2016. The downstream started to gradually overtake between 2016 and 2017, and since 2017, the orderliness of the various regional subsystems has increasingly converged.

Empirical results demonstrate the following: (1) From an upstream perspective, the increasing orderliness of the subsystems indicates that passenger and freight transportation is continuously expanding. This reflects the significant impact of investment in transportation infrastructure as part of the Western China Development Strategy, considerably enhancing transport capacity. This enhancement has promoted the rapid circulation and efficient allocation of resources, stimulating economic growth in the western regions. As integration with the “Belt and Road” initiative deepens, numerous provinces and cities upstream have become crucial international hub nodes. The pace of openness in inland and border areas continues to accelerate, generating substantial transportation demand, driving an increase in transportation volume, and accelerating the rise in the orderliness of the subsystems. (2) From the perspective of the midstream section, the fluctuations in the highway passenger and freight transport volumes as well as railway freight volumes have influenced the subsystem’s ordered degree. These variations also mirror the gradual optimization of the transportation and industrial structures, with noticeable improvements. The fluctuation in freight transportation via highway and railway, initially decreasing then increasing, reflects a reduction in the demand for transporting traditional energy sources followed by a gradual recovery. This alleviates excess capacity and leads to a more rational and stable supply structure. It marks the transition from a traditional resource-based industry structure towards a more intensive, eco-friendly, and efficient orientation. Concurrently, the continued annual increase in airport passenger and freight throughput has also contributed to the rise in the subsystem’s orderliness, indicating that the demand for transporting high-end products is gradually increasing. This transformation reflects the economic development model of the midstream region is gradually changing. (3) Viewed from downstream, the fluctuations in the ordered degree of subsystems also reveal the transition from old to new driving forces under supply-side reforms. The downstream provinces are regions with larger populations and industrial scales, leading to a higher level of economic development compared to other areas in the Yellow River Basin [44,45]. Since the inclusion of the Zhengzhou Airport District in the 13th Five-Year Plan, the approval of the Central Plains Urban Cluster Development Plan in 2016, and the Shandong Peninsula Urban Cluster Master Plan in 2017, downstream areas have seen continuous infrastructure improvements. This development has attracted and supported numerous industries, facilitated the free flow and reasonable concentration of resources, strengthened economic ties, and significantly increased the demand for passenger and freight transport. The increasing ordered degree of the downstream subsystem is gradually surpassing the trends in other regions, also confirming the above points.

From an overall perspective, (1) influenced by the supply-side reform, as an important resource-based industrial cluster, the Yellow River Basin has seen a significant decrease in freight transport volume, and the ordered degree of the various regional subsystems of the comprehensive transportation network has fallen into a low point. (2) In recent years, various regions have actively expanded into new development spaces, promoting the high-end development of the industrial system, with continuous growth in air passenger and freight transport volume. (3) During the 13th Five-Year Plan period, China accelerated the construction of the comprehensive transportation system, focused on improving the railway network in the central and western regions, and introduced relevant policies to reduce transportation and logistics costs, thereby promoting the circulation of resources between regions, increasing passenger and freight transport volumes, and accelerating the orderliness of various regional subsystems. (4) The fairness and sharing of internal development in the Yellow River Basin have received attention. The changes in the various regional subsystems of the comprehensive transportation network are gradually becoming consistent, with significant improvements in transportation service capabilities and technological levels in various regions. We think this indicates that the Yellow River Basin is gradually being valued as a whole, and the transportation network is moving towards complete coverage of the entire basin. At the same time, the relationship between the orderliness of the subsystems in the upper, middle, and lower reaches indirectly confirms the gradient characteristics of the social and economic development in the Yellow River Basin. (5) Influenced by factors such as the global economic downturn, the transition of old and new driving forces domestically, and policy adjustments seeking progress while maintaining stability, the downward pressure on the national economy continued to increase in 2019, with the growth rate of domestic and international demand slowing down, thereby leading to a slowdown in the growth rate of passenger and freight transport volumes and a shrinking growth rate in the ordered degree of various regional subsystems.

4.2.2. Synergy Degree of Composite System

According to Formula (3), we calculate the synergy of the composite system between upstream, midstream, and downstream, as shown in

Table 5. The degree of synergy among the composite systems of regions in the Yellow River Basin.

Year	Upstream-Midstream	Upstream-Downstream	Midstream-Downstream	Upstream-Midstream-Downstream
2013	-	-	-	-
2014	0.125	0.112	0.124	0.120
2015	−0.019	−0.021	−0.070	−0.030
2016	0.075	0.126	0.093	0.096
2017	0.137	0.138	0.154	0.143
2018	0.170	0.132	0.181	0.160
2019	0.023	0.016	0.025	0.021

:

The results show the following: (1) The degree of synergy between the “upstream–midstream” had a negative value in 2015, then increased, reaching its peak in 2018, and significantly decreased after 2018. (2) The synergy between “upstream–downstream” showed a fluctuating trend, with the lowest values in 2015 and 2019, rising in 2017 and 2018, and higher compared to other years. (3) The synergy between the “midstream–downstream” similarly showed fluctuating changes, also reaching its maximum value in 2018, with negative synergy in 2015 and relatively low level in 2019. (4) Overall, the overall synergy level between “upstream–midstream–downstream” is relatively low, with non-synergistic and low-synergistic states in 2015 and 2019, and the highest synergy level in 2018.

The empirical results indicate the following: (1) Under the impetus of supply-side reform, most regions in the Yellow River Basin, which primarily rely on traditional industries, have achieved significant capacity reduction results. This has led to a decrease in demand for bulk commodities such as coal and steel transportation, reflecting a shift towards more sustainable and diversified economic activities. The ordered degree of subsystems decreased, with the degree of synergy among compound systems turning negative in 2015. As the economic transformation progressed steadily after 2015, various regions began to explore new development paths outward. Coupled with the significant effectiveness of measures aimed at reducing costs and increasing efficiency in the transportation industry previously mentioned, the growth of various regional subsystems’ orderliness degree gradually resumed, with the degree of synergy rebounding post-2015. (2) Chinese national strategies are increasingly focusing on the development of provinces in the Yellow River Basin. Factors such as industrial upgrading and transportation infrastructure construction have accelerated the growth of systemic order. In particular, the significant progress of the “Belt and Road” Initiative in 2018 has provided an opportunity for the rise of the Yellow River Basin, with increased freight and passenger transportation in the upper, middle, and lower reaches of the Yellow River. Consequently, the ordered degree of regional subsystems has increased, with higher synergy compared to previous years. After 2018, the rate of change in ordered degree has slowed down and tended to be consistent, showing a trend of “stable improvement”. However, slight negative changes in the orderliness of individual subsystems have led to lower synergy. (3) Overall, the comprehensive transportation network system in the Yellow River Basin has not yet achieved good coordination among different regions, failing to generate the necessary synergistic linkage effects. The development speeds and trends of various regional subsystems are inconsistent, with all regional compound systems at a low level of synergy, less than 0.2. We hold the view that this may be due to adjustments in the transportation structure causing different directions of change in the subsystems of various transportation modes, thereby reducing the growth rate of orderliness of regional subsystems, so that leading to low synergy. This also indicates that further enhancement of connectivity and cooperation in the comprehensive transportation network of the Yellow River Basin is needed. The Yellow River Basin faces challenges related to administrative fragmentation and functional scope segmentation, in addition to the significant regional disparities in development conditions. This makes it difficult for different regions to coordinate governance and achieve collaborative development.

5. Discussions and Conclusions

5.1. Conclusions

Based on the self-organized characteristics of the comprehensive transportation network, we measure the ordered degree and the degree of synergy among the composite systems from the two dimensions of mode and region. We find that influenced by external regulation and internal effects, between 2013 and 2019, in terms of the mode dimension, the ordered degree of highway transportation decreased in fluctuations, while the ordered degree of railway transportation and air transportation continued to increase, and the synergy level of the two was relatively high, overall, at a stage of low coordination development. In terms of the regional dimension, the ordered degree of each subsystem increased in fluctuations, downstream gradually took the lead, and the orderliness of each subsystem gradually tended to converge. The complexity of the degree of synergy among the composite systems was diverse and changed frequently, with an overall low level of coordination. It can be concluded that (1) the comprehensive transportation network system in the Yellow River Basin is gradually optimizing, moving towards a green, efficient, and open direction, promoting the transformation of industrial new and old kinetic energy. (2) The transportation service capabilities and technological levels in various regions are rapidly improving, supporting each region to leverage its advantages and create new economic growth points, accelerating economic circulation speed and increasing the level of openness to the outside world. (3) The internal system has not yet achieved a virtuous coordinated development, the degree of connection and integration between various modes of transportation needs to be improved, and cross-regional connections are still not close enough. There are issues of segmented development in the Yellow River Basin, with economic links mostly occurring within regions, lacking effective mechanisms for regional coordination, downstream areas not playing the desired radiation and leading role, and the pattern of linked development not having formed yet. Compared with previous studies, we focus on the complexity of the comprehensive transportation network system and its close connection with economic development. We reveal the spatiotemporal characteristics of the synergistic evolution of the comprehensive transportation network system in the Yellow River Basin to better leverage its functions and roles, providing a certain basis and policy insights for breaking through the real obstacles to high-quality development in the Yellow River Basin and expanding the research on high-quality development in the Yellow River Basin.

5.2. Measures and Suggestions

5.2.1. National Level

• Establishing the Yellow River Basin Comprehensive Transportation Commission for unified management and strengthening institutional guarantee. The country should actively promote top-level design, and strengthen overall and strategic planning. However, the complexity of the comprehensive transportation network dictates that it must overcome obstacles related to unclear jurisdiction and regional policy differentiation. For instance, the development policy of one province may not be applicable to another, and the absence of a unified action guideline between the two provinces leads to difficulties in coordinated decision-making. To mitigate administrative barriers, some developed countries, such as Japan with its Pacific City Cluster, have established a top-down authoritative body to ensure collaborative development within the region. The government facilitates coordination between regions by implementing adaptive plans [46]. The New York metropolitan area in the United States established The Port Authority of New York and New Jersey to address the issue of administrative fragmentation. This specialized transportation management entity is primarily responsible for the construction, maintenance, and enhancement of transportation infrastructure within the port area, as well as interstate transportation infrastructure [47].

Thus, the Yellow River Basin can draw on the successful experiences of developed countries to establish an authoritative administrative body responsible for the comprehensive transportation network system in the Yellow River Basin (such as the Yellow River Basin Comprehensive Transportation Committee), leveraging the overall effectiveness of the comprehensive transportation network to support and enhance the high-quality development of the Yellow River Basin. On the one hand, it is necessary to implement vertical management, unify planning and layout, clarify the distribution of powers, responsibilities, and related policy standards, play a coordinating role, resolve the drawbacks of multiple management, and ensure the orderly and advanced evolution of the comprehensive transportation network system. On the other hand, it is also important to focus on horizontal coordination, break through administrative barriers, establish sound collaboration and consultation mechanisms, achieve cross-domain, cross-departmental cooperation and linkage, and enhance collaborative governance capabilities and efficiency. Additionally, it is essential to construct a reasonable mechanism for sharing interests and compensation, ensuring the sharing and fairness of interests in the construction and use of the comprehensive transportation network. Measures in this area may be susceptible to political interference; therefore, leadership and oversight at the national level are more effective in ensuring consistent implementation and avoiding regional biases.

2.

Adjusting and optimizing the transportation structure to promote the transformation and upgrading of industries in the Yellow River Basin. Our data analysis suggests that the transportation structure in the Yellow River Basin is evolving towards a more sustainable and efficient model, which is linked to the region’s industrial framework. The country needs to continue the strategic adjustment of the transportation structure, leveraging the comparative advantages of various transportation modes. It is necessary to leverage the backbone role of railway transportation, promote the transfer of bulk cargo transportation to railways, promote the transformation and upgrading of highway transportation, and achieve the conversion of old and new kinetic energy. Additionally, orderly growth of air transportation should be maintained, utilizing the technological and service advantages of air transportation to promote the rise of emerging industries in the Yellow River Basin, leveraging the role of aerotropolis in driving local and regional economic growth. Overall, the goal is to enhance the integration and connection of different transportation modes within the Yellow River Basin, thereby improving the overall efficiency of comprehensive transportation. This improvement aims to support industrial innovation through a green, intensive, and efficient transportation structure.

3.

Strengthen the external connection of the comprehensive transportation network, and improve the level of opening up to the outside. The government needs to continuously improve the construction and layout of infrastructure, enhance the interconnectedness of the comprehensive transportation network, actively connect with the Yangtze River Economic Belt, Pearl River Delta, Beijing–Tianjin–Hebei integration, and Guangdong–Hong Kong–Macao Greater Bay Area, and establish cooperative mechanisms to achieve external linkage. The Yellow River Basin ultimately connects with the Bohai Sea, and many areas along this route are key nodes of the ancient Silk Road. Therefore, it is essential to capitalize on this advantage by building an internationally connected, comprehensive three-dimensional transportation network. This network should integrate into the Belt and Road Initiative and develop the Yellow River Basin into a new hub for northern provinces and cities to open up to the outside world. This development will promote the high-quality flow of production factors both into and out of the region. In addition, continuing to strengthen the construction of the land and port system in the midstream and upstream and the construction of the downstream sea-linking channels, achieving “land–sea domestic and international linkage”, is also essential to stimulate the vitality of open economic development in the entire basin.

5.2.2. Regional Level

• Co-building and sharing a comprehensive three-dimensional transportation network and enhancing internal economic connections. As indicated in the previous text, under the guidance and support at the national level, provinces in the Yellow River Basin should collectively strengthen the construction of a comprehensive three-dimensional transportation network and promote cross-domain and cross-modal cooperation and connectivity. We rely on the multimodal transportation system, on the one hand, to leverage the network effect of the comprehensive transportation network, serving economic development, and on the other hand, to promote the expansion and integration of industries and markets, optimizing the regional division of labor system. Due to the synergy between “railway transportation–air transportation” being relatively high, efforts should be continued to deepen the co-building and sharing of air–railway transport networks, to achieve more efficient and extensive connections between airports and railway networks, especially high-speed railway networks. However, the synergy between “highway transportation–railway transportation”, “highway transportation–air transportation”, and “highway transportation–railway transportation–air transportation” is relatively low. There is a need to increase the infrastructure development of highway–railway transport, highway–air transport, and highway–railway–air multimodal transport.

To ensure the construction and development of intermodal transport, standards and regulations are indispensable. In several developed countries in Europe and the United States, industry organizations such as the International Union for Road-Rail Combined Transport (UIRR) and the Intermodal Association of North America (IANA) have been established. These organizations advocate relevant standards, provide recommended guidance, and contribute to the formulation and implementation of relevant policies, thereby promoting the unification and healthy development of regional intermodal transport [48,49].

Therefore, the Yellow River Basin should be organized and led by the government to establish a unified system of intermodal transport and service standards. In this process, practices from developed countries can serve as references to fully leverage the capabilities of professional industry organizations, preventing regional fragmentation and promoting trade exchanges between regions. This, in turn, will strengthen economic ties within the basin and reduce development disparities.

2.

Integrating regional transportation advantages to form a synergistic economic belt. The development conditions in various regions of the Yellow River Basin vary, with different development directions. For the upper reaches, it is necessary to address the shortcomings in transportation infrastructure construction, and improve accessibility and smoothness. Combine various transportation modes to construct an international transportation artery and improve overall efficiency by making optimal use of the Western Land–Sea New Corridor. Meanwhile, economic and trade exchanges with countries along the route should be strengthened [50], and an important pivot for the opening and extension of the Yellow River Basin to the west should be created to serve and integrate into the construction of the “Belt and Road” initiative. The middle reaches should utilize the bridging role of connecting east and west, strengthen connections with the upper and lower reaches, drive the development of areas along the river and promote the development of the Guan Zhong Plain Urban Agglomeration and the Central Plains Urban Agglomeration. The lower reaches should continuously improve and upgrade the comprehensive transportation network in the Yellow River Basin based on a good development foundation, as well as promote the development of a multimodal transport structure. It is also essential to strengthen and leverage the radiating role of Zhengzhou and the leading role of the Shandong Peninsula, establish a coordinated land and sea opening pattern, and enhance the level of open economy development. Overall, it is necessary to adapt measures to local conditions, make up for shortcomings, and integrate advantages to build an international comprehensive transportation network that is three-dimensional, high-capacity, and efficient. Horizontal transportation should be utilized to link various urban agglomerations and core cities [51], fostering economic growth poles in the Yellow River Basin, promoting the concentration of specialized industries, achieving interactive and coordinated development, and supporting the construction of the Yellow River Basin Economic Belt [52].

3.

Innovate regional cooperation models to enhance the competitiveness of the Yellow River Basin. The Yangtze River Delta region leads the way in economic and integrated transportation development across China. Since 2017, the transportation departments of the three provinces and one city have been continually enhancing pragmatic and efficient systems and mechanisms. They have signed 34 cooperation agreements focusing on hard connectivity of infrastructure as well as soft connectivity in areas such as credit and law enforcement. Currently, a comprehensive express transportation network is in place, which has initially established a collaborative shipping system along the coast and rivers, and has essentially built a regional airport cluster system [53,54].

The provinces in the Yellow River Basin could draw insights from the successful practices of the Yangtze River Delta region and actively explore models of regional cooperation. Under unified planning and guidance, various regional subsystems should actively seek effective paths for collaborative coordination, establish an information-sharing platform, and hold regular joint meetings during the construction and development of the comprehensive transportation network, with strengthening joint deliberations on major affairs, to avoid resource wastage due to unfair competition and enhance the internal driving force for the collaborative evolution of the comprehensive transportation network. Furthermore, it is necessary to leverage the connectivity function of the comprehensive transportation network to promote cooperation among regions in ecology, industry, technology, culture, and other aspects, stimulating the overall synergy for ecological protection and high-quality development in the Yellow River Basin.

Balancing interests and demands is a significant practical barrier to regional cooperation. Collaborative agreements enable local governments to offer services they are unable to provide on their own, or to enhance efficiency and improve services during the provision process, all while preserving local autonomy. This approach is also commonly adopted in interlocal cooperation within the United States [55]. The Yellow River Basin can draw on this approach. Firstly, it is essential to leverage the advantages of our political system by adhering to strategic thinking and firmly establishing a holistic perspective akin to “playing chess as a whole”, balancing the overall and local interests. The provinces must not only create their own competitive advantages but also enhance the competitiveness of the basin to maximize overall benefits. Secondly, the provinces in the Yellow River Basin can establish contractual relationships through intergovernmental cooperation agreements, ensuring collaborative synergy throughout the operation and management processes. Furthermore, it is also possible to jointly commission third-party professional organizations to oversee the unified construction, management, and operation of interprovincial and municipal transportation networks, excluding national trunk railways.

5.2.3. Industry Level

• Promote the integrated development of the transportation industry and ensure regional coordination. The transportation industry in the Yellow River Basin should implement an open and shared platform strategy, establish a unified comprehensive transportation platform, and fully utilize information technology to strengthen the platform’s perception and monitoring functions. Real-time monitoring and tracking of infrastructure, transportation tools, and transportation information within the entire basin should be carried out to support and ensure coordinated command and precise control.

At the same time, the Yellow River Basin can learn from the practices of the Yangtze River Delta urban agglomeration by promoting the basin-specific unified card and certification services, rather than limiting these initiatives to single provinces, which aims to break geographical barriers and enhance public sense of belonging. Encouraging enterprises to improve transportation service levels is also needed, which can reduce intermediate links, achieve seamless multimodal transportation connections, and support efficient regional coordination.

2.

Extend the service chain of the comprehensive transportation network and build a modern industrial system.

The Yellow River Basin is a vital agricultural and energy production base in China. Enhancing the integration of the transportation industry with these sectors will leverage the connectivity of the comprehensive transportation network to reduce both spatial and temporal distances, thereby lowering transaction costs. This integration can accelerate the circulation of production factors, ensure the smooth and efficient operation of various industrial and supply chains, and support the establishment of an innovative, diverse, and fully open modern industrial system. The diverse development of industries will also generate a more varied demand for transportation, necessitating the continuous enhancement of the comprehensive transportation network, collectively promoting high-quality development in the Yellow River Basin.

In terms of practical operations, some regions have attempted similar initiatives; for instance, the Guangdong–Hong Kong–Macao Greater Bay Area, as a frontier of development in China, has seen numerous regions implement policies that offer certain incentives to enterprises engaged in freight operations across the Hong Kong–Zhuhai–Macao Bridge and cross-border transportation or trade between Guangdong and Hong Kong, supporting the integration of the transportation system with logistics, processing trade, and other industries [56,57].

Therefore, the Yellow River Basin can draw on these practices by implementing targeted government subsidies or preferential measures. However, it should not be limited to individual provinces. Instead, it should provide facilitation and incentives for enterprises engaged in interprovincial operations and cross-sector integration, extending the service chain of the comprehensive transportation network, and encouraging transportation companies to expand their scale and develop across sectors and regions. Nevertheless, the implementation of this recommendation may face potential political obstacles, necessitating consensus among regional governments or unified planning and standards by relevant institutions to ensure cross-regional cooperation with a focus on the holistic basin.