Road network model in Thailand for highly efficient transportation

: This research presents a comprehensive model for enhancing the road network in Thailand to achieve high efficiency in transportation. The objective is to develop a systematic approach for categorizing roads that aligns with usage demands and responsible agencies. This alignment facilitates the creation of interconnected routes, which ensure clear responsibility demarcation and foster efficient budget allocation for road maintenance. The findings suggest that a well-structured road network, combined with advanced information and communication technology, can significantly enhance the economic competitiveness of Thailand. This model not only proposes a framework for effective road classification but also outlines strategic initiatives for leveraging technology to achieve transportation efficiency and safety.


Introduction
Transportation infrastructure is the backbone of economic growth and development in any nation.In Thailand, the push towards becoming a high-income country has necessitated a significant revamp of its road network systems, particularly in burgeoning economic zones like the Eastern Economic Corridor (EEC) (Sakorn et al., 2017).With increasing globalization and regional integration, the efficiency of transportation networks has emerged as a critical determinant of competitiveness.The Thai government recognizes this and has prioritized enhancing connectivity and mobility through improving its road infrastructure.This research paper sets out to dissect the intricacies of the country's road network, examining its current capabilities and identifying pivotal areas for transformative development.This analysis serves not only to identify the strengths and weaknesses of the existing system but also to establish the critical need for a revamped and forward-thinking road network model.Central to this endeavor is the need to address the persistent challenges faced by road transportation in Thailand.
management.This extensive literature review presents a multidimensional examination of road management (Thongpan, 2016) and classification systems (Chanapai, 2008), incorporating diverse methodologies and case studies to offer an enriched contextual understanding.The aim of this research is to develop an optimized road network model for Thailand that enhances transportation efficiency, particularly in the EEC.This involves establishing a clear classification system for roads based on their usage, traffic volume, and strategic importance, guiding the allocation of maintenance budgets and responsibilities among governing agencies.Additionally, this research aims to investigate the integration of intelligent transport systems (ITS) to improve road safety, manage traffic flow, and reduce congestion, thereby enabling Thailand's transportation infrastructure to support economic competitiveness and equitable regional development.By incorporating these elements, the research aims to address the critical need for a comprehensive, forward-thinking approach to road network management in Thailand, ultimately supporting the country's long-term economic and social objectives.This paper's aim aligns with Thailand's 20-Year Strategic Plan for Infrastructure Development, which underscores the importance of robust infrastructure to propel economic success.This research leverages qualitative insights from industry experts and utilizes the Analytic Hierarchy Process (AHP) to develop a road network model serving as a blueprint for strategic planning and investment, offering a pragmatic roadmap towards a more connected, efficient, and competitive Thailand.

Sample group
The sample group for this research includes: Corridor, including six directors of engineering, with two from Chonburi, three from Chachoengsao, and one from Rayong, also selected through purposive sampling.

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Four hundred road users and freight transporters across the three provinces of Chachoengsao, Chonburi, and Rayong, selected through quota sampling.

Tools and tool development
Tools used in this research are as follows: 1) Interviews about the condition of the road network for transportation in the Eastern Economic Corridor based on the opinions of personnel from the Department of Highways, Department of Rural Roads, and local government organizations, responsible for road management in Chachoengsao, Chonburi, and Rayong.2) Interviews about problems in construction, restoration, and maintenance of roads for transportation, based on the opinions of personnel from the Department of Highways, Department of Rural Roads, and local government organizations, responsible for road management in Chachoengsao, Chonburi, and Rayong.3) Questionnaires about issues faced by road users and freight transporters in Chachoengsao, Chonburi, and Rayong.4) Interviews about the criteria for clearly and appropriately classifying roads in Thailand to suit the agencies currently responsible, for the purpose of state budget management, based on the opinions of relevant personnel in Chachoengsao, Chonburi, and Rayong.5) Interviews about models and methods to improve the road network for efficient transportation, based on the opinions of relevant personnel in Chachoengsao, Chonburi, and Rayong.

Analytic Hierarchy Process theory
The Fuzzy Analytic Hierarchy Process (FAHP) is a decision-making tool capable of handling multiple criteria decision making (MCDM) (Kongchuenjai, 2020;Wu et al., 2009), which can encompass both quantitative and qualitative criteria.FAHP is based on the Analytic Hierarchy Process (AHP) developed by Thomas L. Saaty in 1980.FAHP integrates the concept of fuzzy set theory with pairwise comparison, replacing the crisp values used in AHP.This allows FAHP to handle decisions under conditions of vagueness and uncertainty, much like human reasoning, thereby enhancing decision-making efficiency (Chen et al., 2011).FAHP is commonly used to address a variety of problems and is typically found in two main forms: prioritizing criteria and selecting alternatives by comparing multiple criteria across multiple levels.
The Fuzzy Analytic Hierarchy Process is often used for multiple criteria decision making because of its ability to transform qualitative data into quantitative data under uncertain and ambiguous conditions.Hence, it is a technique widely utilized in various applications including studies, research, and business operations which often involve solving various problems and making the most appropriate decisions.

Concepts and fundamental theories
FAHP uses a hierarchical structure to represent the structure of alternatives and evaluation criteria hierarchically (Vaidya and Kumar, 2006).The top level of the structure is called the objective, sometimes also referred to as the goal.The next level down consists of evaluation criteria used to assess the most appropriate alternatives to achieve the best possible outcomes according to the objective.Each evaluation criterion may consist of sub-criteria, which are positioned at the next lower level.Each criterion at the same level should have equal importance, and criteria of lesser importance are placed at a lower level.At the lowest level are the attributes or characteristics of each criterion.An example of the hierarchical structure of FAHP is shown in Figure 1.

Analyzing the importance weights by comparison
Let X = {x1, x2, …, xn} be the set of objects or alternatives (Object Set), and G = {g1, g2, …, gn} be the set of goals or decision criteria (Goal Set).Each alternative is analyzed for each decision criterion sequentially.Therefore, the m extent analysis for each alternative can be defined   1 ,   2 ,    for i = 1, 2, ..., n, where    (j = 1, 2, …, m) uses triangular fuzzy numbers for the extent analysis of alternative i for each decision criterion.The calculation steps are as follows: Calculating the fuzzy synthetic extent values for object i in Equations ( 1)-( 4). ) (3) Calculating level of possibility of   ≥   when   = (  ,   ,   ),   = (  ,   ,   );  ≠  in Equation ( 5). (5)

Finding the consistency ratio (CR)
The consistency of the evaluations within both the decision criteria and the alternatives is checked by comparing them against pre-established acceptable values before proceeding with further analysis, as from Equations ( 6) and (7).The acceptable CR depends on the size of the matrix.For example, for a 3 × 3 matrix, an acceptable CR should not exceed 0.05, for a 4 × 4 matrix, an acceptable CR should not exceed 0.08, and for matrices sized ≥ 5 × 5, the CR should be less than or equal to 0.1 (Kabir and Hasin, 2011).If the CR is higher than the acceptable value, the values set for pairwise comparisons in the fuzzy comparison matrix must be reanalyzed and adjusted (Kwong and Bai, 2002).

CI
This research has gathered data from interviews to study the decision-making criteria for selecting the agencies responsible for road networks.Experts have evaluated the importance of each main criterion pairwise as shown in Table 2. Table 2. Pairwise comparison of main criteria importance.In each level of consideration, the importance assessed by experts is divided into 9 levels of intensity using a fuzzy analytical decision-making process, where A represents the main mission of the agency, B represents physical and utility aspects, C represents management and budget, D represents ITS efficiency improvement, and E represents promotion and efficiency improvement by Smart Highway Control Center.The pairwise importance values of the main criteria are compared based on the triangular fuzzy number principle as shown in Table 3.The results from Table 3 are used to calculate the consistency of ratings for each criterion in selecting the agency responsible for road networks.The first main criterion example is the main mission of the agency.217,0,395,0,714) Then, a matrix of average values is created, and a membership function is found with l, u as the lower and upper boundaries respectively, and m as the middle value, which represents the ambiguous triangular shape.The weights of the importance of the criteria are then calculated, shown in Table 4.
The defuzzification process is then carried out, changing ambiguous values into numerical values, as shown in Table 4. Once the Defuzzification process values for each main criterion are known, the reliability of setting the importance values in the pairwise comparison is checked by calculating the consistency ratio (CR) as follows: Calculate the consistency index (CI) and find the random consistency index (RI), then calculate the maximum lambda (λmax) as shown in the example.Then, the consistency ratio (CR) is calculated.

Results and discussion
From the interviews of 21 participants, the results of the fuzzy AHP decisionmaking process revealed the criteria that influence the selection of agencies to manage road networks and the technology used to enhance road transportation efficiency.High-level managers and related personnel or officials prioritize different criteria from highest to lowest importance using the fuzzy AHP method.The weighted importance from highest to lowest is as follows: (1) the main mission of the agency, (2) physical aspects and utility benefits, (3) promotion and efficiency improvement by Smart Highway Control Centers, (4) supervision and budget management, and (5) efficiency improvement by ITS systems.Interviewees place the highest importance on the agency's main mission, followed by physical aspects and utility benefits, which relate to the expertise of personnel in the agency combined with a budget that can support future road development.Considering survey data from road users who regularly travel within the EEC area, it was found that 97% believe that the Department of Highways should be responsible for main roads, 79% believe that the Department of Rural Roads should handle bypass routes, and 16.2% think that local or local government organizations should be responsible for village roads, minor roads, and focus on community services.
In order to establish criteria for classifying roads in Thailand, defining the study area is crucial so that the developed criteria can be applied to other regions as well.For this purpose, the researcher has chosen the Eastern Economic Corridor Development area, which encompasses all forms of transportation networks that are interconnected in various continuous modes (multi modal).Additionally, this area has clearly defined development plans for the future, which can be used to predict traffic volumes (traffic forecasting) (Wicheansan, 2007) up to the level of service in transportation.This will influence the development of future roadways and necessitate the categorization and designation of primary responsible entities to systematically develop continuous routes, as well as to determine budget allocations for maintenance to ensure the most effective use of the infrastructure.Table 5 summarizes opinions from the interviews.The current division of road responsibilities among three major units (national highways, rural roads, and local roads) is well-recognized by road users.However, the distinction between these road types is still not clear due to uniform construction standards (Yimsiri and Ratanaikom, 2020) and safety equipment used across different types of roads.
There is a need for clearer guidelines and standards that distinctly define the responsibilities for different types of roads.This would help in reducing confusion among road users and streamline maintenance and emergency responses.

2) Legislative restrictions:
2) Legislative flexibility: Most personnel are not in favor of existing legal restrictions that prevent the transfer of road responsibility to other agencies.They argue that such restrictions impede flexibility and adaptability in road management, especially when local agencies like Provincial Administrative Organizations (PAOs) lack sufficient budgets for road maintenance.
Amending laws to allow more dynamic assignment of road responsibilities could help respond more effectively to the changing needs of road infrastructure.This is particularly crucial in areas experiencing rapid growth, where the existing road managing body may not be equipped financially or technically to handle the increased traffic and maintenance demands.

3) Budget allocation and management: 3) Budgeting and funding:
There is a call for more flexibility in budget allocation to enable timely upgrades and maintenance, which is currently hindered by stringent legal frameworks.
More flexible budgeting that allows for reallocation of funds based on current road conditions and traffic demands could enhance the overall efficiency of road maintenance.Moreover, exploring alternative funding sources, such as publicprivate partnerships, could provide additional financial support without overburdening any single agency.

4) Adapting to changes: 4) Technology integration:
There is strong support for legislative amendments that would allow road management responsibilities to be adjusted based on changing economic and urban conditions, especially in rapidly developing areas like the Eastern Economic Corridor.
Integrating modern technologies like ITS can significantly improve road safety and traffic management.However, ensuring that such technologies are cost-effective and backed by a solid maintenance framework is essential.The government could facilitate this by standardizing costs and specifications to reduce the financial risk associated with technological investments.

5) Use of technology (ITS and Smart
Highways):

5) Training and workforce development:
The personnel are in favor of adopting Intelligent Transportation Systems (ITS) and Smart Highways to enhance road efficiency and safety.However, they expressed concerns about the high costs associated with the implementation of such technologies, especially when relying on imported materials and equipment.
As technological solutions like Smart Highways are adopted, there is a pressing need for specialized training for existing personnel and hiring of tech-savvy staff.This could involve partnerships with educational institutions to ensure a steady pipeline of qualified professionals capable of managing advanced transportation systems.Participants generally agreed that the current division of road responsibilities among different administrative levels is suitable for the present conditions.However, discrepancies arise due to variations in geographical mapping and actual terrain, leading to the use of nonuniform standards that complicate maintenance and development tasks.
Developing uniform standards for road construction and maintenance that accommodate the specific geographical and economic conditions of different LAOs could help alleviate some of the current challenges.This would also ensure consistency in road quality across different jurisdictions.

2) Legislative constraints: 2) Legislative reforms:
There is a significant consensus against the legislative restrictions that prevent the transfer of road responsibilities.Most personnel advocate for law amendments to provide more flexibility in budget allocation and operational control, which they believe would lead to more balanced and efficient management.
Modifying existing laws to allow for more dynamic management of road responsibilities could lead to better resource allocation and more responsive infrastructure management.This is particularly crucial for adapting to the economic developments within the corridor.

3) Role adjustment: 3) Enhanced coordination:
There is strong support for the idea that LAOs should have the ability to elevate or shift the oversight of certain roads based on specific needs and economic changes, particularly in rapidly developing areas like the Eastern Economic Corridor.

Improved coordination between
LAOs and major road agencies could foster better planning and execution of road works.Establishing clear guidelines for when and how responsibilities can be transferred or shared may help reduce redundancies and inefficiencies.

4) Physical and utilitarian aspects: 4) Technology integration:
The classification of roads into major, collector, and local roads is well understood and agreed upon.It is recognized that this classification aligns well with physical realities and administrative duties, ensuring that road maintenance and improvements are adequately managed.
While there is support for adopting advanced technologies like Intelligent Transportation Systems (ITS) and Smart Highways, concerns about cost effectiveness and implementation challenges remain.It is suggested that investments in technology should be carefully evaluated against potential benefits, particularly in terms of cost savings and improvements in safety.

5) Budget allocation: 5) Funding strategies:
The allocation of funds is deemed sufficient for primary agencies like the Department of Highways and the Department of Rural Roads.However, local entities face significant challenges due to inadequate budgets, which hampers their ability to maintain and upgrade roads effectively.
Exploring alternative funding strategies, such as public-private partnerships or dedicated road funds, could provide LAOs with additional resources necessary for maintaining and upgrading their road networks.
From this interview data, using weighted consideration criteria through the fuzzy AHP process, a table categorizing road types (Chanapai, 2008;Öberg et al., 2018) by agency responsibility can be summarized as Table 6.Serve as connectors between regions, provinces, and districts, emphasizing mobility.
• physical components include a traffic surface width of more than 7.00 m, • road shoulders ranging from 1.50-2.50m, • accommodating traffic volumes of 1000-8000 vehicles/day, • speed limits of 90-110 km/h.

Department of Highways 2 Collector roads
Act as feeders, channeling traffic from main roads into communities and connecting main and secondary roads.

Department of Rural Roads 3 Local roads
Distribute traffic from secondary roads to access areas comprehensively, emphasizing accessibility.
• physical components include a traffic surface width of less than 6.00 m, • road shoulders ranging from 0-1.00 m, • no specific traffic volume set, • a maximum speed limit of 60 km/h.

Local Government Organizations 4 Strategy roads
Serve as strategic support roads for area development, connecting travel to tourist destinations, industrial zones, transportation stations, ports, airports, factories, and warehouses, as well as for border trade and royal initiative projects.

Department of Highways/Departm ent of Rural Roads
From the decision-making process using the fuzzy AHP method, it is evident that the criteria influencing the decision to select agencies for overseeing road networks and enhancing road transportation efficiency are weighed differently by the interviewees.The top two priorities are: (1) the main mission of the agency, weighted at 0.39, which includes the primary construction and maintenance responsibilities held by the Department of Highways and the Department of Rural Roads, and (2) physical aspects and utility benefits, weighted at 0.19, The interviewees emphasize that the Department of Highways should be responsible for main routes, the Department of Rural Roads for secondary routes and bypasses, and local or local government organizations for local roads within communities.The highest priority is given to the main mission of the agencies, followed by physical aspects and utility benefits, due to the expertise of the personnel involved and the budget available to support future road development.This aligns with survey data from road users in the EEC area, showing that 49.75% believe the Department of Highways should manage main roads, 64.00% support the Department of Rural Roads for secondary and bypass routes, and 83.00% think local government organizations should handle local and community roads.These priorities reflect that major agency like the Department of Highways and the Department of Rural Roads, with their specialized personnel and adequate budgeting, are better equipped to maintain significant physical roads, such as those leading to industrial areas, tourist spots, and airports.If local government organizations receive increased funding, they could also efficiently maintain their roads to a standard comparable to that of the major agencies.The main issues with roads under local governance, transferred from major agencies as per the Decentralization Act of 1999, include:

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The non-continuous transfer of roads, hindering consistent maintenance.

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The lengthy transfer process, during which the conditions of roads have changed; for example, what were once secondary networks have become main roads requiring more significant maintenance, beyond the fiscal capabilities of local organizations.

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The legal framework which prevents the re-transfer of roads back to major agencies.

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The lack of specialized personnel transferred to local bodies under the decentralization plan, leading to a shortage of expertise in road management.
To address and mitigate these issues, and to enhance the efficiency of road transportation in Thailand sustainably, three main components should be considered: Legal amend decentralization laws to allow for more flexible re-transfer of roads to major agencies, especially when roads have gained importance and traffic density.
Personnel enhance the capabilities of local agency staff in road management.Budget Increase funding or allow local agencies to request additional budgets from external or central government agencies on a case-by-case basis, or consider transferring certain local roads to the Department of Rural Roads, which has adequate funding for maintenance.
As the considerations highlighted in the decision-making process, a proposed model for a highly efficient road network that addresses the specific needs and strategic goals of Thailand, particularly within regions like the Eastern Economic Corridor (EEC) are summarized as follows: Road network model for highly efficient transportation: Key issues of applying a road network model for Thailand should consider that its road network not only meets current transportation needs but is also resilient and adaptable to future demands and innovations.This approach will help in promoting sustainable development, enhancing economic growth, and improving overall road safety and mobility in the region.A proposed model for a highly efficient road network (Figure 2) is described as follows: • Sustainable infrastructure incorporates green technology in road construction and maintenance to reduce environmental impact, such as using eco-friendly materials and solar-powered road signs.5) Regulatory and policy enhancements • Flexible road transfer policies reform policies to allow dynamic reassignment of road management responsibilities as traffic patterns and regional development needs evolve.

Discussion
The proposed model for a highly efficient road network introduces several advancements and improvements over traditional or existing road network systems (Hu and Wu, 2012) by enhancing the current practices as follows: 1) Centralized oversight and coordination • Old approach road management might be fragmented among different agencies (Injan et al., 2009)  New model flexible road transfer policies and dynamic legislative frameworks that allow for the adjustment of responsibilities as road significance and regional needs evolve.6) Community and stakeholder engagement • Old approach often minimal direct engagement with local communities and stakeholders in the planning process, leading to solutions that might not align with local needs.• New model regular, structured engagement with communities and stakeholders ensures that the road network serves actual local and regional needs (Qian et al., 2012) and builds public trust through transparency.7) Performance monitoring and adaptive management • Old approach periodic or infrequent evaluation of road network performance, with limited responsiveness to identified issues.• New model continuous performance monitoring with established benchmarks and an adaptive management framework that swiftly incorporates feedback and technological advancements into road network planning and maintenance.These improvements are able to create a more resilient, responsive, and sustainable road network system that aligns with modern traffic demands, economic needs, and technological possibilities, setting a foundation for future developments in infrastructure within Thailand and potentially other regions.

Conclusion
Considering these criteria for responsibility and budget allocation, the agencies can be more clearly identified, allowing them to expedite the development of road networks to support economic growth, improve roadwork, and enhance safety without conflicting with existing decentralization laws.This would ensure a complete road network in the area, with interconnected routes managed without restriction by the responsible agency.In terms of Intelligent Transportation Systems (ITS), it can be concluded that ITS is beneficial according to modern management and budgeting principles, using information and communication technology to help manage traffic and transportation, enhancing road transport efficiency, safety, and reducing traffic congestion.The basic objectives and principles of ITS include: 1) driver assistance, 2) driver acceptance, and 3) social acceptance.
As Thailand has not yet developed ITS to match international standards, strategies should be devised to promote the development and implementation of ITS to support road transportation more extensively, based on the necessity to: • Enhance the transport and logistics capacity.

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Promote continuous and diverse multi-modal transportation.• Support transportation and traffic management.• Be prepared for emergencies and incidents.• Boost tourism to stimulate the economy.These strategies should encompass management under a single command center, which could reduce personnel workload and automatically gather data, helping to share useful information about traffic volumes, types of vehicles, speeds, accident patterns, load control, and other security and safety operations, utilizing Big Data effectively within the transportation system.
Author contributions: Conceptualization, CJ, VS and TH; methodology, VS and CJ; software, CJ; data interview, CJ; investigation, CJ; formal analysis, CJ; writingoriginal draft preparation, CJ and TH; writing-review and editing, TH; visualization, TH; supervision, TH; project administration, TH.All authors have read and agreed to the published version of the manuscript.

Figure 2 .
Figure 2. Proposed road network model for highly efficient transportation.
• One high-ranking official from the Ministry of Transport, two from the Department of Rural Roads, and two from the Ministry of Interior.• Eight technical personnel affiliated with the Department of Rural Roads and the Department of Highways in the Eastern Economic Corridor, distributed across various offices: one from Rural Roads Office No. 3, one from Rural Roads Office No. 13, and one each from the rural road districts of Chonburi, Chachoengsao, and Rayong, chosen through purposive sampling.• Six officials from local government organizations in the Eastern Economic

Table 3 .
Pairwise comparison of main criteria importance based on triangular fuzzy number.

Table 4 .
Average values of each main criterion in the form of triangular fuzzy number, the importance scores of each main criterion, and the defuzzification process values.

Table 5 .
Summary of opinions from the interviews.

Table 6 .
Categorizing road types and consideration criteria by agency responsibility.
use of advanced technologies in traffic management and road safety, with sporadic updates and upgrades.• New model comprehensive deployment of Intelligent Transportation Systems (ITS) (Al Mahairzi and Reddy, 2017; Ozaki, 2018) across all road types to optimize traffic flow, enhance safety, and support sustainable practices like green technologies.5) Regulatory and policy enhancements • Old approach static policies that may not adapt well to changing urban and economic landscapes, with rigid road management responsibilities.•