A Systematic Review of the Impact Overload on Road Pavement Batu City, Indonesia

Roads are land transportation infrastructure covering all parts of the road, including supporting buildings and equipment intended for traffic on the ground surface, above ground level, underground and/or water level, and above water level, except for railroads. and cable roads. Based on the Law of the Republic of Indonesia Number 38 of 2004, roads are classified based on their designation, encompassing public roads with functions categorized as arterial roads, collector roads, local roads, and environmental roads. Additionally, special roads are designated for specific purposes such as the distribution of goods and services, and are not intended for general traffic. According to Mohamed et al. [1] for the core transportation infrastructure, the road network has an intrinsic role in developing social and economic growth for each region and country. In addition, the existence of roads is also very important to support the growth of agriculture, culture, and other sectors [2]. Methodological gaps in addressing problems related to overloading, caused by heavy loads or an increase in the number of vehicles in several large cities in Indonesia, are often rooted in the lack of awareness among the public as road users. For instance, there is a significant gap in the predominant preference of the community for private vehicles over public transportation. These factors undoubtedly contribute to the heightened risk of premature damage to road pavements. Despite the government's efforts to enact regulations to tackle these issues, the cultural inclination in Indonesia remains resistant to swiftly comprehending and adhering to new regulations. Consequently, their implementation tends to be a time-consuming process.

Roads are currently often damaged in a relatively very short time (early damage), both roads that have just been built and roads that have just been repaired (overlay). According to Zainal et al. [3] basically, the road will experience a decrease in its structural quality by the increasing age of the road, especially if it is passed by vehicles with heavy loads and tends to exceed the provisions. According to Romadhoni et al. [4] the development and movement of people from one place to another in Indonesia is currently very high, making an efficient and well-maintained road network a very urgent need. Along with the increased movement of people and goods, increasing the concentration of people, especially in strategic areas, many vehicles also use these main roads over the planning limit [5]. In addition, there are physical and environmental developments of the metropolitan area [6], the distribution of the population that forms an urban sprawl result in unplanned and uncontrolled growth on the outskirts of the city, often characterized by low-density housing, single-use zoning, and increased reliance on private cars for transportation [7]. The population of Indonesia is increasing every year, reaching a notable growth rate of 1.13% in 2023 [8] is accompanied by a rising number of vehicles, reaching 153.40 million units [9]. Consequently, there is a substantial demand for road transportation. According to a study by Arifin [10], road construction is intended to provide services based on planned longevity. However, in reality, many sections experience a reduction in service life due to damage to road pavements. The most dominant factor causing rapid road damage is the excessive load received by road construction, exceeding the planned load.

Tourist mobility is a central concern in planning, urban spatial planning, and tourism activities, as well as in maintaining the quality of life for various groups involved. Tourist cities with high visitor potential must organize urban areas by adjusting road user patterns to prevent the blockage of movement circulation [11]. Tourists in Indonesia seek a more flexible mode of travel to accommodate their diverse travel needs, primarily opting for private vehicles [12]. The visiting pattern of tourists in Batu City shows a preference for private vehicles such as cars, motorcycles, or native city buses, as opposed to public transportation options like city buses or local public transport, resulting in an increased traffic load. The number of road users to and from the Batu City area continues to rise annually, leading to frequent vehicle congestion and traffic jams due to the growth of vehicles that is not proportionate to the existing lanes [13]. When examined from a mechanical perspective, the high volume of vehicles entering Batu City leads to the stress experienced by the road structure surpassing the planned capacity. This excess stress can be likened to the stress induced by overloading a vehicle axle, as it produces similar effects, notably resulting in permanent deformation of the road pavement structure. Consequently, the material is prone to cracking at an accelerated rate. The combination of wheel load and high tire pressure that is ignored can damage the surface layer and the overall pavement structure [14]. Regional policy formation greatly influences travel patterns in a city [15]. The local government of Kota Batu has developed and implemented regulations and official frameworks, such as Local Regulation No. 3 of 2011 regarding Permits for Public Transport Routes. This regulation supersedes Regional Regulation No. 10 of 2010, which pertains to Parking Fees on Public Road Sides. Additionally, odd-even rules have been applied to regulate vehicle traffic in Batu City. However, it is perceived that these regulations are still suboptimal in addressing traffic congestion and the growing number of excess vehicles in Batu City. Drawing insights from other tourist cities in Indonesia, such as Bogor, Bali, or Yogyakarta, an emphasis is placed on urban planning and traffic flow management to mitigate road-related issues. Potential strategies include increasing road capacity, redirecting traffic, improving and promoting public transport, and leveraging real-time traffic flow technology.

In connection with the advancement of vehicle overload theory, this research aims to provide an update through an analysis of the impact of overload resulting from the increasing number of vehicles in the research area, thereby generating comprehensive data. This data will serve as valuable input for road pavement life plan engineering to enhance its effectiveness in accommodating vehicular movements. Additionally, the research will formulate policies within a sustainable operational framework at the Batu City government level. These policies will be utilized for the planning and development of tourist areas, incorporating optimal city planning and traffic management practices.

Research on the impact of overloaded vehicles on road damage has been carried out and published in several journals over the last few years. The overload in question is a vehicle with a load that exceeds the Heaviest Axle Load (MST) limit which affects the value of the Equivalent Standard Axle Load (ESAL) and causes road damage to occur more quickly (cutting the actual road plan life) [3, 4, 16-18]. In operational terms, the damage factor represents the number of passes equivalent to one standard axle producing the same wear effect as one truck pass [19]. Adopting from these studies, a journal article on this topic will raise the issue of the effect of excess traffic/number of vehicles going in and out of Batu City on flexible pavement structures which have an impact on reducing the plan life of the road using case studies of tourism cities in Indonesia. The following questions aim to discuss and synthesize open issues relating to future research directions:

1.  What are the main causes of the occurrence of the road load phenomenon related to the age of the road/pavement and the planning of the road network in Batu Tourism City?

2.  What is the impact on the road/sidewalk planning scheme for Kota Wisata Batu due to the increasing number of vehicles using the road in the tourist city?

Specifically, this research will focus on qualitatively identifying the results of data analysis. The methods or approaches employed for data analysis encompass vehicle volume analysis, axle load analysis, the AASHTO method for calculating remaining pavement due to overload [16, 20], the linear regression method for comparing the equivalent value of passenger cars, and the IRI (International Roughness Index) method for assessing road surface conditions. The examination of causal factors will facilitate the determination of the relationship between vehicle growth and its impacts, aiming to propose an operational framework as the primary target for improving policies [21] and road planning in the current and future context of the study area.

3.2 Literature review results

Based on the literature review summary for this study, 30 out of 62 studies, or 48% of the most relevant journals, indicate that vehicle loads exceeding specified limits can notably impact the condition of the structure or the lifespan of highway pavement and potentially lead to an increase in traffic accidents. As explained by Santana et al. [63] overloading the vehicle axle accelerates pavement damage and has an impact on the structure's lifespan, establishing a close relationship between the prediction of pavement life and the increase in the percentage of vehicle load on the road. A total of 14 studies explained that vehicle overload can be identified from normal vehicles and heavy vehicles with loads that exceed the heaviest axle load (MST) limit of each Axle Standard Equivalent Load (ESAL). The extensive variations found in the literature reviewed above contribute to a comprehensive perspective. The benefit obtained from this examination is that the advantages and disadvantages of prior research can be identified, aiding in achieving objectives and enhancing the current research. Generally, the AASHTO method is commonly employed in designing roads, and it provides empirical evidence of traffic loads over the design life. Although this method is widely used and considered the best for problem-solving in road pavement, there has been no update to the method to reflect current times. Nevertheless, other research introduces various methods, particularly the Weigh In-Motion (WIM) analysis, which is recommended and considered more efficient, especially in urban areas with high vehicle intensity. This analysis facilitates the accurate collection of vehicle load data through a sophisticated system. However, the implementation of this method remains uncommon due to its high costs and the need for experienced and professional regulators.

Most of the articles that have been reviewed (as many as 80%) indicate problems related to traffic and roads, including overloading which often occurs in big cities with rapid development and population growth followed by high vehicle movements. The countries with the greatest number of discussions related to problems that occur on the road pavement include China, India, Arabia, and Indonesia. Based on the review of the article above, addressing road problems, especially overloading, can be approached through various means. This includes evaluating the geometric design of the road and reviewing the techniques and materials used in planning road pavements. Furthermore, existing issues serve as a basis for enhancing discipline by establishing models, regulations, or policies that coordinate all activities within a city. This involves considering multiple aspects such as the city's function, roads as infrastructure, accessibility, and vehicles as means of transportation. The implications of such policies generally involve interventions such as simulating travel models or altering the function of vehicles in the city, with an emphasis on promoting the use of public transportation as a primary driving force. Local governments, as stakeholders, play a crucial role in conducting focus group discussions and formulating policies. Notable examples include New York City implementing a smart city approach to realize its built environment policy, the United Arab Emirates formulating and implementing an effective weight limit law for road safety, and China planning the layout of a tourism toll road network.

3.3 Key findings and discussion

This research in the context of the discussion will discuss the current limitations with ongoing research flows in the future for investigations between policy enforcement and the impact of vehicle overload on road pavement. Table 1 provides a summary of several forms of problem-solving efforts related to the impact of overloaded vehicles in urban areas. However, there are still many deficiencies in analyzing the problem in question, including a lack of supervision of vehicles crossing urban roads, a lack of firmness towards road users, drainage or supporting road bodies that are not functioning properly, and pavement construction that is not strong and easily damaged to support the vehicle load [3, 4, 16, 17, 40, 43]. However, so far there has been no research related to vehicle overloading that examines the number of vehicle movements. This research will encourage further efforts to overcome existing problems by establishing policies that are sought directly from the city government of the research location.

Contextual factors that influence overloading include: First, the results are affected by the context of vehicle overload which can reduce the life of the pavement plan so that the road will be damaged more quickly [40]. There are other factors that might influence this, so the literature suggests considering the types of vehicles that pass with a tendency to exceed the maximum provisions [3, 16, 63] checking the large vehicle [3, 4, 61, 69] measuring the reproducibility of the vehicle flow model between zones or adopting a choice of sequential destinations [57, 70] maintenance costs and overloaded vehicles [31, 46, 55] vehicle speed and design of pavement structures or mixes [45, 51, 64, 71], geometric design of roads [14] replacement of vehicle equipment [72] maintenance of waterways (drainage) [2, 4] or modification of road pavement forming materials [48, 64, 71].

Second, discussion of the city context from a socio-economic perspective is as a center for tourism activities which is very dependent on road, transportation, and communication infrastructure [67]. In addition, the high level of urbanization causes the intensity of urban growth concentration to also increase [73]. Future issues related to urbanization suggest the need for a direction to improve spatial planning based on city conditions [65] and provide easy accessibility, topography, availability of vacant land, transportation routes and land prices [7] while issues related to the activities of tourist cities, namely changing the pattern of visiting tourists by public transportation [12] collecting lots of data from different cities and find scope for several factors in capturing the overall characteristics of tourism activities [74] develop a tourism mobility plan [29, 58, 66], overcome overtourism and support tourism development [42] or developing the integration of expressway networks and tourism resources [49, 75].

Third, the context that leads to organizational and policy implications can be seen from the relationship between personality and road and traffic safety behavior [76]. Several literatures provide input to overcome the problem of road maintenance and enforcement of overload control [21, 60] by means of cost optimization and setting fines [21] provision of separate special vehicle operating environments with an effective framework [55] installation of weighbridges [30] or weigh in motion (WIM automatic) [38] pavement rehabilitation [77] traffic control [33] zero overloading policy [52] or a proposed discrete choice model to determine community location choices and departure times [47].

In order to overcome the phenomenon of overload due to the very high number of vehicle movements at the study site and investigate the questions raised for future research, it is necessary to carry out an important combination of theoretical studies and empirical studies. This is done because there has not been found similar research or research that is relevant to similar case studies based on the literature that has been collected. From this point of view, the existing literature shows that there are many factors that cause premature pavement damage due to the phenomenon of vehicle overload (most of them are trucks, tow trucks, and semi-trailers [3, 4] problem analysis was also carried out using various types of methods adapted to the conditions of the study area and the supporting equipment available in the city or country concerned (interview/questionnaire [28, 49] simulated traffic movements [44] visual observations with weighbridges or WIM motion sensors [30, 38] or track data from GPS [57, 70, 77]. Apart from that, decision/policy making really needs to be done, one of which is for the sustainability of road transportation [53] and smart transportation innovation [54]. This innovation is possible because many big cities in the world have invested in and recognized the concept of smart tourism cities and strategies relate to optimizing a sustainable environment [50]. Methods from the literature have their respective weaknesses including in terms of time, cost, and other aspects. This weakness underlies researchers to carry out developments in the hope that implementation can function not only at the study site but globally.