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Conventional bitumen pavement is no longer suitable for handling increasing loads and weather variations, which cause road deterioration, Thus, the modification of bitumen has been suggested to counter this issue. This study provides a detailed assessment of various additives for modifying natural rubber-modified bitumen used in road construction. This work will focus on the use of additives with cup lump natural rubber (CLNR), which has recently started to gain attention among researchers, especially in rubber-producing countries such as Malaysia, Thailand and Indonesia. Furthermore, this paper aims to briefly review how the addition of additives or modifiers helps elevate the performance of bitumen by highlighting the significant properties of modified bitumen after the addition of modifiers. Moreover, the amount and method of application of each additive are discussed further to obtain the optimum value for future implementation. On the basis of past studies, this paper will review the utilisation of several types of additives, including polyphosphoric acid, Evotherm, mangosteen powder, trimethyl-quinoline and sulphur, and the application of xylene and toluene to ensure the homogeneity of the rubberised bitumen. Numerous studies were conducted to verify the performance of various types and compositions of additives, particularly in terms of physical and rheological properties. In general, additives enhance the properties of conventional bitumen. Future research should investigate CLNR because studies on its utilisation are limited. [ABSTRACT FROM AUTHOR]

Bus services have played a significant role in public transportation, especially in urban areas throughout the years. Since bus services compete greatly with other types of public transportation, such as e-hailing services and private vehicles, they have recently attracted scholars to conduct many relevant studies. However, research in assessing public transport networks in urban areas by researchers by using systematic literature review is lacking. There are definitive gaps between quality standards set by the transportation regulatory authority and what bus operators can provide based on their obligations. Therefore, the present study had concentrated on the service quality of bus services in Asia by using the systematic literature review of articles. This study was based on previous studies, specifically on service quality of performance. Several previous studies were selected by using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRIMSA) approach. SCOPUS and Science Direct were chosen as the main journal database. Through this approach, 41 articles were selected for further analysis. This study was focused on three primary themes: study approach, stakeholders, and service quality attributes. An advanced analysis on these primary themes was used to formulate another 18 sub-themes. All themes and sub-themes which reflected the significant impacts of service quality towards bus services were discussed in detail. This study addressed several qualities of bus services and bus performance in regard to the improvement of urban transportation polices. Several recommendations that can provide necessary knowledge and information for future research were also presented. [ABSTRACT FROM AUTHOR]