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Air quality in the Special Capital Region of Jakarta has shown a concerning decline in recent years, largely due to high emissions from motor vehicles as the main source of pollution in urban areas. The Provincial Government of DKI Jakarta issued Governor Regulation Number 66 of 2020 concerning Exhaust Emission Testing for Motor Vehicles as a public policy instrument aimed at controlling air pollution. This study aims to analyze the implementation of the regulation from a public policy perspective and to identify supporting and inhibiting factors in its execution. The research employs a normative juridical method with statutory and conceptual approaches, supported by qualitative analysis of policy documents and reports on the implementation of emission testing. The results reveal that the implementation of the regulation has not been optimal due to limited emission testing infrastructure, low levels of public awareness and socialization, and inconsistent enforcement of administrative sanctions. Nevertheless, there are opportunities to improve policy effectiveness through strengthened inter-agency coordination, digitalization of monitoring systems, and increased environmental literacy among the public. Therefore, the success of emission control policy implementation is highly dependent on resource support, regulatory consistency, and community awareness, necessitating a comprehensive and continuous multi-stakeholder improvement strategy and stronger commitment.

The brake system on a vehicle is an important component for driving safety, brake malfunction can cause danger and driving safety is disturbed to the point of failure which can cause serious accidents. The object of the study was chosen original brake discs and variation discs used for Yamaha Matic Mio motorbikes. in the general public it is better known as brake discs, Hardness testing was carried out using the Rockwell method with 10 pressure points on the braking friction area with an average value of the original disc with a value of 57 HRC, and the value of the variation disc with a value of 53 HRC with a slight difference of 4 HRC, Brinell hardness value and the original disc tensile test averaged 586 HBS and the average variation disc value was 501 HBS. while the conversion tensile test value from the Rockwell hardness test value on the original disc was 1645 N / mm² and the variation disc brake was 1597.2 N / mm² thus the Rockwell test value, Brinell conversion and the original disc tensile test were still greater than the variation disc tensile test value.

This study aims to analyze the differences in motorcycle traffic flow (Q) during the morning and afternoon peak hours as an indicator of roadway operational performance, referring to the Indonesian Road Capacity Guidelines (PKJI) 2014, with a case study on Mawar Street–Wijaya Kusuma Street, Jember Regency. The research data were obtained from 12 observation points through traffic surveys that recorded motorcycle traffic flow in vehicles per hour (veh/h). The analytical methods used include descriptive statistical analysis, normality testing, and paired sample t-test. The results show that the average motorcycle traffic flow during the morning peak hour is 115.58 veh/h with a standard deviation of 62.97, while during the afternoon peak hour it is 63.25 veh/h with a standard deviation of 28.57. The paired sample t-test yields a significance value of 0.015 (p < 0.05), indicating a statistically significant difference between morning and afternoon traffic flows. These findings suggest that the level of roadway capacity utilization is higher during the morning peak hour, which is closely associated with dominant routine travel activities such as commuting to work and school. The results of this study are expected to serve as a basis for evaluating roadway operational performance and to support traffic management and traffic engineering planning aimed at improving road network performance and reducing congestion.

Motorcycles are one of the main modes of transportation widely used by the Indonesian people due to their practicality, efficiency, and ability to support daily mobility. However, many motorcycle users complain about the suboptimal engine power, especially when the vehicle is used on extreme terrains outside urban areas, such as uphill roads, rocky paths, or long distances. This situation has driven the development of various innovations in the automotive field to improve engine performance. One widely applied method is the oversize technique on the piston and piston block, which aims to increase the combustion chamber capacity, thereby maximizing the power output. This study aims to analyze the significant comparison of engine performance after the application of the oversize method on the KVY engine type, as well as to examine the factors influencing the optimization of engine performance based on the philosophy and needs of the vehicle owner. The testing method used a dynamometer to measure the increase in torque and engine power. The test results showed that the daily oversize application resulted in a torque increase of 1.19 Nm and a power increase of 0.85 Hp compared to the standard condition. Meanwhile, the oversize for competition needs showed more significant improvements, with a torque increase of 7.97 Nm and a power increase of 8.12 Hp. These findings demonstrate that the oversize method can significantly enhance engine performance according to its intended use.