MRTJ 1000 series

The MRT Jakarta 1000 series, known legally as the Series K1 1 18, are the first generation rolling stocks to operate in the MRT Jakarta system. The train set is also known as the Ratangga. The train set was manufactured by Japanese company Nippon Sharyo under Contract CP108, all sets were built in 2018 and started operation on 24 March 2019. It is classified as an executive class train operated with a formation of six trains in each set.

History
The manufacture of the Ratangga trains is included in the Phase I North–South Line project as CP 108. The CP 108 contract for the procurement of the Jakarta MRT rolling stock was awarded to the Sumitomo Corporation - Nippon Sharyo consortium on 3 March 2015. The 16 trains, consisting of six trains each, were ordered at a cost of approximately ¥10.8 billion (Rp145 billion). The trains themselves were made at the Nippon Sharyo's Toyokawa, Aichi plant.

In the middle of the production period, the train design was changed in 2017. This design change was prioritised on the machinist's cabin which was considered to 'look like a cricket.' The design change changed the contract agreement and was estimated to increase production costs by as much as Rp64 billion.

Ratangga deliveries were made in 2018. The first shipment of two trains arrived at Tanjung Priok Port on 4 April 2018. The name Ratangga as the designation of the train was announced on 10 December 2018.

The first train test was conducted on 9 August 2018. This test was conducted to test the signalling and train systems. Meanwhile, the first trial of the series with passengers was carried out on 12 March 2019 which was also a limited public trial. The Ratangga series was first fully operated in conjunction with the inauguration of the Jakarta MRT North-South Line on 24 March 2019.

Naming
This series of electric railway trains is called Ratangga. The name Ratangga after deliberations between PT MRT Jakarta and the Ministry of Education and Culture's Language Agency. The name Ratangga is taken from the Arjuna Wiwaha and Sutasoma books by Mpu Tantular. Ratangga itself means wheeled vehicle, chariot, or war chariot in Old Javanese. The choice of the chariot naming, synonymous with a strong and dynamic horse-drawn carriage, is expected to symbolize a prayer for the smooth operation of the Jakarta MRT. The naming was announced on December 10, 2018, by the then Governor of Jakarta, Anies Baswedan, who gave the first batch of MRT Jakarta trainsets their current name.

Specifications
Each car measures approximately 20 m in length, 2.9 m in width and 3.9 m in height, similar dimensions to many Japanese commuter trains. Each train has four doors on each of its two sides, except for the first train and the sixth train which have an additional driver's cabin door on each side. These trains use the CBTC signaling system and are equipped with automatic train operation (ATO) under GoA 2. The automatic train control is centralised at Lebak Bulus Depot. However, there is still a driver on the train to control the doors and operate the train during emergencies. Like the KRL Commuterline, the MRT trains are also powered via overhead catenary.

Formation
Each Ratangga consists of six trains. Each train has two driver cabins located at the front and rear of the train. The two trains do not have motors, also known as trailer cars (Tc). Meanwhile, the second to fifth trains have motors, also known as motor cars (M). All Ratangga trains are classified as executive trains and have serial numbers K 1 18 01 to K 1 18 96. The complete formation of a Ratangga train consists of Tc1-M2'-M1'-M2-M1-Tc2. The sets offers a women-only carriage during morning peak hours from 7AM to 9AM and in the afternoon from 5PM to 7PM.

In popular culture
The Ratangga and part of the North-South MRT Line tunnel are featured on the front of the Rp75,000 design. The electric railway train is placed just below the images of Sukarno and Mohammad Hatta and next to the Youtefa Bridge and the Rp75,000 currency value text. The Ratangga train is included in the design to symbolise the achievement of infrastructure development in the 75 years of the Republic of Indonesia.