operation of the Class GI sets. However, this conflicts with the documentation on the DK4 sets, which uses 750 volts with a +20% and a -38% tolerance. A 1999 KBS news broadcast stated that two lines were under construction, with line 3 to run from Kwangbok station to Mangyongdae, while the location of line 4 was unknown. The two lines were to open for the 55th Party Foundation Day. In 2012, Korean Central Television released renders of a new station bearing the name Mangyongdae displayed at the Pyongyang Architectural Festival. In 2018, NK News claimed that there would be possible extensions to the metro system, with anonymous sources claiming activity to the west of Kwangbok Station. Commercial satellite imagery revealed only one structure under construction, and it speculated an absence of announcements from state media was due to funding issues, as well as due to the 1970s tunneling accidents. In 2019, Kaeson station and Tongil Station were modernised, adding TVs that show the next service and brighter lighting. This was followed by Jonu station and Chonsung station in 2020. The TVs can also display a digital version of the Rodong Sinmun. At the 8th Congress of the Workers' Party of Korea, it was announced to push forward on the updating and renovation of the Pyongyang Metro, along with the production of new-type subway trains. Operation The Pyongyang Metro was designed to operate every few minutes. During rush hour, the trains can operate at a minimum interval of two minutes. The trains have the ability to play music and other recordings. In actual service, they run at every 3 minutes in rush hour and every 5 minutes throughout the day. The Pyongyang Metro is the cheapest in the world to ride, at only five North Korean won (worth half of a US cent) per ticket. Instead of paper tickets, the Metro previously used an aluminium token, with the emblem of the Metro minted on it and the Korean "". It has used a paper ticket system, with "" printed with blue ink on it. Tickets are bought at station booths. Nowadays, the network uses contactless cards that feature the logo of the network and a train set on the front, with the terms and conditions on the other side. Gates display the number of trips remaining on the card, with a trip being a tap on entry and exit. Smoking and