trains. Three RE20-services continue onward to Gothenburg Central Station each day. Architecture Peter Andreas Blix was hired as the national railway architect in 1873 and awarded the task of designing the stations on the Østfold Line. His designs drew inspiration from Medieval architecture, Gothic architecture and contemporary English villa styles. He let the interior plans dominate the outer shape and avoided symmetry. Most of the station buildings were in wood and standardized designs. Stations which were expected to have larger traffic received a separate goods sheds. The four main towns received brick stations. Halden Station was the most prominent, with an exterior which drew elements from a Medieval fortresses inspired from Fredriksten Fortress and the town's role as a border town. Moss, Fredrikstad and Sarpsborg received the same design with three gables on each facade. Future The Østfold Line is part of the InterCity Triangle and one of four prioritized lines in Norway being upgraded to high-speed rail. The entire section from Oslo to Halden is scheduled to be upgraded by 2034. The first step was construction of the Follo Line, a new line which runs in a tunnel almost the entire length from Oslo to Ski. It allows all passenger trains heading south of Ski to save 11 minutes, and free up capacity on the old double track for more commuter and freight trains. Construction started in 2015 and the Follo Line was opened in 2022. It may also include a new connection to Kråkstad. Once completed, the old double track from Oslo to Ski will receive an overhaul. Upgrades southwards are split into four phases. By 2026 the missing double-track link from Sandbukta via a new Moss Station to Haug is scheduled for completion. The line from Haug to Seut north of Fredrikstad is planned to be finished within 2029, two years before the double track to Sarpsborg. The final stage to Halden is scheduled for completion in 2034. The National Rail Administration is working on possibilities of expanding the double track further south and in conjunction with Swedish authorities complete a high-speed link between Oslo and Gothenburg. On the Swedish side the final to Öxnered is already finished. The Østfold Line has the largest potential for an increase in freight traffic, with an estimated eleven trains in each direction per day. These include freight trains to Götaland in Sweden, including a shuttle service to the Port of