The "Kořenov rack and pinion railway", the Tanvald - Kořenov line, was built as part of the Liberec - Tanvald – state border line with a connection to the former Prussian State Railways line which led along the state border - Petersdorf – Hirschberg route. This was a line of international significance despite its operating length of a mere 6.7 km. The line overcomes a height difference of 235.1 m and its gradient reaches a value of 58 per mille. It was equipped with a unique rack and pinion system because of the extreme gradient. Nowadays, the line attracts the interest of railway enthusiasts, tourists and skiers. Originally, it was mainly of significance for freight transport – it connected the industrial areas of Liberec and Jablonec with the carboniferous basin in neighbouring Silesia. There were originally four stations (Tanvald, Desná, Dolní Polubný and Kořenov) and one stop (the Kořenov stop) on the line. After the Second World War, part of the originally Prussian line with the Strickerhäuser Stop (now Harrachov) was added to the line which meant that its length increased to 12.721 km. However, cross-border operations ceased after the War. The track crosses four large bridges and passes through four tunnels with a total length of 1422.5 m, which means that 21% of the line is located in tunnels. The added former Prussian section includes one tunnel and there is a large bridge spanning the deep Jizera River valley directly in front of it.
Let’s start at the Tanvald Station. This was originally only the terminal station for the line from Železný Brod. The station building is single-storied and it has a covered passenger platform. Its central section is the original structure dating from 1875, while the side wings in the same style as the original building were added in 1894. In the 1950s, the single-story building housing the staff changing room was added between the station building and the store. The rails leading towards Kořenov rise steeply immediately after the outer points, because they have to pass over the level crossing with the road to Tanvald - Žďár. There is a steel bridge across the Desná River directly after the crossing and the first rack and pinion section begins after the bridge. When the locomotive passes onto the rack and pinion mechanism, it is necessary to reduce the speed to 5 km/h and the speed of both (the adhesive and rack-and-pinion) machine sets must be the same. The entire operation requires experience and skill on the part of the engine driver. The entrance to the first tunnel, which is quite short (a mere 68 metres), is located several hundred metres on.
The end of the first rack and pinion section soon arrives and then there is a break in the gradient and the line no longer climbs, but descends slightly for 260 m. The following station at Desná used to have a beautiful art nouveau façade and it was very nice and well maintained during the time of the Austro-Hungarian Empire. Nowadays, it is somewhat desolate and this not surprising considering that no railway staff are based there. After the Desná Station, there are two bridges one after the other; an iron bridge across the White Desná and a steel bridge across a district road. After the Desná Tunnel, the line traverses a deep gorge on an embankment. It crosses the Black Desná and the state road to Harrachov (the E 65) along a stone viaduct with five arches. The second section of the rack and pinion system is located in front of the viaduct. The Dolní Polubný Station is located immediately after the end of the Dolní Polubný Tunnel. The rack and pinion system ends there above the tunnel’s portal and it begins again at the site of the former entry points from Kořenov. The 193 m section of a 58 per mille ascent begins immediately after the Dolní Polubný Station and from then on the gradient value remains in the area of 55 per mille. This is the section with the greatest gradient on the entire track. The train enters the 940 m long Polubný Tunnel after the Kořenov Stop. This is the longest single-rail tunnel in the Czech Republic. The tunnel ends in the settlement of Horní Polubný and the rack and pinion system ends just above its portal. The line’s gradient is more or less flat for a short while and then it slightly descends and the train heads to the Kořenov Station.
The station is now just a shadow of its former glory. The Kořenov Station was built and operated as a border crossing station until 1938. From there, Prussian State Railways trains travelled to the former territory of Prussian Silesia. From Kořenov, the line leads above the Jizera River valley for about 2 km. It then twists to the right and crosses the valley over the Jizera Bridge and passes through the 280 m long Jizera Tunnel into the realm of the Krakonoš, because the Jizera River forms the border between the Jizera Mountains and the Giant Mountains. After travelling through forests for about 2.5 km, the line reaches the Harrachov Stop where regular trains currently finish.