The idea of building a road to cross the ravine was conceived in the 1950s and 1960s, when a small-radius (70-250 m) road with a very steep rise and fall (5-6%) profile was traced around a mill near Lorupe. The story goes that the miller had a beautiful daughter and, having fallen in love with her, the engineer road-router deliberately twisted this section of the road. With the development of car traffic, crossing the Lorupe ravine, especially in winter, was quite unpleasant.
Professor Kārlis Gailis of the Latvian State University said that several generations of engineers had worked on the reconstruction of the Lorupe ravine. The former Department of Highways and Earth Roads has a very large file.
In drawing up the design brief, it was a hard fought battle with the authorities and engineers who wanted to solve the problem by filling in the 200 m wide and 30 m deep ravine with soil. This would have required about 200 000 cubic metres of soil and the construction of a 140 m long culvert to cross the river. Extracting this amount of soil from nearby quarries would destroy the magnificent landscape.
The experimental construction of the Lorupe Viaduct aroused great interest among engineers in the USSR and also in Germany. In Germany, probably because the author of the Riokaroni Bridge project, the German Professor F. Leonhard, included material on the Lorupe Viaduct in German bridge textbooks. The construction site of the Lorupe Viaduct was frequently visited by specialists from the Ministry of Transport Construction of the USSR, as well as by scientists.
The viaduct is also remarkable because it made history as the first bridge in Latvia and in the entire territory of the former USSR to be assembled using the longitudinal sliding method. This example determined the choice of the general design of the viaduct's span and the assembly technology. The viaduct over the Lorupe ravine is a five-span continuous beam of 33 m + 3 x 43.25 m + 33 m on flexible piers up to 24 m high. The total length of the bridge is 195,75 m.
The project manager was Ziedonis Vecvagars. The design work was carried out by engineers H.Nartišs, L.Jostiņš, J.Lapainis, J.Zavickis, I.Jurka, U.Matīss, architect V.Reifelde and technician G.Zirnis.