Germany, for example a trailer car for Dresden in 1918 and two tramcars with Jacobs bogies for Duisburg in 1926. However, interest for these cars was low and the concept of articulation fell into obscurity. It was only after World War II that articulated cars were manufactured again; the first, small series of GT4 Jacobs bogie cars was deployed for Stuttgart in 1953 by Maschinenfabrik Esslingen. From 1956 on, Duewag manufactured large numbers of articulated tram cars for operators in Germany and abroad to replace old pre-war models. Starting in 1959, Maschinenfabrik Esslingen and Hansawaggon, the latter mainly in Bremen and in Munich, tried to get into the market with their Kurzgelenkwagen construction — however, in West Germany their market share remained small compared to the Jacobs bogie cars made by Düwag. The Hansawaggon design was copied later by CKD Tatra, which manufactured large numbers of KT4D tram cars based on this design for use in the GDR. Apart from the larger series, small numbers of cars were rebuilt for operators with odd requirements, for example the Bremer Straßenbahn AG received a series of 3-axled and Augsburg bought several 5-axled cars. In the 1970s, the first urban railway cars were developed in the Federal territory. In some cases, tried and tested tram types were modified in such a way that they were also suitable for elevated platforms; While long-distance articulated wagons with a trajectory of curves were built for Frankfurt and Hanover, the Stuttgart tram was followed by the opposite route, although a number of Stuttgart lines were also used as a conventional tram. In their first versions, the new Stuttgart double-wagon consisted of two four-axle single-wagons without a transition, and their bogies were much further apart than with classic streetcar trucks. In the 1990s, high-pressure low-floor trains were developed. In part, considerable changes were noticeable after large numbers of units were already in use. Also some older articulated cars were improved after 1990 with a low-floor segment. In order to avoid problems with low-floor technology, there are also new designs that are not completely low-floor, such as the Flexity Swift, developed for Cologne since 1995, whose axle distribution with four wheels is firmly developed underneath a short middle segment from a conventional articulated carriage type of the Zurich tram, the middle segment of which, however, has an exterior door. A pioneer in the development of Regiotram is Karlsruhe. Since