The Bundesbahn was then more skeptical about the Maglev technology, and forced, from their side, more research into high-speed rail using conventional rail-wheel technologies. A test section of rail on the Hamm–Minden railway was (from 1973) already available for testing, and a specially modified Class 103 locomotive was able to reach speeds of up to . During the test runs a lot of knowledge was gained about the effects of high-speed rail. These insights also impacted the service of the Intercity trains that were to reach up to . The National Transport Plan ("Bundesverkehrswegeplan") of 1973 laid the important foundations for the construction or upgrade of up to railway lines for them to be rated for speeds of .