Carbo-Link delivered the prototypes at the end of September 2016, and in October Motavalli's team began mechanical testing. The most important task was to simulate 100 years of railway operation on the CFRP hangers - within a few months. This corresponds to a stress of more than 11 million crossings. The high oscillation frequency of 4.2 Hz, which was chosen for time and cost reasons, initially led to dangerous overheating at the contact surfaces between the CFRP and the titanium thimbles. The project threatened to fail until it was decided to reduce the load amplitude, which had been greatly exceeded out of ambition, to a realistic level. In the end, the two hangers examined survived the approximately 11 million load cycles without any problems.
The task of Empa experts Urs Meier - a pioneer in CFRP research - and Peter Richner, now Deputy Director of Empa, was to analyze and evaluate the extensive data. In addition to the fatigue properties, they also had to consider issues such as weathering resistance, lightning, fire, the influence of electrical and magnetic fields, and vandalism. On May 17, 2017, Meier and Richner sent their report to Stuttgart after just over seven months. All had worked under high tension and enormous time pressure. And then ... nothing happened. Months went by, and both Carbo-Link CEO Winistörfer and Meier and Richner came to the conclusion: "A waste of time and effort".
They had already written off the project when, on April 10, 2018, a letter suddenly arrived from the licensing authority in Baden-Württemberg, which allowed the use of CFRP hangers in the construction of the bridge over the A8 motorway under certain conditions. Among other things, Empa's expert opinion and the requirements it contained had to be included in the tender documents for the project. Only one offer was received in response to the subsequent invitation to tender for the project; at the time, the construction industry in Germany was experiencing overheating. As the costs in the bid were significantly higher than the planned budget, things looked bleak again in autumn 2018 for the network arch bridge with CFRP hangers. The project was in danger of finally failing for cost reasons. However, shortly before Christmas, those responsible surprisingly decided in favour of the future-oriented technology.