Complex sentence: This first stage of the underground consisted of 2,7km of tunnels and 0,7km of ramps and bridges, and the costs were estimated between 35 and 40 million Swiss francs.
Split into simpler sentences: This first stage of the underground consisted of 2,7km of tunnel tracks and 0,7km of ramps and bridges. He estimated it would cost between 35 and 40 million Swiss francs.