Els running on traditional steel structures can be pretty noisy. Using concrete structures could cause a lot of shading to the streets below I feel. I wonder w

Els running on traditional steel structures can be pretty noisy. Using concrete structures could cause a lot of shading to the streets below I feel. I wonder why this system https://en.m.wikipedia.org/wiki/Wuppertal_Suspension_Railway https://en.m.wikipedia.org/wiki/Wuppertal_Suspension_Railway has been used only once worldwide.