We're doing something similar here in Rio de Janeiro: the Perimetral (https://pt.wikipedia.org/wiki/Elevado_da_Perimetral https://pt.wikipedia.org/wiki/Elevado_

We're doing something similar here in Rio de Janeiro: the Perimetral (https://pt.wikipedia.org/wiki/Elevado_da_Perimetral https://pt.wikipedia.org/wiki/Elevado_da_Perimetral) was demolished, and will be replaced by a new 3 km tunnel pair (http://www.portomaravilha.com.br/viaexpressa http://www.portomaravilha.com.br/viaexpressa). One major difference would be that the Perimetral was demolished before finishing the tunnel. We'll see how well it works when it's opened this year.