Upon the filing of a complaint and after the filing of plans and specifications as provided in section 18-619, the governing body shall fix a time for hearing such complaint and give notice thereof to the railroad company or companies. At the time so fixed the governing body shall sit as a board of equalization and assessment and at such hearing shall receive and hear such evidence as may be offered on the question of whether public safety, convenience, and welfare require the construction of such viaduct or subway, whether or not the cost of such viaduct or subway will exceed the benefits to be derived therefrom, and evidence on the question of the extent to which such railroad company or companies and the public will be respectively benefited by the construction of such viaduct or subway.