Which factors push forward the municipal construction?

With the big progress of cities, the urban centers have a high-density development with large population flocking in, which leads the surge of total travel; at the same time, the urbanization of suburb and exurban areas causes a lot of long-distance travel demands. So solving the traffic problems as one item of the municipal construction is increasingly urgent, and subway building, road building, bridge building, etc. are a kind of effective method. Many heavy-duty machines are used like KSL Overhead Bridge Crane