 Complete the following phrase:  First in the 1870s a dam was built at the location of the future bridge. This dam provided the traffic over land with access point to the island. In the 1920s the transit for ships was made possible across the narrower branch of the Danube, and the dam was demolished. The bridge was built in its place. The northern half of the bridge served rail traffic both cargo and commuters and the southern part served the road traffic. The retreating German army destroyed the bridge during the 