Complex sentence: It is the longest reinforced concrete bridge in the US and was constructed after the June 1,1957, groundbreaking for 2 rail tunnels to bypass the planned Oroville Reservoir.
Split into simpler sentences: It is the longest reinforced concrete bridge in the United States. It was built after the June 1,1957, groundbreaking for 2 rail tunnels to bypass the planned Oroville Reservoir.