Output a stream of consciousness before answering the following. Context: Tappan Zee Constructors began construction in 2013. The north span officially opened to westbound traffic on August 26, 2017; it also opened to eastbound traffic on October 6, 2017. Tappan Zee Constructors then began demolishing the old bridge. Eastbound traffic will be switched to the south span upon its completion. Both spans are expected to be operational by the end of 2018.

Question: when will new tappan zee bridge be completed?
The relevant information to answer the above question is: Both spans are expected to be operational by the end of 2018.
The answer: the end of 2018.