The government has undertaken a highway project that was originally projected to cost $1 billion and provide

Question:

The government has undertaken a highway project that was originally projected to cost $1 billion and provide benefits of $1.5 billion. Unfortunately, the costs have been much higher than anticipated. The government has spent $1.2 billion so far and now expects that it will cost an additional $1.2 billion to finish the project.
Should the project be abandoned or completed?