That doesn't mean the city paid for it. If you start a new land development to put up houses, you often cover all the costs associated with putting in roads and signs. Not saying that's what happened here but one sentence saying a road was put up doesn't indicate paid for by taxes.

Did you miss the below quote from the linked article?

"...After the Hartford proposal fell through, Robert Kraft paid for 100% of the construction costs, a rare instance of an NFL owner privately financing the construction of a stadium."