It’s been fifty years since the Big Dig was first conceived, thirty years since construction began, more than a dozen years since it was completed – and the final twist is: the project has largely delivered on its promises. How do we reconcile that reality with the scandal and outrage we’ve heard so much about?

Just as the project turns the corner towards completion, its entire legacy becomes clouded. The tunnels are leaking, concrete suppliers are being arrested, and everyday drivers are forced to wonder: are these tunnels safe?

By the year 2000, the Big Dig has passed through many hands, but in its final years a power struggle spills into public view – over who will determine the project’s fate, and who will take responsibility for its mistakes.

As work progresses through the 1990s and the tunnels take shape, the true cost of the Big Dig remains unknown to the public, until a series of revelations pulls down the curtain and shakes confidence in the whole project.

In 1991, the Big Dig is handed off to a new leader – the brash, aggressive, hatchet-toting Jim Kerasiotes – who makes it clear he plans to shake things up. The one thing he can’t shake is the equally aggressive private company managing the project. Now they have to work together.

The project faces an unexpected challenge on the home front: resistance from local environmentalists and residents – the very people the Big Dig was intended to please. Now, they say that Fred Salvucci has lost his way.

The Big Dig needs federal funding. House Speaker Tip O’Neill is determined to get it; President Ronald Reagan is determined to stop it – setting up a final showdown in one of the great political rivalries of the 20th century.

In the early 1970s a radical idea took shape: tearing down Boston’s elevated downtown highway, and rebuilding it underground. But making it happen will require a grand bargain between two competing tunnel projects, and between bitter enemies.

There is a strange irony behind the Big Dig: the most expensive highway project ever built in America began with a man who hated highways. This is the story of Fred Salvucci’s journey into activism, during what is perhaps the most transformative anti-highway movement in the nation’s history.

Can America still do big things? Can we build the ambitious projects we will need to survive climate change and improve our cities? This 9-part series looks for clues in the story of the Big Dig – one of the most notoriously troubled infrastructure projects in American history. The nine episode series is produced by GBH News and hosted by Ian Coss.