The cost overrun for the Boston tunnel project, known as the Big Dig, was approximately $14.1 billion when adjusted for inflation.
Understanding the Big Dig's Financial Scope
The Big Dig, a complex series of highway and tunnel projects in Boston, Massachusetts, faced significant financial challenges throughout its lifespan. Initially, the project was envisioned with a much lower budget and an earlier completion date, but various factors contributed to substantial cost increases.
Original Estimates vs. Final Costs
The disparity between the projected and actual costs highlights the scale of the overrun. Here's a breakdown of the key figures:
| Financial Metric | Original Estimate (Inflation-Adjusted as of 2020) | Actual Final Cost (Inflation-Adjusted) |
|---|---|---|
| Project Cost | $7.4 billion | $21.5 billion |
| Cost Overrun Amount | N/A | ~$14.1 billion |
| Cost Overrun Percentage | N/A | Approximately 190% |
- Original Vision: The project was initially estimated to cost $2.8 billion, with a target completion in 1998. When adjusted for inflation, this original estimate equates to approximately $7.4 billion as of 2020.
- Actual Completion: The project eventually concluded in December 2007, nine years behind its original schedule. The final cost surged to over $8.08 billion in 1982 dollars, which translates to a staggering $21.5 billion when adjusted for inflation.
The Magnitude of the Overrun
The difference between the final inflation-adjusted cost ($21.5 billion) and the original inflation-adjusted estimate ($7.4 billion) reveals a cost overrun of about $14.1 billion. This figure represents an approximate 190% increase over the initial inflation-adjusted budget, making it one of the most expensive highway projects in U.S. history.
