HARTFORD, Conn. (WTNH)– Parts of some busy highways may go underground.

For years, the Department of Transportation has known it had to do something to ease congestion on the I-84 viaduct, that’s the part that currently goes through Hartford on a series of bridges up in the air. Now a plan to bury the road underground has passed the state Senate.Related: Hartford tunnels proposal gets a boost from state Senate

The DOT is considering three options: Build new, wider bridges next to the current ones. That would be expensive and disruptive. They could bring the highway down to ground level, which would mean changing the streets and railroad lines that are below the highway right now. Or, build a tunnel underneath Hartford and the Connecticut River. That’s the most expensive idea, but the one least disruptive to the city and current traffic. It won’t be easy. Some compare it Boston’s big dig which was horribly over budget and took years longer than expected.

The Hartford tunnel would cost an estimated $10 billion. If you’re wondering how the state legislature can be talking about a $10 billion tunnel in the middle of a budget crisis, this bill is worded so that it only says that it allows the state to use federal money to build this tunnel.

It has been championed by Congressman John Larson, and now his brother, Senator Tim Larson, has gotten this approval through the state senate. The bill now goes to the house for approval.