46,000 bridges across the country as structurally deficient and in poor condition. this bridge, between indiana and illinois, is rotting away, closed since 2012. >> here you can see some deteriation. >> a railroad bridge near boston he says is no longer safe. herman insists this traditional infrastructure is overdue for san overhaul. but it is caught in the middle of politics. >> it shouldn't be a political battle. it should be something we just invest in to make our lives better. >> they're under a lot of pressure here. >> reporter: transportation secretary pete buttigieg toured the i-40 bridge, the biden administration's $1.7 trillion infrastructure plan is larger than the plan proposed by congressional republicans. advocates hope whichever plan is passed pays for the $125 billion backlog of repairs they say that bridges need. >> i think this is just a reminder of how much we depend on these assets, and a reminder that it costs money to look