Like the weather, the need to repair America’s troubled bridges is something that everyone talks about, without doing a thing about it. Or at least they do not do nearly enough.

President Obama is trying to change that equation. He has said so repeatedly in his State of the Union speeches and other messages, and he returned to that theme a few days ago. This time, Mr. Obama called for closing loopholes in corporate and business tax codes to free up $302 billion that would be spent over four years to fix or replace aging bridges, roads, tunnels and rails — an infrastructure that he has described quite reasonably, if inelegantly, as “raggedy.”

What becomes of this latest presidential appeal is swathed in doubt. Anything that smacks of a tax increase is bound to face resistance in Congress, especially in this election year. Even catastrophe has failed to create a sense of urgency sufficient to spur officialdom to do much more to keep the ground, literally, from falling out from underneath us.

That is a lesson reinforced by this week’s Retro Report, the first in a new season of weekly documentary videos that re-examine leading stories of decades past. It revisits the disastrous 2007 collapse of the I-35W Bridge spanning the Mississippi River in Minneapolis. Scores of cars tumbled into the water. Thirteen people died. Nearly 150 others were injured. Investigators later concluded that blame lay with a design flaw dating from the bridge’s construction four decades earlier. Steel sheets known as gusset plates, which tie beams together, were half as thick as they should have been and gave way under an unusually heavy load.