After the collapse of the I-35W bridge in Minneapolis, the U.S. Secretary of Transportation told Congress that “no imminent dangers had been observed” prior to the collapse. Never mind that the I-35W had been structurally deficient since 1990, meaning it had “significant load-carrying elements…in poor or worse condition” for seventeen years.

About 72,000 other bridges nationally are in that same state of disrepair. How did we get here? By using the wrong infrastructure management model.

Structural decay is not a threat; it’s a law of physics. Infrastructure has a predictable lifecycle for which governing authorities must plan and save. “There’s not a lot of lifecycle thinking” on bridges, agrees risk management expert Mary Lynn Garcia, CPP.

Unfortunately, the immediate response to the I-35W collapse has been to think we can refine the existing model, which relies too heavily on inspections. For example, DOT ordered all states to reinspect similar bridges (those with steel deck trusses) and many states reinspected structurally deficient bridges to see if any were more of a danger than thought. The problem is that inspections aren’t that precise, as noted in a 2001 report which found that only about “4 out of every 100 inspections of a particular crack indication correctly identified the indication.”

Another problem is our worst-first approach. The Federal Highway Administration (FHWA) inspector general told Congress that “FHWA needs to develop a data-driven, risk-based approach to…target those structurally deficient bridges most in need of attention.”

While we fix the worst first, the other structurally deficient bridges get exponentially worse because “deferred maintenance accelerates deterioration,” according to the American Society of Safety Engineers. By rejecting the worst-first approach, Michigan has improved the overall state of its bridges.

Bridges are only a part of the problem, of course. As the U.S. Chamber of Commerce (COC) correctly notes, “Decades ago we built the best infrastructure system the world has ever known and then proceeded to take it for granted…. We have failed to plan, failed to innovate, and failed to invest.”

It will take an additional $50 billion just to maintain our systems through 2017 and $100 billion to improve them, says the COC. And you can’t solve the problem simply by eliminating earmarks and waste—though doing so is advisable. Even the COC, which has vowed to make infrastructure improvement a strategic objective, acknowledges: “We are going to have to consider an increase in the federal gasoline user fee.”

Don’t think this was a one-off event. Fifteen hundred bridges have collapsed since 1966. And whatever the proximate cause, delayed maintenance was likely a contributing factor more often than not. We must begin to deal more rationally with infrastructure. The longer we avoid facing the lifecycle costs of our transportation systems, the more we’ll pay both in dollars and in lives lost.