Sometime within the next five years, taxpayers probably will have to find $250 million to replace a key bridge at Washington, D.C. That is the estimated life remaining in the Arlington Memorial Bridge across the Potomac River.

National Park Service officials, who have jurisdiction over the 84-year-old span, say it cannot survive without a complete reconstruction. No doubt that will happen. The bridge is a vital part of the transportation network in the Washington area.

But it is worth asking whether this is a project that had to occur.

NPS officials say the bridge needs major work because its steel supports are rusting through and its concrete decking has deteriorated drastically. Would those things have happened had there been better preventive maintenance on the bridge?

Possibly so. Steel, periodically recoated, can resist rust for a long, long time. Local residents know that; cables holding up the Wheeling Suspension Bridge, built in 1849, did not have to be replaced for more than a century.

If proper preventive maintenance was not done on the Arlington bridge, why not? Lack of money? Shoddy management? An attitude that it didn’t matter because taxpayers could cover virtually total replacement of the bridge?

Congress no doubt will have to find the needed $250 million – but not until those questions are answered.