How do you move 35 million people out of harms’ way as quickly and safely as possible?

Japan’s government would have had to answer that nightmarish question last March had deteriorating conditions at the earthquake-and-tsunami-battered Fukushima nuclear power plant spread radioactivity to metropolitan Tokyo, according to a new report issued by an independent review panel.

The government’s worst-case scenarioa potential chain-reaction of reactor explosions combined with exposure of spent fuel rodswould have necessitated an evacuation zone of 120-150 miles (200-250 km) from the plant, encompassing the densely populated region surrounding the capital centered approximately 124 miles to the southeast.

As it turned out, the evacuation zone extended only 12 miles, though occasional spikes of radioactivity have been found Tokyo since the March 11 disaster.

The response of the Japanese government following the earthquake and tsunamithe report’s primary focuswill likely be criticized for decades. Still, one wonders how, had the evacuation order had been issued, all of those people could have been safely relocated beyond the reach of Fukushima’s deadly radiation?

All major cities have emergency management plans, and Tokyo is no exception. A radiation-driven evacuation would have likely mirrored the city’s civil protection plan for a terrorist attack, with the region’s extensive rail system shouldering handling much of the population movement.

Tokyo’s susceptibility to earthquakes makes one hope that the population in general would be more attuned to the need to prepare and act had the evacuation order been given. Would the same have been true in the U.S.?

After all, evacuation plans are by necessity based on myriad assumptions, e.g., citizens are ready to respond and will behave reasonably, “official” information channels are recognized and reliable (and can compete with the increasingly ubiquitous, not-always-reliable social media channels), the existing transportation infrastructure is fully functional and capable of handling such massive movements, and all of these people have someplace to go.

New York City and Washington, DC, commuters would probably prefer to forget what it was like trying to get home following the 9/11 attacks. And the 2005 exodus from Houston in advance of Hurricane Rita illustrates how a mass migration can quickly bog down into gridlock. Even something as natural as a moderate winter storm arriving around rush hour is enough to knock an otherwise fine-tuned multi-modal regional transportation system out of kilter.

So imagine what an exodus would be like on a network of already overcrowded highways, barely serviceable bridges, and maintenance-starved transit systems.

My intent here is not to plea for more funding for transportation infrastructure, or argue where it should come from. My job as a construction journalist, after all, is to report on such things as objectively as possible.

Rather, it’s a hope that as the advocates and decision-makers tout transportation’s critical role in creating all those “good jobs” and enhancing our quality of life, they’ll not neglect its potential importance in saving some lives as well.

If that’s not enough to move the debate beyond platitudes and sound bites, what is?