Virtually everyone who follows cities has come to the same basic conclusion: somehow, they're going to be completely transformed by self-driving vehicles.

Of course, we don't know how, exactly, that will happen. Maybe the technology will render transit moot. Maybe it will reduce congestion and slow down the push for roadway expansions. Or maybe it will drastically reduce car ownership.

But one group of people who appears to be slow preparing for the implications of self-driving vehicles -- ironically enough -- are the planners who will be charged with figuring out how to implement them.

A new paper in the Journal of Planning Education and Research says almost all major metropolitan planning organizations have failed to include self-driving vehicles in their long-transportation plans.

Just one of the country’s 25 largest metropolitan planning organizations even mentions driverless vehicles in its most recent plan, according to research by Erick Guerra, an assistant city planning professor at University of Pennsylvania. Guerra's examination was based on plans in place in spring 2014.

And the one that did -- Philadelphia's Delaware Valley Regional Planning Commission -- only made a reference to the technology in a sidebar highlighting the uncertainty around it.

The implications of the failure of these organizations to plan for the technology could be huge, Guerra writes.

"Unfortunately, the extent and direction self-driving cars’ impacts, particularly if transformative, are unlikely to be fully understood until they have already started to happen," Guerra said in his paper.