Create roads polygon from untraced area

Hello, I am using ArcInfo 10.1 Build 3035

I am looking for a solution that would involve digitizing roads as polygons from the untraced space they take up. If you look at the attached image, I traced everything except the roads. Now my boss has come back and asked for the road area to be calculated.

So either I need to determine the white space somehow, or have polygons created for the roads. Anyone know a process that doesn't involve tracing all the roads?

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