To clarify a bit:

\b      matches before bar
\w+     matches "bar"
\s*     matches as many spaces as it can swallow (it's greedy),
        i.e. " "
(road)? matches "road"

but

\b   matches before bar
\w+  matches "bar"
\s*? matches the *empty* string (it isn't greedy)

so

(road)?  attempts to match " road" - which of course fails
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