Well, if you analyze the statements in terms of prepositional logic, then all the English language conjunctions "and", "but", "though", etc. map to the only type of logical conjunction ∧.

But natural language is richer than (directly mapped) prepositional logic. I interpret the statement "Local roads, though, are still predominantly conventional." as a clarification of "Intelligent roads are in use, primarily for long-distance travel.".

Formally, if you just claim:
"Intelligent roads are in use, primarily for long-distance travel."
it is equivalent to:
"Intelligent roads are in use, primarily for long-distance travel." ∧ ( "Local roads are still predominantly conventional" ∨ ¬"Local roads are still predominantly conventional" )
which is different from
"Intelligent roads are in use, primarily for long-distance travel." ∧ "Local roads are still predominantly conventional"

However, we can assume that if you claim:
"Intelligent roads are in use, primarily for long-distance travel."
you also wanted to communicate that
"Local roads are still predominantly conventional"
not that you are undecided between
"Local roads are still predominantly conventional", ¬"Local roads are still predominantly conventional"
otherwise you would have probably stated that explicitely.

Therefore, the information content of:
"Intelligent roads are in use, primarily for long-distance travel."
and:
"Intelligent roads are in use, primarily for long-distance travel. Local roads, though, are still predominantly conventional."
is rougly the same.