divided highway
US /dɪˌvaɪdɪd ˈhaɪweɪ/
UK /dɪˌvaɪdɪd ˈhaɪweɪ/

1.
a highway with a median strip or barrier separating traffic flowing in opposite directions
:
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The new divided highway has significantly reduced accidents.
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Driving on a divided highway is generally safer than on a two-lane road.