Southbound roads or vehicles lead or are travelling towards the south.
...the ~ train from the Scottish Highlands.
...the ~ carriageway of the M61.
ADJ: usu ADJ n
SOUTHBOUND
Meaning of SOUTHBOUND in English
Collins COBUILD. Толковый словарь английского языка для изучающих язык Коллинз COBUILD (международная база данных языков Бирмингемского университета) . 2012