Trotro (the archive's form 'Trotroe' is unattested in sources consulted) is the Ghanaian name for privately operated shared minibuses running fixed or semi-fixed routes without timetables. According to Wikipedia, the name is believed to derive from a Ga word 'tro' meaning threepence, said to have been the standard fare in the 1940s; an alternative account cited there explains the doubling as meaning 'threepence each'.
She took a trotro into central Accra.