они ехали по широкой дороге, по обе

они ехали по широкой дороге, по обе стороны которой росли деревья

Результаты (английский) 1:

they were travelling along the wide road, on both sides of which have grown trees

Результаты (английский) 2:

They drove along the wide road on both sides of which were trees

Результаты (английский) 3:

they were driving on the road, on both sides of the trees