Pamagite

$last_city = ''; // initial empty value
foreach($cities as $city) {
	if ($last_city != '') { // if value not empty show transit option
		echo '<option value="'.$last_city.'-'.$city['name'].'">'.$last_city.'-'.$city['name'].'</option>'. PHP_EOL;
	}
	echo '<option value="'.$city['name'].'">'.$city['name'].'</option>' . PHP_EOL;
	$last_city = $city['name']; // store value for next iteration
}