The easiest way: array_pop() which will pop an element of the end of the array.

As for the 2nd question:

if (end($transport) == "") { 
    array_pop($transport); 
}

Should handle the second.

EDIT:

Modified the code to conform to the updated information. This should work with associative or indexed based arrays.

Fixed the array_pop, given Scott's comment. Thanks for catching that!

Fixed the fatal error, I guess empty cannot be used with end like I had it. The above code will no longer catch null / false if that is needed you can assign a variable from the end function and test that like so:

$end_item = end($transport);
if (empty($end_item)) { 
    array_pop($transport); 
}

Sorry for posting incorrect code. The above I tested.

It's important to note, looking at the other answers, that array_slice will leave the original array alone, so it will still contain the elements at the end, and array_splice will mutate the original array, removing the elements at the beginning (though in the example given, the function creates a copy, so the original array still would contain all elements). If you want something that literally mimics array_pop (and you don't require the order to be reversed, as it is in your OP), then do the following.

$arr = range(1, 10);
$n = 2;
$popped_array = array_slice($arr, -$n);
$arr = array_slice($arr, 0, -$n);
print_r($popped_array); // returns array(9,10);
print_r($arr); // returns array(1,2,3,4,5,6,7,8);

If you require $popped_array to be reversed, array_reverse it, or just pop it like your original example, it's efficient enough as is and much more direct.

try

end($array); //pointer to end
each($array); //get pair