Strictly speaking it has two runways , however , the northern runway -LRB- 08L/26R -RRB- can only be used when the main runway -LRB- 08R/26L -RRB- is out of use , for example because of maintenance or an accident .

It is also often quoted as the world 's busiest single runway airport , although strictly speaking it now has a second ` stand-by ' runway , which can only be used when the main runway is out of use .
