There are various ways to get from Dulles International Airport to Washington DC. We decided to opt for the cheapest - and in my humble opinion the best - form of transport available. Outside the front of the airport terminal, bus service 5A takes passengers into the heart of Washington. It cost only 6 dollars. And whilst the traffic on the roads was barely moving, the bus zipped past on the hard shoulder, getting us to Washington far quicker than any taxi could have achieved.