Utrecht is well-connected to the Dutch road network. Two of the most important major roads serve the city of Utrecht: the A12 and A2 motorways connect Amsterdam, Arnhem, The Hague and Maastricht, as well as Belgium and Germany. Other major motorways in the area are the Almere–Breda A27 and the Utrecht–Groningen A28. Due to the increasing traffic and the ancient city plan, traffic congestion is a common phenomenon in and around Utrecht, causing elevated levels of air pollutants. This has led to a passionate debate in the city about the best way to improve the city's air quality.
What limits the amount of traffic in the city?