The streets of central Ottawa follow a grid pattern, but it is frequently disrupted by the Rideau River and Rideau Canal, ensuring that few streets in most of the older neighbourhoods are very long. Outside of the core, the roads follow the modern standard of large avenues forming a grid, interspersed with a network of crescents and cul-de-sacs which create low-traffic, suburban neighbourhoods. The Queensway, a major highway, crosses almost all of the city from east to west, going just south of downtown. It was built in the 1960s, mostly over former railway tracks, and thus did not entail the same urban destruction as expressways in other cities. There are five road bridges, and one rail bridge, crossing over the Ottawa River, four of which are in the downtown area, ensuring that much of the interprovincial traffic, including many large trucks, pass through the centre of town.