The layout and position of the city roads in Thimphu are dictated by its unique topography. Most premier roads, typically wide, are aligned in a north–south direction, parallel to the river; the most important artery is the Norzin Lam (''Lam'' - road/street). Branch roads wind along the hill slopes leading to residential areas. Footpaths are also well laid with access to the commercial areas and the Wang Chu River. However, its entry point is at a narrow location from the south crossed by a wooden bridge. South of the bridge is the road to Paro, Punakha, Wangdi Phodrong, Tongsa and further to the east and north. The expressway which has been built has had a large impact on development, shifting land values, decreasing transportation costs, and increasing potential growth opportunity in the southern part of the valley.