Mumbai has a large concentration of commercial and administrative functions in the southern end of the island. Transportation is a huge problem due to the island geography and the only highways running north-south along the coasts. Various forms of transportation exist in Mumbai including traditional walking and carts, local buses and trains, and long-distance rail, road, water, and air transport. Traffic jams are a major issue faced by pedestrians, the elderly, and disabled due to bad road conditions and high population density, sometimes worsened during riots when traffic rules are not followed.