The Department of Public Works is responsible for maintaining and expanding the state highways system and major district roads. The Kerala State Transport Project (KSTP), which includes the GIS-based Road Information and Management Project (RIMS), is responsible for maintaining and expanding the state highways in Kerala. It also oversees a few major district roads. Traffic in Kerala has been growing at a rate of 10–11% every year, resulting in high traffic and pressure on the roads. Traffic density is nearly four times the national average, reflecting the state's high population. Kerala's annual total of road accidents is among the nation's highest. The accidents are mainly the result of the narrow roads and irresponsible driving. National Highways in Kerala are among the narrowest in the country and will remain so for the foreseeable future, as the state government has received an exemption that allows narrow national highways. In Kerala, highways are wide. In other states, national highways are grade separated, wide with a minimum of four lanes, as well as 6 or 8-lane access-controlled expressways. The National Highways Authority of India (NHAI) has threatened the Kerala state government that it will give higher priority to other states in highway development since political commitment to better highways in Kerala has been lacking. , Kerala had the highest road accident rate in the country, with most fatal accidents taking place along the state's national highways.