The country has over one lakh kilometres of national highways (NHs), but there is no scientific road network pattern and drivers can't take a straight road to reach from one place to the other. To address this issue, NHAI is said to have prepared a grid of 27 horizontal and vertical national highway corridors at a distance of every 250 km crisscrossing the country. And it's discussing these plans with states to avoid overlapping and duplication. All these stretches will be made of four lanes and will provide more road space for seamless transport. The total length of these corridors, including ones such as Kanyakumari to Srinagar, Porbandar to Kolkata, Surat to Paradip Port, Rameswaram to Dehradun and Mangalore Port to Chennai Port, is about 36,600 km. Out of this, about 30,100 km are already NHs. But only 18,800 km of them is of four-lanes. The rest are either single or two lanes and the country has a missing NH link of about 6,500 km, which are either state highways or major district roads. These stretches need to be converted into NHs and widened to four lanes for smooth travel. Sources said going by the standard costing, the government will have to invest about Rs 25,000 crore for completing four-laning of the routes.