Highway encounters with trucks &mdash those thunderous mega-masses of steel, kitschy art and tacky couplets &mdash aren&rsquot exactly calculated to enhance the joy of travel. Shrieking, high-decibel horns ablare, they command right of way with a badass swagger that intimidates other vehicles lower down the pecking order of automobiles into yielding. And, yet, these rajas of the road are in many ways the lifeline of the economy, carting everything from alu-pyaaz to passenger cars up and down the 33-lakh- kilometre network of Indian roads. And a whole ecosystem (and an ethno- sphere), which we don&rsquot always see or experience as we hurtle through life in the fast lane, exists just to keep these engines of the economy humming.