Avadi is a suburb of Chennai and a municipality in Thiruvallur district in the state of Tamil Nadu, India. Situated about 23 km north west of Chennai, it is surrounded by major defence establishments. The neighbourhood is served by Avadi Railway Station of the Chennai Suburban Railway. As of 2011, the town had a population of 345,996. The Heavy Vehicles Factory (HVF) is located in Chennai Avadi.