From Central take Tambaram train and get down at Pallavaram (35 mins) and then take 66/ 166 bus to Kundrathur. By this route you can reach Kundrathur in 1 hour. Buses from Central to Poonamallee are always crowded like hell and it takes a long time to reach because of traffic. Even if you take direct bus to Poonamallee you will have to get down at Iyyapanthangal/ Porur or Kumananchavady and change to 66/166 or other buses.