Gta -tds

Please state me the provision in regards of TDS deduction in case of GTA (Goods Transport Agency) 1.when TDS should be deduct in case of GTA 2.No. of vehicle requirement as I hear somewhere that GTA should hold more than 10 vehicle than only we need to deduct TDS also provide me provision in regards of Certificate to be obtained 3. PAN no requirement to deduct TDS that is whether TDS should be deduct if he does't hold PAN no. 4.Presentation in TDS return if we are making payment to GTA but not deducted TDS due to any valid reason Please provide me clarification on such issues ,thanks in advance