Never quite understood how the cost of single fares were worked out but the £1.80 single seems to cover most trips now. For example, Sunderland to South Hetton on the 55 £1.80 and I believe you can do Sunderland to Peterlee on the 62 for £1.80 as well. There is still the evening offer as well I believe but as I don't work lates, I'm not 100%. The new duo ticket or whatever they call it is app only