PTIP is an excellent program that encourages the use of public transportation and reduces daily vehicle emissions. It encourages employees to live near public transportation to use the benefit to best advantage, thereby helping to curb sprawl development in the "ex-urbs." Thru PTIP, the government sets a good example for other large employers to do their part to reduce traffic congestion and pollution. My suggestion is to subtract from an employee's monthly PTIP benefits the full days of sick leave and annual leave he or she uses (similar to what is done for Telework): if an employee is on leave, he or she does not need transportation coverage. You'd have to link PTIP to the leave-tracking system somehow so the benefit subtraction could be done automatically for each pay period.