By Claudia Vargas and William Bender, includes “The Philadelphia pension perk known as DROP cost the city at least $237 million over a 16-year period ending in 2015, a new study commissioned by the Pennsylvania Intergovernmental Cooperation Authority (PICA) has concluded. … DROP allows employees to pick a retirement date up to four years in the future, then immediately start accumulating pension payments in an interest-bearing account while still earning a salary. They then collect a lump sum upon retirement. …”