sentences:  Construction began on the first piece of the line, from Arsenal (then on the West Chester and Philadelphia Railroad) over the Arsenal Bridge to Washington Avenue west of 25th Street (then on the Philadelphia, Wilmington and Baltimore Railroad's main line), in 1860.The PRR acquired trackage rights over the WC&P from their main line at Market Street south to Arsenal in exchange for building a second track to handle the increased traffic.The PRR also gained trackage rights over the PW&B and their leased Southwark Rail-Road to the foot of Washington Avenue at the Delaware River, and the line opened on January 27, 1862; the PW&B was allowed to use the Arsenal Bridge as part of the agreement.