phase在一句话中的意思
The five new subway lines - Fangshan Line,Changping Line,the first phase of the No 15 Line,Yizhuang Line and Daxing Line - have a combined length of 108 kilometers,bringing the city's total metro length to 336 km and the total number of subway lines to 14.请问这句话中the first phase of the No 15 Line是15号线第一段（路线）的意思吗?