I took the from 50 St to Atlantic Av-Barclays Center to take the LIRR home. When the got to 36 St, the was across the platform on the local track. The left first, then the came in and left followed by my train finally leaving 36 St. My train passed by the train express at 25 St but never passed by the . What was the doing on the local track? Does this usually happen?