The LIRR Bay Ridge Line continues to the northwest in a trench running through Midwood.
McDonald Avenue / Avenue I Station: The tracks cross under McDonald Avenue, which at this point hosts the elevated BMT Culver Line (F train). At the time the original Bay Ridge Line was built, McDonald Avenue was called Gravesend Avenue and the Parkville station was located here.
The 2006 Hagstrom street map I have still indicates a spur of some kind extending to the southeast of the Bay Ridge Line and, presumably, into whatever was in this area before it became a ShopRite grocery store. The large, decrepit concrete building to the south of the ShopRite certainly looks like it had an industrial past and whatever the ShopRite was before the facade modifications may have been industrial as well. However, I found no trace of the spur in the pedestrian passage between the dead end of 19th Avenue and the retail area, and whatever cut was there may have been filled in - unless there's a hidden tunnel?)
This intersection presents some challenges for direct transfer between lines as the Bay Ridge Line passes a few hundred feet north of the end of the platform for the Avenue I elevated station. One suggestion from the RPA's 1996 proposal is to construct a tunnel down McDonald Avenue to replace the slow-moving elevated track. The Avenue I station would then, presumably, be integrated with the rail-line station. As much as the businesses and residents of the area would probably like a tunnel (but reject it because of the street disruptions needed for its construction), the costs and complexity of such a modification (whether deep-bore or cut-and-cover) would only add an additional obstacle to getting anything built.
Next: Avenue H Station, Flatbush, Brooklyn