Ok so I have done some experimenting and have realised that it will be better to just make the segment of the whole subway one piece this does sacrifice on quality a little bit but performance wise it is allot better and I don’t have any problems with gaps in the planes once it gets imported into unity. So one segment is modelled and the train tracks are as well I also need to do a seat so ill get some reference for it now. While I'm doing that I might model the pylons that will give the subway its believable structural integrity. As far as seats were concerned I was thinking of a combination of the three below with possibly less wood panels to reduce pollies a quick estimate of the object and I have calculated it to be around 300 at the maximum pollies well I am going to model it now and see how many I can make.