Several ways to solve this one:
First, find out how much soap is used annually by NYC train authority to clean windows, estimate total fleet size, frequency of cleaning schedule, soap needed per square foot, number of windows per train - and you got your answer
Second, windows are held by rubber caulking. They tend to get brittle over time and need replacement, FInd out how many feet of rubber caulking was purchased by NYC train authority ( probably the same person who gave you the soap used), estimate lifetime replacement cycle of rubber caulking, number of trains in system, number of windows and with the circumference get the total area
Third, train windows shatter rather often. Estimate number of shatters/year/train. Ask the same guy at NYC train authority how much glass they buy each year, use the same info as above and you'll get the glass area
Fourth, Google Bombardier's web site, ( the manufacturer of NYC trains) , find the right - or approximate picture of train in web site. Web site probably also gives typical dimensions of trains and thus estimate window size ( # of windows too). Alternative, estimate window size by comparing known entities in pictures ( eg.. human being, lamp post, etc. etc) and work from there to get window dimensions. You can probably get the exact # of windows from one of these nice sales pictures Bombardier has in their web site
Finally, go to Linkedin, pose the question - who works at PPG ( the glass manufacture of these windows) and get him/her to provide the right area per window, Estimate # of windows from above other options and get the necessary square footagekarchimex
