I really wish they would build trains with 4 doors instead of 3
The idea of 4 doors per side was proposed when the specification for the 4k car procurement was being drawn up. The staff shot the idea down because of the added weight of the structural elements that would be necessary to allow for 4th door opening. The 7k cars are allegedly causing vibration issues because of their greater weight. The 7k cars are similar to the rest of WMATA's rolling stock in that they are of monocoque type construction. Adding a 4th door opening would require the cars to be heaver for the same reason. I will also note that latest generation of cars procured by NYCT are heaver then WMATA's 7k cars, are 15' shorter and have 4 doors per side. Some but not all of that weight is in the heaver trucks used under those cars.
John in the sand box of Maryland's eastern shore.