While there this past week, we rode in a train that had larger sides to the cars. The older trains have no sides to the cars. You just step right in and the flooring of the car is level with the flooring of the loading area. For one of the trains we rose in had, there was an enclosing 10 inches or so of metal that you had to step over. No big deal, but it did seem a little safer (and I wasn't as worried about losing my backpack). Perhaps this is what they're renovating since all the cars did not have this new 'protection.'
RyMickey