This goes not just for safety but for operations. Metro has learned how to maintain shorter headways consistently, for example. Now for the first time, Metro has the added challenge of coordinating shared use of light-rail track. Thus, the Flower Street segment is especially important to get right, and if necessary, "over-engineer".
On the subject of Flower Street, does anybody know how the signal timing is going to work? I understand that now it currently works such that trains leaving at the right time from 7th street catch the green lights, but once Expo comes online, there will all of a sudden be twice as many trains. Has the DOT commented on that at all?