Huh? I see this sign frequently. So I went ahead and figured it out. The diagram below reveals the door schedule. I assigned a number to each of the times the door is closed, 1=9:30 pm - 4:00 am ; 2 = Monday - Friday; 3= 9:30 pm etc.. So I guess they only unlock the stair wells on weekends when no one is in the office. Must be a security measure. :)
| Sat, Sun | Mon | Tues-Thurs | Friday | Holidays | |
| 00:00am-04:00am | 1 | 1,2,5 | 1,2 | 1,2,4 | 1,6 |
| 4:01-9:29pm | OPEN | 2,5 | 2 | 2 | 6 |
| 9:30pm | 1,3 | 1,2,3,5 | 1,2,3 | 1,2,3 | 1,3,6 |
| 9:31pm-11:59 pm | 1 | 1,2,5 | 1,2 | 1,2 | 1,6 |
