Does anyone know why Montrose bridge over Allen Parkway was closed this morning?

Live in Montrose, commute to Heights and usually take Montrose to Studemont into the Heights on way to work. Today, at the bridge over Allen Parkway,!cops were diverting traffic away from the bridge and barriers were set up. Couldn't see any construction on Allen itself (and when I left work a little while ago, bridge was open). Diverted through downtown and it looked like there were other Allen-adjacent streets closed as well. I tried some cursory Googling but couldn't find anything useful. I feel like it was also inexplicably closed a few weeks ago (the Saturday after the marathon, I think.) Anyone know what's up with the closure?