The recent presidential inauguration was an unusual special event, even though inaugurations happen every 4 years in Washington, D.C. Among the more noticeable features were the temporary chain link fences used for crowd control.
I hope to see some additional analysis of the special event planning, but this article provides a start: Lessons on emergency preparedness from the presidential inauguration
I did find a 30-page Guide for Planning Special Events from the DC Homeland Security and Emergency Management Agency, dated 2016. I imagine a revision may be coming.