Metro had a plan to run more trains on the Fourth of July. It didn't happen. – Greater Greater Washington
A draft proposal floated by Metro could have allowed the agency to run more trains for the Fourth of July. But in the end, Metro didn’t ask permission from the independent Metrorail safety oversight commission to do so, and the agency settled for amassing as many of its older railcars for the post-firework timeframe that it could.
Source: ggwash.org