Shortly after 9 a.m. this morning, a “system wide radio communication problem” caused a noticeable delay along Metro’s Red Line. Normal service resumed about an hour later.

At least one riders reported that the Red Line appeared to come to a “complete halt” due to the communication breakdown. WMATA spokesperson Dan Stessel explained to us that the issue was exacerbated when an operator had to use a platform phone at the Medical Center station to communicate with Metro Central Control. Most Metrorail service, Stessel notes, was unaffected by the radio issue.

“It’s important to note that the routine movement of trains is governed by signals, not radios,” Stessel said. “So, with the exception of the Red Line delay noted above, trains continued to operate normally.”

Stessel also said that WMATA is looking into the cause of the radio failure.

UPDATE: Stessel follows up, and tells us that the problem was not a infrastructure issue. Rather, the radio problem developed after “a foot pedal used to key the mic on a console in Central Control was stuck” and the “open mic prevented other radios from broadcasting.” Someone get WMATA some WD-40, stat!