Heat-related metro delays along Blue Line

WASHINGTON — Attention Metro riders: You should expect delays during your evening commute along the Blue Line. 

On Monday, Metro said trains are single-tracking between Pentagon City and National Airport because of a heat-related track defect outside of Crystal City. Delays are expected to add 20 minutes to riders' commute.

Some trains traveling along the Blue Line will be offloading at specific locations to minimize congestion, then turn around to keep other trains moving. 

WUSA9 Meteorologists have issued an excessive heat warning as the heat index is expected to reach 110 degrees. Metro did not say how long trains along the Blue Line would single-track.