If you ride the Yellow or Green Line for your morning commute, leave yourself some extra time Friday morning.

Both Metro lines experienced residual delays after the Yellow line was forced to single-track some trains for about an hour.

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WMATA made the temporary changes due to a cracked rail outside the Pentagon station.

Cracked rails on Metro lines sound alarming, but they're actually fairly common in transit systems. News4 covered the issue back in 2018 , when our own Adam Tuss reported three cracks that year, 13 in 2017, 31 in 2016 and 35 in 2015.

However, if cracked rails are left unattended to, they can cause bigger problems, such as train derailments.

That's why Yellow Line trains single-tracked between Pentagon

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