The reason isn&#x27;t actually so silly.  Because BART is a single track-per-direction system, they have to shut the system down in order to do nightly track maintenance.  The decision to make the system single-track was made when BART was planned in the 60s.<p><a href="http:&#x2F;&#x2F;www.bart.gov&#x2F;guide&#x2F;latenight" rel="nofollow">http:&#x2F;&#x2F;www.bart.gov&#x2F;guide&#x2F;latenight</a>