Indiana Harbor Belt and other "terminal railroads"

[cthart]

Hi again,

According to
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the Indiana Harbor Belt is "the largest terminal railroad in the US". What is a terminal railroad?

According to
<!-- m --><a class="postlink" href="http://www.ihbrr.com/">http://www.ihbrr.com/</a><!-- m -->
they call themselves "the largest switch carrier in the US"...

Can someone describe to me -- in overview -- how this railroad operates?

Thanks,

Colin