What is Catenary Wire?

Amtrak Cat Car

The polar vortex continues to sweep the country and record low temperatures are being reported from the Midwest to the Southeast and Northeast.

What does this mean for Amtrak trains running along the Northeast and Keystone corridors? These two services are powered by an overhead wire system called a catenary system. The catenary system provides electrical power to these trains, allowing them to move quickly up and down the corridor. Dramatic swings in temperature (both hot and cold) can cause the catenary wires to expand and contract.

In extreme cold, like what we are experiencing due to the polar vortex, the tension that supports the wires increases tremendously as they contract.  These large tension swings can sometime cause components in the catenary system to fail.

The wires are electrified so power along segments where catenary wire has been damaged must be shutdown, sometimes causing a stoppage of service or delays in the area. Catenary wire is repaired by Amtrak engineering crews using a specialized maintenance vehicle nicknamed a “cat car”, which must be moved into the area in order to make repairs.  As always, our goal is to keep the trains moving and minimize delays, so our crews always work as quickly and safely as possible to restore the catenary systems and return the system to its full capacity.