 Although not allocated to the depot, Class 91, Class 180 and Class 800 units, as well as HSTs may also be visible with Grand Central, TransPennine Express and London North Eastern Railway storing units and/or contracting out maintenance at this depot.Northern Class 158s, Class 144s and Class 150s also regularly visit Heaton for maintenance.Network Rail's New Measurement Train is allocated to Heaton, and returns there regularly for scheduled maintenance.