Third rail
M8s have the additional capability of running east of New Haven and along the Hell Gate Line west of New Rochelle to Penn Station over the former Harlem River and Port Chester Railroad. In order to run east of New Haven, the M8s are equipped with Advanced Civil Speed Enforcement System (ACSES) as required by Amtrak. In order to run from New Rochelle to Penn Station, the cars will be equipped with third rail shoes that can operate on both over- and under-running third rail systems. Third rail will have to be extended in Queens for the M8s to overcome a gap between suitable catenary (Amtrak's catenary supply changes in Queens from the compatible system to the incompatible , the M8s would need to have extensive modifications in order to support the electrical system) and the third rail utilized by the Long Island Rail Road.