The Metro North/ Department of Transportation Geometry Train cruises over the Harlem Line and exits the New Haven Line on the Woodlawn Junction flyover in the Bronx borough of New York City. The train is tasked with traversing all of Metro North's mainline track while the middle coach, DOTX 221, collects geometry data reports for the FRA and US Department of Transportation.

The DOTX 221 is an ex- Canadian National Pullman coach painted in Pennsylvania Railroad colors equipped with a track geometry measurement system, a rail profile measuring system, and other state-of-the-art instrumentation for conducting railway research.