Freight crews used cabooses, or cabin cars, as lookouts, rolling offices, and home away from home, climbing into the cupola to watch the train ahead for trouble such as smoke from an overheated axle bearing or a shifted load that could cause a derailment, doing paperwork there, sleeping in bunks at the end of a run, storing clothes and tools in bins, and cooking and heating with a coal-fired stove; many such cars could fill ten tracks with crews resting or eating before their next run. The Pennsylvania Railroad, often called the Pennsy, used the distinctive name cabin car, and its N5 class, introduced in 1914, was the industry's first all-steel caboose; this car was built in Altoona in 1929. As safer wheel bearings, reliable radio communications, and electronic trackside monitoring of axles came into use, cabooses were phased out, and today they are used mostly on local runs with long back-ups where it is unsafe for crew to ride the side or end of a freight car, while crews away from their home terminal now sleep in a motel.