New York City in both of its stations – Grand Central and Pennsylvania Station – do not permit diesel exhaust in their tunnels due to the health hazard. As such, diesel service on Metro-North, Long Island Rail Road, and Amtrak uses special diesel-electric locomotives that have the ability to be electrically powered by third-rail. This kind of locomotive (for example the General Electric P32AC-DM or the EMD DM30AC of LIRR), can transition between the two modes while underway. The third-rail auxiliary system is not as powerful as the diesel engine, so on open-air (non-tunnel) trackage the engines typically run in diesel mode, even where third rail power is available.