Dual-mode locos?

[tbdanny]

Aside from the FL-9s, were there any other locos designed to be both diesel-electric and switch to getting their power from an external supply?

[pajrr]

Dual-mode locomotives are very prevelant here in the NY City area. Amtrak uses P32ACDM, Metro- North uses P32ACDM. These are the replacements for the former NH FL-9. Long Island RR uses DE30AC-DM and NJ Transit is purchasing a dual mode model as well. The Hudson River Tunnels and East River Tunnels (both ex-PRR) and the Park Avenue Tunnel (ex-NYC) do not permit diesel operation. That is why all passenger carriers serving NY City have Dual mode locomotives, straight electric or MU equipment. The only "traditional" units (before Amtrak or commuter agencies) I believe were the New Haven FL-9s. There were various experimental and industrial switchers made, but the FL-9 was the only "mainline" type that I am aware of.

[CSSHEGEWISCH]

We should also add the various tri-powers (straight electric, diesel, battery) and dual-powers (diesel, battery) of the 1930's on NYC, DL&W and RI.  North Shore Line also had a pair of dual powers (straight electric, battery) that worked local freights and could switch industrial spurs that didn't have overhead wire.

[Jerry Pier]

The prohibition in the tunnels is not just for diesels but for any combustion engine. The rule was imposed by the NYC Fire Commisioner in the 19th century and while it was written for prime movers, it has since been applied to APU's as well. The RTL Turboliners had dual mode traction but retained the gas turbine APU for hotel load. The RTLIII Turboliners included DC inverters for in tunnel operation. II is interesting to note thet the 3rd rail system, which runs for only 7 minutes per trip, costs as much, or more, as the primary power system.