Simply because they wouldn't work very well. An aircraft can be held in place just using its brakes, even if the aircraft is at full power. I have seen this during noise tests on twin-engine military fighter: the brakes held while the engine was running at full power and on full afterburner. The tarmac melted a bit, but the aircraft stayed put. A jet engine would be unable to generate enough thrust to overcome the rolling resistance of a stopped train. Little test sleds are one thing, ten thousand tons - not even a particularly heavy train - is quite another. Not to mention the cost of doing this. A large gas trubine is a very expensive item, far more costly than diesels. And you would need more than one. They are also very expensive to run - and not just in fuel costs. How would you mount the gas turbines on a train? You need to provide a path for the exhaust - they are thrust engines. If you mounted them on top, the locomotive would be very tall and top heavy. If mounted on the sides, it would make the locomotive very wide. An increase in the amount of space allocated to railway right of ways would be hugely expensive. ------------------------------------------------------------ Re: "Gas Turbine locomotives were built in the 1960's but the thrust did not propel the train." Canadian National, CN, operated several gas turbine-powered, high-speed passenger trains - the Turbo trains. They were introduced in 1968 and were operated primarily in the Montréal-Toronto corridor. The last of them were retired from service in Canada in 1983. In 1979, some were sold to Amtrak in the US. They were built by Montreal Locomotive Works (MLW) and were powered by Pratt & Whitney PT6 gas turbines, built at the P&W plant in nearby Longueuil. A little information on the Turbo trains can be found at http://en.wikipedia.org/wiki/Turbo_(train) . The PT6 is a compact gas turbine used in smaller turboprop aircraft and in helicopters. Some 50 variants of the unit have been produced over the several decades it has been in service, including the PT6T TwinPac, which uses two PT6 turbines, situated side-by-side, driving a common gearbox. Information on the PT6 can be found at http://www.pwc.ca/en/3_0/3_0_0.asp . I never had an opportunity to ride the Turbo while they were in service, although other members of my family did. The interior finish was reportedly similar to that of an aircraft - quite a departure from the spartan commuter trains that I rode in the late 60s and early 70s.

Additionally, turbojets are very very loud. This would be a problem in residential areas.