Nothing new under the sun

I lived with a railroad signalman in college and he used to drive a convertible rig -- a heavy truck that could drive either on the streets or on the tracks with retractable steel wheels.

Apparently someone noticed that this might be a great idea for lots of applications. Watch:

I lived with a railroad signalman in college and he used to drive a convertible rig — a heavy truck that could drive either on the streets or on the tracks with retractable steel wheels.

Apparently someone noticed that this might be a great idea for lots of applications. Watch:

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