Why don't the airlines use the same so-called "mule" vehicles that pull them away from the gates to tow them along the ramps to the end of the runways for takeoff? Think of the huge savings. If the "mules" are not geared for sufficient speed, then refit them with gear boxes similar to those in semitrailer drive trains. Then start the plane engines only when they are first or second in line for takeoff.
Glenn M. Jensen
Salt Lake City