In fact within a dozen years after its christening the wonderful depot was overtaxed. Even Vanderbilt's vision could not grasp the growth that was coming, not only to New York, but to the great territory his railroads served. In a dozen years workmen were clearing a broad space to the east of the main structure for an annex train shed of a half-dozen tracks, to relieve the pressure upon the original station. Another twelve years and the laborers were again upon the Grand Central, this time adding stories to the original structure and trying to simplify its operation by new baggage and waiting rooms. Within the third dozen years the workmen were busy with air drill and steam shovel digging the great hole in the rock that was the first notice to the old Grand Central that its short lease of busy life was ending. And in the fortieth year of its life they were tearing down the old station--old within the span of two generations--old only because it had been outgrown. * * * * * The problem of the new Grand Central was both engineering and architectural. It is the engineering side of the problem which interests us here and now. It was that side which it was necessary to solve first. To solve it meant that the passenger traffic into New York from the north and east for another fifty or a hundred years must be discounted--not an easy matter when in the case of a single famous trunk-line railroad it has been found that the passenger traffic has doubled each ten years for the past three decades. When the statisticians put down their pencils the engineers whistled. To fashion a station for the traffic of 1960, even for that of 1935, meant such a passenger station as no railroad head, no engineer, no architect had ever before dreamed of building. At a low estimate, it meant that there would have to be some forty or fifty stub-tracks in the train shed. In the great train shed of the Union Station of St. Louis, there are thirty-two of these stub-tracks and the span of that shed is 606 feet. That would have meant in the case of the new Grand Central a train house with a width of nearly a thousand feet. The engineers shook their heads. They knew their limitations--with the Grand Central hedged in by the most expensive real estate in the city of New York. To buy any large quantity of adjoining land for the new station was quite out of the question. Fortunately there was a way out. There generally is. The electric locomotive had begun to come into its own. For the operation of this station, including the congested four-track tunnel under Park Avenue, from the very throat of the train-shed yard up to Harlem, four miles distant, it represented an almost ideal form of traction, largely because of its cleanliness and freedom from smoke. For the engineers who were giving their wits to the planning of a new terminal it was the solution of their hardest problem.