The following is a condensed article written by D.B. Steinman, the chief engineer of the Mackinac Bridge. It originally appeared in Lawrence A. Rubin's book Mighty Mac, The Official Picture History of the Mackinac Bridge, published in 1958. It is reprinted here with Mr. Rubin's permission.

The Mackinac Bridge is the greatest bridge in the world. Its cost is more than that of the George Washington Bridge and the Golden Gate Bridge combined. The record cost of $99,800,000 is a measure of the magnitude and the difficulty of the project. Both artistically and scientifically it is outstanding. No effort has been spared to make it the finest, safest, and most beautiful bridge the world has ever seen.

The bridge is five miles long. In the middle of the bridge, in the deepest water, spanning a submerged glacial gorge, we have a suspension bridge bigger than the George Washington Bridge. With a length of 8,614 feet from anchorage to anchorage, Mackinac is the longest suspension bridge in the world.

Before construction, people said that the rock underlying the Straits, because of the unusual geological formation, could not possibly support the weight of a bridge. To resolve any doubts, outstanding geologists and soil-mechanics authorities were consulted. Exhaustive geological studies, laboratory tests, and "in-place" load tests on the rock under water at the site established, without a doubt, that even the weakest rock under the Straits could safely support more than 60 tons per square foot. This is four or more times greater than the greatest possible load that would be imposed on the rock by the structure.

The foundations were made large enough and massive enough to keep the maximum resultant pressure under 15 tons per square foot on the underlying rock. The foundations of the Mackinac Bridge contain more than a million tons of concrete and steel to form massive piers and anchorages. Three-quarters of this mass is under water, to provide enduring stability. These foundations will be more enduring than the pyramids.

Because the public has been alarmed by unscientific claims that no structure built by man could withstand ice pressure in the Straits, I added a further generous margin of safety. According to the most recent engineering literature on the subject, the maximum ice pressure ever obtained in the field is 21,000 pounds per lineal foot of pier width. In the laboratory, under specially controlled conditions for maximum pressure, the greatest ice pressure producible is slightly greater, 23,000 pounds per lineal foot. I multiplied this higher figure by five and designed the piers to be ultra-safe for a hypothetical, impossible ice pressure of 115,000 pounds per lineal foot.

The maximum pull of the two cables on the anchorage is 30,000 tons. Each anchorage has a mass of 180,000 tons of concrete and steel, providing a generous safety factor of six against the maximum cable pull.

The public has been irresponsibly told that no structure could resist the force of storms in the Straits. So I made the design ultra-safe against wind pressure, too. The greatest wind velocity ever recorded in the vicinity was 78 miles per hour; this represents a wind of 20 pounds per square foot. I multiplied this force by two and a half, and I designed the bridge to be ultra-safe against a hypothetical, unprecedented wind pressure of 50 pounds per square foot.

The main span at the Mackinac is a suspension bridge, which is inherently the safest possible type of bridge. In fact, by utilizing all of the new knowledge of suspension bridge dynamics, particularly my own mathematical and scientific discoveries and inventions, I have made the Mackinac Bridge the most stable suspension bridge, aerodynamically, that has ever been designed.

This result has been achieved not by spending millions of dollars to build up the structure in weight and stiffness to resist the effects, but by designing the cross-section of the span to eliminate the cause of aerodynamic instability. The basic feature of this high degree of aerodynamic stability is the provision of wide open spaces between the stiffening trusses and the outer edges of the roadway. The trusses are spaced 68 feet apart, but the roadway is only 48 feet wide.

These open areas constitute the scientific design. They eliminate the closed corners in which pressure concentrations are producible by wind, and they also eliminate the solid areas on which such pressure differences would otherwise act to produce oscillations of the span.

By this feature alone, (the open spaces between the roadway and stiffening trusses) the critical wind velocity was increased from 40 miles per hour to 632 miles per hour!

But I was not satisfied with raising the critical velocity to this fabulous figure. For still further perfection of the aerodynamic stability, I provided the equivalent of a wide opening in the middle of the roadway on the suspension spans. The two outer lanes, each 12 feet wide, are made solid, and the two inner lanes and the central mall, 24 feet wide together, are made of open-grid construction of the safest, most improved type.

By this additional feature of aerodynamic design - adding the central opening to the lateral openings previously described, I achieved a further increase in aerodynamic stability and raised the critical wind velocity from 632 miles per hour to a critical wind velocity of infinity!

Michigan's bridge is not only a scientific and economic triumph. It is also an artistic achievement.

Devoted thought and study were applied to the development of forms, lines, and proportions to produce a structure of outstanding beauty. A suspension bridge is a naturally artistic composition, with the graceful cable curves and the symmetry of the three spans, punctuated by the dominant soaring towers and framed between the two massive, powerful anchorages. There is a symmetry about each tower and overall symmetry of the three-span ensemble. The suspension span framed by the two lofty towers is "a harp outstretched against the sky," a net outspread to hold the stars. The bridge as a whole is a "symphony in steel and stone," a "poem stretched across the Straits."

For the painting of the bridge, I chose a two-color combination - foliage green for the span and cables and ivory for the towers - to express the difference of function. (I may be joshed about the "ivory towers.")

During the cable stringing, lights were strung along the catwalk for the night work. My suggestion that such illumination of the cables, necessary for construction, be made a permanent installation was enthusiastically adopted.

The Mackinac Bridge is my crowning achievement - the consummation of a lifetime dedicated to my chosen profession of bridge engineering. As far back as 1893, when I was a newsboy selling papers near the Brooklyn Bridge, I told the other newsboys that someday I was going to build bridges like the famous structure that towered majestically above us. They laughed at me. Now I can point to 400 bridges I have built around the world, and to my masterwork - the Mackinac Bridge - the greatest of them all.

The Mackinac Bridge represents a triumph over staggering obstacles and difficulties - some man-made and others imposed by nature. We had to overcome the difficulties of legislation and financing in the face of ignorance, skepticism and prejudice. The structure has been made generously safe t defy all these natural forces with an unprecedented high margin of safety.

Aerodynamically, it is the safest bridge in the world; in fact, it is the first long-span bridge ever designed and built to have perfect assured aerodynamic stability for all wind velocities up to infinity. This result has never before been approached or attained.

Finally, my staff and I are proud of our record of building the Mackinac Bridge within our estimate or cost and within our estimate of time. We have generously fulfilled our promises and commitments. We have kept faith with the Mackinac Bridge Authority and the people of Michigan. The Mackinac Bridge may well be called the bridge that faith has built.

THE CHIEF ENGINEER of the Mackinac Bridge, Dr. David Steinman, had the utmost confidence in his massive bridge - and perhaps an outsized ego to match. (Photo courtesy MDOT Photography Unit)