Hyphens in the Highways

PHOTOGRAPHS BY NORMAN G. WALLACE-LAYOUT DESIGN BY GEORGE AVEY

So, leaving the builders to their technical skills, consider the bridges themselves. They are brave things, staunch and enduring, not only responsible for the continuity of the highways but holding the power to stop the story abruptly if they falter or fail. They have individual personalities, widely differing histories, and separate jobs to do but every bridge you cross has solved its own problem and is helping you solve yours, asking nothing for itself. They are so unassuming and dependable we accept their services without a thought but to me since I began to think about them in this way, they seem incredibly unselfish and patient, and mighty good friends to find along the way. In Arizona, according to the sort of person you are, you can appreciate or thoughtlessly snub a surprising number of these friends. Exclusive of dams used as bridges, of overpasses and of all structures with less than a twenty foot span, exclusive of thousands, many thousands, of concrete and metal pipe culverts, there are still more than twelve hundred major bridges CIVILIZATION WRITES its record across the land in the flowing lines of its highways. Cities, villages, the homes of men, like commas, colons, and periods punctuate the thrilling story and we notice them in passing, if for no other reason, because they tend to slow us down. For exactly the opposite reason the fact that it does not slow us down but speeds us on our way the most indispensable punctuation mark of the highways is almost universally passed over unnoticed. This is the hyphen, that essential line joining the road together where chasm would otherwise interrupt it-big bridges, little bridges, overpasses, culverts any piece of highway that runs along in the air when solid ground dips below a level convenient to the traveler.

Wherever a thing like that happens somebody has had to do a lot of persuading, it simply is not natural for a road to leave its bed and take to the air. This thought decided me to get acquainted with a few bridge engineers and let them tell me just how the persuading is accomplished. They tried. You've no idea how earnestly they tried but to this moment the secret of why bridges bridge is still a mystery to me. The job of making them do it is hard, scientific work, not to be mastered con-versationally of steel and concrete in the state to speed your humming wheels over the three thousand six hundred and twenty-four miles of state highways. Proportionately this is a large number. Florida, abounding in swamps and water, has less than two thousand bridges (more than one thousand being all timber construction) on over eight thousand miles of highways while the old state of Ohio with about thirteen thousand miles comprising its highway system shows in a recent report about seven thousand bridges of more than ten foot span. This raised to a twenty foot basis would undoubtedly cut this number considerably. So it is safe to claim that a state by state bridge census would place Arizona high on the list, not only in numbers but in quality. R. A. Hoffman, Bridge Engineer of the Arizona Highway Department, was accommodating enough to lay the major bridges end to end for me in a way of speakingand they added up to more than one hundred and fifty thousand feet of highway running in the air. I tried to pin him down on lesser bridges and culverts but even I could see that would entail an endless amount of calculation.

On maps Arizona is a block of country arbi-trarily marked off in what is called the Great Southwestern Desert. It is, therefore, designated as a desert state and according to all pictures of deserts its rivers should be negligible and its surface flat, requiring few bridges. Which proves pictures fool you sometimes. As a state Arizona may be short on rivers but the ones it does have are far from negligible; and as to being flat, it has more wrinkles than a baked apple, with one so deep it is celebrated as a Wonder of the World the Grand Canyon of the Colorado. As a matter of fact writing high-ways on such a rugged surface and hyphening up all the gaps is no sissy job in Uncle Sam's Baby State. It is true that in comparison with the broad, slow-rolling Mississippi there are no large riv-ers for Arizona bridges to deal with. But desert rivers, though not monsters in size, do strange things; sometimes they run, sometimes they don't; from year to year they unpredictably reroute their channels, eat their banks and tear out abutments; some hide underground and lie in wait so long you'd think they were dead but always, sooner or later, they wake up fighting and look for a bridge. The San Pedro tried that trick in 1926 and demolished eleven bridges in eleven hours. No, they couldn't be called negligible. Instead, they are erratic, more or less mad, and when they are on their way have abnormally destructive habits.

THE HIGHWAYS BY GUSSE THOMAS SMITH

In addition to river eccentricities desert bridges also combat their own peculiar foundation problems. Often side by side rock, solid to the earth's core, and sand, unstable for hundreds of feet down, must be broken and harnessed as a team to bear thousand-ton loads of steel and concrete. Double trouble results when sand and river work together as they frequently do.

This is notably the case with the Hassayampa on highway 70-60-89 south of Wickenburg. It is said that just one drink of water from that river of subversive influence is enough to destroy any man's veracity for life so it is not surprising that the hard-drinking sand at the foundations of a succession of Wickenburg bridges has proven traitorous and untruthful. When you cross the Hassayampa there give that bridge considerable credit for being there at all.

The hardest working bridge in Arizona also has the distinction of being the most beautiful. The scientific traffic count maintained by theHighway Planning Survey Department proves the first part of that statement and the Encyclopedia Britannica establishes the second. This is the Tempe bridge over Salt river east of Phoenix and you will find its picture, with that of only one other bridge praised for aesthetic preeminence in modern bridge architecture, in your encyclopedia. With its ten multiple arch spans it is also the longest and largest concrete bridge in the state; and it was this hyphen joining Phoenix and Tempe, adding to both greater meaning and usefulness than either could ever attain separately, that suggested my present efforts for increased appreciation of all bridges.

Highway Planning Survey Department proves the first part of that statement and the Encyclopedia Britannica establishes the second. This is the Tempe bridge over Salt river east of Phoenix and you will find its picture, with that of only one other bridge praised for aesthetic preeminence in modern bridge architecture, in your encyclopedia. With its ten multiple arch spans it is also the longest and largest concrete bridge in the state; and it was this hyphen joining Phoenix and Tempe, adding to both greater meaning and usefulness than either could ever attain separately, that suggested my present efforts for increased appreciation of all bridges.

In the work it is doing now and has done for centuries in supplying irrigation water to peoples along its lower course, the Salt river, in spite of its prosaic, misleading name, is Arizona's most important stream, and its many bridges are equally outstanding. To cite only two in addition to the Tempe beauty-first, the most expensive bridge entirely within the state, the Roosevelt Dam, costing millions but putting a stop to most of the river's earlier wastefulness; second, the newest, called Salt river bridge, on U. S. highway 60, midway between Globe and Showlow, connecting the low desert country with the White Mountain area.

For sheer grandeur the setting of the latter is incomparable; the stupendous sweep of scenery as the highway curls its way downward from the towering mountain tops to the depths of Salt river canyon challenges the magnificence of the Grand Canyon itself. Yet, from miles away, in spite of the immense proportions of the landscape, the grace and beauty of the bridge dominates the picture. All the way down from the canyon rim come frequent breath-taking glimpses of the extremely elongated, fairy-like S of silvery steel. At first it seems fragile and dainty, its end-curves touching lightly the stern, black canyon walls, but when you descend at last to its level the true size and strength of its foundations as well as the length of its span are impressive. Its presence there at all is spectacular, and you realize this more fully if you remember that this bridge is eighty miles from any railroad and that all material, some single pieces weighing as much as ten tons, had to be hauled that distance and be brought down the rugged walls of the canyon. Few states in the Union have as many major bridges in remote locations as Arizona. Which brings us back to the subject of the more or less unique difficulties encountered by desert bridges and their builders.

One of the biggest surprises of my blundering about behind the scenes was the discovery that the beneficent desert sunshine, so lavish in its gifts of health and happiness to man, creates definite symptoms of St. Vitus Dance when it falls on steel cables and girders. The story of the Dome bridge is essentially a struggle with the sun. This magnificent suspension bridge crosses the Gila river twenty miles upstream from Yuma and is the longest and largest of its kind in the state, having an eight hundred foot clear span. A particularly troublesome combination of sand, rock formation and river scour, precluding the use of stepping stones, forced the bridge to swing across the whole distance on cables.

In furnishing these cables a group of world famous eastern contractors experienced the same surprise I did in regard to the potency of the desert sunonly theirs cost them money and trouble. To construct the cables at the bridge site they erected massive concrete emplacements at required distances to serve as rigid anchors around which the cable ends were secured. These pillars were no flimsy affairs! They weighed tons and stood deeply emplacéd on solid concrete foundations. Hundreds of strands of heavy wire, stretched taut by men sweating under the July sun, had no more unsettling effect on their stability than so many cotton strings. But the sun went to bed, the men went to bed, and the thermometer went into reverse. When the temperature dropped fully fifty degrees, as happens every night in desert country, the hot, relaxed cables, shocked by the sudden chill, drew knees under chin and gave the anchors such a pull they toppled out of line, leaned toward each other, and gave up the struggle to stand erect.

Mr. Hoffman ended the story by saying briefly that the eastern contractors were forced to change their standard method of winding cables and that, thereafter, all work was done by night instead of by day in deference, of course, to the sun, not the men. In this way so far as the building of that bridge was concerned man outwitted the sun but even yet that same sun heckles that same bridge day in and day out. On account of the extreme variation in temper-ature, daily equalling or exceeding the average yearly variation in most parts of the United States, these cables expand and contract with

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