Crossing at Glen Canyon

War. But in this century, the enemy is the hostile country itself. To change the face of the land and the life of its people, the Bureau of Reclamation plans one of the world's largest dams. The site, far up in northern Arizona near the Utah border, where the Colorado River, over the millenniums, has carved out Glen Canyon, a chasm 700 ft deep and 1,000 ft across. But this is the middle of nowhere. And for the truck and heavy equipment that will build the dam, the banks of Glen Canyon are 200 mi apart. 200 roundabout mi of hard desert driving. The gorge must be spanned. The Bureau draws up blueprints for the world's highest arch steel bridge, graceful in design, daring in concept. The question of how to build a bridge is left up to the low bidders on the project, the joint venture of Peter Kiewit, Judson Pacific Murphy. It was the how that was the challenge at Glen Canyon. For like most living things, a growing bridge must be supported until it can support itself. And how can thousands of tons of steel be propped up with nothing but a roaring river far, far below? The bridge builders' engineers are flown in to inspect the site. The how was the challenge for these men. Their answer, if the growing bridge cannot be propped up from below, it must be suspended from above. This was how the bridge grew in the minds of these engineers. First, highlines must be spun from tall, slender towers. A smaller one to ferry men and lighter loads, and a stronger one for setting steel. Concrete foundations will be poured for the roadway on top and for the supporting arch. But the key part of their solution is the holdback towers that will support the growing arch from above. From these towers cables will stretch down into the canyon to carry the weight of the blossoming spiderwork of steel. With the arch completed, the bridge will be self-supporting. The new highway can then be laid and the web of towers and high lines removed. The bridge has been built in the minds of these engineers. It will be up to their steelmen to put the idea together at a height greater than the Washington Monument. February 1957. Work begins. But the first step is to build a small city to house the construction men and a call tower for the radio network that will link the teams on either bank. The surveyors move in. This is where a thousandths of an inch can mean a million dollars. Seeking tiny footholds and crannies for their delicate instruments, the surveyors paint their strange hieroglyphics on the ancient rock, marking out the caves that must be blasted in the cliff 200 ft below the canyon rim. These excavations will hold the concrete foundations or skewbacks for the arch itself. The scalers go over the side in bosun's chairs and with acrobatics drill the holes for the blasting charges. The dynamite men follow, using only small charges for fear of disturbing the towering sandstone walls. And the caves the Colorado neglected to carve out millions of years ago are blasted into existence by dynamite in a matter of weeks. Inside these excavations holes are drilled 30 ft deeper into the rock and dowel rods inserted to form the roots of the arch. On the mesa above the truck crane arrives to raise the 120 ft tower for the first high line. The tower seems immense but it and its twin on the other bank will carry the smaller of the two high lines, the one to be used for ferrying men and lighter loads across the canyon. With the first towers up the cable for the lighter high line is spun out across the chasm like a strand of silk from a spider. A strand 2 in thick made of the strongest possible steel. It is a spinning job that calls for a little fancy footwork on the spider's part. Fancy footwork and a strong grip. It's now July of 1957. Five months have passed and the only direct communication across the gorge has been by radio telephone. But now the aerial tramway is ready to roll. The complexity of spinning wheels and whirring cables that will pull the passenger cage back and forth across the canyon is tested and works well. What was once a 200-mi trip by jeep or truck is now only a giddy thousand-foot hop for the passenger high line. Time of trip 2 and 1/2 minutes. Capacity 12 tons. At least its passengers hope so. This type of commuting may not be quite as comfortable as the banker's special but it is far more refreshing. And the vistas are superb. Heavy equipment was moved across the chasm to the heretofore inaccessible far bank. Meanwhile, back at the skewbacks, they are ready to pour the concrete foundations for the arch. The forms are up and the reinforcing rods woven into the steel sinews that will give the concrete the strength to withstand the tremendous pressures the arch will place upon it. Like dentists, the construction men take a final look at their drilling work before they fill the cavity. Bring on the concrete. The recipe for concrete includes sand and water. But strangely enough, in the middle of a desert with a swift-flowing river less than 1,000 ft away, both sand and water are in short supply. The right kind of sand is difficult to find, and the muddy Colorado has been aptly described as too thick to pour and too thin to plow. Before its waters could be added to the recipe, they had to be piped to big settling basins where the rich sediment gradually drifts down to the bottom. Water for the new city itself was an even greater problem. And in the beginning, it had to be trucked to the site from the closest town, Kanab, Utah, 75 mi away. To get the expensive mixture down to the skewback excavations, the passenger highline goes into the freight business, hauling the big concrete bucket back and forth and up and down to the skewback excavations. There, the bucket is positioned. The latch pulled, and slowly the caves fill with concrete. The taller towers for the main highline now go up alongside the first ones. The main highline, a cable 3 in in diameter, will stretch high over the center line of the bridge, carrying up to 27 tons of steel at a time. But the bridge is 40 ft wide. And And to set the steel along the edges, these towers must be hinged at the base so that they can be tilted or left laterally, swinging the Highline 20 ft to either side. With both cableways in operation, the chunky 120-ft high holdback towers go up and are crowned with giant steel saddles. These towers are the crux of the whole project. On their broad shoulders rests a grave responsibility. For the cables that will support the growing arch down in the canyon, will be anchored to the saddles on the tops of these towers. To take this tremendous strain, concrete deadmen are sunk into the desert 265 ft back from the base of each tower. And cables are stretched from these deadmen back up to the saddles. The site is ready. It's time to bring on the steel. It's a long, long way from the Judson Pacific Murphy Fabricating Yards on the shores of San Francisco Bay to the middle of nowhere. Specifically, it's 800 mi by train to Flagstaff, Arizona. At the railhead in Flagstaff, a special crane must be built to transfer the heavy steel to the trucks. And then come a grinding 145 mi across the desert to the bridge site. On the first leg out of Flagstaff, the highways are good. But, on the last stretches, new roads must be laid across the wastes of sand and sagebrush to get the lumbering trucks to the stockpiling yard near the canyon's edge. From here on in, it will be up to the trains and the trucks to keep ahead of the steelmen. February 1958, a year of hard work has gone into erecting the towers and pouring the foundations, and only now is everything ready for the first piece of steel. This is the skew back shoe, a 23-ton chunk of metal that will sit solidly on top of the concrete foundations for the arch 200 ft down the face of the cliff. This example of man's handiwork, so smoothly machined, so perfectly crafted, seems strangely out of place in the weathered rock and shifting sands of the rough, convoluted country, almost like a visitor from another world. Those 12 holes in the polished base of the shoe must fit exactly over 12 anchor bolts embedded in the concrete foundations, bolts which will lock the arch in place. Upper here. Easy with the load. The age-old sign language of the men who build. Now then, madam, let's just slip the shoe on for size. This is an important link. Upon the four shoes, two on each bank, will rest the main weight of the bridge, more than 3,500 tons of steel. There you are, madam, a perfect fit. The roots are in, and the bridge is ready to grow. On the mesa above, the first cord of the arch, 54 ft long and weighing close to 27 tons, is plucked up by the main highline, and soars into the desert sky like some strange new species of bird. Then plummets over the rim down into the gorge. A pattern of flight that will become only too familiar in the next few months. In the gusset plates in one end of the cord are large holes that must line up with holes in the shoe. A steel pin, 16 in in diameter, will slip through these holes like a giant collar button hinging the cord to the shoe. The birth of a bridge brings forth the photographers like opening night at the theater. The steelmen are waiting nervously in the wings for their cue. So excited they can hardly eat a bite. The big steel pin is pulled through the holes with a jack and the first cord is hinged into place. The connectors now go to work high over the Colorado. The cord is still being held up by the big hook from the main highline far above. But the highline is needed to set more steel. Thus the first tieback cables are jacked into position to take over the job of supporting the newborn bridge. The tieback cables are attached and stretched tautly over the canyon rim to the holdback towers above. The first cord is now in suspension and the passenger cage swims over to take a look at this strange new object protruding out into its canyon. A giant piece of steel that seems but a matchstick in these surroundings. The other bottom cord is now set in place 40 ft from the first. This will be the width of the bridge. The main highline had to be swung 20 ft to the left to set the first cord and 20 ft to the right to set the second by luffing the towers on the mesa above. And now it is as though the bridge had emerged from its womb in the cliff out into the desert sunlight. With its roots well set, the bridge shoots forth rapidly feeding on a steady diet of ponderous steel members. Its appetite is voracious and the highline makes trip after trip carrying the steel high into the air, out over the chasm and down to where the arch is growing quickly up across the canyon. There the steel men go about their jobs as casually as though a solid factory floor were just beneath their feet. Instead, they get no hazard pay for this hazardous work. They get only the satisfaction of building. The satisfaction of putting pieces together to make something entirely new, something that will serve a useful purpose, something that will fill a need. And so the arch grows. The vertical, diagonal, and transverse members, the top and bottom chords are joined one to the other to form a box-shaped truss capable of bearing tremendous weights. The function of each slender piece of steel, the stresses it must take, and the loads it must bear have been calculated well in advance by the builders' engineers and the figures checked and rechecked until there is no room for error. Thus the arch soars forth reaching up over the river. And from the other bank, far across the chasm, its twin stretches out waiting arms. The very life of the bridge and the life of each man who builds it hangs upon the tieback cables taut as violin strings. As the arch grows, more and more cables are brought into play to carry the ever-increasing weight. More than 9 mi of these cables are needed to hold the arch. Each cable an inch and a half in diameter. The cables are attached to yolks and the yolks secured by big pins to special gusset plates riveted to the cords when they were fabricated in Emeryville months before. And as the bridge grows, so does the strain on the holdback towers high above. 100-ton jacks adjust the tension on the cables. Water is used in these hydraulic jacks instead of oil for fear that a leak would mean slippery footing and this is no place to slip. The jacks were constantly in use delicately adjusting the tensions on each set of cables. These tensions were measured time and time again with dynamometers as a triple check on the loads the individual cables were carrying. No way could be found to measure the tension on the engineers. A cardinal rule of bridge building is that when you work your way up to a good position, stick to it. For the man on his way down, there are safety nets. These heavy Manila nets stretched under the growing bridge at all times are largely responsible for the remarkable safety record compiled on the hazardous project. Not a single life lost and only a few minor injuries. The big nets are lowered into the canyon as a fisherman might dip for fish. Only here the catch will be in human lives. Of course you have to start somewhere and there are no nets stretched beneath the men who stretch the nets. But it's a worthwhile risk. Three times during the building of the bridge men slipped. Three times the safety net did its job. When a friend loses his grip and plummets down towards a roaring river hundreds of feet below, there is no better feeling than to see him clamber back up again a few minutes later. Besides, nothing beats a net for a lunchtime siesta. As the solid ponderous rectangular chunks of cold steel are fed into the growing arch, they're magically transformed into a living creation of spidery beauty. A metamorphosis that never ceases to delight. The arch was literally built twice. Once over the Colorado and once earlier in the Judson Pacific Murphy Fabricating Yards in Emeryville. By laying out the arch on the ground, 21 panels at a time, the engineers could physically control the alignment and camber. And only then were the holes for the rivets drilled full size. Even so, the measurements are ticklish. The giant chords, for example, were milled to within 1/10,000 of an inch. Piece by piece the puzzle is reassembled in midair by the steelman. From their precarious perches, they reach out to swing the huge behemoths into place, slipping the gusset plates of one over the square end of the other. With their heavy malls, they pound home the bull pins and drift pins through the rivet holes to make the temporary connections. It is a job that calls for agility, muscle, skill, and a perfectionist nature. For each huge piece must fit to the tolerance of a nat's eyelash. It is difficult work, dangerous work, hard work, but it is satisfying work. And the ringing of their malls sets the rhythm for the construction symphony. Like commuters everywhere, the bridgemen find special shortcuts to the office. Although this isn't to be recommended while carrying a briefcase. The commuter special serves an invaluable role in the building of the bridge. Running busily to and fro, 10 ft from one side of the arch, it performs scores of little tasks, freeing the main highline for the all-important job of placing the steel. Riveting is a dying art, and the Glen Canyon crossing may be one of the last big bridges where the skill of the rivet teams will be employed. It is an art worth recording. Other methods may prove more economical, but they will never be as colorful. The blazing coals ready for the barbecue, the glowing rivet, the casual toss, again and time again. It is an art that calls for close teamwork, indeed close friendship. If you're going to perch on a narrow ledge hundreds of feet above a river while someone throws red-hot steel at you all day, it's always good to know his intentions are friendly. Tinker's to ever's to chance. Heater to catcher to bucker to riveter. The catcher plucks the glowing rivet out of his scoop and hands the tongs to the bucker who slaps the rivet in its hole and wedges it in place with his heavy air jam. From the other side, the riveter's gun compresses the pliable steel in the few moments before it grows too cool, leaving the neat button head that has been the hallmark of steel work for more than a century. More steel, more pins, more rivets. The reaching arms almost touch. August 6th, 1958. This is the day long awaited, the day of the wedding. The guests are here and stand about chatting expectedly. The engineers are as busy as the mother of the bride. Their worries are slight, however. The pins hinging the steel work to the skew backs would allow each half of the arch to be raised or lowered by adjusting the tieback cables, giving 8 in of leeway on where the two halves of the bridge will meet in midair. With this much margin, there is no question in the minds of the steelmen that the final chord will fit. But, there is the question of pride of workmanship. They have built an arch more than 1,000 ft long high over a gorge. How accurately have they planned? How well have they built? The project manager signals this one in himself. The gap is 1/4 of an inch. It is time for congratulations, for handshakes, and for broad grins of quiet satisfaction high over the Colorado. A final pin is used to simplify the closure. Jacking achieves just the right camber in the arch, and the bottom chords at midspan are then drilled, and the structure riveted, making the center pin inoperative. The union is made. Skewbacks, hi-line towers, holdback towers, tieback cables, safety nets, and the main cableway. The arch poses for its wedding portrait. With the grins, and the handshakes, and the guests, it seems indeed like a wedding. The living things that sprang from the caves on either bank have grown to maturity in their flight across the canyon, and have joined to become a new entity, independent of all ties, able to stand alone. The tieback cables, those steel umbilical cords, are no longer needed. Their work is done. The new arch now rests securely on its own foundations. Slowly, the tension leaves the tieback cables. Slowly, the cables relax, like a man sinking to rest when the strain of an all-important job is ended. The miles of tieback cables are removed. Building the roadway seems almost an anticlimax, and yet it has its moments. Toughest is the placing of the vertical columns nearest the banks, each 162 ft long and weighing 29 tons, slightly more than the capacity of the main cableway. The smaller passenger cableway is called in foreign assist, and with careful balancing handles the overload. While the arch was riveted, the Bureau specifications allow high-strength bolts to be used in building the roadway on top. The bolts are tightened with pneumatic impact wrenches, which are calibrated daily to make sure that each nut is turned down with exactly the same amount of pressure. The columns of graduated lengths are soon up, and on their level tops the steel floor for the decking is laid. The beams for the deck slip in place one after the other, and the work goes quickly. Slowly the age-old canyon is changing. The huge keyway in which the dam will rest has been blasted out of the sandstone, and a new shadow is cast across the sheer face of the ancient cliff. The bridge is nearing completion, and the painters move in. Before shipment from Emeryville, each steel member was sandblasted and given up to three coats of paint. The painters dangling from bosun's chairs now apply the final aluminum coat, transforming the glaring orange steel into a silvery spiderwork. The arch is built. The columns are up. The decking is laid. The Colorado is spanned. The steelman's work is done. The carpenters hammer together the forms for the sidewalk, one of the few places on the bridge where nails were used, even temporarily. The main highline performs its final chore, carrying the big concrete bucket back and forth to the roadway. While wooden forming was used for the sidewalk, for the roadway itself, steel forms, which are left in place, prove the most practical. And with these methods, the concrete decking is poured in just 12 days. February 20th, 1959. The new highway that will unlock vast untouched vistas to the American motorist is open, a full 3 months ahead of schedule. The job is done. The crossing at Glen Canyon was a big job, a dangerous job. And yet, it turned out well. No lives were lost. No problems were met that couldn't be solved. The engineers who designed it, designed