You probably saw the concrete bridge piers rise from the ground.

And you certainly noticed cranes hoist massive bridge girders onto the piers.

But you may not have thought the future bridge at I-10 and Ruthrauff looked like an actual bridge – until the recent work to pour a concrete deck atop the girders.

The concrete pour signals another important step in the process of building a new Ruthrauff Road/El Camino del Cerro bridge that will span I-10 by next year as part of a $129 million interchange reconstruction project in Tucson. It’s the first of several concrete pours that will take place through next year as crews build the structure in phases.

While you can see the concrete deck in place, few people saw the concrete pour because it took place in the middle of the night. Crews worked from about 1 a.m. to 5 a.m. on a recent day to complete pouring 290 cubic yards of concrete. 

Those hours aren’t the most fun for a lot of us, but there’s a good reason behind the schedule. The concrete is more workable during cooler nighttime hours at this time of year. And it’s less likely to crack in that temperature range because the concrete sets up more gradually.

Crews poured concrete over just half of the existing structure, and they’ll be back in about a week to finish the remaining portion of the bridge above eastbound I-10.

You’ll see the entire process again above westbound I-10 beginning in early 2021. That will require shifting eastbound and westbound I-10 traffic beneath the portion of the bridge that’s under construction now.

During the entire process, ADOT will maintain three lanes of traffic in each direction during daytime hours. And we’ll maintain access to local businesses.

For updates and traffic alerts, please visit azdot.gov/RuthrauffTI.

When you think of a bridge, you probably imagine some long span crossing a deep canyon or large river. It's easy to overlook the humbler examples that cross small crevices and washes. 

And that's exactly what you'll find with the Ligurta Wash Bridge, not to be confused with the nearby and similarly named Ligurta Underpass, which we told you about in a previous blog.

Located on Old US Highway 80 near the eponymous community, the Ligurta Wash Bridge began its life in 1930. The Arizona Highway Department wanted to improve the Yuma-Wellton Highway (as that section of US 80 was then called), which started just east of Ligurta and ended about 5.5 miles away, before Wellton. The improvement plans included the construction of two nearly identical reinforced-concrete bridges over intermittent washes.

And speaking of design, the bridge is also one of the best surviving examples of a new girder standard. The state of Arizona was using concrete for bridges as early as 1910. The earliest girder bridges, such as the Antelope Hill Bridge, had two deep girders cast as part of the concrete deck. By the 1920s, the new standard was four or more shallower girders, which allowed for greater clearance under the bridge. The Ligurta Wash Bridge uses this refined design.

Construction began in the summer of 1930, and the bridge was opened to traffic the following spring. For many years, the Ligurta Wash Bridge carried much of the US 80 traffic. When Interstate 8 was built in the late 1960s, US 80 traffic dropped quite a bit, but the bridge remained standing. Now overseen by Yuma County, the Ligurta Wash Bridge lives on in its original form, carrying local traffic alongside I-8. It may not see the amount of traffic it used to, but its design has withstood the test of time.

At first glance this photo might seem a little ordinary. A couple vehicles driving down a road next to some powerlines and buildings.

For those who enjoy visiting Lake Powell or, like us, are road buffs, you'll recognize this as the US 89 bridge that crosses the Colorado River just south of the Glen Canyon Dam near Page. Though, truth be told, that doesn't make this photo seem less pedestrian (pun intended).

But when we found this undated photo in our archive, we started thinking about that bridge and the US highway that runs over it. What could this ordinary scene tell us about Arizona's transportation history?

As we've told you about before, US 89 is actually the first designated north-south highway in the state and was part of the first batch of highways to actually be given a number in the mid-1920s. Our 2012 Transportation History report has a whole section just on this one highway, which adds that at one point US 89 stretched between Canada and Mexico, and was planned to be part of a projected intercontinental road that would have ended in Buenos Aires.

For the first few decades of its existence, US 89 actually stretched between Nogales in the south and Fredonia in the north, connecting Tucson, Florence, Mesa, Phoenix, Wickenburg, Prescott, Ash Fork and Flagstaff. As part of its traversing of the state, it crossed two important bridges, at Cameron over the Little Colorado River and then Marble Canyon over the Colorado River.

With the completion of the Glen Canyon Dam in 1963 and the bridge in this photo the following year, US 89's route was changed to swing through Page and then down to Flagstaff, making the Fredonia to Bitter Springs section the alternative, or US 89A. And, like most of the early highways, US 89 was heavily impacted by the interstates, which took away much of its raison d'être as a major north-south connector. By 1992, all but the northermost stretch had been decomissioned as a US highway. 

Once you consider all that, we guess it makes this photo look a lot less ordinary. What additional fascinating bits of highway history might be sitting under other well-traveled routes?

Today three bridges cross the Little Colorado River near Cameron. The newest two spans for north- and- southbound traffic are flanked by the original 1911 crossing that today carries only an oil pipe.

As Arizona grew after becoming a state, so did the need for trappers, traders, and prospectors to cross the Little Colorado. Increasingly sophisticated bridges were constructed at the site in 1911, 1958 and 2016, which is where the Arizona Highway Department, and later ADOT, comes in.

But at the turn of the 20th century, there were no bridges.

“This was out in the middle of no-where,” said Merlin Carson, 78, an aero-space engineer turned Native American art expert who spends his days at the historic Cameron Trading Post. “There was nothing but sheep trails all over the place and a great many trading posts.”

The main way to cross the river at the edge of the Hopi and Navajo reservations was Tanner’s Crossing, named after Mormon prospector Seth Tanner from Tuba City. However, the rocky ford left much to be desired. Flooding and quicksand were unpredictable and dangerous.

BRIDGE PROJECT I

In March of 1911, Congress appropriated $90,000 for construction of a bridge built by the Midland Bridge Co. for the Office of Indian Affairs.

“At that time, there were hardly any cars,” Carson said. “It was a bridge for the Navajo people. The bridge was the earliest safe crossing of the river. It was meant for walking across with your cattle or your sheep.”

There's even a story that in 1937 a large herd of sheep crossing the bridge caused it to sway badly and nearly collapse, leading to some repairs to shore it up. 

The Cameron Construction Bridge is an engineering marvel that played a large role in Arizona’s growth, according to an Arizona State Historic Preservation Office report.

According to the report, the bridge “is significant for its association with the initial growth of Arizona’s highway system as a major bridge which opened the northern portion of the state to development … A hybrid of suspension and truss forms, the bridge has engineering significance as the oldest surviving highway suspension bridge in the state and that utilized novel engineering techniques to cross the wide canyon of the Little Colorado River.”  

Decades passed, technology advanced and foot traffic gave way to large vehicles. By the mid-1950s this became a problem as the old bridge was not capable of carrying heavy construction equipment needed to build the Glen Canyon Dam.

BRIDGE PROJECT II

It was a fight in Congress to get funding for the next bridge. The leading advocate was Arizona Sen. Carl Trumbull Hayden, who was elected in 1912 as the state’s first congressman and retired 56 years later after serving seven terms in the US Senate.

He wielded great power in his role as Senate Appropriations Committee chairman, and it was in this position that he argued eloquently and successfully for nearly $1 million in funding to build the Cameron Truss Bridge.

“I have in mind particularly construction of the bridge across the Little Colorado River in Arizona, absolutely essential in order to get material out to Glen Canyon Dam that is to be built,” Hayden said during hearings on Supplemental Appropriation Bill, 1958, according to a report in the Library of Congress.

“The present structure will not carry a heavy load, and the State of Arizona has obtained a very favorable contract for the bridge.”

To further accommodate construction equipment, US 89 was widened at that time and modernized from Flagstaff to Page.

In 1959, the Cameron Truss Bridge was completed over the Little Colorado just east of the original 1911 bridge. The truss bridge was useful for the next 57 years. That's just one year more than Hayden, its champion, served in Congress.

BRIDGE PROJECT III

In 2014, work began on an ambitious ADOT project that included tearing down the truss bridge and erecting a modern, wider crossing in its place. It was part of a $38 million, two-year project that also included expanding US 89 from two lanes to four and adding three miles of upgrades south of the bridge. New sidewalks, streetlights and four pedestrian and livestock underpasses were completed.

Before work on the new bridge could kick into gear, engineers faced the formidable challenge of removing the solid, heavy, steel truss bridge. Engineers solved it by first removing the deck, then cutting the remaining structure into six pieces, which were disassembled and hauled off site.

The modern replacement has two bridges, one each for northbound and southbound traffic. Each lane measures 12 feet.  

When it was completed in 2016 it became the new neighbor of the old 1911 bridge. That first span doesn't carry traffic anymore, but utility lines over the Little Colorado River. While its usefulness as a traffic bridge has long ended, it continues serving Arizona faithfully.

It’s among the lures of travelers who frequent the historic Cameron Trading Post, where you might run into art expert Carson.

And the new bridge at Cameron? Like its forebearers, it will serve travelers for decades to come.

It's a mere memory now, but there was a time when Antelope Bridge was one of the most important bridges over the Gila River.

Nestled at the foot of Antelope Hill near Tacna, Antelope Bridge was a vital part of the Ocean-to-Ocean Highway across southern Arizona. The site was first surveyed in 1912 with an original design of 15 girder spans supported by massive bullnosed concrete piers. The bridge's overall length was almost 1000 feet, not including the timber trestle approaches on the ends.

The state began construction in 1913 using prison labor. When it became apparent that would not suffice to get the job done, the original engineer redesigned the project and requested bids. But fate seemed to be against the project. The original builder badly underestimated what was needed to erect such a structure and defaulted. Not long after, Gila River floods damaged the partially completed bridge. The state pushed on with more prison labor, and in 1915 the bridge opened with a gala picnic and thousands of well-wishers.

All the excitement in the world, however, couldn't overcome one vital fact: The site was a poor selection. Antelope Bridge suffered extensive damage with almost every major flood on the Gila. After years of repeated reconstruction of the concrete bridge and timber pile approach trestles, the bridge was replaced in 1929 by the now-abandoned McPhaul Bridge.

Antelope Bridge is in ruins today, but it was a major crossing on a nationally important transcontinental route. It's also significant in state history as one of the few structures remaining from the early state period built using prison labor.

A highrise of sorts is now standing within a few feet of US 60 where the Pinto Creek Bridge replacement project is underway east of Superior, but drivers passing through can be forgiven for overlooking it.

That’s because the towering structure is a 158-foot tall bridge pier rising from the bottom of a deep canyon, topping out roughly at the same level drivers pass through the area on the existing bridge.

The bridge pier is significant not just for its height, but also because its construction comes at what is roughly the halfway point of the $22.7 million bridge replacement project. This video gives a different perspective of how much progress ADOT is making, and you can really appreciate the height of the new piers as well as the existing bridge. If you still want more, we recently shared a fantastic slideshow showing what crews have been up to.

Once the three sets of bridge piers are complete in the coming months, crews will work into early 2021 to construct the bridge deck. That work will be a little more visible to drivers, as crews will work within about 30 feet of the existing bridge and at the same level as passing traffic.

Fortunately for drivers, ADOT will continue to minimize traffic impacts by keeping both lanes of travel open on US 60 in the project area during nearly all other stages of the project. 

Drivers can expect some restrictions when the concrete bridge deck is poured in early 2021. When the project nears completion next summer, US 60 will close for up to 5 days while crews realign the highway to the new structure. The existing bridge will be dismantled after traffic is shifted to the new structure.

For more information, please visit azdot.gov/PintoCreekBridge.

Traffic is now driving on the new Fourth Street bridge, which opened recently after crews put the new bridges in place using an innovative method known as bridge sliding.

The bridge slide method is a technique that basically moves precast bridges using hydraulic jacks. The new Fourth Street bridges were moved nearly 50 feet into place after the old bridge was removed! This technique shaves a ton of time off of normal bridge construction. We’re talking days instead of months.

Fortunately for you, a member of ADOT’s video team was onsite to capture the Fourth Street bridge sliding into place. Check it out in this video to the right.

The new bridge is wider, adding a lane in each direction. It also includes a walled-off section for bicycles and pedestrians to cross the bridge, connecting the Flagstaff Urban Trail System across I-40.

The project as a whole is expected to wrap up this fall.

ADOT is always looking for new, innovative ways to deliver highway projects that can reduce delays and inconvenience for drivers. The bridge sliding technique is another way ADOT is delivering a safe, reliable transportation system more efficiently.

We didn't have to search too far back to find this interesting shot of a bridge in the process of being built.

Drivers who travel between the Phoenix area and Payson may have no difficulty recognizing this as the State Route 87, known as the Beeline Highway. The photo comes from 1998 in the middle of a project to upgrade SR 87 to four-lane divided highway. The bridge that would eventually support the highway is being built using segemented construction. Basically, the bridge is built bit by bit with cast-in-place concrete segments that are added on using a specialized casting machine. That's the big white rigging you see there.

You'll notice, however, that there is a second machine in background on the other side of the bridge being built. The same work is happening on that end in what is known as cantilevering. Basically, segements are being added out from the supporting pier on both sides either simultaneously or in alternating turns to keep the entire structure in balance. Eventually all segements are connected and you have one, long bridge to drive across. In this case, the photo appears to be of the Screwtail Bridge, just south of Sunflower, which wound up being an impressive 1,080 feet, spanning a 105-foot-deep canyon. 

This innovative method was needed because the terrain between Phoenix and Payson is pretty rugged, as reflected in some of the curves and grades of the road's original alignment. By building bridges this way, ADOT was able to straighten and flatten the roadway a bit while also widening it and making sure to steer clear of sensitive riparian areas and wildlife corridors.