By Timothy Tait / ADOT Communications

The two women look out over the Little Colorado River, pointing into the distance, northward, at destinations yet to come on their journey of northern Arizona. They are standing next to the now iconic US 89 bridge at Cameron, its modern suspension design contrasted against the smooth cliffs, hiding the river below.

While the postcard wasn’t mailed, in neat cursive on the back, the traveler wrote of her adventure:

“Just across the street from where we ate, at Cameron, Ariz.”

The scene is documented on a picture postcard, perhaps from the 1940s, that came to me from a relative who hunts for antiques – in Michigan. Who the women are remains a mystery, their destination and journey concealed by time. How did a postcard of two women from the ‘40s documenting their visit to Arizona end up in Michigan before returning back to Arizona? Who snapped the photo? We’ll probably never know of their adventure or the path this postcard took before landing at ADOT. But it’s fun to wonder.

Bridge over Little Colorado River

Here’s what we do know: That iconic bridge, constructed in 1911, still stands today, carrying not traffic but utility lines over the Little Colorado River. While its usefulness as a traffic bridge has long ended, it continues serving Arizona faithfully. ADOT recently completed a new, wider bridge over the Little Colorado River, replacing a 1958 bridge that was built to accommodate construction traffic for the Glen Canyon Dam.

Historic Cameron Trading Post

Travelers today are still stopping at the historic Cameron Trading Post for a bite to eat and souvenirs before continuing their journey. And that new bridge at Cameron will serve traffic for decades to come, shuttling travelers across the gorge protecting the Little Colorado River on their way to … adventure.

If you’ve been keeping up with us here on the ADOT Blog, you know that crews are currently working on the US 89 landslide repair project near Page. You also know they’re busy blasting, digging and hauling approximately a million cubic yards of dirt and rock material that will be used to build a 1,400-foot-long buttress to stabilize and reinforce the mountain slope that carries US 89.

While we don’t have much that’s new to report (moving a million cubic yards of dirt will take while!), we did want to show you some recent photos of the progress. Taken just last month, the pictures above give a glimpse of all of the work that’s happening on the site…

We’ve got some good news to share with you today about US 89…

Just last week, ADOT finalized an agreement with a contractor for preconstruction engineering services, which includes assistance with the final design and construction logistics for the ultimate fix.

That means ADOT is one step closer to its goal of starting the US 89 landslide repair to reopen this roadway by the end of the year (see, we told you it was good news)!

US 89T contractor will work on landslide repair preconstruction

Tempe-based FNF Construction, Inc. was selected by ADOT as the contractor for pre-construction services on the landslide-damaged highway that links Bitter Springs and Page.

FNF Construction is the same contractor ADOT successfully partnered with to complete the Temporary US 89 (US 89T) project, which now serves as the primary detour to and from the Page and Lake Powell areas. If you’ve been following along with us for the past year, you’ll remember that the previously unpaved Navajo Route 20 was paved in only three months to become US 89T, which opened to traffic in August.

Through a Construction-Manager-At-Risk contract, FNF Construction will work with the project design team. This early collaboration can lead to completing projects faster with reduced costs. Preconstruction services will also include the design of access roads at the project site that will be needed when construction starts as anticipated this summer.

One important thing to point out – this new preconstruction agreement with FNF Construction does not include the construction project to repair US 89. That contract is expected to be finalized later this spring.

What’s ahead?

Recently, ADOT received the necessary environmental and utility clearances on the ultimate repair of US 89. Without the clearances, ADOT cannot use federal funds for this repair project.

ADOT also continues to work with the Navajo Nation on obtaining the new right-of-way easements that will be necessary prior to construction. An agreement between the Federal Highway Administration, Navajo Nation and Bureau of Indian Affairs must be reached to establish an expanded easement that facilitates construction, as well as operations and maintenance, of the repaired roadway.

One year ago today, a landslide caused major damage to a stretch of US 89 located in northern Arizona.

Back then, months before an extensive geotechnical analysis would be concluded, no one could really be certain of what caused the roadway to fail. Here’s a sample of what we blogged at the time:

A 150-foot section of the road “buckled” (Feb. 20, 2013) in an area about 25 miles south of Page – the cause of the highway damage may have been a geologic event.

If you’ve been following us since that initial blog post/video, you know that much has happened in these 12 months, including a vast geotechnical investigation, the paving of US 89T and, more recently, environmental site surveys.

So what’s next?

Currently, ADOT is gearing up to start construction in early summer and potentially complete the emergency repair by the end of this year – if there are no environmental, utility or right-of-way hurdles.

Since August, ADOT has retained an engineering design firm and developed plans for the eventual repair; finalized all federally required environmental reviews that include cultural, biological and water quality measures; and completed the plans for the required right-of-way easements.

The environmental and design process for a normal project can take two years to complete, but ADOT has been working with the Federal Highway Administration, Navajo Nation, Navajo Division of Transportation and the Bureau of Indian Affairs to expedite the environmental, utility and right-of-way clearance and approval process, knowing the lack of a usable road between the Bitter Springs and Page communities is a hardship for many people.

Major milestone

ADOT passed a major milestone this week toward beginning construction on the ultimate repair of US 89. The final environmental documentation was submitted to the Federal Highway Administration yesterday (Feb. 19, 2014) for review. Without this clearance, ADOT cannot use federal funds for this project. While that approval is pending, ADOT continues work on the pre-construction elements of the project, like finalizing the design of the repair.

ADOT also continues to work with the Navajo Nation on obtaining right-of-way easements that will be necessary prior to construction. An agreement between the Federal Highway Administration, Navajo Nation and Bureau of Indian Affairs must be reached to establish an expanded easement that facilitates construction, as well as operations and maintenance of the full repair.

More on the project

The repair is currently estimated to cost $25 million. The project will include moving the roadway approximately 60 feet toward Echo Cliffs and using that rock to construct a downslope buttress to stabilize the area. ADOT wants to start the repairs as soon as possible following environmental, utility and right-of-way clearances.

The US 89 emergency repair project is eligible for reimbursement through the Federal Highway Administration’s emergency relief program, which provides funding to state and local agencies for the repair or reconstruction of highways, roads and bridges that are damaged in natural disasters and catastrophic failures.

The long-term fix for US 89 will involve cutting back the mountain slope, building a gravity buttress wall for support and constructing the new road. But before crews can begin on all that, there’s a lot that has to get done.

Environmental work is one of the first tasks at hand and, as you can see in the video above, ADOT is coordinating with a number of agencies to make sure this project will have as little impact as possible on any nearby waterways.

“We had ADOT, the Army Corps of Engineers, ADOT’s consultants and the Navajo EPA water quality folks,” says ADOT Water Quality Analyst Julia Manfredi in the video. “What we are looking for is areas that would be considered Waters of the U.S. by the U.S. Army Corps of Engineers, so what we have to do is identify where the Waters of the U.S. are, so that we can tell if this project is going to cause a discharge of dredge or fill material to those Waters of the U.S. and if it is going to, then we will have to permit that through the Army Corps of Engineers and also through the Navajo Environmental Protection Agency.”

By the way, Waters of the United States basically refers to any interstate waters or wetlands (you can read a good, detailed definition on the Environmental Protection Agency’s website).

In the case of the US 89 project, washes on the site that lead to the Colorado River are the focus.

401 and 404

The permits referred to in the video have to do with the Clean Water Act (specifically sections 401 and 404).

Section 404 of the Clean Water Act outlines the regulation of any dredged and fill material that gets discharged into the waters of the United States. The U.S. Army Corps of Engineers is responsible for 404 permitting.

Projects that require a 404 permit, must also apply for a 401 certification from a local jurisdiction (for US 89, it’s the Navajo Environmental Protection Agency). While 404 permits deal more with hydrological connections to interstate waters, a 401 certification focuses on water quality and ensure that the project plan complies with local discharge rules.

More environmental work
As we stated earlier, there’s a lot more to be done before construction can begin. So, stay tuned … we’ll keep you posted on what’s next, including archaeological and biological surveys of the site.

It was just about three months ago that construction got started on Temporary US 89 (aka US 89T) and from the onset, crews really have had their work cut out for them.

Back in June, it was estimated that about 300,000 cubic yards of dirt would need to be moved on the project even before the gravel and asphalt could be placed. Then there was the paving – 27 miles worth to be exact.

But grading and paving are only part of the project. Prior to opening any new state highway, proper signage, striping, right-of-way fencing and other safety measures are necessary to ensure a safe roadway. US 89T also requires cattle guards, swing gates and centerline rumble strips.

So, back to that fencing…

Crews are still actively working to complete some remaining construction items on US 89T, including fencing.

US 89T is located on a rural, open range area on the Navajo Nation, which has a large amount of livestock. Fencing is a critical part of this project because it is designed to prevent livestock from crossing onto the highway, which is a major safety concern (see the photos above for just a glimpse of what we’re talking about).

What all of this mean for drivers
ADOT is set to open the newly paved US 89T tomorrow, Aug. 29, albeit with some restrictions.

Until construction and fencing is completed, the roadway will be open only during daylight hours (except for local residents) and there will be a 25 mph speed limit.

ADOT reminds drivers that while the US 89T has been improved, motorists need to slow down and pay attention to their surroundings. Drivers should be aware that this roadway is prone to animal crossings.

To help reduce delays, detour signage will remain on the previously established primary detour route (US 160 to State Route 98) until US 89T is completed. This established detour may be a quicker route while construction continues on US 89T because of the 25 mph speed limit.

When construction is finished, the speed limit will be raised and nighttime restrictions will be lifted.

We know many of you are eager for construction on N20 to finish and we want to let you know that we hear you and understand just how ready you are for this roadway to open!

While work on the route isn’t done yet, we hope you can be patient for a little bit longer and know that ADOT is taking ALL the steps necessary to ensure that N20 (also known as US 89T) is a safe roadway that motorists will be able to use for years to come.

There are a number of things that must be completed before ADOT can open the road to traffic.

Paving is only one part of the project – prior to opening any new state highway, proper signage, right-of-way fencing and other safety measures are necessary to ensure a safe roadway. N20 also needs cattle guards, swing gates and centerline rumble strips (as you can see in the video above, the large number of animals in the area means fencing is vital on this project. Crews are working now to install fencing along the route to keep livestock off the road).

The good news is that ADOT is still on track to complete the project prior to the Labor Day holiday weekend.

For now, we want to reiterate that N20 is still closed and is an active construction zone, particularly in these last couple of weeks as crews put the finishing touches on the project.

Good news for drivers who have seen their commute impacted by the US 89 landslide…

Last Friday (April 12), during its monthly meeting in Tucson, the State Transportation Board approved funding to pave Navajo Route 20.

You might remember that last month we told you about N20 – it’s the Navajo Nation tribal road that runs parallel to US 89. Once improved, N20 could establish a shorter route for the many drivers who regularly travel to Page and the Lake Powell area (see we told you it was good news for drivers!).

While the primary detour to and from Page and the Lake Powell area has been established by using US 160 and State Route 98, ADOT acknowledges the 115-mile-long detour, which is 45 miles longer than the direct route, can be a burden on drivers who have to use it every day. By paving N20, the detour route would be cut nearly in half and similar in length to the closed US 89 route.

The $28 million N20 paving project is scheduled to start next month — as long as all right-of-way and environmental agreements can be obtained through the Navajo Nation, Bureau of Indian Affairs and the Navajo Division of Transportation.

“After numerous face-to-face meetings, roundtable discussions and several presentations from Window Rock to Flagstaff, ADOT and its many partners, including Navajo Nation, Navajo Division of Transportation, Bureau of Indian Affairs and the Federal Highway Administration, have demonstrated great teamwork to put us in position to begin paving Navajo Route 20 next month if all agreements can get signed, sealed and delivered,” said Dallas Hammit, ADOT deputy state engineer of development. “ADOT is anxious to move forward to pave this road and create a more direct temporary detour route.”

The project would improve the existing 44-mile-long tribal route and upgrade so it could accommodate the anticipated traffic volumes, including commercial truck traffic. The major work is paving 27 miles of dirt road stretching from Bodaway-Gap to LeChee.

Construction could begin next month. ADOT’s goal would be to complete the work by early summer.

The project is eligible for reimbursement through the Federal Highway Administration’s emergency relief program, which provides funding to state and local agencies for the repair or reconstruction of highways, roads and bridges that are damaged in natural disasters and catastrophic failures. ADOT has already received $2 million in quick release funds to assess the damage and the stability of the mountain slope and conduct emergency operations.

The State Transportation Board designated N20 as Temporary US 89 (US 89T) during its special telephonic meeting on March 21. It had to be designated a state route before ADOT could spend any money improving the road. After the reconstruction of US 89 is complete, US 89T will be relinquished to the Navajo Nation.

There is no timetable for reopening the highway, but ADOT is committed to restoring this important travel route as soon as safely possible.

ADOT is currently conducting a geotechnical investigation, which is the first phase of the solution. Crews are monitoring the stability of the slope and the ultimate repair of US 89 will be based on the results of the geotechnical work.

We have heard from a lot of people who want to know when US 89 is going to reopen…

While we don’t have any sort of a timeline to give you yet, we can report that the geotechnical investigation is entering its final stages. Once complete, the information gathered will help engineers uncover the best long-term solution to restore the landslide damaged US 89 highway.

After receiving environmental clearance, heavy construction started Tuesday. Crews are working to cut a pathway down the slope to the base of the mountain slope.

That access path will allow the geotechnical engineers to dig pits, approximately 20-40 feet long and 10-15 feet deep, which will provide critical information regarding any movement that may be present at the base of the slide. The excavation work is necessary because it will lead to recommendations by the geotechnical team on what options are available within the site to realign the roadway or rebuild the existing roadway.

“This is the final piece of the puzzle we’ll need to wrap up this geotechnical investigation,” said Steve Boschen, ADOT deputy state engineer of design. “Prior to this, our drilling crews were only able to access this area via helicopters.

ADOT’s goal is to repair this critical section of highway and restore connectivity throughout the region as soon as possible. But before we can start the repairs, we need to determine the cause of the landslide and assess the safety of the slope.”

ADOT’s geotechnical investigation at the US 89 landslide site is the first phase of the solution. Crews are monitoring the stability of the slope and the ultimate repair of the highway will be based on the results of the geotechnical investigation. Efforts also continue on exploring the use of Navajo Route 20 as a temporary detour route while US 89 repairs are addressed.

You might remember that we blogged about inclinometers back in February – they’re the instruments used to measure slope inclination or movement at specific locations.

Well, today we have another technology that we want to tell you about called Time Domain Reflectometry.

Like inclinometers, TDR can help our geotechnical experts and geologists measure movement of a slope or a landslide. However, TDR technology looks and operates a little differently from inclinometers.

How does it work and what is it used for?

TDR technology consists of a coaxial cable (similar to the one that's coming out of your television set – but more heavy duty) that’s embedded or grouted within a vertically drilled hole (it might help if you can recall our milkshake straw analogy from the inclinometer post).

Alternately, a TDR cable can be attached to a grouted inclinometer casing (see photo above). That coaxial cable that's in the ground is then connected to a cable tester that sits outside the drilled hole.

You should know that the cable is installed in a precise way so that the zones of ground movement (shear planes) in the landslide mass are intersected.

Once the cable is in the ground, it will be able to detect ground movement that’s happening within the vicinity of the cable. If there is movement in the landslide mass, the cable becomes kinked, stretched or even sheared.

This damage creates a change in the impedance of the cable, which can be detected by the cable tester, says ADOT Engineering Geologist Nick Priznar.

“The cable tester sends an electronic voltage pulse that is reflected like radar from a damaged location in the coaxial cable,” he said. “The returned signal will show where changes have occurred along the length of the cable and can be compared to the signal obtained originally when the cable was undamaged. This makes it possible to determine the depth, progression and general magnitude of movement of the landslide zone that was intersected.”

TDR technology is often used in conjunction with inclinometers. That’s because the lifespan of the inclinometer casing is limited – slide plane movement can shear or distort the casing, eliminating its stable base or reducing its diameter to a point where the inclinometer probe cannot pass through the casing.

When, or if, that happens, the TDR system can be used to continue to monitor the movement/displacement. That’s because the TDR cable is usually more resilient to displacement than the inclinometer casing.

However the two systems are not equivalent, according to Priznar. While the inclinometer data provides actual measures of deflections the TDR cable tester can only provide depth and relative magnitude of displacement.

How are TDRs being used on US 89?

At this time ADOT engineers are in the process of developing the best strategy for implementing TDR technology for US 89.

In anticipation of utilizing this technology, TDR cables are being be secured along the outside diameter of select slope inclinometer guide casings (again, see photo above).

Transportation Defined is a series of explanatory blog posts designed to define the things you see on your everyday commute. Let us know if there's something you'd like to see explained ... leave a comment here on the blog or over on our Facebook page!