UPDATE (5/30/2014): Due to the firefighting efforts against the Slide Fire in Oak Creek Canyon, the State Route 89A improvement project along the switchbacks north of Sedona was temporarily on hold. However, the project will resume this weekend.

The previously-scheduled closure of the three-mile stretch of SR 89A between the Pine Flat Campground and the Vista scenic overlook south of Flagstaff will remain in place for several weeks while crews remove loose rocks above the switchbacks, complete other safety improvements and resurface the highway.

SR 89A will reopen to traffic before the Fourth of July weekend. While the switchbacks section along SR 89A is closed, ADOT recommends drivers use Interstate 17 and State Route 179 to travel between Flagstaff and Sedona.

Read our recent news release for more information.

Anyone who has driven State Route 89A through the Oak Creek Canyon switchbacks knows that it’s one of the most narrow and winding roadways in the state’s highway system...

That’s why an upcoming project to restore the pavement along a 3.5-mile segment of SR 89A is going to require a full closure.

“We’ll be closing down approximately three miles of the roadway just through the switchbacks because its such a narrow portion of the road, it can’t safely be worked on with the motorists traveling on it at the same time,” says ADOT Senior Resident Engineer Adam Umholtz in the video above.

Here’s what drivers need to know

Beginning on Monday, April 21, crews will start work on the $2 million improvement project that will repave the roadway between Pine Flat Campground and Oak Creek Vista overlook (mileposts 387-390). The project area is located in the Coconino National Forest midway between Sedona and Flagstaff, just north of the popular tourist destinations in Sedona and Oak Creek Canyon.

In the first phase of the project (April 21- May 22), a single-lane restriction during daytime hours will be required Monday through Thursday throughout the project length as crews begin preparations for a full closure of SR 89A. The roadway will be open, without lane restrictions, during the Memorial Day weekend, May 23-26.

During this time, access will remain open to Pine Flat Campground and Oak Creek Vista overlook, although flaggers will be present to guide traffic through the work zone. Delays are possible. There will be no restrictions during weekends, holidays, or at night prior to the full closure when there will be no public access.

Full closure required

In order to complete the work in safe and timely manner, a full closure of SR 89A through the switchbacks, which have steep grades with little to no shoulders, will be necessary for up to five weeks following the Memorial Day holiday and prior to the Fourth of July holiday (May 27 – July 2). While the closure isn’t expected to last more than five weeks, ADOT is offering incentives to the contractor to complete the work as quickly as possible, while focusing on safety and quality. During construction, access will be maintained for emergency vehicles.

The time frame for the full closure from May 27 to July 2 was chosen because it’s the most favorable time to apply the new pavement, which is temperature sensitive, and it’s before monsoon season, when rain can delay paving.

In addition to removing and replacing the existing asphalt, crews will also make repairs to the surface of the historic Pumphouse Wash Bridge and perform rockfall mitigation work in this area, which is prone to rockfalls.

The full closure will allow crews sufficient space to safely perform rock scaling work, which involves workers rappelling from a cliff and using hand tools to remove loose rocks that could potentially fall onto the roadway and injure motorists or damage the roadway.

For Sedona and the Oak Creek Canyon area, it is business as usual during this time because the project is located north of these popular destinations.

Detour Route

During the closure, the recommended detour from Sedona to Flagstaff will be to take State Route 179 to Interstate 17. The detour could add up to an extra half hour of travel time for motorists who are commuting between Sedona and Flagstaff (View the map).

Throughout the full closure, access will be maintained at either end of the full closure to allow entry to both Pine Flat Campground on the southern end and Oak Creek Vista overlook at the northern end. Signage and message boards are currently being used in advance of the closure to ensure traffic is properly detoured via SR 179 to I-17.

For more information on the project, please visit the project Web page.

Monsoon season doesn’t officially start until June, but try telling that to Mother Nature...

We’ve already experienced a few early dust storms and there’s no way of knowing too far in advance when dry and windy conditions will whip up another.

That’s why we’re bringing you today’s public service announcement. Consider it a sneak peek of our upcoming “Pull Aside, Stay Alive” campaign (yes, we’re planning to bring back the #HaboobHaiku!).

For now, please watch the video above, check out PullAsideStayAlive.org and review these tips for drivers who encounter a dust storm:

• Avoid driving into or through a dust storm.
• If you encounter a dust storm, check traffic immediately around your vehicle (front, back and to the side) and begin slowing down.
• Do not wait until poor visibility makes it difficult to safely pull off the roadway — do it as soon as possible. Completely exit the highway if you can.
• Do not stop in a travel lane or in the emergency lane; look for a safe place to pull completely off the paved portion of the roadway.
• Stop the vehicle in a position ensuring it is a safe distance from the main roadway and away from where other vehicles may travel.
• Turn off all vehicle lights, including your emergency flashers.
• Set your emergency brake and take your foot off the brake.
• Stay in the vehicle with your seatbelts buckled and wait for the storm to pass.
• Drivers of high-profile vehicles should be especially aware of changing weather conditions and travel at reduced speeds.
• A driver’s alertness and safe driving ability are always the top factors in preventing crashes.

For even more information on dust storm safety, re-visit some of our previous posts.

The wait is over and now the new Loop 101 HOV-lane ramps are open at Maryland Avenue in Glendale...

Not that it was a particularly long wait – work only started about five months ago. This accelerated project was built using the Design-Build method of contracting, which can yield big results in a short amount of time by pairing the design team with the construction team from start to finish.

“We worked very closely with the city of Glendale and the Maricopa Association of Governments in making sure that the funding was lined up,” explains ADOT Public Information Officer Doug Nintzel in the video above. “Then we made sure we were on a fast track with construction because the goal was we were going to complete these ramps in time for the 2014 Cardinals season and certainly in time for Super Bowl 2015”.

What drivers will now experience

The new ramps were designed to improve access in and out of the Westgate Entertainment District and the area's sports facilities (that includes the University of Phoenix Stadium and Jobing.com Arena).

All four ramps connect to the center of the Maryland Avenue bridge via the Loop 101 HOV lanes.

HOV lane refresher

Like all HOV lanes, the new ramps are only open to vehicles carrying two or more people, as well as other approved vehicles during weekday rush hour periods of 6 a.m. to 9 a.m. and 3 p.m. to 7 p.m. The ramps (and all HOV lanes) are open to all vehicles at other times, including weekends.

Last month, we showed you the lead abatement process used to strip Chevelon Creek Bridge of some very old paint. The procedure was fairly involved and included wrapping the entire bridge with plastic in order to protect the surrounding environment.

Believe it or not, that was only part of the entire bridge rehab project.

You can see in the video above that crews also had to replace the bridge deck, complete steel repairs and make modifications to the abutments.

If all the work sounds extensive, you have to remember that we’re talking about a bridge that was built over 100 years ago.

Yep, that’s right – the Chevelon Creek Bridge has been around almost as long as Arizona has been an official state! But age isn’t the only noteworthy aspect of this bridge...

A historically significant bridge

The Chevelon Creek Bridge is one of the first highway structures to be undertaken by the newly formed State of Arizona.

According to the state’s Historic Bridge Inventory, the deep, rocky canyon over Chevelon Creek formed a “practically impassible topographic barrier to the Santa Fe Highway across northern Arizona. In 1912, the newly formed state legislature appropriated $5,500 from the State Road Fund for construction of a substantial new structure here.”

On Oct. 2, 1912, the state contracted with the Missouri Valley Bridge & Iron Works for construction of the bridge. According to the document, Arizona accepted the completed bridge in July 1913 for a total cost of $4,985.

“The Chevelon Creek Bridge carried mainline traffic on the Santa Fe Highway until a realignment sometime between 1917 and 1924 moved the route north of the Little Colorado River,” according to the Inventory. “The bridge and the adjacent roadway were then relegated to county road status.”

Calling it, “one of Arizona's most historically and technologically important spans,” the Inventory informs us that the Chevelon Creek Bridge was the first truss built by the state, designed, fabricated and erected by a nationally important bridge firm."

Today, the bridge still serves as an important transportation corridor for drivers in Navajo County and, after the completion of the recent rehabilitation project, it wouldn’t be unreasonable to believe that the bridge will be around for another 100 years.

“That’s a good looking bridge,” says Navajo County Assistant Public Works Director Bill Bess in the video above. “They don’t make them like that anymore!”

You might think that highway construction is all about big machinery, heavy-duty vehicles, massive structures and materials by the ton – but it’s not.

Sure, those are important, but when it comes to building a road, science plays a strong role too. In fact, the work ADOT does off the project site and inside a lab is so significant that we are highlighting it here on the blog with a new series we’re calling, The Science of Transportation.

We’ll start today with a look into one of the methods used by ADOT to analyze soil samples.

The sieve analysis test, as you can see in the video above, is a way for technicians to create a profile of the sample’s size properties. That profile, in conjunction with other test results, is used to classify the soil – something that is useful for geotechnical engineers, road designers and construction crews.

This test is fairly straightforward.

First, the technician must prepare the sample by drying it and making sure there aren’t any clumps in the material. They weigh it at this point, too.

Next, the sample is screened through a series of sieves. The test starts with a very coarse sieve, and continues with sieves that get finer and finer. The ADOT technician records the weight of the material retained by each sieve.

You can see in the video that a (loud) mechanical shaker is used to move the material through the sieves.

When it gets down to the very, very fine material, technicians will need to split the sample, dry it, weigh it, wash and dry it again before continuing on to the next set of sieves. The screens on these sieves have very small openings that let only the smallest particles through.

Once all the material from the sample has been sieved, the sum of the individual weight of the material from each sieve is compared to the weight of the entire sample that was taken prior to sieving. If the difference between the two weights is more than 1 percent, the sample must be recombined and the sieving process would start all over again.

All of the information is recorded to provide a profile of the material’s size properties.

So, why does ADOT (and other transportation agencies) go to such lengths just to determine the size of the soil particles?

Transportation Tech John Miller sums it up best in the video above…

“You need to know what type of material you’re building on,” says Miller adding that it could be a heavy clay or sand – two soils that behave differently from each other. “It’s very important to run this test.”

For more on the Soils and Aggregate group, visit the ADOT website. Be sure to stay tuned to the blog ... in the coming months, we'll be featuring more of the tests this group performs.

Have you driven the stretch of I-17 that’s just south of Camp Verde, lately? If so, you’ve probably noticed the construction.

Those of you who read this blog post from last year know that the work is being done to add an additional southbound “climbing lane” to help ease the flow of traffic (and if you read this blog post, you know more about what a climbing lane is).

But, if you haven’t been keeping up with the ADOT Blog, don’t worry because today we’ve got a project update that will tell you everything you need to know...

Blasting is over

Since early 2013, motorists traveling late at night on I-17 (primarily between 11:30 p.m. and 3:30 a.m.) have had to plan ahead to avoid more than 70 planned one-hour closures required to safely remove the rock material from the mountainside of Copper Canyon. Those restrictions ended with the final overnight blasting closure on Feb. 18, but additional lane restrictions are anticipated in the future as crews move to pave the new lane.

With the blasting phase of the project completed on Copper Canyon and the project 80 percent finished, crews have already begun building the subgrade for the new pavement on the climbing lane, which will add a third travel lane for motorists to climb to the top of the steep Copper Canyon.

ADOT will start final paving operations for the project in early summer when temperatures are ideal for this type of work.

More about the project

Since the January 2013 start of this $11.8 million safety improvement project, ADOT has moved approximately 350,000 tons of dirt and boulders from Copper Canyon to clear a path for construction of the first-ever climbing lane (and third travel lane) on southbound I-17.

When complete, the additional southbound lane through the final two miles to the top of Copper Canyon will make it easier for motorists to pass large trucks and slow-moving vehicles whose speed drops because of the sustained grades along this stretch of highway (mileposts 280-282), which is the primary travel route linking Phoenix and Flagstaff.

In addition to the climbing lane, ADOT is also building a two-mile-long merging lane between the State Route 260 junction and General Crook Trail traffic interchange (mileposts 285-287), which is located just before the approach to Copper Canyon. The merging lane will allow larger vehicles to gain speed before merging onto I-17 while also providing more room for passenger vehicles traveling past slower traffic.

ADOT expects to complete the entire project in early summer.

For more information, visit the project Web page.

Remember when we first told you about the Loop 101 freeway ramp project that’s under construction out in the West Valley?

It was just back in November, but already work is now around 80 percent complete. Since this project is moving fast, we thought now would be a good time to share some recent photos from the site.

Of course, Loop 101 drivers in Glendale already know what this project looks like – they’ve got a front-row view of progress being made on the new freeway ramps that will connect with the Maryland Avenue Bridge near University of Phoenix Stadium.

More on the project

In one of the latest milestones, crews have attached all four of the ramps to the bridge. The ramps are connected to the bridge via the freeway's HOV lanes.

The project remains on schedule for completion by spring.

The project, designed to provide additional access points in the Westgate area, will be finished well ahead of the Arizona Cardinals' 2014 season and Super Bowl XLIX early next year. The work started last October.

ADOT is managing the construction of the $11.7 million project, which is supported by the city of Glendale and paid for with regional transportation funds from the Maricopa Association of Governments.

You can learn more about the project on our website or by checking out our previous blog post.

While it does have a number of valuable uses, lead can be pretty toxic to humans and animals, so it’s best to steer clear the stuff when possible.

But, if you can’t avoid it – say when it’s in paint that was used to coat the surface of a 100-year-old bridge you’ve been charged with rehabilitating – your best bet is to have it safely removed by professionals.

That’s the route ADOT took, as you can see in the video above.

Lead abatement

According to ADOT Hazardous Materials Coordinator Ed Green, any painted surface that’s going to be modified, renovated or demolished by ADOT is always tested for lead.

If a structure tests positive, as was the case with the Chevelon Creek Bridge, steps are taken to either remove the lead paint or encapsulate it so it’s not a hazard to the environment.

For the Chevelon Creek Bridge, the only option was to completely remove the paint…

Located in Navajo County, about 12 miles southeast of Winslow, the Chevelon Creek Bridge was built in 1913 on the old road that connected Winslow and Holbrook prior to the construction of Route 66.

The bridge, which had been painted and re-painted several times since it was first constructed over 100 years ago, was due for a little rehab that included deck replacement, steel repairs, etc. (we’ll tell you more about the entire project soon).

In order to comply with the National Environmental Policy Act, crews had to figure out how to get the lead paint off the structure without introducing it into the environment and water below.

“What we had to do is what we call lead abatement, which means we’re going to remove all that lead-bearing material and get it out of the environment,” says ADOT Historic Preservation Specialist David Zimmerman in the video above. “We’re going to take it to a special landfill where they’re engineered to deal with these kinds of materials.”

How’d they do it?

Crews built a temporary aluminum deck underneath the bridge. Next, they covered the whole bridge in plastic so that none of the toxic lead paint could fall into the canyon below.

Once the bridge was “cocooned” in plastic, workers sandblasted the lead paint off the structure, contained it and properly disposed of it before repainting the bridge using modern, non-lead based paint.

Fun fact: Since sand is very abrasive and would have degraded the bridge’s metal, crushed walnut shells were used to blast the paint off (baking soda can also be used for a less abrasive “sand” blast).

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!

There’s a chance for snow in parts of the state today and tomorrow, which means ADOT’s snowplow drivers are getting ready for the storm ahead…

Now, while the rest of us may prep for wintry weather by finding a blanket and a warm mug of cocoa, ADOT’s snowplow drivers have a much bigger agenda.

They’re charged with keeping the state’s roads clear and safe, but many motorists may not realize the effort it takes. That’s why today’s video is so great, because it shows us a day in the life of a snowplow driver.

And, what a long day it is!

“Our shift runs from midnight until noon … if it’s snowing, we’re out here all night long,” says snowplow driver Joe Chavez.

Respect the plow!

As these snowplow drivers do their job, they need the cooperation of other motorists. Here are a few tips to remember if you’re driving near a plow:

• Never pass a snowplow! Slow down and be patient.
• Stay at least four car lengths behind snowplows and equipment. Plowed snow can create a cloud that reduces visibility, and spreaders on trucks throw salt or sand that can damage your vehicle.
• Watch for snowplows operating in multiple travel lanes or in tandem.
• If approaching an oncoming snowplow, slow down and give the plow extra room.

Get more driving tips and find useful information over on our “Know Snow” Web page. You can also check out our previous blog posts and videos for even more about how ADOT prepares for the snowy season.

You know that there are layers of dirt and rock beneath the surface you drive on, but would you guess that some roads are built on top of a special material (in addition to all the dirt and rocks)?

What we’re referring to is called geogrid, which is a polymer material that is used to reinforce soil.

If the term sounds familiar, we’re glad. Because that means maybe you watched our video from August about the paving of US 89T (we definitely appreciate our devoted blog/YouTube followers!).

In that video, you can see that a geogrid material was used on that project. You can also hear a good explanation of how geogrid works with the dirt and rocks. In case you missed it…

“AB is aggregate base – it’s the gravel that goes down under the asphalt. It helps distribute the weight of the traffic that’s on the asphalt,” Resident Engineer Steve Monroe says in the video. “By using the geogrid, we can cut out two inches of that AB. The geogrid is much less expensive and easier to put down than hauling in all that extra AB.”

How is geogrid installed?

Once the subgrade material (that’s the layer under everything else) is prepared, a geogrid is placed on top (sometimes along with a geotextile filter fabric used to keep fine material from migrating into the aggregate base). The openings in the geogrid are meant to interlock with the granular aggregate base – check out the video above to see what we mean.

After the geogrid goes down, the aggregate base is placed and finally, paving takes place on top of all those layers.

Why does it work?

When testing determines it necessary, geogrid material can improve the ability of the subgrade to carry traffic loads and reduce rutting or pavement failure over weak soils. It does this by providing tensile strength and distributing the load from a vehicle to a wider area.

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!