As March turned into April, Arizona Department of Transportation crews working near the international border in Nogales celebrated the first anniversary of work on State Route 189 the way only roadbuilders can: Moving the last of a combined 8.5 million pounds of concrete-and-steel girders into place.

Last March, Governor Doug Ducey, along with government and business leaders from southern Arizona, broke ground on a project that is expected to create economic growth in Santa Cruz County while making one of Nogales’ busiest roads safer and less congested. 

ADOT is building two ramps connecting SR 189 with Interstate 19. When the work is complete this fall, the ramps will make Nogales a more attractive place for international commerce to enter the US. That’s significant; the Mariposa Port of Entry saw about $25.5 billion in imports and exports in 2019, including much of the winter produce consumed in the U.S.

They’ll also save trucking companies time and money by eliminating the need to stop at three traffic signals, and they’ll make SR 189 safer for Nogales High School students who will no longer have to navigate around those trucks to get to school.

The ramps provide an impressive site for southbound drivers on I-19. The northbound ramp runs for just more than half a mile, while the southbound ramp is just more than one-third of a mile long. They come together just west of Frank Reed Road. The ramps include 122 girders, each averaging about 70,000 pounds and 135 feet long.

Between now and when the work is complete, crews will be pouring concrete decks on the ramps, finishing a new roundabout at Target Range Road and completing the remaining tasks to make SR 189 better for Nogales, better for international trucking and better for Arizona’s economy.

“Better roads,” Governor Ducey said at last year’s groundbreaking, “mean a better future for Arizona.” 

In Nogales, that better future is just a few months away.

The blue mountains depicted on the wall at Interstate 19 and Ajo Way in Tucson mirror the hills rising behind it – an aesthetic touch that is definitely intentional.

The triangular representations are paired with similarly geometric shapes in the same bold blue. Birds, butterflies and saguaros adorn the walls of the new construction.

This beautification is but icing on the cake, a visual gift in addition to the the benefits of safety and ease of driving that are the core of the two-phase project that revamped the interchange. Improvements included reconstructing and widening northbound and southbound I-19; creating a “braided” ramp alignment and replacing both the Michigan Avenue pedestrian bridge and the Ajo Way bridge over the Santa Cruz River.

This close-up is among a host of other photos taken of the project by John Dougherty, ADOT's Video Services supervisor, whose images illustrate many of our Art of Transportation blog posts. You can find many more showing off the completed project on our Flickr page.  

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Art of Transportation
We think there is beauty in transportation. It’s not all hard hats and pavement. Art of Transportation is a blog series featuring unique photos our team has taken while on the road or on a construction project.

It's a question that occasionally pops up on our social media feeds: Why is it called Interstate 17?

And it's not the "17" part they are asking about.

Rather, it's the fact that all 147 miles of highway runs between Phoenix and Flagstaff ... and that's it. How can it be called an "interstate" when it never reaches outside of Arizona? The same question can be asked about Interstate 19, which runs 102 kilometers (63 miles) between Tucson and the international border.

If we went solely off Webster's definition of "interstate," it admittedly doesn't make much sense. But when we talk about interstate in terms of highways, we have to turn to a different criteria. 

According to the Federal Highway Administration, the Federal-Aid Highway Act of 1956, which created the system, called for uniformity in construction standards. These standards were developed by the American Association of State Highway Officials (now the American Association of State Highway and Transportation Officials or AASHTO) and are the benchmark for any highway that wants to be an interstate. The metrics include having controlled access, design speeds of 50 to 70 MPH depending on terrain, a minimum of two travel lanes in each direction, 12-foot lane widths, a 10-foot right shoulder, and a 4-foot left shoulder.

And the criteria for adding another highway to the system is also straightforward: it must meet the interstate standards, be a logical addition or connection, and be coordinated among all jurisidictions it will pass through.

The Federal Highway Administration also has a fantastic page dedicated to debunking myths about the interstate system. There the agency specifically address highways that don't ever leave their state of origin.

"The key," according to the Federal Highway Administration is "each highway must meet Interstate standards, be a logical connection to the interstate system, connect to an existing route or be a congressionally designated future interstate corridor that eventually will connect on at least one end." 

This definition is why you'll see interstates that are beltways around large metropolitan areas or in places such as Hawaii, Alaska and Puerto Rico that cannot connect to other states. It's also why I-17 and I-19 both can be called interstates.

Though they don't go anywhere nearly as far as I-40 or I-15, both I-17 and I-19 have fascinating histories that can give additional insights into these intrastate interstates.

Drivers in Tucson will notice many changes and upgrades to Interstate 19 between Ajo Way and Irvington Road. But something they can't see from behind the wheel is a big step-up for those living near the freeway.

The newly constructed Michigan Street Pedestrian Bridge over I-19 features new ramps that comply with the Americans with Disabilities Act. The bridge was installed in mid-January to connect city neighborhoods on either side of the freeway. It replaced the old pedestrian bridge, which was not ADA compliant because it had stairs and no ramps.

“The new bridge is well lit, has ramps that comply with the Americans With Disabilities Act, and it is more aesthetically pleasing due to its artwork and more modern design,” said Senior Resident Engineer Chris Page.

You can see for yourself that "aesthestically pleasing" part in the slideshow to the right from our Flickr page.

The pedestrian bridge is part of the $84 million I-19/Ajo Way traffic interchange project, which is in the second of two construction phases.

Other work includes

• constructing a braided ramp alignment — first of its kind in southern Arizona — connecting Ajo Way with I-19 separately from the I-19 traffic exiting at Irvington Road.   
• reconstructing and widening southbound I-19 within the project area.
• widening northbound I-19 to add an auxiliary lane between Irvington Road and Ajo Way.
• completing I-19 noise walls south of Michigan Avenue and along the south side of Ajo Way between Kostka Avenue and I-19.
• completing drainage improvements and improving drainage collection features.
• replacing the Michigan Avenue pedestrian bridge.
• replacing the Santa Cruz River Bridge on Ajo Way.
• constructing bank protection and the new Rodeo Wash outlet into the Santa Cruz River.
• reconstructing and widening Ajo Way from Holiday Isle to I-19.

The first phase included a new traffic interchange at Ajo Way and I-19, major drainage improvements, sound walls, utility relocation and an upgraded traffic light at 16th Avenue.

Often when we find historic road construction photos we have to do some guess work on either when they were taken or exactly where. Fortunately, we don't have that problem today.

This photo from the construction of Interstate 19 was clearly labeled as being snapped in February of 1977. So far so good.

But if you look in the upper left corner of the photo, you'll notice the prominent rock outcropping that's part of the background mountain range. Anyone who has spent time in the greater Green Valley or Tubac areas can tell you that it's Elephant Head, a prominent landmark in the Santa Rita Mountains. This is also one of the easiest angles to see why the formation has that name. It's okay, we'll give you a second to squint and make out the head, large ears and trunk. 

Did you see it? Great!

So we were lucky enough that someone to captured this image that tells us both the when and the where. But let's talk about the why for a moment. 

While the earliest portions of I-19 date back to the mid-1960s, it took more than a decade to have one complete interstate going from I-10 in Tucson all the way down to the Nogales. The 11-kilometer (roughly 6.8-miles) section between Chavez Siding Road and Canoa Ranch that this particular section is a part of was finished in 1977. After that, only two more sections, finished in 1978 and 1979, were needed before the 102-kilometer (63-mile) interstate was declared done.

And hopefully the next time you head down south, whether to see the historic Canoa Ranch, shop in Tubac or cross the international border at Nogales, this photo will spring to mind as a reminder to appreciate the view.  

By David Rookhuyzen / ADOT Communications

For today's Throwback Thursday, we have a little "remember when?" treat for people who live south of Tucson. Recognize the interchange in this undated photo along Interstate 19? For the majority of the nearly 30,000 people who live alongside it now, the answer is probably a resounding no.

A similar shot today would find an active adult community on one corner and a shopping center on another. You could possibly see a slew of houses in the background. But given that the highway appears to be under construction, all of that was quite a ways in the future when this photo was snapped.

The image is labeled as being taken at I-19 at Helmet Peak Road. But today it isn't called Helmet Peak Road when it crosses the interstate; it's called Sahuarita Road after the bustling town that incorporated in 1994.

So if you live down south, this is just a fun reminder of the way things use to be.