ADOT Kids: Building highways is a blast!

Have you ever wondered what it takes to move mountains?

Let’s dig in and learn more! 

The I-17 Improvement Project corridor is one example of an ADOT project that required entire sections of the mountainsides to be blasted and excavated to make way for additional lanes. That includes 15 miles of widening and 8 miles of flex lanes along the entire 23 miles from Anthem Way to Sunset Point. 

The rock and material removed during the blasting process were hauled to another area of the project to be used again in the new roadway. A large portion of the blasted material was crushed and then used as aggregate base, embankment and rock mulch along the 23 miles of new lanes. The construction team recycled the rock to eliminate the need to purchase new material and cut down on construction costs. 

In the areas where rock material was too hard to be ripped it needed to be blasted instead to widen the roadway. Crews had just one hour to close the highway to nighttime travelers. Many times the highway was only closed for 20 minutes to complete the blasting  operation, clear the debris and reopen the highway as shown in this video. 

Each blast was made up of individual explosions that are timed to detonate only milliseconds apart. That is about the speed of a human eye blink. Watch this second video and notice the sequence of light flashes as an explosion occurs. Timing each blast to happen one after the other rather than all at the same time, helps to make the blast safe and control the rock fragments to fall in one location. That helps excavators, loaders, bulldozers and dump trucks haul away the rock quickly and more efficiently. The infographic shows how much rock was moved during the project.

Behind the scenes, work is directed by a blasting engineer who must first create a plan. The plan is important because it shows the location of the rock planned to be blasted and where holes will be drilled in the rock to hold a specific amount of the blasting material. 

These are the some of the important steps required to manage the blasting operation:  

• Make sure all personnel and traffic is at least 2,500 feet away from the blast.
• Start the countdown for everyone to hear and then execute the blast.
• Inspect the results of the blast and confirm all of the explosives have detonated.
• Provide the "all clear" so that crews may begin moving the rock and debris.
• Confirm the highway may be reopened to traffic once the roadway is clear of debris.

   

ADOT’s Senior Resident Engineer Joshua Wentzlof PE, is one of three resident engineers working on the I-17 Improvement Project, and he is familiar with this type of blasting operation. The PE or Professional Engineer designation after Wentzlof’s name references an engineer who is licensed to practice in the profession of engineering.

“The favorite part of my job is the constant problem solving and seeing a project being built from start to finish,” said Wentzlof. “I would say math and science skills are essential for construction engineering. These subjects require you to practice and use your problem-solving skills, which are put to use on a daily basis in construction. Geometry, especially in road construction, is important when reading construction plans.”

Wentzlof began his career with ADOT after receiving his civil engineering degree from Northern Arizona University.  He joined the department’s Engineer In Training (EIT) program and spent five years gaining experience in construction planning and managing large projects before becoming a resident engineer. 

The I-17 Improvement Project is just one of many roadway construction projects happening on state highways in Arizona. If a career in roadway engineering sounds like a blast to you, read about what some ADOT engineers say about their EIT training experience. Check out other highway projects ADOT engineers manage every day in Arizona. 

Please visit ADOT Kids for more stories, activities and videos about engineers.