PNL QUALITY EXAMINER

PNL is providing essential quality testing, inspection and engineering services for the ongoing I-10 Broadway Curve project-ADOT’s largest urban freeway reconstruction project, over the last 12 months. PNL has tested and inspected elastomeric bearing pads, steel reinforcing bars and 7 wire strand for multiple segments of the project, including the 48th St. underpass, Broadway Road underpass, and Guadalupe Road underpass widening. The Maricopa Association of Governments (MAG) initiative had been approved by voters in Maricopa County in 2004 through Proposition 400. The venture began July 23rd 2021-a 3 ½ year, 11-mile-long rebuilding and widening restoration of the freeway.  MAG Regional Transportation Plan (RTP) identified the need for this project to reduce travel times on the I-10 during peak hours, improve airport access, support ridesharing (HOV-high occupancy vehicles) and transit as well as prepare the region for future growth projections by rebuilding and widening the freeway.

For those who are interested in staying “ahead of the curve” there is a downloadable app available for updates and information about the I-10 Broadway Curve Improvement Project. Everyone who drives, lives or works in or around the project area can learn about closures and restrictions; real-time traffic information and detour routes. 

There are several types of aerial lifts used to access work areas on construction sites where it is inconvenient or impractical to erect scaffolding. These lifts are vehicle mounted, boom supported platforms that are controlled by one or more operators. The six classifications for this type of equipment are Personnel Lifts, Towable Boom Lifts, Walkie Stackers, Bridge Inspection Booms, Scissor Lifts, and Aerial Boom Lifts. Scissor lifts and aerial boom lifts are the two most employed aerial lifts on construction sites. The major causes of injuries and fatalities while utilizing aerial lift machinery are falls, electrocution, collapses and tip overs. Operators must always follow the manufacturer’s recommendations for use. It is of paramount importance that the workers are properly trained, tested and certified. PNL provides training through United Rentals, a third-party organization, for lift training.

The guidelines that must be followed before using all aerial lift equipment include four basic steps: First a complete walk around inspection, assuring operational fire extinguishers and emergency controls, and checking leakages and tire inflation pressure is performed. Second, a work site assessment i.e., checking for bumps, floor or ground obstructions, debris, inadequate surface support for the load forces, weather conditions and power lines must be confirmed. Thirdly, the function test checks regarding functionality of the controls by starting in neutral, operating manually all functions and emergency stop controls are authorized. Finally, proper operation such as regulating travel speed according to ground conditions, maximum loads and the potential for hoses, ropes, or electrical wires to become entangled must be proven. All workers are to wear PPE: hard hats, safety glasses and harnesses at all times. One should never be positioned between overhead obstructions where the platform basket could be crushed by overhead beams. Always assume all power lines are energized and wheel chocks should be placed on brakes when the position is inclined.

While OSHA may not require a spotter in all circumstances, it is a good practice to designate a person as a spotter while the lift is in motion. When the aerial lift is in motion and the operator does not have full vision of their surroundings a spotter is required. The spotter can view a hole or uneven surface in the distance and alert the operator of the condition. Additionally, construction sites may have PVC, electrical conduit, post tension cables etc. extending upwards from the concrete which need to be avoided to prevent damage to both the vehicle and infrastructure.  

Thomas Young a British scientist and Simeon Poisson, a French mathematician and physicist are the two theorists who devised the tensile concepts; Young’s Modulus is based on the principles of elasticity of materials, and Poisson’s ratio, the expansion or contraction of materials isometrically (in all directions). A universal test machine performs the most fundamental and common types of mechanical testing. PNL’s laboratory maintains three universal test machines, one customized hydraulic compression machine designed and engineered by PNL, and two bend test machines.

A tensile test applies tensile (pulling) force to a material and measures the specimen's response to the stress. By doing this, tensile tests determine how strong a material is and how much it can elongate. A standard tensile test is a common destructive test that can measure multiple useful properties such as tensile and yield strength, ductility or elongation, the modulus of elasticity, strain hardening characteristics as well as other tensile properties. Tensile tests are typically conducted on electromechanical or universal testing machines, are simple to perform, and are fully standardized. ASTM provides several standards for determining tensile properties of materials. A tensile testing machine consists of a test frame that is equipped with a load cell, testing software, and application-specific grips and accessories, such as extensometers. The type of material being tested will determine the type of accessories needed, and a single machine can be adapted to test any material within its force range simply by changing the fixturing. Our largest Instron universal test machine which has a capacity of up to 450,000 pounds, is often used for multi strand wire and metal testing for highway bridge pylon infrastructure. Our hydraulic compression machine is used predominantly to inspect our elastomeric bearing pads with a compressive capacity of over 2 million pounds and simultaneous shear capacity of 300,000 pounds. We provide these tests for hundreds of U.S. and international cities’ highways and bridges projects.

A bend test is another type of destructive test used to evaluate the performance of a material. One method of bend testing is a guided bend test. Guided bend tests can be used as a method to evaluate the ductility of a material by checking the materials ability to resist cracking during one continuous bend operation. Guided bend tests are typically performed on specialized machines made specifically for bend testing.  Our lab is equipped with two such bend test machines used for testing reinforcing steel (rebar) and welding qualification tests. Other types of bend tests can be configured using our universal machines.

PNL’s lab offers complete flexibility and capabilities for all your tensile and bend test projects. We utilize Instron universal testing equipment, a leading manufacturer of materials testing equipment. We offer a variety of different sizes and force capabilities ranging from 110 lbf to 450,000 lbf of tensile or compressive force and up to 2 million lbf of straight compressive force. We can perform tensile, compression, bend, peel, tear, shear, friction, puncture, and other mechanical tests.

For more information regarding our abilities email: Kyle Fleege at kyle@pnltest.com.

This Quality Examiner’s Tech Talk issue explores PNL’s Mechanical Laboratory testing capabilities. Matt Sorce Advanced NDT Project Manager interviews Kyle Fleege, P.E., who has worked at PNL for 14 years and has managed the Mechanical Lab since 2012.