DOT labs take the guesswork out of highway safety, quality Story and photos by SHERRY HALBROOK When you get in your car to go somewhere, how aware are you of the roads and bridges you travel? Chances are, you only really notice the road during pothole season, or the painted lane markings when they disappear in snow, rain or fog. Normally, we can take our highway system for granted, because thousands of PEF members at the state Transportation Department sweat those details and countless others for us. How do they know the best site for a new highway interchange, what kind of drainage it needs, what kind of fill to bring in and which grades of steel, concrete and asphalt to use? DOT engineers turn to the DOT laboratories for answers to these and other technical questions. DOT civil engineer Ed Lucas, a steward in PEF Division 177, works in the department’s Technical Services Division, which develops and recommends many of the engineering policies, standards and specifications for building highways and bridges that are safe, durable and cost-effective. “We couldn’t do it without the labs,” Lucas says. “They provide the proof-positive way of knowing what will work and what won’t.” Inquiring minds The labs are clustered into two basic groups — geotechnical and materials. The Geotechnical Laboratories analyze and test the soils and rocks on which highways and bridges are built. They also test geosynthetics, such as textiles used to prevent erosion. The Materials Laboratories focus on testing just about every other component of highways and bridges, from concrete and asphalt to steel and paint. The bulk of the testing is done at the statewide labs in Albany. Nearly all of the people working at the DOT labs are PEF members. They perform more than 100,000 tests each year: Tests range from grading the size of rocks in soil samples to using atomic absorption to check recycled concrete for toxic substances, and from measuring how well freshly poured concrete holds its shape to pulling steel rods until they snap. About 80 percent of that work is in testing materials, soils and gravels in use on state construction projects to ensure they meet the specified standards for the job. Sift it, compress it PEF members in the Geotechnical Labs will tell you the first thing you must look at when you want to build a highway or a bridge is the ground that will go under it. Is it rock-solid or unstable? “We’re mainly judging three characteristics: gradation, durability and clay content,” says PEF member Steve Mabin, who runs the soils engineering lab. “After soil is compacted in the field, we use radio-active probes to measure the density of the soil and its moisture content,” Mabin says. When they receive a sample at the lab, they dry it, sift it and classify its components. They also test to find out how the stones in a sample will be affected by road salt and the effects of freezing and thawing. If a sample is meant to be topsoil for the areas along the sides of the highway, how rich in nutrients is it? Will grass and other plants thrive in it? “Blind” tests are conducted on samples from contractors and vendors, to ensure they all face the same unblinking standards. “During construction season, we run hundreds of samples each week,” Mabin says. “And in the fall and winter, we visit all 11 regional labs in the state to inventory and check equipment.” Winter is also a catch-up time for the labs to focus on training field inspectors and making any needed repairs on the many measuring and testing instruments that will soon face another season of use. Heat it, push it DOT’s Materials Bureau maintains a list of approved materials, manufacturers and suppliers that includes thousands of entries ranging from ice-retardant additives to “elastomeric bridge bearings.” Localities, businesses and even other states often join New York in relying on this list as a guide to quality and reliability in selecting products and suppliers for highway projects. They also monitor projects in progress to make sure the materials being delivered are the ones that were ordered for the job. And they are constantly analyzing and testing samples taken by inspectors in the field to find out how well older roads and bridges are holding up, what needs maintenance or replacement and how soon. Million-dollar questions While the task of testing seems straightforward, at stake are safety issues, millions of tax dollars and sometimes even the economic viability of localities. Lucas, for instance, turned to the experts at the labs for help when his section was assigned to figure out what had to be done to get an important highway overpass downstate back in safe working order after disaster struck. “A traffic accident had caused a tanker truck to explode on the highway beneath the overpass,” Lucas says. “The concrete and steel were super hot from the flames when the fire department began to blast it with cold water and blew the concrete right off the walls.” Traffic had to be rerouted until the state could figure out how much of the remaining steel and concrete had to be replaced to make the overpass safe again. Lifespans and lawsuits PEF member Rosemary Mahoney and her staff in the chemical testing section of the Materials Lab have been focusing on traction and the effects of friction, pressure and temperature on asphalt. “Friction becomes a big issue in lawsuits involving skidding accidents,” Mahoney says. Ideally, asphalt binds materials in the concrete together, keeps water from penetrating into the road bed, and resists wear and rutting. “The asphalt now on Interstate 87 has a lifespan of about 10 years,” says PEF member Peter Hennessy, a materials analyst in the lab. “We’re trying to get that up to 20 years. How long it lasts, really depends a lot on traffic levels and climate. “We want to know how the materials will behave on the hottest day on Long Island and the coldest day in Massena,” Hennessy says. “We send inspectors to the mixing plants for the concrete where they take samples of the binders and test them. If they fail to meet the state’s specifications, it usually results in a financial penalty to the contractor, because it could shorten the useful lifespan of the pavement.” The testing this lab does on asphalt and the reflectivity of paints are just two examples of how the state labs work with national programs to improve highways and bridges throughout the United States. Snap! Crackle! Pop! PEF member Bill Koniowka runs the physical testing operations of the Materials Laboratory. This is a world of big machines that make big noises. In this lab, they mix concrete and they crunch it. They rip steel guide rails, and they pull steel rods and push girders until they crack or snap. From the tiniest components to the largest, this lab gets very physical in pushing materials to their breaking points. They want to know just how far it will bend or stretch before it breaks. “Roughly half of the tests we do are for durability, and the other half are to determine specific properties,” Koniowka says. The right stuff While samples that come into these labs may endure the tortures of the damned, it’s all for a very good cause — your safety. So, the next time you drive in a storm, cross a bridge in a high wind or sit in traffic backed up by highway construction projects this summer, remember the people at the DOT labs and smile. You’re a whole lot safer thanks to them. The Communicator Home Page