INSIDE THE SPS-2 TECH DAY

31 years of pavement performance

The Washington Department of Transportation (WSDOT) and the IGGA recently co-hosted a Specific Pavement Studies Experiment 2 (SPS-2) Tech Day in Ritzville, WA. The SPS-2 sections in Washington are part of the broader Long-Term Pavement performance (LTPP) program, which was created to study how pavements perform over time under real traffic, climate and maintenance conditions. LTPP provided both the research framework and the long-term performance data behind the Washington SPS-2 Tech Day, while the event gave participants a chance to connect those decades of findings to firsthand field observations. 

The event brought together more than 30 transportation professionals to

examine 31 years of SPS-2 pavement performance and translate those lessons into future preservation practice. In addition, Federal Highway Administration (FHWA) Director Jean Nehme of the Office of Infrastructure R&D, participated in the event—the first director to do so—underscoring the national value of Washington’s SPS-2 data. 

A field review three decades in the making 

The Washington SPS-2 project is located on SR 395 in Adams County, southeast Washington. The project was constructed beginning in 1994 and opened to traffic in November 1995. Now 31 years in service, the Washington SPS-2 sections provide a rare, field-verified look at how design choices perform over decades of traffic and climate exposure. 

Event presenters included Robert Seghetti, president of ACME Concrete Paving, Inc., who delivered a presentation on ACME’s original construction of the specific US 395 test sections as part of the Washington SPS-2 experiment, giving attendees firsthand insight into the design variables, equipment challenges and installation of the 13 experimental sections.

His remarks bridged historical construction practices with modern performance results and helped set up the field review by explaining exactly how the 13 different experimental sections were installed. 

After the morning session, participants visited the US SR 395 corridor under a WSDOT-provided lane closure for a two-hour review of the SPS-2 test site. Karen Carlie, P.E., WSDOT, shared, "Walking a live lane closure allowed us to inspect 13 distinct concrete test sections up close to see exactly how varying thicknesses and base types have held up under three decades of heavy traffic and Eastern Washington weather." 

What 31 years revealed 

Field observations showed that all sections of the 31-year-old project are still performing well, including the hot pour joint sealant and the state’s undowelled supplemental test section. These observations underscore the value of sustained field monitoring, offering a firsthand look at SPS-2 over the years. As part of the largest concrete pavement experiment ever undertaken, the test sections continue to deliver actionable insights on how thickness, base type and other structural factors influence long-term performance. 

From field data to future policy 

The event concluded with an interactive Concrete Summit that connected field observations to SPS-2 pooled-fund research, future preservation policy and pavement design practice. 

This work builds on a substantial body of research completed under the SPS-2 pooled fund, with WSDOT serving as the lead state. Learn more about SPS-2 and concrete pavement preservation at www.igga.net/contact-us.