At long last (in my opinion, anyway) there is a hint of fall in the air. After the rain and heat of the spring and summer, I can’t be the only one ready for a change of seasons. All that rain has taken a toll on our transportation infrastructure in Virginia. From washed-out culverts, overtopped bridges, mudslides, and the always popular potholes, VDOT and our partners have had our hands full. When you are already behind schedule and feeling as though you continue to get more so every day, it’s easy to say there’s just no time for anything new, no time for implementing that research recommendation or thinking outside the box. When in fact, there is no better time. Now, when the need to be innovative, to do things better, quicker, and in ways that last longer is critical. So, despite the mildew on my pencil, I’d like to offer a few thoughts on how innovation is making a difference in Virginia this fall and how we can all work together to keep our network one of the most envied in the country.
I write this while temporarily wearing two hats, not giving up my role as the Director of the Research Council (although Mike Fitch is doing all the work) and serving as the Acting Director of Innovation in the Secretary of Transportation’s Office. It’s an amazing experience for me to see the commitment to innovation at the very highest levels. The Office of Innovation was created to promote new technology, processes, and policies across the modal agencies. Initial focus areas for the office include data and analytics, Automated Virginia, and fiber/broadband/wireless initiatives. Underpinning all of these areas are a number of cross-cutting issues including cybersecurity, resiliency and support for pilot projects. At first glance, these may seem a bit removed from the innovations we typically talk about in the pavement world, but the connections are there, and they are important. First, when we talk about vehicle automation, a big part of the Automated Virginia focus area, we can’t forget about the importance of the state of good repair to the success of these systems. Auto manufacturers are telling us they need smooth pavements and well-defined pavement markings as a minimum for deployment. Finding ways to deliver these things in a manner that lasts will be critical as the technology advances. And the focus area around data and analytics may help us get there. We know that there is much to learn about what works and what doesn’t work just by digging into the data. But, that means we have to collect, store and maintain that data in ways that facilitate analytics and look for opportunities to integrate with other disparate data sources. Our pilots involving the electronic capture of data are purposeful steps in the right direction.
Speaking of electronic data collection, we’re making tangible progress on our State Transportation Innovation Council (STIC) project to develop a tablet-based system designed to assist with quality management in the delivery, lay-down and compaction of asphalt materials. Our application developer is now working with an “early-adopter” asphalt producer, VDOT field inspection staff and VAA to do validation trials. Deployment is expected throughout the coming year and will result in new data availability for a variety of analyses.
Research also continues to support VDOT’s move to adopt performancebased (balanced) design specifications for asphalt plant mixtures. A previous article (Finding the Right Balance with RAP, Asphalt News, Spring/Summer 2018) discussed VDOT’s move toward performance mix design for use with high RAP. Ongoing work seeks to learn more about currently produced mixtures and to begin to relate results from performance indicator tests to actual material performance under traffic and environmental stresses. The study, Performance Mix Design (PMD) – Phase I, is designed to address specification development from three aspects:
- Additional benchmarking of currently produced surface mixtures, via collection and testing of time-of-production, created (non-reheated) specimens, specimens that are made later from the loose mixture (reheated), and (where possible) field cores. This aspect of the study serves as both a means of assessing currently produced mixtures and addressing the potential influence of specimen type (non-reheated/reheated/ core) on performance test results.
- Collaboration with industry partners during the design process. This aspect is intended to provide information on how to address performance during the mix design process. By collaborating with industry and VDOT District partners, researchers hope to gain insight into the design process while providing feedback on how changes to designs impact performance parameters.
- Construction of field trials to assess how the use of PMD processes will impact plant operations, quality control and assurance practices, and acceptance. Integration of performance testing into the acceptance process is likely to have a variety of consequences, many of which may not be obvious without the real-world experience of field trials. Some aspects to consider include availability of testing equipment and manpower, testing frequency, response time, acceptable variability between producer and agency results, and addressing failing results, among others.
Additional phases of the work are anticipated to address the impacts of aging on mixture performance during both testing and in service, as well as to relate measured performance properties to long-term in-service performance.
To date, VTRC has collected and tested mixture samples from four producers that include non-reheated specimens, reheated specimens, and pavement cores. Six additional mixtures have been collected with the assistance of industry volunteers, although that sampling does not include pavement cores. Testing of those materials will continue through the fall and into the winter.
An example of the test results is shown below in Figure 1, which represents the Cantabro test for durability. Data from earlier benchmarking efforts, reheated specimens only, are shown with grey Xs. Colored data points indicate recently sampled mixtures; open shapes represent specimens fabricated at the plant with no reheating, while filled shapes represent reheated specimens. For three of the four 2018-sampled mixtures, reheating the mix to fabricate test specimens appeared to result in higher mass losses than that seen in unreheated specimens. Of course, additional mixtures and further analyses are needed to evaluate this trend, but it highlights the diversity of responses shown by various mixtures, and the potential influence of specimen preparation methods.
In addition to the Cantabro testing, cracking resistance and rutting susceptibility are evaluated for all mixtures. Table 1 provides an example testing plan detailing the tests under evaluation as well as specimen types. As data is collected, results will be shared.
It is an exciting time for innovation in the Commonwealth. Our continued focus on research and implementation at VTRC combined with our strong industry partnerships will continue to bring about positive change in the delivery of our asphalt pavement program. Layering on the commitment to innovation at the highest levels of state government can only accelerate our progress.
I look forward to seeing where we can take this, together.