Robert Rasmussen, Vice President and Chief Engineer-The Transtec Group, Inc., recently posted a report on LinkedIn titled, “Pavement Engineering for Tracks and Proving Grounds: How to Begin?” For highway or airfield projects, much of what is “pavement design” focuses on selecting a pavement structure: pavement layers of a given thickness to resist the punishment of heavy loads. However, for racing circuits, test tracks, and proving grounds, loads are generally much lighter. Unless the track is intended for heavy vehicle use, only a minimum structure is necessary. Pavement layer types and thicknesses are instead selected to meet functional objectives.
Specialty pavement surfaces require designs and specifications that facilitate predictable and consistent vehicle and tire responses. For race tracks, grip is of paramount importance, and oftentimes evenness too. For automotive test surfaces, design objectives can be more complicated. Handling, braking, NVH, and ride surfaces sometimes require target response levels, and specifications with both minimum and maximum control levels are necessary to achieve this.
Some surfaces push the boundaries of paving technology; for example, coastdown tracks that require exceptional evenness. Pass-by noise tracks conforming to ISO 10844 include an acoustical absorption requirement, which is unheard of by most road builders. Many vehicle and tire regulations such as NCAP, UNECE, and FMVSS also include surface requirements. But possibly the biggest challenges are when replicating an existing surface, or when a subjective user requirement is the desired outcome.
Uniformity is another common objective. Spatial variability can be reduced through best practices in construction, but reducing variability over time presents unique challenges. Most pavement surfaces “evolve” as the pavement ages from the moment it is constructed. Burnishing can sometimes accelerate this initial change, but can also damage the surface. Seasonal, daily, or even hourly changes in the surface are also possible, which make interpreting vehicle and tire test results difficult. Controlling these variations is often achieved through proper material selection.
One final but important pavement design objective is durability. For track owners and managers, budgets can be scarce, and while no pavement will last forever, it is possible to increase durability by investing in better materials and construction methods.
Meeting these objectives is undoubtedly a challenge. Success is possible by understanding how pavements can impact vehicle and tire performance. Capitalizing on the combined experience and expertise of all stakeholders is also important. In the coming weeks, we at The Transtec Group, Inc. will explore this all in more detail … please stay tuned!
For the LinkedIn article, please go to: https://www.linkedin.com/pulse/pavement-engineering-tracks-proving-grounds-how-begin-rasmussen