Understanding the Long Term Pavement Performance Program

Do guys on an asphalt trucks make pavement maintenance decisions? Nope.  Safe and smooth roads benefit from extensive national data collection and analysis.

With literally millions of miles of pavement crisscrossing the US, it stands to reason that the asphalt and concrete that make up our nation’s roads and highways should be studied. Roads cost a great deal of money to be installed, to be maintained, and ultimately recycled and replaced. The nation’s economy depends on it as well: ships, planes, and trains can only go so far in transporting goods and people.

Our nation’s infrastructure – roads, highways, freeways, not to mention commercial parking lots and sidewalks – have given rise to a vital and ever-growing industry of asphalt paving contractors, as well as concrete repair contractors.

Which is why the Federal Highway Administration established, in the early 1980s, the Long-Term Pavement Performance Program (LTPPP), an ongoing research project that collects and analyzes pavement data. It looks at the effects of specific materials used, maintenance practices, traffic, and weather on road surfaces as a means to understand how to make roads and bridges safer and more economical.

The data is collected by independent contractors at 2,500 sites in four different regions (including in Canada, as the US FHA shares data with the Transportation Association of Canada). This data is shared via what’s called the InfoPave™ portal, which local departments of transportation (DOTs) can use to search for vulnerabilities and solutions to the needs in their jurisdictions.

In addition to raw data collected on cracks, potholes, smooth asphalt, and worrisome bridge trusses, the LTPPP repository has images, reference materials, resource documents, and a comprehensive reference library with more than 1,200 research reports, technical briefs, and program documents that can be accessed electronically to assist in pavement design, pavement product development, and pavement maintenance. 

One example of its use is found in a research paper written by a graduate student (Matild Dosa with faculty professors Mamlouk, Kaloush and Zapata, 2012) at Arizona State University. Her paper title, “Relative Benefit of Chip Seal Application in Different Climatic Conditions Based on Initial Pavement Roughness,” speaks to the many variables that face highway departments the world over. Dosa says in her report introduction, “This document examines the effectiveness of chip seal treatment in four climatic zones in the United States. The Long-Term Pavement Performance database was used to extract roughness and traffic data, as well as the maintenance and rehabilitation histories of treated and untreated sections. The sections were categorized into smooth, medium and rough pavements, based upon initial conditions as indicated by the International Roughness Index.”

In other applications, a state department of transportation might reference a publication such as the LTPPP Distress Identification Manual. This provides definitions of such pavement failures known as pattern fatigue cracking, transverse cracking, and longitudinal cracking by metrics that define severity (low, moderate and high) by the program.

Of course, other variables affect pavement quality beyond those identified by LTPPP, such as funding (or a lack thereof) and utility work, the latter of these that might be poorly timed against a recent repaving of a street or highway. All of which goes to show the challenging responsibilities borne by municipalities and states at keeping our roads as smooth, safe, functional and affordable as possible.