Institute for Transportation

Superheavy loading vehicles, commonly referred to as superloads, with their non-standardized loading configurations and high gross vehicle weights and axle loadings, can cause unexpected distresses on Iowa road infrastructure systems compared to those caused by conventional vehicle class types categorized by the Federal Highway Administration.

These vehicles encompass a wide range of types, such as implements of husbandry like grain carts and superheavy loads like dual-row modular semi-trailer trucks, and they are becoming increasingly prevalent in the Midwest. In particular, Iowa lawmakers recently passed legislation that allows vehicles to exceed gross weights by up to 12%.

To help county engineers and other road asset owners better quantify structural damages and associated treatment costs of Iowa’s roadway infrastructure under diverse superload scenarios, a recently completed research project studied these vehicles and their impacts and ultimately developed a user-friendly analysis tool.

The Road Infrastructure-Superload Analysis Tool, or RISAT, developed as part of a Program for Sustainable Pavement Engineering & Research (PROSPER) project and available upon request, will help local agencies evaluate the full scope of superloads’ effects on paved roads.

“By addressing the complex interplay between superload characteristics and road responses, this research contributes to the development of sustainable strategies for preserving and maintaining Iowa’s road network amidst the evolving demands of heavy transportation vehicles,” said PROSPER Director Halil Ceylan, who was the principal investigator on the project.

He added, “Moreover, the development of the RISAT provides a user-friendly platform for engineers and planners to evaluate the structural damages and associated treatment costs induced by superload traffic, enabling informed decision-making and efficient management of road infrastructure.”

The RISAT is a Microsoft Excel-based automation tool comprised of a navigation panel and several sub-tools. The tool initially asks users to select either jointed plain concrete pavement or flexible asphalt concrete pavement, choose one from a variety of superload types and provide details about its loading configuration, and then provide more specific details about the particular roadway case.

The outputs after entering the particular details gives users highly accurate predictions of pavement damages, treatment costs, and service life reductions.

Throughout the project, the research team assessed the performance of both paved and unpaved roads and quantified potential structural damages and associated treatment costs when they are subjected to various types and payload levels of superloads via structural road analysis, through life-cycle cost analysis (LCCA), artificial intelligence (AI)-based predictive modeling, remote-sensing data analysis, and finally the development of the prototype tool.

It also identified repair and rehabilitation alternatives as well as funding alternatives for infrastructure damages resulting from superloads.

“Incorporating field data into the RISAT also enhanced its reliability and applicability in pavement management practices, providing engineers and planners with valuable insights to inform their decision-making regarding pavement design, maintenance, and rehabilitation strategies,” said Ceylan.

Additional findings from the research, including a user guide incorporated into the final report, along with the contact information to request the RISAT are available on the project page.

Ceylan and other PROSPER research teams have created other tools for local agencies to better quantify their road networks including the Iowa Pavement Analysis Techniques (IPAT) tool, the Pavement Structural Analysis Tool, and a smartphone-based road performance data collection tool called CyRoads. The IPAT tool and PSAT both include the tools and user guides on their respective project pages, and the final report available on project page for the CyRoads tool includes details about how to access the tool in its user manuals.