The Grainger College of Engineering
Illinois Center for Transportation

New ICT-IDOT projects

1/17/2025 McCall Macomber

Illinois Center for Transportation is pleased to announce the start of new Illinois Department of Transportation-sponsored projects, from most recent start date.

R27-277: Update of Traffic Factor Equations for IDOT Mechanistic-Empirical Pavement Design
Imad Al-Qadi, University of Illinois Urbana-Champaign
Charles Wienrank, Illinois Department of Transportation

E-truck platoons are expected to reduce fuel consumption and emissions as well as lower freight costs, reduce congestion, and minimize braking and acceleration. However, they could potentially accelerate pavement damage due to channelized traffic and increased weight from batteries.
E-truck platoons are expected to reduce fuel consumption and emissions as well as lower freight costs, reduce congestion, and minimize braking and acceleration. However, they could potentially accelerate pavement damage due to channelized traffic and increased weight from batteries.

Transportation agencies must adapt pavement design procedures to meet changes in traffic and advances in new technologies such as electric vehicles and trucks, which are expected to accelerate pavement damage due to increased weight from batteries.

Researchers will update the equations used by IDOT pavement designers to convert mixed-traffic axle loadings into traffic factors for asphalt and concrete pavements while accounting for current traffic conditions and axle configurations. Traffic factor represents the total number of 18-kip equivalent single-axle loads, expressed in millions, that a given pavement may be expected to carry. They will also incorporate the impact of e-trucks and platoons — a group or convoy of closely spaced vehicles — on pavement design.

Updating the traffic factor equations to meet current and future demands will allow the agency to properly design pavements to carry the anticipated loadings.

The project will conclude June 2027.

R27-SP74: Evaluation of Concrete Overlays
Jeffery Roesler, University of Illinois Urbana-Champaign
Charles Wienrank, Illinois Department of Transportation

Longitudinal cracking on an Illinois highway that has been rehabilitated with an unbonded concrete overlay.
Longitudinal cracking on an Illinois highway that has been rehabilitated with an unbonded concrete overlay.

Existing concrete pavements that have reached the end of their service life may be rehabilitated using an unbonded concrete overlay — where a new concrete surface layer is placed over existing pavement.

Researchers will assess the performance of three projects with unbonded concrete overlays in Illinois through visual surveys, nondestructive testing and coring. The assessments will provide current overall overlay performances, structural condition, and the potential interlayer condition and interfacial contact integrity.

The results are expected to assist in developing or modifying specifications and standards for the design, construction and maintenance of unbonded concrete overlays.

The project will conclude August 2025.