RESEARCH—A Hallmark of IDOT’s Guiding Principles

The Illinois Department of Transportation’s Strategic Planning Initiative identifies the department’s guiding principles as Safety, Integrity, Diversity, Responsiveness, Quality, and Innovation. Through the lens of IDOT’s guiding principles, we have highlighted several federally funded contract research projects administered and managed through the Illinois Center for Transportation that have had a lasting impact and led to changes to IDOT policy, specifications, and guidelines.

SAFETY:  Improving the safety of workers and the traveling public

R27-72 (2010) Improving the Safety of Moving Lane Closures

To improve the safety of moving lane closures for workers and motorists, ICT researchers investigated driver behavior around and in moving lane closures, the effect of different components of current traffic control scenarios, and the effect of various traffic control devices and sign messages. Specifically, the results designated the best type and length of advance warning zones and transition zones to use for moving lane closures. The results of the study were used to make changes to IDOT’s Moving Lane Closure Standards and Work Site Protection Manual.

According to Aaron Weatherholt, the Technical Review Panel chair who led this research project, “The value of this research is very simple: to reduce crashes and save lives.” Continuing, he says that “this research will allow the department to take an analytical view of the interactions between motorists and the system of devices used for moving lane closures in order to modify our current standards and practices, if needed, to increase the expectations of the motorist as well as reduce work zone intrusions and crashes.”

INTEGRITY: Doing what’s right and protecting our environment

R27-147 Development of Chloride Reduction Training

The purpose of this project was to create a training program that could be used for IDOT personnel who operate snow plows and spread road salt during winter storms. The goal of the training was twofold: demonstrate the impacts of road salt on the environment, and show how winter operations personnel can keep the roads in service during winter storm events while also reducing the quantity of salt introduced into the environment. Classroom training materials and videos were developed by the ICT research team and are used to train IDOT winter operations staff.  In addition, IDOT’s Bureau of Local Roads shares the training material with local entities through the Tech Transfer (T2) program; the materials have also been shared with other states that are members of the Clear Roads Pooled Fund study, TPF-5(218).

Tim Peters, Local Policy and Technology Engineer for IDOT, served as chair of the Technical Review Panel that oversaw the project. He says, “The materials developed by this project have been received well by both state personnel and local public agencies. The materials very effectively convey important concepts in an easy-to-understand way.”

RESPONSIVENESS: Proactive measures improve safety on rural roadways

R27-SP30 (2016) Speed Harmonization: Design Speed vs. Operating Speed

Excel VBA interface for user inputs.

This study analyzed the impact of design speed vs. legal/posted speed and operating speed on highway safety features. Drivers exceeding posted speed limits is a common problem in rural highways with curves in roadway alignments. In these rural settings, there are more free-flow traffic conditions, and enforcement opportunities are limited, which often lead to increased roadway departures and crashes. In this study, ICT researchers analyzed the resultant increase in operating speeds and how engineers can predict crash rates, appropriate operating speed profiles, and speed limits on curves based on roadway geometry. The implementable outcome of the study is an Excel Visual Basic Application (VBA) into which designers can input roadway parameters along with budget constraints to select appropriate safety measures and prevent crashes. The outcome of this project will be beneficial to county engineers and IDOT designers in districts with rural highways.


QUALITY:  Ensuring high performance and value-added practices

R27-24 (2010) Evaluation/Modification of Illinois Department of Transportation Foundation Piling Design and Construction Policy

The study identified a more accurate pile capacity verification formula that allows designers to require approximately 10% less piling. With IDOT’s $13 million average annual piling expense since 2010, the new policy saves the department more than $1 million per year in construction costs.  With this study costing the department about $125,000 and the policy in place for the past 5 years, the research yields a benefit–cost ratio of approximately 40 to 1. The findings of the research resulted in a recalibration of IDOT’s pile length estimation method to better correspond to the new verification formula that is expected to result in fewer splices, less pile cutoff waste, and reduced downtime waiting for additional pile length to be delivered, which will all also add to the expected savings.

Bill Kramer, the Technical Review Panel chair who oversaw this research project, states, “As the chair of the project, I am excited that over the past 10 years, IDOT has greatly improved their research efforts to allow more areas of the department to get involved in research like this project, making it possible to save the taxpayer several million dollars each year.”

INNOVATION:  Improving the state of practice

R27-128 (2015-16) Testing Protocols to Ensure Performance of RAP/RAS (I-FIT)

This study developed and implemented the Illinois Flexibility Index Test (I-FIT) to determine whether an HMA mix is prone to premature cracking. The I-FIT protocol is the first of its kind to use fracture mechanics to accurately predict cracking resistance in recycled asphalt pavement. IDOT has installed I-FIT testing machines in three of nine district offices to test the mix designs with reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) for selected projects. IDOT is planning to implement I-FIT by constructing 11 pilot projects using its new I-FIT specification. That specification requires I-FIT testing and compliance for mix design verification and plant-produced mixtures. In May 2016, AASHTO approved the I-FIT protocol for a provisional standard, “Determining the Fracture Potential of Asphalt Mixtures Using Semicircular Bend (SCB) Geometry at Intermediate Temperature” (TP-124). The project in which I-FIT was developed and validated was selected as an AASHTO Sweet 16 High Value Research project for 2016.