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 highlight 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 in IDOT policy, specifications, and guidelines.

SAFETY: Improving the Safety of Workers and the Traveling Public

Development and Application of Safety Performance Functions for Illinois (R27-020)

The State of Illinois initiated the Strategic Highway Safety Plan (SHSP), which set a goal of zero fatalities. This research project introduced the concept of safety performance functions (SPFs). SPFs are used today by IDOT’s traffic engineers, planning administrators, and operations engineers to calculate a roadway site‘s potential for safety improvement (PSI), help the department identify locations that have the highest potential for improvement, and prioritize them during the safety project planning process.

INTEGRITY: Doing What’s Right and Protecting Our Environment

Restoration Progress and Flood Disturbance at IDOT Wetland Mitigation Sites (R27-114)

Applications of this research include using flood regimes in a landscape context to guide site selection for floodplain wetland mitigation, with particular consideration for vegetation-based functional replacement goals. This approach will allow IDOT to shift from the one-size-fits-all approach, ensure better performance from the sites selected, and mitigate the effects of flood disturbance on species composition and vegetation structure.

DIVERSITY: Ensuring All Citizens Can Use the Transportation System

Development of Public Right-of-Way Accessibility Guideline Resource Material (R27-136)

The findings and results of this research project led to the development of comprehensive federal and state accessibility design guidelines for designers and construction personnel. The manual is available for public use on IDOT’s website. In addition, IDOT implemented an e-learning module and conducted in-house training on the design/field guide throughout its districts in Illinois. Because the societal benefits to the citizens of Illinois are of upmost importance, IDOT will use the guidelines to ensure compliance and accessibility in current and future construction projects.

RESPONSIVENESS: Responding to and Preventing Secondary Incidents

Development of a Highway Incident Management Operational and Training Guide, Phase I and Phase II (R27-064, R27-118)

The overall goal of these projects was to reduce responder fatalities and injuries and to prevent secondary crashes, especially those involving incident responders. To date, more than 3,000 responders from law enforcement, fire and rescue, transportation, and the towing and recovery sectors have been trained through the learning modules created from the research. The results of these research projects and training opportunities are expected to bring a decrease in responder injuries and fatalities, and the number of secondary incidents—as well as a reduction in travel time related to congestion caused by these incidents.

QUALITY: Ensuring High Performance and Increased Service Life

Best Practices for Implementation of Tack Coat, Part 1: Laboratory Study, and Part 2: Field Study (R27-100)

The findings from this project, based on field and laboratory testing, have enabled IDOT to revise its tack coat specifications related to cleaning, optimizing tack coat application rates, and specifying appropriate tack coat types. Implementation of this research resulted in amendments to Section 1032 and Section 406 of the Standard Specifications for Road and Bridge Construction. IDOT has also worked with prime/tack manufacturers to help them improve their products, conform to the new specifications, and make the product cost-effective for contractors to use by reducing set time.

INNOVATION: Creating New Methods and New Technology

Mechanistic-Empirical Design, Implementation and Monitoring Flexible Pavements (R28-1, R28-2, R39, R27-60)

The objective of this series of projects over 14 years (2000–2014) was to update Illinois’ mechanistic-empirical (M-E) full-depth hot-mix asphalt (HMA) pavement design procedures to reflect current Illinois materials and mixture design practices. As a result of this research, the Pavement Design chapter of IDOT’s Bureau of Design and Environment Design Manual, was updated to reflect the new asphalt fatigue algorithm for both full-depth HMA and rubblizing design procedures, which reduced pavement thickness approximately 1.5 to 2.5 inches for the average pavement design statewide. HMA pavement projects awarded between 2008 and 2014 were reviewed to determine savings related to pavement thickness as a result of using the new pavement design procedures. Benefits were estimated to be a savings of 63,180 tons of HMA binder annually, valued at $5.1 million. Additional benefits were to the environment—in the form of reduced CO2 emissions—and were estimated to be approximately 2,529 tons annually, with a value of approximately $96,000. Together, the total benefits realized from the HMA pavement design procedure refinement efforts totaled $5.2 million per year.