Innovative Curve Enhancements on Oklahoma’s Roadways

This project received an internal Horizon Innovation Award.


In civil engineering, innovation is not just about creating new technologies—it’s about finding new ways to solve problems. This is exactly what the team at Freese and Nichols did when tasked with assisting the Oklahoma Department of Transportation (ODOT) with enhancing the safety of their roadways.

The Challenge


ODOT tasked Freese and Nichols with the development of an analysis methodology, the completion of the analysis, and the creation of plans, specifications, and estimates (PS&E) for construction aimed at enhancing safety on roadways with horizontal curves throughout the state. Given a construction budget of $1.5 million and a stringent timeline of under four months, the team had their work cut out for them.

The Approach

The team developed a unique methodology for the analysis of existing horizontal curves based on a 5-year collision history, degree of curvature and curve classification along all state-owned facilities, location of 8-year work plan projects, and Annual Average Daily Traffic (AADT) data. These data points were cross-referenced to identify the best candidate locations for improvements.

Subsequently, they designed countermeasure implementations to address these safety concerns. Because a survey wasn’t provided for the project, all work was completed using aerial mapping and field reconnaissance.

The proposed solutions, which included signage, enhanced pavement markings, and pavement treatments, were cost-effective and efficient. They were designed and built without the need for survey data, resulting in significant savings in time and resources. The team referred to the guidance provided by the Federal Highway Administration (FHWA) to gather case study data, which was then applied to similar locations within Oklahoma.

The Results


Using the developed methodology, a total of 155,149 curves within the state were considered. This was narrowed down to 80 curves in 18 locations across four counties. Site visits were conducted, proposed solutions developed and final designs were completed.

Safety improvements were implemented, including the application of High Friction Surface Treatment, the addition and enhancement of signage (including solar-powered signs equipped with flashing lights), the installation of rumble strips, and the improvement of road striping.

The benefits of this project will be fully realized once the project is constructed. ODOT will be tracking the reduction in crashes in both number and severity. The methodology developed by the project team was so well received that ODOT requested the team document the methodology for future use.

The savings in time by eliminating the need for a survey and using readily available data meant that the funding ODOT received from FHWA could be fully allocated within the necessary timeline, paving the way for additional funds in the future.

This project is a testament to the power of innovative thinking in engineering. By developing a unique methodology and leveraging readily available data, Freese and Nichols was able to deliver a solution that not only met the project’s objectives but also set a new standard for future projects.