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Public Roads - March/April 2016

March/April 2016
Issue No:
Vol. 79 No. 5
Publication Number:
Table of Contents

Guest Editorial

Flexible Design Is Key to Improving System Performance


From construction of the interstate system during the Eisenhower era through establishment of the National Highway System in 1991, the Nation has become more dependent on the performance of highways than anyone could have predicted. Geometric design criteria help highway engineers design roads efficiently and consistently, but simply meeting standards does not guarantee reaching performance goals. Information gathering and analysis help engineers better understand how flexible design choices affect performance. Applying this knowledge has the potential to make infrastructure more sustainable, strengthen the economy, and improve safety, mobility, and livability for all U.S. residents.

Of particular interest to the Federal Highway Administration’s Office of Program Administration in recent years is the progress being made in understanding the safety effects of design choices. More than ever before, practitioners with the American Association of State Highway and Transportation Officials; the Transportation Research Board; and Federal, State, and local officials use this information to develop flexible design solutions that deliver improved performance.

More agencies now use practical design to inform decisions and balance what, how, and how big to build within their tightened budgets. This concept is not new. But, by increasing the use of data-driven predictive analysis of performance, FHWA officials believe that all transportation departments--from the smallest towns to the largest States--will be able to unlock more flexible designs. This flexibility will result in delivery of context-sensitive solutions at a lower project cost while improving the overall performance of the transportation system. Performance-based practical design, as this process is called, represents the next step in the evolution of highway design.

To accelerate improvements in system performance, the industry needs to improve professional skills in applying performance-based practical design. Implementing new tools and approaches will facilitate rewriting the fundamentals of highway design so that they are more flexible and better meet the Nation’s critical transportation needs.

A new report, Evolving Geometric Design Decision-Making in the United States, discussed on page 28 in this issue of Public Roads, was developed through an AASHTO and FHWA partnership. Representatives of both organizations presented the report in June 2015 at the 5th International Symposium on Highway Geometric Design in Vancouver, Canada. The report describes many of the efforts undertaken in the last 5 years to accelerate improvements in system performance.

Recognizing the need to adapt, FHWA leadership recently proposed streamlining the required 13 controlling criteria for design and their application on the National Highway System. The proposed changes, published in the Federal Register, represent one of the latest examples of how performance-based knowledge is shaping the future of flexibility in highway design. State and local agencies too should consider how to incorporate performance-based design flexibility into their decisionmaking.

As the industry’s understanding of the relationship between design and performance grows and more tools become available, practitioners’ confidence in applying design flexibility also will grow. The profession is taking steps to embrace new design approaches and apply them more consistently. Doing so will further improve system performance and return on taxpayer investment--not to mention the benefits to mobility, safety, and livability for all.

Thomas D. Everett
FHWA Office of Program Administration