The concepts of Performance-Based Practical Design (PBPD) date from the early 2000s. Their formation and development have been motivated by two main recognitions:

These recognitions have prompted the development of data-based tools and compilation of data to determine the associations between roadway features and actual roadway performance.

This leads to a greater understanding of what improvements or physical features are likely to produce desired outcomes and allows design decisions to be made based on defensible and reproducible analyses.

Research that has analyzed safety and other data has found that some long-standing practices and long-held assumptions did not necessarily reflect reality.

Even for elements known to have sizable effects on performance, the criteria that govern their selection are often overly simplistic and insensitive to the full range of context, leading to their misuse (e.g., selection of larger horizontal curve radii or “desirable” lane and shoulder widths without thought to how the performance is affected).

Rigid adherence to dimensional guidance without understanding the nuance of how small variations affect performance leads to large expenditures with little benefit

. An increased knowledge base allows for a more flexible, confident, and cost-effective design approach.

Through PBPD, TxDOT can weigh project-level results and associated trade-offs against system-wide performance needs and goals. By focusing on system-wide performance, TxDOT can better manage the cumulative effectiveness of individual project investments and build upon the goals of Context Sensitive Solutions, Flexibility in Design, Practical Design, Asset Management, and Value Engineering. A PBPD approach relies on

quantitative analyses

to guide decision-making throughout the project development process, which results in maximizing system performance while minimizing project cost. The next sections will outline the approach designers will take to implement PBPD on TxDOT projects.