Making a Case for Microsimulation as a Concept Development Tool: Case Studies of Innovative Design Concepts

As congestion increases and space & resources become more constrained in the United States, transportation professionals seek new and innovative solutions through their design concepts. As such, more designs are becoming highly complex and unique to specific sites with specific constraints. This complexity introduces new challenges in evaluating the effectiveness of these designs.

A shift in the conventional design process provides opportunity to utilize the power of analysis to drive and shape these unique designs. The concept of dynamic design has been applied effectively to multiple design projects over the past years and allowed for the development of innovative design solutions by integrating analysis and design together into a single stage of the design process.
The idea of innovative design concepts as a way of increasing the capacity of highly constrained facilities is nothing new. What is considered as innovative is something that continues to change. In the United States, the latest in innovative intersection and interchange design incorporate diverging diamond interchanges, displaced left turns, median u turns, or other ways to reduce the number of conflicting movements at a given point.

While these concepts may not sound complicated, research is underway to find a deterministic analysis method to allow for quick and easy analyses of concepts that involve the interaction of many parts and often the interconnection and progression of multiple signals. In practice, our deterministic analysis methods currently fall short leaving a choice of having either inaccurate analyses using existing methods and software that need to be “tricked” into doing what is needed, or excessively complicated simulation-based analyses that are time and work intensive to perform. Among the examples to be discussed include the I-4 at SR 535 interchange in Lake Buena Vista, Florida. Set on the edge of Walt Disney World at one of the most congested interchanges in the State of Florida, the SR 535 interchange concept includes elements taken from echelon intersections, displaced left turns, diverging diamond interchanges, median u turns, and quadrant roads blended together in a 1.5-mile segment that could not be developed or analyzed using deterministic methods.

This paper/presentation will use case studies from projects recently completed or currently in progress to highlight a unique approach to concept development. A typical project involves traffic and engineering and roadway design working in sequence with some iterations, but typically working one at a time. This process used to develop the concepts used in the project case studies involves microsimulation and roadway design occurring concurrently and iteratively resulting in the ability to create truly innovative solutions that are often blends of multiple “innovative” concepts into one-of-a-kind solutions tailored to site-specific problems.