Conclusions and Recommendations
The purpose of this document is to help Federal, State, Tribal, and local agencies understand the benefits of utilizing interactive 3-D visualization to assist an RSA team in assessing the safety effects of potential roadway designs. This effort comprised a series of four RSAs in four different regions of the country that incorporated 3-D visualization into the standard eight-step RSA process. Developed from various electronic files provided by the designers of each roadway project, the 3-D models were based in a common PDF format that allowed them to be viewed using Adobe software that is both free and readily available to the general public. A minimum of 100 man-hours were expended in the development of each model.
RSA projects that may be prime candidates for 3-D visualization are those characterized by any of the following:
- Large or complex projects
- Innovative or unusual designs
- Significant differences in elevation and/or grade
- Inaccessible locations (due to weather, terrain, security restrictions, etc )
- Potentially significant impacts to community, cultural, or historic interests
The use of 3-D visualization in the RSA process provides the following benefits to the RSA team:
- Enabling persons who are not proficient at reading roadway design plans to comprehend the proposed improvements
- Illustrating how proposed features supplemental to the roadway (e g , signs, structures, traffic signals, etc ) will affect the appearance of the roadway environment
- Allowing users to view the proposed conditions from a countless number of vantage points
- Providing visual support of the RSA team's findings and recommendations
- Helping to maximize the effective time of the RSA team members
This case study document summarizes the key benefits of 3-D visualization observed for the four RSAs conducted under this effort, but additional benefits may be realized for other types of projects. This may be especially true for designs with complex vertical elements. For example, a good candidate for visualization may be an existing at-grade intersection in an urban or suburban environment at which grade-separation has been proposed. Additionally, the combination of roadway attributes may be difficult to assess from a safety standpoint without a clear picture of how these elements come together. These elements include changes in the roadway, introduction of grade alterations, elevated structures that may limit sight distance or roadway perception, and the interactions of many types of roadway users.
Three-dimensional visualization can be a useful tool in assisting RSA teams to make a more thorough assessment of safety. Using 3-D visualization resulted in support for improvements identified during the RSA resulting in those changes being incorporated into the construction plans. The 3-D model assists the RSA team in understanding a future design. When used effectively, 3-D visualization is a tool that will save the RSA team time and yield a heightened awareness of safety issues related to the design project. It is recommended that 3-D visualization continue to be incorporated planning stage and design stage RSAs.
References
- Moving Ahead for Progress in the 21st Century Act (MAP-21). Available:http://www.gpo.gov/fdsys/pkg/PLAW-112publ141/html/PLAW-112publ141.htm
- FHWA's Every Day Counts Initiative. Available: https://www.fhwa.dot.gov/everydaycounts/edctwo/
- FHWA's FOCUS, SHRP 2: Accelerating Utilities Innovations. Available: https://www.fhwa.dot.gov/publications/focus/10mar/05.cfm