Handbook of Driving Simulation for Engineering, Medicine, and Psychology

The Use of High Fidelity Real-Time Driving Simulators for Geometric Design

Authors
Thomas M. Granda+, Federal Highway Administration
Gregory W. Davis, Federal Highway Administration
Vaughan W. Inman, SAIC
John A. Molino†, SAIC

+ Retired from Federal Highway Administration
† Present affiliation Tech-U-Fit Corporation

Abstract
The Problem. Roadway geometrics play an important role in road safety and mobility. The success or failure of a geometric design is directly related to whether or not the physical manifestation of the design elicits the appropriate responses from the driver. So roadways must be designed with the driver in mind. The Role of Driving Simulators. Driving simulators can play an important role in helping roadway engineers design and evaluate alternative roadway configurations that conform to driver expectations and maximize the probability that drivers react appropriately. This is especially true in the case of unique roadways that exist only in the design or early development stage. The Requirements of Geometric Design-Related Driving Simulation. To help define the parameters of driving simulators that are used for geometric research, the physical and functional requirements of such driving simulators are discussed in terms of mechanical set-up, computer hardware and software requirements, and rendition of visual imagery. Examples of the Use of Driving Simulators in Geometric Design. This is followed by a number of applied research examples in a variety of geometric areas such as intersections and interchanges, geomet-ric design safety measure evaluations, countermeasures to problematic geometric elements, visibility, and speed management. Related Issues. These research examples are followed by a discussion of selected issues related to the use of driving simulators for evaluating highway geometrics. These examples include advantages and disadvantages of driving simulators, validation of driving simulators, and simulator sickness.

Keywords
Geometric Design, Geometric Evaluation, Roadway Geometrics, Roadway Simulation, Driving Simulator Research, Simulator Validation, Simulator Sickness

Key Points
• When roadway design engineers use the term geometrics, they primarily refer to the physical aspects of the roadway. That is, they are largely concerned with topics such as horizontal and vertical alignment, road curvature, road width, and grades. Associated issues include such items as sight distance, signing and marking, traffic signals, landscape, and lighting.
• Essentially, driving simulators can be classified into three different categories: (1) desktop PCs with a single monitor, steering wheel, and pedals, (2) mid-level driving simulators that utilize a non-motion-based driving buck and projectors, and (3) high-fidelity simulators that use a full car cab on a motion base, a wide field of view using projectors, and software that is specifically programmed on an experiment-by-experiment basis by trained computer graphics professionals. Obviously, the capabilities within these three categories can vary greatly.
• The physical and functional requirements for driving simulators that are used for evaluating highway geometrics can be organized into the following categories: mechanical set-up, computer hardware and software requirements, rendition of visual imagery, and integration of these elements to achieve the overall project objectives.
• Driving simulators can be used to study such geometric topics as new intersection designs, geometric design safety measure validation, evaluating countermeasures for problematic geometric elements, visibility of roadway delineation treatments, and speed management.
• While there are advantages to using driving simulators for studying roadway geometrics, there also are disadvantages.
• Using a driving simulator can lead to simulator sickness. But there are ways to predict and/or mitigate these effects.
• There are various ways to validate driving simulators used for studying the effects of geometric design on drivers.

Web Resources
Web Figures 34.1-34.7. (click for all)

Web Figure 34.1: FHWA Highway Driving Simulator is comprised of a number of networked computers (color version of Figure 34.1).
Web Figure 34.2: Diverging diamond interchange traffic flow (color version of Figure 34.2).
Web Figure 34.3: Diverging diamond interchange crossover as it appeared in the driving simulator (color version of Figure 34.3).
Web Figure 34.4: Near-side traffic signals were added to the design as a result of sight-line problems detected during the visualization (color version of Figure 34.4)
Web Figure 34.5: Bird’s-eye view of one side of the conventional diamond interchange that was used to provide a baseline against which driver performance in the diverging diamond interchange could be judged (color version of Figure 34.6).
Web Figure 34.6: In the roundabout context, many drivers did not understand the meaning of the lane restriction sign (far right) and lane restriction markings (center) (color version of Figure 34.8)
Web Figure 34.7: Photograph (left) and simulation (right) of Curve No. 2 in subsequent visibility studies. (color version of Figure 34.9)

Key Readings
Federal Highway Administration. (2007). Drivers evaluation of the diverging diamond interchange. FHWA TechBrief. Retrieved November 19, 2008, from http://www.tfhrc.gov/safety/pubs/07048/07048.pdf

Federal Highway Administration. (2008). Evaluation of sign and marking alternatives for displaced left-turn intersections. Summary Report (Rep. FHWA-HRT-08-071).

Molino, J. A., Opiela, K. S., Andersen, C. K., and Moyer, M. J. (2003). Relative luminance of retroreflective raised pavement markers and pavement marking stripes on simulated rural two-lane roads. Transportation Research Record, 1844, 45–51.

Tornros, Jan. (1998). Driving behavior in a real and a simulated road tunnel: A validation study. Accident Analysis and Prevention, 30(4), 497–503.

Yan, X., Abdel-Aty, M., Radwan, E., Wang, X., and Chilakapati, P. (2008). Validating a driving simulator using surrogate safety measures. Accident Analysis and Prevention, 40, 274–288.