EXPLORATORY ADVANCED RESEARCH

Breakthroughs in Vision and Visibility for Highway Safety Workshop Summary Report - August 13-14, 2014

Chapter 1. Introduction

About the Exploratory Advanced Research (EAR) Program

The Federal Highway Administration (FHWA) EAR Program focuses on longer-term, higher-risk research with a high payoff potential. The program addresses underlying gaps faced by applied highway research programs, anticipates emerging issues with national implications, and reflects broad transportation industry goals and objectives.

Motivation

Understanding the choices that drivers, bicyclists, and pedestrians make is critical to improving the safety and efficiency of the Nation’s roadways. An important research tool has been the use of driving simulators to observe and record traveler behavior under a variety of simulated situations. However, simulator research has several limitations, particularly in regard to modeling interactions between road users.

In recent years, there have been rapid developments in the simulators and related models that could be applied to highway transportation research. These developments have the potential to advance research in the areas of safety, operations, planning, and policy and could ultimately lead to decreases in crashes, congestion, and carbon emissions. However, there are great challenges as well, according to Jalali et al. as follows:

Simulation models are typically developed by domain experts who have an in-depth understanding of the phenomena being modeled and are designed to be executed and evaluated independently. A grand challenge is to facilitate the process of pulling all of [the] independently created models together into an integrated simulation environment wherein we can model and execute complex scenarios involving multiple simulators.⁽¹⁾

FHWA seeks to understand the technological challenges of advancing the use of federated simulation and modeling and the different uses that researchers and practitioners envision for this technology. As such, this report examines the current state of the practice in connected simulators and related models and the challenges that remain. This report also reviews the potential uses for this technology—connecting simulators with simulators, simulators with models, or models with models—and the types of transportation research to which it can potentially be applied.

Defining Connected and Federated Simulators

Connected or federated simulators integrate two or more simulators to better understand transportation systems in a dynamic modeling and simulation environment.For the purposes of this report, simulators may be broadly categorized into driving, pedestrian, bicycle, truck, and bus simulators on the one hand and microscopic and mesoscopic traffic simulators on the other. Transportation planning models could also be connected and are of interest to FHWA.

Each simulator or model in a connected network is called a “federate.” The following four major features define the types of connected simulators and models:

• They can all be connected at the same site or distant sites (local or distant).
• They can operate asynchronously (at different times) or synchronously (at the same time).
• They can all be simulating or modeling the same mode of transportation (uni-modal) or more than one mode (cross-modal).
• They can all use the same make of simulator or model (single-platform) or different makes (cross-platform).

This report focuses on the distinction and technical challenges and opportunities of asynchronous versus synchronous federated simulation and modeling at distant sites within a single mode. However, this focus does not indicate a limited interest in just these combinations of features. Table 1 summarizes the types of simulation discussed in this report.

Table 1. Current and future uses of connected simulators and models.