Infrastructure Initiatives to Apply Connected- and Automated-Vehicle Technology to Roadway Departures
The Federal Highway Administration’s (FHWA’s) Safety Program features a roadway-departure (RwD) roadmap of activities focused on how connected-vehicle (CV) and automated-vehicle (AV) technologies can be considered with various safety countermeasures developed to prevent RwD crashes. CV and AV technologies have the capability to enhance highway safety by providing drivers with precise vehicle control and restoring appropriate driver attention to traffic and roadway conditions. These technologies have immense potential to reduced RwD crashes. The objective of this study was to develop a framework for the FHWA to understand how the infrastructure may need to be adjusted to accommodate these technologies. The study generated 11 initiatives for consideration based on input gathered from literature review, consultation with technology developers, vehicle manufacturers, and three web meetings in 2017 with 27 representatives from industry, State departments of transportation, and the research community. These 11 initiatives and their implementation plans focused on changes in infrastructural components needed to accommodate CV and AV technologies and their benefits on RwD and how to prepare State and local transportation department staffs to acquire the necessary skills to embrace these emerging technologies.
- Tighten standardizations in the Manual on Uniform Traffic Control devices (MUTCD). This should be done within and between states to make the manufacturers job easier as it would increase the probability of lane-markings being recognized by AV’s machine vision systems.
- Use infrared markings and radio frequency identification (RFID) tags to enable and enhance machine-readable signs. Compatible approaches are needed when developing machine-readable signs. It is suggested to use treatments that would be invisible to a human, such as infrared markings, RFID tags, quick-response codes and bar codes.
- Refresh maps and inventory continuously. New electronic mapping technology offers advantages to travelers and transportation agencies. States and local agencies need maps to maintain inventories for asset management, design improvements based on maps of existing conditions and evaluate sites before visiting. Navigation needs much more precision than an asset inventory as the condition of the road and roadside can change hour by hour. Therefore, a map or inventory must be refreshed almost continuously.
- If DSRC is used for Vehicle-to-Infrastructure (V2I) applications, ensure that V2I equipment is interoperable with the DSRC equipment on all vehicles. As different states are investing in V2I equipment such as signal controllers, they need assurance that their systems will be compatible with the standards implemented.
- Understand that there are still many uncertainties for V2I communication. For example, how to ensure that V2I applications function the same in all States and if any features will vary and require that the applications differ by State is still unclear. In addition, the messages sent and received through V2I communication (e.g., the contents of a Traveler Information Message (TIM) and the MAP message) are still under review.
- Use pavement markings that benefit both human and machine vision. Human drivers are in control of CVs, so conventional signs would still be necessary. Virtual signs, through V2I communication, would supplement information available to both types of vehicles.
- Broadcast information with real-time updates for work zones and traffic incidents. As signs can be obscured by weather or other vehicles, and pavement markings fade, broadcasting information was considered technology neutral.
- Consider broadcasting sign information in a TIM or encoding it in a MAP. Using technologies such as DSRC or adding RFID tags to current signs is less expensive than maintaining actual signs. Replacing signs for those with machine-readable fonts would be tremendously expensive.
- Provide relative location of the infrastructure is important, compared with absolute location. For example, if a vehicle obtains information about the number of lanes and their width, then it can be positioned within its lane relative to a road edge or guardrail.
- Be aware of the trade-off between the crash-reduction benefits from V2I applications and deployment costs for sparse rural areas. Although V2I can be more effective than V2V communication in rural areas, the optimum density of Roadside Units (RSUs) to support V2I communication in rural areas is unknown and providing electrical power to remote RSUs remains a problem.