CAVs have the ability to communicate with vehicles around them, traffic infrastructure and other travelers and/or automate some or all of the driving functions. The vehicle and roadside infrastructure – like traffic signals, crosswalk signs and blind roadway curves – communicate to make traveling safer. Based on input from on-board sensors, systems on the vehicle may take over some or all of the driving functions, also improving safety.
Even though the terms automated vehicles and connected vehicles are often used in tandem, they are actually vastly different technologies. Some vehicles will be connected but not automated, others will be automated but not connected, and some will have both capabilities.
Connected vehicles wirelessly communicate with each other, connected infrastructure (like traffic signals) and other travelers. The data sent from connected vehicles is anonymous. This data can help drivers avoid crashes and enable transportation agencies to improve mobility and reduce congestion. Connected vehicle systems can involve vehicle-to-vehicle (V2V) or vehicle-to-infrastructure (V2I) communication. Vehicles may also communicate to other travelers, like pedestrians or bicyclists, sometimes referred to as vehicle-to-pedestrian (V2P) communication. The combined capability of these modes is often referred to as vehicle-to-everything (V2X).
Automated, “driverless” or “self-driving” vehicles utilize sensors, cameras, GPS, artificial intelligence, and other hardware and software to control, navigate and drive the vehicle without direct human input. Vehicles that are fully automated are not available yet.
Automated vehicles are vehicles that have some automated features but are not completely automated. Using the same on-board sensor technology as in automated vehicles, these vehicles can take over some, but not all, of the driving function of the human driver. The driver still needs to be available to monitor or take over other driving functions. Many newer automobiles have automated features.
CAV technology can work in a variety of ways based on its function. Connected vehicles use special short-range radios to wirelessly communicate with each other, connected traffic signals, or other infrastructure features. Automated vehicles utilize artificial intelligence, sensors, cameras, GPS and other hardware and software to operate, partially or fully, without direct human input to control the steering, acceleration and braking. A connected and automated vehicle can use a combination of these technologies. CAV technology is a buzz word lately, but some CAV technologies have been deployed on our vehicles for several years already. Adaptive cruise control, blind spot monitoring, braking assistance and back up assistance, using automated vehicle technology, are all early forms of a CAV.
Safety: CAV technology has the potential to save lives, prevent injuries and reduce crashes. The National Highway Traffic Safety Administration (NHTSA) estimates that 94 percent of serious crashes are due to human error. Automated vehicles see more, react faster and never become drowsy, unlike human drivers. In addition, connected vehicle technology can mitigate 83 percent of non-impaired crashes through vehicle-to-vehicle communication. Taking the human error factor out of the equation has the potential to protect drivers and passengers.
Mobility: Emerging CAV technology will greatly improve Utah’s transportation system, including decreased travel times and increased transit reliability. The data shared by these vehicles enables traffic engineers to operate roadways more efficiently. CAVs can also help increase mobility to meet the needs of those with disabilities, the elderly, or those otherwise unable to drive. Increased mobility could improve access to healthcare, education and employment.
Economic vitality: The capabilities of CAV technology to constantly monitor and analyze a variety of road conditions, traffic flow, weather conditions and other driving hazards results in the smart movement of goods, services and people. According to NHTSA, motor vehicle crashes cost the United States $242 billion in economic activity, and $594 billion due to loss of life and decreased quality of life in 2010. CAV technology will greatly reduce motor vehicle crashes, thus easing these economic costs.
Air quality: CAV technology will prevent crashes. Those crashes are a frequent cause of congestion. CAV technology will also help traffic move more efficiently by providing accurate data to drivers and traffic managers. As traffic moves more efficiently, there will be a reduction in vehicle emissions and improved air quality.
Many new vehicles today have some automated features, such as adaptive cruise control, automated parking or lane changing. Automakers are continually improving and expanding those features. It will likely be years before vehicles will be available that are fully automated, or driverless.
Connected vehicle technologies have been deployed on a limited number of General Motors vehicles in the U.S. over the past few years. Other automakers have indicated intentions to add these capabilities by 2022 or 2023. UDOT and other agencies have deployed connected vehicle capabilities on some fleet vehicles, and will expand those deployments.
CAV technology is being used in a variety of ways. Equipped vehicles can communicate with traffic signals to improve movements of buses and emergency vehicles. Infrastructure devices can also communicate weather hazards and other road conditions to drivers using this technology. Vehicles can communicate with each other to have an awareness of their movements. The information flow between vehicles will be used to inform drivers about potential accident threats and prevent them. Sensors can detect pedestrians and bicyclists and send warnings to vehicles about their presence. These sensors are also being used by automated vehicle systems to control vehicle speed and prevent collisions. Automated vehicles, like low-speed shuttles, could provide transportation to and from transit, or provide transportation to individuals who are unable to drive.
All vehicles are required to be compliant with Federal Motor Vehicle Safety Standards. The National Highway Traffic Safety Administration (NHTSA) monitors the transportation system and recalls vehicles that are not operating safely. The safety of automated vehicle systems is a topic of active discussion. NHTSA has issued a policy document outlining 12 key safety design elements and is working on safety standards that will apply specifically to vehicles that are highly automated. The companies that build automated vehicles test their vehicles aggressively and certify that they comply with NHTSA safety elements. NHTSA states that although companies are testing complex and advanced automated vehicles, they will not be released to the public until their safe operation is ensured.
A TSP system uses V2I communication between transit vehicles like buses and traffic signals. When buses are behind schedule, the TSP system can automatically request additional green time from a connected traffic signal so the bus can have priority to move through the light and get back on schedule. UDOT has deployed a Transit Signal Priority system on several routes in Salt Lake and Utah Counties.
A preemption system uses V2I communication to allow critical vehicles, like emergency responders, to request a green light at a connected traffic signal so the vehicle can continue toward its destination without stopping. UDOT utilizes a connected vehicle preemption system on some roadways to keep snowplows moving through traffic signals while they are actively plowing. Snowplow preemption will enhance safety by allowing for quick and efficient removal of snow from our roadways.
Connected vehicle curve speed warning systems use V2I communication to send warnings to vehicles about upcoming curves in the roadway. The system evaluates the geometry of the curve and the speed of the vehicle to determine the nature of the warning message. UDOT is planning to implement this V2I warning system at various roadway curves that have high numbers of crashes.
Connected vehicle spot weather impact warnings use V2I communication to send location-specific weather warnings directly to drivers as they approach adverse road conditions like ice or fog. Sensors installed along the road, and information gleaned from previous vehicles, provide the information needed to determine the nature of the warning message. Providing specific warnings at roadway segments with high rates of weather-related crashes will reduce these crash rates.
V2X systems are being designed to follow nationally-adopted standards. According to these standards, messages that are sent by the vehicle do not include any information that identifies the specific vehicle, its make, model, VIN or registration number, or identity of the owner or driver. Only the vehicle length is transmitted. In addition, these messages will be encrypted with a security credential, similar to the credentials that protect our credit card information when we shop on-line.
Cars that employ automated vehicle features sometimes have cellular-based telematics systems that communicate vehicle performance information to the company that built the vehicle. This is used to detect problems with the system and to update software over-the-air. Owners of these vehicles agree to sharing this information as part of their license agreement. This communication is separate and distinct from connected vehicle technologies for safety and mobility improvements.
Dedicated Short-Range Communication (DSRC) is a wireless radio technology, much like wifi, that facilitates very fast communication of critical data over a range of about 1000 feet. These systems use the FCC-designated 5.9GHz spectrum. DSRC technology, and the standards that support it, have been in development for almost 20 years. Most of the currently deployed V2X systems, including most of the UDOT deployments, use DSRC.
Cellular-V2X (C-V2X) is a cellular technology that also facilitates very fast communication of critical data. These systems are based on 4G-LTE cellular technology, but uses the 5.9GHz spectrum and communicate directly between devices, not through a cell tower. C-V2X is not the same as 5G (see “How Does 5G Fit Into All of This?). C-V2X has been developed in recent years, and is deployed in only a few locations at this time, with limited evaluation of its capabilities. UDOT has deployed and tested this technology.
As noted, the FCC-designated 5.9GHz spectrum is necessary for V2X systems to work effectively. DSRC and C-V2X both use this spectrum, but they are not interoperable. In a recent decision, the FCC has voted to reduce the bandwidth for DSRC and C-V2X. Developers and users of V2X technologies uniformly agree that a reduction in the 5.9GHz spectrum will be detrimental to connected vehicle systems and will damage current efforts to use these technologies to prevent crashes and improve transportation efficiency. The FCC has also voted to phase out the use of DSRC in favor of C-V2X. UDOT has filed several responses to the FCC urging them to not reduce this important spectrum, and to maintain the use of DSRC.
Anonymous data shared in V2X systems can be transmitted to traffic management agencies. Data sent and received by the roadside V2X device is typically transmitted over fiber optic cables from the traffic signal to the Traffic Operations Center. This data may be used in real time to identify crashes, determine road conditions, respond to congestion or provide useful information to motorists. It may also be stored in local or cloud-based data systems for broader analysis of conditions. This anonymous data is usually aggregated for analysis.
Fifth-generation wireless or 5G is the newest mobile network that’s replacing the current 4G-LTE technology by providing a number of improvements in speed, coverage, and reliability. When fully mature, 5G will revolutionize our ability to stream data on our phones and will facilitate the “internet of things”, where a broad variety of devices are connected.
5G systems will eventually be installed in vehicles to provide telematics services, much like 4G is today. These services will include navigation aids, music and movie streaming, and other infotainment systems. These services will continue to be subscription based; vehicle owners will pay a fee for this information.
C-V2X communications for connected vehicles are currently based on 4G technology. It is anticipated that there will be a 5G-based V2X system, known as “Advanced C-V2X” in the future, but that technology isn’t yet developed and it may not be forward compatible with current C-V2X systems.
Our roadways always have mixed forms of traffic: cars, buses, trucks, old and new vehicles, vehicles driven by experienced drivers and vehicles driven by newer drivers. Vehicles with CAV capabilities will increase gradually over several decades and will mix with vehicles with many different capabilities. CAVs are being designed to operate in the same way traditional vehicles do, generally following the same traffic laws. In fact, highly automated CAVs may be more compliant with traffic laws than human-driven vehicles. CAVs will have the enhanced capability to detect activities all around them and respond appropriately. When a human-driven, traditional vehicle speeds up, slows down, or turns, the CAV will respond to those actions. Similarly, human drivers will respond to actions by CAVs.
One unique feature of a vehicle without a human driver is that another traveler (driver, pedestrian, bicyclist, etc) will not be able to make eye contact with the automated vehicle. Eye contact is a function we use to ensure our safety by acknowledging that we have been seen. Automated vehicle developers are working on systems to replace this kind of interaction, such as light indicators.
CAV developers are exploring ways to provide needed information to first-responders. These vehicles need to respond to sirens and flashing lights, provide vehicle registration data to officers, and otherwise comply with traffic laws. These features are being actively developed.