The Safety Band: Separating Myths from Facts
The radio waves that make up the electromagnetic spectrum (“the spectrum”) include waves as low and long as 30 hertz (Hz) traveling up to 10,000 kilometers, and as high and short as 300 gigahertz (GHz) traveling about 1 millimeter (mm). The ability to harness these diverse wave types has been transforming our lives since the last century, and has made countless inventions possible, including long-distance communications, radio and television broadcasts, radio navigation and location, and more recently, mobile communications.
Until recently, devices using radio waves required turning to specific spectrum. As a result, today, we have frequencies within the spectrum allocated for specific uses—such as AM/FM radio stations, defense, air traffic communications, radar, or maritime communications. The Safety Band allocation offers a similar, dedicated set of airwaves for transportation safety. In 1999, the Federal Communications Commission (FCC) allocated 75 MHz of radio spectrum in 5.9 GHz band—the Safety Band—for use with vehicle and infrastructure safety-of-life, system efficiency, and mobility communications. In the 20 years since, infrastructure developers, vehicle manufacturers, and other transportation stakeholders have used the Safety Band to develop, test, and put smart transportation technologies into use. These technologies deliver public benefits and improve transportation every day for drivers, pedestrians, and other travelers thanks to the designated use of the Safety Band.
Why is it important for the Safety Band to remain dedicated to transportation communications?
Communications via the Safety Band are crucial to the U.S. Department of Transportation (U.S. DOT) mission of keeping Americans safe. In order to fully realize the life-saving capabilities of those communications, vehicle-to-everything (V2X) and other related transportation safety applications must have reliable access to spectrum that can deliver messages ten times per second—nearly instantaneously--free from the kind of harmful interference that can obstruct or corrupt this high-speed transmission environment. Under interference-free conditions, the spectrum and the transportation technologies can function to prevent crashes. The communications exchanges result in important public benefits such as:
- Crash prevention: Vehicles communicate with all nearby vehicles about threats and hazards forming in the roadway; vehicles effectively “see” around blind curves and intersections, alerting drivers to potentially dangerous situations and preventing accidents.
- System efficiency and mobility: Infrastructure applications can operate more efficiently to reduce congestion during daily commutes or support drivers when navigating around work zones or stopped vehicles. Road weather applications assist with safety during weather situations that limit driver visibility or vehicle mobility, whether it be blinding sunlight, dangerous precipitation, or dense fog. Freight applications can better and more safely manage port and traffic logistics.
- Public safety: Emergency responders move faster to accident sites, and lower the crash risk while in service.
In 2018, there were over 6 million vehicle crashes in the United States that resulted in 36,560 lives lost. The National Highway Transportation Safety Administration (NHTSA) estimates that safety applications enabled by vehicle-to-vehicle (V2V) communications could address up to 80 percent of non-impaired crashes, including crashes at intersections or while changing lanes. The Safety Band’s significance to transportation research and roadway safety cannot be understated.
Dispelling myths from facts:
There are some common myths about the state of the Safety Band, and who, how and why is is relied on today. Here are the facts:
MYTH: The Safety Band isn’t being used.
FACT: Currently, 97 locations are actively utilizing the Safety Band and another 66 sites are in the planning stage. This is a 50 percent growth over the last three years since the US DOT and industry proved the safety capabilities of these communications. Today’s deployments total over $1.5 billion of tax-payer funded investments based on Federal, State/local, and private sector matches. Communities are using the Safety Band for a number of crucial transportation technologies, including V2V, vehicle-to-infrastructure (V2I), or vehicle-to-pedestrian (V2P) applications; work zone management; road weather safety operations; truck platooning; congestion management; fleet and transit operations; and emergency response, among others. On the international stage, the United States is one of the largest deployers of connected vehicles.
MYTH: Connected vehicles don’t need all 75 MHz of the Safety Band to operate safely.
FACT: Ensuring the availability of spectrum at times when it is most needed—for safety-of-life and for public safety—is the first and foremost requirement of the Safety Band. While 75 MHz may not be in full use in all geographic areas at all times, the entire band will be in operation in highly congested, complex and challenging urban and suburban areas. The design of the current V2V, V2I, V2P, and V2X applications rely upon this availability and can “hop” to available spectrum within the 75 MHz—making the current operations spectrally efficient. And, cooperative communications are growing in importance for automated vehicles.
MYTH: Automated vehicles do not use the Safety Band.
FACT: As Automated Vehicles (AV) develop, industry finds that cooperative communications are important for automated vehicles and other road users to share the roads safely. Cooperative automated driving systems (ADS) advance the safe introduction of AVs into our current fleet, allowing today’s vehicles and drivers to anticipate the maneuvers of AVs. The Federal Highway Administration’s CARMA (SM) program (in cooperation with the Federal Motor Carrier Safety Administration) demonstrates cooperative ADS for vehicle platooning, speed harmonization, and cooperative lane change and merge functions. These advanced applications rely upon access to Safety Band spectrum for safety—using the V2V and V2I channels—and then use additional spectrum within the band for cooperative ADS functions.
MYTH: Unlicensed Wi-Fi and cooperative ITS communications can share the Safety Band.
FACT: Sharing the Safety Band with unlicensed communications and/or reducing the band to giveaway the spectrum to unlicensed Wi-Fi may create major safety risks and/or render transportation communications unsuccessful. The combined Federal-State/local-private sector-academia partnership has developed more than 100 public benefit applications; this technology will simply not see its full potential for saving lives and improving transportation for all modes if the spectrum is shared or significantly reduced. Additionally, “barrier channels” are necessary to protect cooperative communications from interference from other channels on the top and bottom ends of the spectrum. “Sharing” the Safety Band could mean effectively eliminating transportation communications from the Band completely.
MYTH: We should just wait for 5G.
FACT: University of Michigan estimates that putting off implementation of V2X communications for another 5 years may continue our crash rates at about 12-13 million crashes per year resulting in about 75,000 deaths and approximately 5 million injuries. Telecommunications technologies evolve every 3-5 years, whereas transportation investments are much longer (up to 17 years for infrastructure technologies and an average of 10-15 years for vehicles). At this time, no ability exists that allows for over-the-air-updates to switch from one communications type to another, but industry is working on these innovations. Even if there were such a capability, any new technology requires safety testing. We cannot afford to wait for each new market introduction—we would never deploy existing technologies. However, with the certainty of access to all 75 MHz for V2X use across the Nation, US DOT and industry can focus on transition planning and can reconcile these discrepancies—and allow transportation to advance to each next generation of communications seamlessly and safely. And, with this certainty, the US DOT and transportation industry can lead on deciding which technologies are most appropriate for safe for use in a transportation environment.