Have you ever been driving in the center of a city and hit an unexpected winning streak? Green light after green light at every intersection, taking minutes off your expected journey time and making your commute a breeze?
What about the alternative? Have you ever sat at a red light for what feels like five minutes while there are no other cars in sight?
In the first scenario, you could feel like your journey has been blessed with divine intervention; in the second, you’re cursing your terrible luck.
But neither of these cases is a coincidence. Most likely, they’re the result of the equipment being used at each intersection and the broader traffic strategies being implemented (or not implemented) in that city or region.
For decades, intersections were governed by mechanical timers, changing from green to yellow and red regardless of the time of day or traffic conditions. More recently, cities are investing in smart signals, video cameras and sensors which can regulate traffic based on what’s actually happening on the roads. Smart intersections offer numerous benefits beyond simply moving cars more efficiently through the city, and the more intersections a city upgrades, the better the results. When a city has several smart intersections, it can perform simulations of potential traffic flows to determine how to regulate throughput most efficiently.
However, for cities still relying on legacy technology, the clock is ticking. New technology breakthroughs promise to make smart intersections more valuable than ever, but the longer you wait to upgrade, the more challenging and expensive the transition.
Benefits of Smart Signals and Sensors
The efficiency benefits of smart signals at intersections are obvious. When a stoplight responds to real-time data rather than a preset, inflexible timer, traffic will naturally flow more efficiently through the intersection. And when several stoplights are connected to the same system and working in harmony, the efficiency benefits extend even further.
However, that traffic throughput has additional benefits that may not be as obvious to your everyday driver. When intersections operate more efficiently, cars spend less time idling at intersections than they would otherwise. On an individual level, those seconds or minutes of savings might seem inconsequential. But when you multiply those savings across the thousands of cars that pass through an intersection every single day, those savings add up to massive reductions in greenhouse gas emissions. The more intersections a city or region upgrades to smart signals, and the sooner they make the transition, the cleaner their air will be in the years to come.
Smart signals also offer tangible safety benefits for both drivers and pedestrians. If you’ve ever been in a hurry to get to your destination and hit multiple red lights in a row, you understand the natural response: you’ll try harder to “beat the light” at the next intersection. Those frustrating, high-stress moments for drivers are particularly hazardous, increasing the likelihood of an accident at the intersection or, worse, a collision with a crossing pedestrian. Smart signals reduce the odds that cars will spend an extreme amount of time waiting at intersections, making those crossings safer for everyone involved.
Smart signals, cameras, and sensors can also work together to protect pedestrians. If a pedestrian is slow to cross the intersection, a sensor can transmit that information to the stoplight, ensuring that the light doesn’t change until the pedestrian has safely reached the other side.
V2V and V2I — The Future of Smart Roads and Intersections
Smart signals can deliver massive benefits at signalized intersections — those with a stoplight rather than stop signs. But when you think about the world’s roadways, those intersections make up a tiny fraction of the overall infrastructure. There are roughly 320,000 signalized intersections in the United States — most sources estimate that under 10% of those intersections use smart, adaptive technologies.
So, while there is still a lot of work to be done to make those intersections more efficient, there is not an insurmountable number of traffic signals to upgrade. We also need to account for what happens between intersections. Two of the most promising technologies that could help make roads safer and more efficient are vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications.
With V2V communications, the onboard sensors and computers on vehicles exchange information on their relative speed, position and direction. In the future, V2V communications could make roads safer by reducing the likelihood of an accident. When the vehicles determine that an accident is imminent, they can automatically slow down to prevent the collision.
V2I communications would enable the same onboard technology in a vehicle to communicate in real-time with surrounding infrastructure, such as traffic signals and sensors. This data would make it possible to regulate traffic more effectively on long stretches of road without intersections, for example, by adapting speed limits to improve throughput. V2I communications are also valuable during emergencies. For example, if a car accident has blocked a lane of traffic on a major freeway, V2I data could inform overhead signage, displaying which lane is blocked and directing traffic accordingly.
While this level of communication and integration is undoubtedly a long-term vision, it’s worth noting that many cities have already achieved some level of V2I communications. Many intersections are equipped to respond to emergency vehicles, automatically triggering the necessary red lights when an ambulance or fire truck approaches; once the emergency vehicle has crossed through the intersection, the traffic signal resumes normal operation.
Cities Can’t Afford to Wait
Upgrading an intersection from a timer to a smart signal takes time, planning, and money. Many cities opt to begin with a pilot project, upgrading only a few of their intersections before committing to a more comprehensive project. But the reality is that these projects will only become more expensive and more complicated as the years go by.
Legacy traffic signals, which use timers instead of sensors, may be decades old, and upgrading those signals can be a difficult and time-consuming process. The older a traffic signal, the less likely that it can simply be modified to accommodate new technologies. By upgrading signals now, cities can ensure that they have the baseline technology needed to keep pace with new innovations in the coming years.
As car manufacturers introduce new communication and safety technologies into their vehicles, cities have the opportunity to upgrade their infrastructure to enhance public health and safety. We can’t afford to wait to bring our intersections into the 21st century.