4-Color Traffic Lights Coming for Self-Driving Vehicles?
In what would be the first major change in nearly 100 years, Japan may introduce white traffic signals to help self-driving vehicles communicate.
What’s new: On March 10, 2024, a research team led by Professor Ali Hajbabaie of North Carolina State University in the United States made a provocative new proposal: to add a white light to the familiar red, yellow, and green1 traffic signals that have been the global standard since 1931. It would light up based on real-time information when autonomous vehicles are approaching and also help control traffic depending upon the movement of pedestrians. A white traffic light would act like a kanban2 in a factory, signaling that all passing vehicles are communicating with each other. Although to the casual observer, when a white light is on, it may appear that cars and trucks are entering and exiting an intersection chaotically almost simultaneously, the electronic communication systems behind the scenes would actually be controlling everything to ensure the optimal flow of traffic.
"Recent advances in electrification, connectivity, automation, and computational technologies provide opportunities to improve traffic operations and safety... (but) most research focuses on vehicle movements with little or no attention to pedestrians." - Professor Ali Hajbabaie, North Carolina State University
The automated traffic system would rely on autonomous vehicles equipped with Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) communication functions, which would be used to obtain real-time information on acceleration and deceleration. Various traffic monitoring agencies in Japan are seriously considering this new system to help reduce road congestion and traffic accidents.
What’s happening: For the past 20 years, Japan has been experimenting with intersections that have separate traffic signals for vehicles and pedestrians. At these locations, the traffic signal system controls the interval between when pedestrians and vehicles pass through the intersection so that vehicles turning right or left and pedestrians crossing the intersection do not intersect.
For example, conventional signals alternate between north-south and east-west signals, allowing vehicles and pedestrians traveling in the same direction to pass simultaneously.
On the other hand, at “scramble intersections3” where separate traffic signals are used to separate vehicles and pedestrians, the typical pattern is [north-south (vehicles)] → [east-west (vehicles)] → [pedestrians]. The famous Shibuya Crossing is a good example of this type of intersection, where safety is enhanced because vehicles in all directions stop when pedestrians cross.
By using communication technology to know in advance about red lights and traffic jams at intersections ahead, automated vehicles can begin to slow down smoothly. Just as basic V2I communications are linked to on-board navigation systems in manually driven cars and trucks, drivers will be alerted to traffic ahead sooner, and car navigation systems can suggest alternative routes.
Yes but: Although the separate signal system contributes greatly to safety, the waiting time for both vehicles and pedestrians is fundamentally longer because they have to wait for two traffic signal cycles before they can pass. Depending on the location and time of day, the line of cars waiting for such a signal can be quite long.
Why it matters: If a new color is gradually added to traffic signals over the next decade, it would be the first major change in about 100 years of automated road signage. Along with automated driving systems, the new technology could help ease traffic congestion and reduce accidents.
Starting with the "baby step" of separating pedestrian and vehicle traffic signals, traffic safety could improve dramatically. The professor's model suggests that traffic congestion at urban intersections would be reduced by about 40% compared to current traffic light optimization software.
By the numbers: As Japan's metropolitan areas are among the most congested in the world, there is an urgent need to improve driving conditions.
Gnarled Traffic: According to the annual TomTom Traffic Index published by Dutch location-based company TomTom, the 2023 edition, which covers 387 cities in 55 countries, ranked Sapporo 14th, Nagoya 25th, Tokyo 27th and Osaka 56th. London was ranked as the world's most congested city, taking an average of 37 minutes and 20 seconds to travel 10 kilometers (6.2 miles). Sapporo took 26 minutes and 30 seconds. Other major Japanese cities also fared poorly: Nagoya 24 minutes 20 seconds, Tokyo 23 minutes 40 seconds, and Osaka 21 minutes 20 seconds. Traffic congestion can be attributed to a variety of factors, including both left- and right-turning vehicles blocking straight-ahead vehicles, localized congestion caused by sightseeing, congestion caused by commercial facilities, on-street parking and loading/unloading, and congestion caused by stopped buses. The most important factor is, however, simply that the number of vehicles often exceeds the capacity of a particular road. This is why congestion is more likely to occur in large cities, where people and goods are concentrated.
Need to Get Up-to-Speed: While most of Japan's highways are designed for speeds of 99 km/h (62 mph), the average actual speed was only 83 km/h (52 mph), representing a loss rate of 16%, based upon records gathered in 2021. Similarly, all of Japan's non-expressway general purpose roads combined were designed for an average speed of 61 km/h (38 mph), while in reality the actual speed was only 36 km/h (22 mph), a loss rate of 44%. The loss rate for all roads in Japan has been calculated to be 41%. In other words, 41% of automobile travel time is lost due to inefficiencies such as congestion. This equates to about 3.7 million working hours, or about 1.3% of Japan's total CO2 emissions.
Low Inter-City Drive Times: Japan's intercity travel speeds (the shortest distance between cities divided by the shortest time required) also appear to be lower than those of other countries: Only 62 kmh (39 mph) in Japan vs. 88 kmh (55 mph) in France, 84 kmh (52 mph) in Germany, 74 kmh (46 mph) in the United Kingdom, and 77 kmh (48 mph) in South Korea. This is due to the short length of highways relative to land area and population.
Land of the “Teisoku Doro” (低速道路) or “Low Speed Expressway”: Roads with speed limits of 80 km/h (50 mph) or higher account for only 7,800 km (4,850 miles) in Japan, compared with 31,700 km (19,700 miles) in Germany and 18,500 km (11,500 miles) in France.
Narrow Thoroughfares: While less than 10% of expressways in the U.S., South Korea, France, and Germany have three lanes or less, 40% of Japan's expressways only have two provisional lanes. With one lane in each direction, congestion is more likely to occur, not to mention the need to close the road in the event of an accident. In South Korea, provisional two-lane sections accounted for 60% of all expressways until the 1980s, but the country decided to eliminate them altogether in 1992, and by the end of 2015 almost all expressways had been converted to four lanes.
Encouraging Safety Improvement after Conversion to a Scramble Intersection: According to the National Police Agency, tests of scramble intersections at 100 locations nationwide in 2002 resulted in a 40% reduction in traffic accidents involving personal injury and a 70% reduction in accidents involving pedestrians struck by moving vehicles. Based on these results, scramble intersections have been gradually introduced in Japan over the past 20 years. As of the end of March 2023, there were 10,184 nationwide, accounting for about 4.9% of the total number of traffic signals in Japan (about 210,000).
Commentary: Japan would seem to be an ideal "laboratory" for testing fully automated driving technology, given the high quality of its roads, its technological prowess, its extreme attention to detail, its early and relatively widespread adoption of scramble intersections, and, of course, the need to improve efficiency.
Autonomous driving technology is finally beginning to reach the stage of practical application in Japan. With the lifting of the ban on Level 44 vehicles, the pace of these efforts is expected to accelerate.
I wholeheartedly support continued research and field testing. While I still have at least a quarter century of driving on my own left in me (knock on wood), I am counting on this technology to keep me mobile in old age.
It is unlikely that the final iteration of this technology will resemble Johnny Cab from the 1990 movie classic Total Recall, but there will probably be some similarities. Maybe Johnny will just be a hologram. In any case, I would be satisfied if "Johnny" could just get me from point A to point B.
What’s next: In reality, the impact of automated driving on reducing traffic congestion is still a long way off, and it is unknown how much of an impact it will have.
In the near term, it will be interesting to see how the proliferation of V2V and V2I technology will reduce congestion as well as how the proliferation of shared automated driving services in urban areas will affect road capacity.
The development and commercialization of automated driving has begun with buses, taxis, and other transportation services, but the public transportation environment will change dramatically as the technology becomes more advanced and reaches the stage of widespread adoption and mass production.
It will lead to low-cost, relatively unrestricted travel. There will be a shift away from private cars, especially in urban areas, and the number of vehicles on the road will decrease, creating more capacity on the roads. As a result, traffic congestion should be reduced.
Of course, if the technology for road navigation evolves this far, it would only be a matter of time before the third dimension of altitude could be applied to personal flying equipment and drones large enough to be used as air taxis.
What do you think? What do you think about self-driving technology? All responses are completely anonymous, even to the author.
Links to Japanese Sources: https://jidounten-lab.com/u_46377, https://jidounten-lab.com/u_46149, and https://jidounten-lab.com/u_34323.
Link to Overseas Source: https://onlinelibrary.wiley.com/doi/10.1111/mice.13178
#TrafficLights #PedestrianSignals #TrafficCongestion #AutomatedVehicles #AutonomousDriving #V2V #Vehicle-to-Vehicle #V2I #VehicletoInfrastructure #ConnectedAutomatedVehicle #CAV #ConnectedHumanDrivenVehicles #CHV #pedestrian #intersection #PedestrianScramble #ExclusivePedestrianInterval #ShibuyaCrossing #ScrambleIntersection #SelfDrivingVehicle #自動運転 #自動運転車 #信号 #歩行者用信号 #交通渋滞 #路車間通信 #歩行者 #交差点 #スクランブル交差点 #渋谷スクランブル交差点 #渋谷交差点 #高速道路 #低速道路
Random Fun Fact about the Japanese Language: Traffic lights in Japanese are called ao shingo (青信号), which literally translates to "blue signal." The reason why green is sometimes called "blue" in Japanese is due to the history of the vocabulary used to describe colors in Japanese. Originally, Japanese had only a handful of basic color terms, such as red, white, black, and one word, "ao," which included both blue and green. It was like a single category for these similar hues. Later, around the 11th or 12th century, the word midori (緑) came into use specifically for green. But even today, ao (青) can still be used for certain things that are green, especially in older expressions.
A kanban (看板) is a visual workflow management system that originated in manufacturing. It emphasizes continuous improvement and uses boards to help teams visualize their work, optimize flow, and maximize efficiency. Colors can represent different workflow stages or priority levels. For example, a green card might represent a task in the "Done" stage, yellow for "In Progress," and red for "To Do" with a high priority. This allows team members to quickly see the overall flow of work.
Also called “pedestrian scramble” or “exclusive pedestrian interval”
The definition of Level 4 Automated Driving (Advanced Driving Automation) is "an automated driving system that performs all dynamic driving tasks and responds to difficulties in continuous operation in a limited area. The user is not expected to respond to requests for intervention when it is difficult to continue driving.
So the future is here... As a non-driver who has no interest whatsoever in cars, I'm not particularly excited, but I'm looking forward to seeing those self-driving machines in action.
One thing I don't understand is:
- one sentence in your articles says, "with automated driving systems, the new technology could help ease traffic congestion."
- But according to another paragraph, "Although the separate signal system contributes greatly to safety, the waiting time for both vehicles and pedestrians is fundamentally longer because they have to wait for two traffic signal cycles before they can pass. Depending on the location and time of day, the line of cars waiting for such a signal can be quite long."
They seem to contradict each other.
This is really one of my hot-button issues with Japan. Since arriving here, Japan's traffic management systems have been the biggest source of dismay to me. My principal complaint is that the systems seem to be based on something other than common sense and public health and safety. Giving a green light to both vehicles and pedestrians at the same time at intersections is a good example. Allowing or tolerating cyclists to ride on sideWALKS is another, and so is the complete absence of sidewalks on most side streets. The list goes on and on and on.
I also think autonomous vehicles are a bad idea. I guess the jury is still out on whether they kill/injure more people than vehicles driven by humans; but the reason I object to them is that they are another example of humans becoming reliant on machines/technology. It may make life easier and more "cool" in some ways; but it also means we become less self-reliant. There are those who wish to see humans and machines merge. I can't think of anything worse. Rudolf Steiner, the Austrian thinker, was already warning about these dangers more than a century ago:
https://www.waldorflibrary.org/images/stories/articles/WJP19_steiner.pdf