Published on Apr 1, 2024

The navigation map on the phone announced a system reminder: “The red light is about to turn green,” as the traffic signal at the intersection ahead flashed to green, indicating passage.

In 2022, the top two navigation apps in China successively introduced the feature of traffic light countdown reminders, sparking heated discussions among users upon its release. Comments in the forums were filled with questions like “When will it be available in my city?” “Some intersections have reminders, while others don't.” “The countdown at intersections is sometimes accurate, sometimes not.” Users shared their experiences, some praising the convenience and practicality of the feature, while others found it lacking in user experience. Most raised concerns about the inconsistency of the countdown reminders in different cities and intersections.

In August last year, Gaode announced that it had covered over 80,000 traffic signal intersections nationwide. In December, Baidu Maps officially announced that its countdown feature covered over 1 million directions, supporting nearly 3,000 cities and districts nationwide. Despite the seemingly extensive coverage, there are still gaps in coverage in certain areas and discrepancies in coverage within the same city.

How do navigation maps acquire traffic signal information? What are the reasons behind some cities not being covered? Why do coverage discrepancies exist within the same city? The progress of the traffic light countdown reminders on navigation maps resembles an examination, determining who truly excels as the intelligent traffic control "top performer"?

Where does the countdown data come from?

Firstly, it's important to understand how navigation maps obtain the remaining time of traffic signals. The current mainstream approaches are as follows:

1. Directly obtaining city traffic signal timing data through traffic management platforms: For instance, in Xi'an, Baidu Maps retrieves real-time signal status from the city's intelligent signal control system, which has undergone a comprehensive smart signalization upgrade. When drivers use navigation functions, the map automatically links to signals along the route. As the vehicle approaches an intersection, the signal countdown is displayed on the navigation interface. While this method offers high accuracy and minimal errors, the limited openness of current data poses obstacles to widespread adoption.
2. Deriving timing data through "calculated" methods using big data analysis: This is the primary data source for traffic signals in current navigation maps. For example, in September 2022, Amap publicly disclosed a patent for a "method for mining red light duration, electronic devices, and computer program products," filed on March 17, 2022. This method utilizes data samples to analyze user behaviors such as stopping and starting at intersections, deducing signal timing schemes. While big data is more readily accessible for navigation maps, calculated timing schemes may incur errors and update delays.
3. Installing cameras at intersections to provide real-time monitoring and traffic signal information: This approach requires a significant number of cameras and entails higher costs.
4. Other methods include directly reading signal timing information from traffic signal control boxes at intersections, transmitting this data to network platforms, and then implementing it into practical applications through relevant industry organizations.

The Blind Spots of Countdowns Unpassable

The traffic light countdown reminder feature on navigation maps has been in operation for nearly a year now, and while coverage has significantly improved compared to the initial trials, there are still instances where certain road segments lack reminders or entire regions cannot support the feature. What causes these "countdown blind spots" to remain uncovered?

Firstly, there's the issue of acquiring timing information. The methods provided by traffic management platforms for accessing timing information are limited due to concerns regarding safety and data openness. Additionally, schemes that rely on big data calculations face challenges in areas with low traffic volume and usage rates, leading to insufficient data samples for analysis. Moreover, factors such as the cost of installing data collection equipment at these intersections may also hinder coverage. Consequently, there are blind spots where obtaining timing information proves difficult.

Secondly, overly complex road conditions, such as multi-way intersections with designated lanes for straight-ahead and turning traffic, and intricate signal patterns, can affect the accuracy of calculations. In consideration of safety factors, these situations may not display countdowns.

Besides these factors, as smart traffic infrastructure continues to advance, more cities are adopting intelligent control methods like adaptive and sensor-based control. When faced with such intersections, navigation maps currently cannot "anticipate" countdown information through calculations. Until the issue of data openness is resolved, these smart intersections will remain blind spots for the traffic light countdown feature on navigation maps.

Signals controlled by adaptive and sensor-based methods adjust their operation modes, including duration and direction, based on factors such as traffic volume and waiting conditions. This dynamic adjustment minimizes the fixed duration of traffic lights, reducing driver waiting times and improving intersection efficiency. These control methods do not have fixed timing cycles or countdown displays. They operate more like adaptable traffic officers, changing according to the needs of traffic flow. Therefore, there is no possibility of being calculated.

Overcoming these blind spots is no easy task and will require time. Additionally, addressing safety concerns arising from the existence of blind spots is another challenge in the practical application of the traffic light countdown feature on navigation maps.

Hazards of Navigation Traffic light Countdowns

There have always been differing opinions regarding the necessity and safety implications of traffic light countdowns. Many industry scholars and frontline traffic officers believe that there are safety hazards associated with them and advocate for cautious usage.

Firstly, there's the issue of coverage. Due to factors like data sources, road conditions, and smart infrastructure upgrades, there are still gaps in the coverage of traffic light countdowns on navigation maps. This might lead to inconsistent user experiences. If users rely too heavily on the countdown reminders from navigation maps, they might neglect paying attention to real traffic signals, especially at intersections within coverage gaps, posing safety risks.

Secondly, the current predominant method of obtaining timing data through big data analysis still presents accuracy issues. In practice, some intersections may have timing discrepancies of around 3-5 seconds. Internet companies may intentionally delay the display of green lights by a few seconds to enhance safety. Moreover, when timing schemes are adjusted at most intersections, navigation map data updates may not synchronize in a timely manner.

Cai Xiaoke, the director of the Xiangtan Traffic Police Command Center, conducted a verification test in Xiangtan City, where they had recently implemented sensor-based control at an intersection. Despite the change in timing strategy from fixed to sensor-based control, the navigation map continued to display countdown reminders based on the previous data, leading to situations where the map indicated waiting at a red light while the actual intersection had a green light for passage, and vice versa.

The significant delays in data updates could potentially trigger unsafe driving behaviors. Additionally, there are substantial gaps in research regarding traffic driving behaviors and psychology. From the perspective of driving safety, more complex and discerning information demands would inevitably increase the attention requirements for drivers, reduce information processing speed, and reaction time. As a critical variable affecting traffic safety, from this perspective, the imperfect and potentially erroneous traffic light countdown feature in navigation maps doesn't contribute positively.

Due to these reasons, the current navigation map countdown feature mostly serves as a reference. After interviewing several experienced drivers, it's apparent that while the feature is good in theory, its practical utility is limited. The lack of strong user experience might be attributed to its relatively singular application scenario. Features like mitigating the effects of large vehicles blocking visibility or alleviating waiting anxiety, which are emphasized in promotions, may not manifest strongly in actual needs. Considering the investment in technology, it may feel like using a sledgehammer to crack a nut.

From the perspective of the majority of navigation users, the introduction of traffic light countdowns is a nice addition, but many users are somewhat curious and eager about this feature. In the wave of the internet, users are willing to experiment with new features for novel experiences. Even if the feature is not particularly useful, users generally have understanding and tolerance for features that do not affect the driving experience significantly and involve certain technical complexities. Therefore, navigation maps don't receive overly negative reviews due to this feature.

In user comments, many users have raised the question of whether the navigation map can support viewing the waiting conditions at upcoming intersections and the status of traffic lights. After addressing more adaptability issues, whether the navigation map's red light countdown reminders can further evolve to support functions like green wave guidance, enhancing travel assistance, remains a matter of imagination...

More Like an Examination

Despite its shortcomings, the introduction of traffic light countdowns in navigation maps signifies not only an awareness of traffic services but also demonstrates impressive computational capabilities, serving as evidence of the continuous progress of intelligent transportation. The process of popularizing the traffic light countdown feature in navigation maps has also served other purposes.

It's more like an examination. For intersections where countdowns can be easily calculated, the signal timing scheme may remain unchanged for a considerable period. But is the current scheme truly optimal? Some intersections boasting intelligent timing are similarly derived from overall countdown schemes through computational means. In this light, one may question whether they are genuinely "intelligent" or simply wearing the label of intelligence.

Beneath the exam paper, after excluding roads with minimal traffic or complex intersections, the cities and roads that have yet to implement signal light countdowns in navigation maps are mostly the "top performers" with their own mature traffic control strategies. The more flexible and advanced solutions they employ are beyond the conclusion that can be drawn solely based on the current level of computational power.

Conclusion

The question remains whether navigation maps with traffic light countdowns can still be trusted in areas where blind spots persist and how they should be used moving forward. It requires consideration from various perspectives.

The upgrade of navigation traffic light countdown features and the further promotion of intelligent control methods evoke echoes of the ongoing debate surrounding signal light countdowns. Regardless, what matters most is finding the right path that suits one's own needs through practical exploration.

Author: Shusen (7ITS)

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