[Letters] Prudent traffic signal systems are needed

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[Letters] Prudent traffic signal systems are needed

The Seoul Metropolitan Government and the Seoul Metropolitan Police Agency have established a new traffic signal system and started a test run. Drivers find the new signal system unintuitive and confusing, and one of the most controversial features is the use of red arrow signaling prohibited left and right turns. The new system introduces a completely new idea and drivers are confused as an arrow generally indicates an okay to proceed to the direction.

The new system lacks meaningful compatibility as the expectation and interpretation of the drivers do not coincide with the intention of the police agency expressed through the traffic signal. Drivers perceive a directional arrow as a “command.” In other words, if the light is off on the arrow signal, drivers consider to have received no command. Once an arrow is on sight, they interpret that they are given an okay. The color is interpreted next. In the signal design, an arrow symbol and a color may be used redundantly to boost perceptiveness.

However, the new signal system produces a contradictory effect. A lighted arrow signal sends a positive message of commanding the drivers to turn while red is a color with negative connotation, prohibiting the turn. Therefore, instead of reinforcing the message through redundancy, the red arrow naturally creates confusion.

International standard on color is also ambiguous. Generally, red is accepted as a color of “prohibition,” but it is only a social custom and contract. For example, stocks traded at higher price are indicated in red in Korean stock exchanges. Of course, in the United States and stock markets in other countries, green means up. When the color code was first introduced in the Korean stock market, there must have been a mistake.

But the Korean stock market still uses the system as Koreans have gotten used to it. If the financial authorities suddenly announce to change the color indicators and implement a new system, the financial market would panic. An official at the police agency claimed that red means stop in any situation but what about color-blind drivers?

A redundancy in design applies various indicators at the same time to allow all users to interpret the same meaning and direction by accommodating people with handicaps, not to create a conflict and confusion.

Another traffic signal that creates and adds confusion are the red lights that are installed in the middle of the street, not at the intersections or pedestrian crossings. They are intended to inform the drivers about a signal 100 meters ahead, but they also create a serious cognitive confusion. A red light intuitively means a “command” to stop at the spot instantly. Drivers are often puzzled how to interpret the command with no context, standing on the road with no crosswalk or intersection. Many drivers immediately think whether they should stop the car.

Driving is a process that demands the drivers to make countless cognitive decisions. There is no guarantee that all drivers are able to make the best possible decisions all the time. When designing all traffic signal systems that are closely related to safety, the authorities must make prudent choices by taking all circumstances and contexts of the drivers and pedestrians into account.

Moreover, it takes time for the drivers to train themselves and get used to the new signal. It is hard to believe that the city of Seoul and the police agency announced such a significant change to the traffic code without holding public hearings or consulting experts.

*Letters and commentaries for publication should be addressed “Letters to the Editor.” E-mailed letters should be sent to eopinion@joongang.co.kr.


Lee Seong-il, a professor of systems management engineering at Sungkyunkwan University.
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