What is Traffic-Sign Recognition?

Jessica Shea Choksey | Jun 29, 2022

As carmakers identify new ways to keep vehicle occupants safe, the list of advanced driving assistance systems (ADAS) continues to expand. One of the more recent innovations on the ADAS front is called traffic-sign recognition (TSR). Traffic-sign recognition essentially serves as a second set of eyes for the driver by raising awareness of specific roadway markers to help make better and safer driving decisions.

Traffic-Sign Recognition

Photo: CarExpert

How Does TSR Work?

Traffic-sign recognition is a safety tech system that recognizes traffic signs and relays the information displayed on the sign to the driver through the instrument cluster, infotainment screen, or head-up display. Most TSR systems can identify speed limit, stop, and “do not enter” signs. More sophisticated systems may be able to recognize other types of signs.

The primary purpose of TSR is to increase driver focus. If a driver misses a sign, TSR can make them aware of it so they can react accordingly. The idea is simple: TSR identifies road signs the driver might have missed and alerts them of their presence.

This technology uses advanced forward-facing cameras positioned high on the windshield, generally adjacent to the rearview mirror housing. Aimed to “see” traffic signs, the cameras scan the side of the road relative to the car.

Once the camera captures a sign, the system’s software processes the image to establish its classification and meaning. The system then relays this information to the driver almost instantaneously in the form of an icon or graphic representation of the sign. However, TSR’s ability to accurately identify a sign depends on the speed of the vehicle and its distance to the sign.

Some TSR systems also work in conjunction with advanced cruise control, which is set to maintain a speed above or below the scanned signs. For example, if TSR detects a 40-mph speed limit, it updates the cruise set speed to 40 mph unless the driver sets the parameters above or below the detected speed limit.

Aside from cruise control-related functionalities, TSR may use the same forward-facing ADAS camera that tracks lane markings to inform the vehicle’s lane-departure warning system or distracted driver alert system. So, it’s common for these features to come with TSR in the same ADAS package.

The Limits of TSR

Current TSR technology cannot determine all traffic signs or operate in all conditions. Several circumstances limit the performance of TSR systems, including:

  • Low visibility due to poor weather (fog, snow, heavy rain, etc.)
  • Dirty or improperly adjusted headlights
  • Foggy or blocked windshield
  • Warped, twisted, or bent signs
  • Abnormal tire or wheel conditions
  • A tilted vehicle due to a heavy load or modified suspension

While TSR and similar camera- and sensor-based technologies are potentially significant to moving us toward an autonomous driving future, there is still a long way to go. At this point, TSR is still primarily a driver-assistance system meant only to assist. Drivers cannot rely solely on this system to make steering or braking maneuvers/adjustments.

TSR Calibration

Forward-sensing cameras are not self-calibrating. Professional calibration is necessary for most ADAS to work correctly following an accident, windshield replacement, suspension work, or alignment changes. During calibrations, technicians realign forward-facing cameras to the proper position.

Which Car Brands Offer TSR?

Because of how new this innovative safety technology is, not many auto brands include TSR as standard or optional equipment on their models. Premium brands like AudiBMW, and Mercedes-Benz commonly offer TSR on their models, while safety stalwart Volvo provides the technology on every model in its lineup. While it is less common among mainstream brands, several of them, including Ford, Honda, and Mazda, also offer TSR as part of their higher-level ADAS packages on specific models.


Traffic-sign recognition is still a new technology but effective in elevating driver awareness of speed limits and other road rules for a safer overall driving experience. More automakers will likely add this valuable technology to their ADAS suites soon.

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