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What does the black ice (hidden ice) sign mean in Turkey?
Last updated: 28 October 2026 · Sign code: T-37 · Warning signs
In short: This warning sign means the road may be covered with a thin layer of ice you cannot see, even if it looks dry. It is a red-bordered triangle with a black snowflake.
What should you do when you see this sign?
- Slow down before the sign when it is cold.
- On bridges, viaducts and shaded sections, avoid sudden braking and steering.
- Leave a bigger gap to the vehicle in front.
Where and why is it used?
Bridges and viaducts are open to cold air underneath, so they freeze before the rest of the road. There can be ice on a bridge even when the temperature is just above zero.
Red-bordered white triangle Warn you that there is a hazard ahead. When you see one, slow down and be ready for the danger. Warning signs are placed before the hazard.
Which sign is it confused with?
How is it asked in the Turkish driving exam?
The 2 questions below come from testcim's free question pool, in English. Tap an option to see the correct answer and the explanation.
Question 1
With the air temperature just above zero, a driver approaching a bridge that looks dry sees the sign shown. Which statement is correct?
Show answer and explanation
Correct answer: D) They should slow down before the bridge, as there may be unseen ice
T-37, hidden icing (black ice), warns that a thin, invisible layer of ice may be present even if the road looks dry. Bridges and shaded spots cool faster, so ice forms there first. Reduce speed before reaching the slippery section and avoid braking or sudden steering on ice.
Question 2
In winter, which parts of the road usually freeze first?
Show answer and explanation
Correct answer: C) Bridges and shaded areas
Bridges are cooled from below too, and shaded areas get no sun, so they ice up faster.
Warning signs: other signs
- Dangerous bend to the right (T-1a)
- Slippery road (T-8)
- School crossing (T-12)
- Farm animals (T-14a)
- Two-way traffic (T-19)
- Uncontrolled crossroads (T-21)
- Junction with a minor road (T-22a)
- Roundabout ahead (T-24)
- Level crossing with barriers (T-25)
- Level crossing without barriers (T-26)
To see every sign with pictures on one page, go to the Turkish road signs guide. For the other traffic topics, try the traffic questions.
This is a simplified drawing for learning; the official sign's dimensions and details may differ.
Sources (Turkish): Highway Traffic Law No. 2918 · Highway Traffic Regulation · KGM road signs handbook, vertical signs
Türkçe: Gizli buzlanma işareti