Tunnel Category
The sign indicates tunnel category
When You See This Sign
When you see the T23 plate at the tunnel entrance, treat it as information about which safety and evacuation category the tunnel belongs to. Continue driving as usual according to applicable traffic rules, but be extra alert for supplementary signage and instructions as well as other road users.
Rules & Regulations
- The sign is an additional (supplementary) plate and indicates the tunnel's category according to the Swedish Transport Administration's classification.
- The tunnel sign T23 does not impose any speed limits or prohibitions — any regulations are shown on separate road signs or in local regulations.
- The tunnel category is used by emergency services and the road authority to plan evacuations, ventilation and rescue operations; the category can therefore affect which safety installations are present in the tunnel.
- For transports of dangerous goods, the tunnel category may be part of the assessment of whether special routes or permits are required under applicable regulations.
Tips for Drivers
- Note which category is indicated and pay attention to any additional signage or instructions at the tunnel entrance.
- If something happens in the tunnel (fire, smoke, accident), the category designation can be important when contacting emergency services — if possible, provide the tunnel name and category.
- Keep normal attentiveness and follow the usual tunnel rules (keep distance, use low beam) because the sign informs about the tunnel's design and safety level, not about new traffic rules.
- If you are transporting dangerous goods, check well before the tunnel entrance whether the category implies specific restrictions or an alternative route.
Common Mistakes
- Believing that the sign itself imposes a speed limit or a prohibition — it is only informative/a supplementary plate.
- Failing to look for additional information at the tunnel entrance and assuming all tunnels have the same safety standard.
- Assuming that the tunnel category immediately affects private drivers' behavior when it is primarily used by authorities and emergency services.
Test Yourself
Road Sign: Tunnel Category
What applies when you see this sign at the tunnel entrance?
- A The sign indicates the tunnel category and the rules that apply to that type of tunnel.
- B The sign shows the length of the tunnel in meters.
- C The sign warns of low clearance in the tunnel.
- D The sign indicates the distance to the next emergency exit.
Exam Tip
On the theory test you will often have to choose between options stating that the sign establishes a rule (e.g., a speed limit) or only informs. Remember: T23 is a supplementary information sign — it does not introduce its own traffic rules.
Did You Know?
Supplementary plates for tunnel category were introduced as a way to provide quick and standardized information to both emergency services and professional drivers. You most often see them at larger road tunnels and on roads where specific tunnel preparedness is established.
Frequently Asked Questions
Does the sign mean I must slow down?
No. T23 only indicates the tunnel category and in itself does not impose any speed requirement. Any speed limits are indicated on separate signs.
Does the sign apply differently to different vehicles?
The information on the sign applies generally but can be particularly relevant for vehicles transporting dangerous goods. Any restrictions for certain vehicles are specified in other regulations or signage.
Should I do anything different if I see a specific letter or number on the sign?
The letter/number shows which category the tunnel belongs to for authorities and emergency services. For ordinary drivers, it mainly means being attentive to additional instructions and safety installations in the tunnel.
Why does the sign exist at all?
The purpose is to provide quick and uniform information about the tunnel's safety level to emergency services, the road authority and professional drivers, which facilitates responses and planning during incidents.
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