In this post, find out what the safe distance between cars is, how to calculate it on highways and in tunnels, and why a V16 light like Help Flash can help improve visibility on the road.
What is the safe distance between cars?
The safety distance between cars is the space you must maintain from the vehicle in front of you to avoid collisions if it brakes suddenly. It's not just a recommendation: it's regulated by the General Traffic Regulations, and failure to comply with them can result in accidents and fines.
Although many drivers are not aware of it, maintaining this minimum safety distance can save your life and is especially critical on fast roads or in low-visibility situations.
Safety distance on motorways and dual carriageways
On highways and motorways, where speeds are higher, the safety distance must be even greater. There's no fixed number in meters, but a simple rule:
You must be able to stop your vehicle without crashing if the vehicle in front brakes suddenly.
As a practical reference, it is recommended:
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Leave at least 2 seconds between you and the vehicle in front of you.
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If it is raining or foggy, increase to 3 or even 4 seconds .
How do you check? Choose a fixed point on the road (a sign or post) and count: "one thousand one hundred and one, one thousand one hundred and two..." If you reach the point before you finish, you're going too close.
Minimum distance in tunnels
In tunnels, safety distance becomes even more important. Here , a minimum distance is required by law , even in traffic jams.
When to apply the 100 m and when to use the 4 s reference?
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If you cannot pass the vehicle in front , you must maintain at least 100 meters or a 4-second interval .
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If you can overtake, maintain a safe distance , allowing you to react safely.
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In the event of a stop inside the tunnel , leave sufficient separation to avoid multiple collisions.
Many tunnels are equipped with signs that warn you if you're breaking this rule, so it's best not to rush.
How to calculate your safety distance
In addition to the rule of seconds, you can use this basic formula:
Distance (in meters) = Speed (in km/h) / 2
For example:
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If you are driving at 100 km/h → you should leave at least 50 meters.
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At 120 km/h → 60 meters minimum.
This formula serves as a reference under normal conditions, but remember that the distance should be increased in case of rain, poor visibility, fatigue or extra load .
Factors that force an increase in distance
There are situations in which maintaining the minimum distance isn't enough. You should increase it if any of the following factors apply:
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Wet pavement, ice or gravel
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Driving at night or in fog
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Tiredness or lack of concentration
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Loaded vehicle or vehicle with trailer
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Vehicle too close behind (accordion effect)
The more leeway you have, the more chances you have to react in time without putting yourself or others at risk.
Signal a stop with a V16 emergency light on
If you are forced to stop your car on a highway, dual carriageway, or tunnel, in addition to maintaining a safe distance, you must signal your position to avoid being hit .
Since 2021, you can replace the triangles with a V16 emergency light , and from 2026 it will be mandatory to carry a connected beacon such as Help Flash IoT+ , which communicates directly with the DGT 3.0.
Why is Help Flash IoT+ the best option?
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The most powerful v16 beacon on the market.
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It activates in seconds, just by pressing a button.
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You don't need to walk on the shoulder to place it, avoiding accidents.
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It emits a light of 250 candles , visible even during the day.
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Connected to the DGT 3.0 , it transmits your location and warns other drivers through dashboards and browsers.
A simple, legal, and effective tool to protect yourself while maintaining distance… and safety.
