Part 5 of 8 in ADAS (driver assistance systems)
Intelligent speed assistance (ISA)
Intelligent speed assistance (ISA) reads signs and map data, but can show the wrong limit at roadworks. If they differ, the sign decides, not the screen.
Written by Chris Prosman Reviewed by Dirk van Zuijlen
Updated Reviewed on 2 min read
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ISA (intelligent speed assistance) shows the speed limit and warns you when you drive too fast. The system can be wrong. You read the signs yourself and choose a safe speed.
What is ISA in a car?
ISA stands for intelligent speed assistance. In Dutch it is called snelheidsassistent. The system shows the speed limit that applies at that moment. If you drive too fast, you get a signal.
ISA is not a fixed speed limiter. You can always override ISA, for example by pressing the accelerator further. That does not mean you may drive faster than the sign.
How does intelligent speed assistance work?
ISA knows the limit from a camera that reads signs, from map data, or from both. If you drive too fast, the system gives a signal. This can be:
- a warning with a sound or a vibration;
- resistance in the accelerator pedal;
- the car adjusting its own speed.
Your owner’s manual tells you which type your car has.
The sign beats the screen
Maps can be out of date and a camera can miss a sign. At roadworks there is sometimes a temporary 50 sign while the screen still shows 80. Then 50 applies. So always read the signs yourself. Is a lower speed shown on a matrix sign above the road? Then that lower speed applies.
A maximum is not a safe speed
Even when ISA shows the right limit, that speed may be too high. In rain, fog, slippery conditions or heavy traffic, drive slower. Towing a trailer? Then a lower limit often applies. Check whether your ISA takes that into account. More under speed with a trailer.
How to turn off intelligent speed assistance: is it allowed?
Yes. In cars that meet the EU rules you can switch ISA off. It is back on every time you start the car. How to switch it off differs per car. Do it before your trip or in a safe place, not while driving.
Switching off or overriding does not mean you may go faster. The speed limit still applies when the system is off.
Is ISA mandatory since 2024?
Yes, for new cars. Since 7 July 2024 every new car and van in the EU must have ISA. For new models this already applied from July 2022. Older cars do not have to be fitted with ISA. The rules are in the EU General Safety Regulation and the EU ISA regulation.
Practise like the exam
Example questions like in the CBR exam
Real questions from the Theorio app. You can expect similar questions in your CBR exam.
Question 1 of 3
The temporary sign shows 50 and ISA displays 80. Which limit do you follow?
Tap the answer you think is right.
The limit is 80 but rain reduces visibility and grip. What do you do?
Tap the answer you think is right.
ISA provides resistance at the accelerator. What does that mean?
Tap the answer you think is right.
Answers and explanations for the example questions
Question 1: The temporary sign shows 50 and ISA displays 80. Which limit do you follow?
Correct answer: 50 because the applicable temporary sign controls
Actual rules and signs determine the limit. ISA may miss temporary information.
Question 2: The limit is 80 but rain reduces visibility and grip. What do you do?
Correct answer: Drive more slowly when conditions require
A maximum limit does not make that speed safe in all conditions.
Question 3: ISA provides resistance at the accelerator. What does that mean?
Correct answer: One possible form of support; you still obey the limit
ISA has several forms and may allow override. That does not change your legal obligation.
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