Crash Assist Technologies explained – What is Active Cruise Control?

Active Cruise Control

CO-PILOT: The system detects preceding vehicles by means of radar sensors or cameras and adjusts speed to maintain a constant distance in front of your car. Image courtesy of

We all know how annoying it can be trying to keep your vehicle’s speed steady and below the speed limit on long trips. 

Many vehicles now have cruise control, which aims to keep the speed of a car at a set point by adjusting the accelerator automatically. Typically the system doesn’t apply the brakes on downhill stretches, so it is recommended to be used only on relatively flat, straight roads, although a few models provide braking by changing down the automatic gearbox to a lower gear.

There are two views on the influence of cruise control on crash rates:

  1.  It relieves you of the necessity of controlling your speed and gives you more time to concentrate on other dangers around you, so it is advantageous.
  2. The lack of attention to speed control leads to boredom and a greater likelihood of mistakes due to fatigue, so it is detrimental.

There is not enough evidence yet to determine which is the more likely. However, fatigue, at least, can be addressed by regular rest breaks.

Active cruise control is an enhancement of cruise control and uses cameras or radar to detect the car you are following and controls the accelerator and brakes to maintain the same speed.

As our roads become increasingly busy and congested this can be a very useful feature. However, on busy multi-lane roads the systems sometimes brake heavily if a car cuts in front of you, which can be annoying. It can be useful in steadily moving traffic but it can’t anticipate congestion conditions as well as a person can, so it won’t react to a traffic slowdown until the car in front does.

Some systems will reduce speed to zero when the car in front stops, then accelerate again when it moves off. Most need to be “prompted” if there is too long a stop, by pressing a button on the steering wheel or touching the accelerator.

It is also called Adaptive Cruise Control or Autonomous Cruise Control. It is not yet widespread in new vehicles and is only available in luxury and top-level variants but, as with all new technology, will become more common with increasing volume and falling cost.

What’s your experience with ACC? Is it a feature you like?

Next time, we’ll take a look at Collision Warning Technologies, plus other safety  innovations that are changing the way we drive.

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This entry was posted in Driving Safety, Motoring, Technology and tagged , , by Jack @ NRMA. Bookmark the permalink.

About Jack @ NRMA

Jack is the NRMA’s advocate and champion for vehicle technical and environmental issues. He has been with NRMA for 24 years and previous to that worked for a vehicle manufacturer and ran an emissions laboratory. He analyses new technologies, suggests any testing required and manages the NRMA’s involvement in national programs such as ANCAP, the high speed crash test program that provides safety ratings for purchasers of new vehicles; the Used Car Safety Ratings, that provide similar ratings for used cars; the Child Restraint Evaluation Program, to rate child restraints; and the Consumer Rating and Assessment of Safety Helmets (CRASH) to rate motorcycle helmets. Jack also presents NRMA policy and test results from these programs in the media, so you may see him on TV or hear him on the radio.

6 thoughts on “Crash Assist Technologies explained – What is Active Cruise Control?

  1. I don’t agree with this device. And a lot of new devices.

    I see the point of this item in, lets say America, or Europe where road networks are good and they have long, straight, 3 lane roadways and people have better driving manners.

    In Australia, it would be impossible to use. I drive a modern car from Newcastle to Gosford occasionally and Newcastle to Sydney when I can’t avoid it. 90% of the road is 2 lanes and it’s almost impossible to use cruise control. And active cruise would almost certainly lead to an increase in fuel use as you would be in the left lane at 110kph, it would sense a person decreasing in speed, it would slow down, then they would accelerate, you would accelerate and so on for 10km down the road. You move into the right hand lane to overtake after waiting for the 80′s model Tarago to overtake you at 111kph valve bouncing its head off and blowing steam out of its tail pipe, it slows to 100kph, so you overtake both and then pull back in and then both cars would overtake you. Repeat process for another 20km.

    What should be introduced is active policing. Where a police car actively drives on the highway, 24hrs a day, looking for offenders. People who sit in the right hand lane, people who speed recklessly etc.

    Better still, introduce active driving. Which means you drive and look for an Accord that will no doubt be driving 20kph slower than the traffic flow, so you don’t arrive upon it and hold a whole lane of traffic up. You pay attention to your surroundings. You plan your route out before you leave so you don’t realize you need this exit when you’re in the right hand lane and cut across 3 lanes of traffic at 50kph.

    Yes, gadgets are cool. But the more sophisticated they become, the worse drivers, and driving standards will become. Think of it as spell check in a car, oh, I don’t need to pay attention to the traffic conditions in a 2 tonne vehicle moving at 110kph as the computer will do it for me, but computers fail.

  2. It only makes sense on long road trips. And even then it’s dangerous cos might lead the driver to nod off. If you don’t want to drive your car on long trips, take a train or plane. Or else wait for Google to come up with a self-driving one!

  3. What’s the point of having a car if you can’t drive it!

    I own a classic GT Falcon. It’s noisy, heavy to steer, the brakes are more of a slowing aide rather than a stopping aide, headlights are decoration only, you can’t see the dash in the dark, the fuel gauge is a conservative eastimate, and the list goes on.

    It’s pretty to look at and it smells nice and sounds awesome, but driving it is most definitely my favourite part of owning it. Let me add, it has 500 odd horsepower and it’s driven in 40/50/60kph zones and it has no traction control, no abs, no speed warnings, no driver aides of any kind unless you count a FM radio, but I manage to drive it 3000 odd k’s a year with no fines and no crashes.

    A large part of driving is driver awareness. When I learned to drive in a UC Torana, nothing was left to chance. I always thought race drivers of the 60′s were being funny when they said they’d tap the brake on Conrod to make sure they had a pedal at the end of the straight. Now I know they weren’t.

    I notice a lot of P Platers and young drivers rush to a corner, dive on the brakes and then accelerate like a cut cat back around the corner, there’s no consideration for mechanical sympathy, or for a brake failure, or missing a gear, or that they might slip on the steering wheel. Drivers who learn on older cars give a lot of consideration into what could possibly go wrong and have learned to drive smoothly and cautiously and a lot of the times can maintain a faster speed around the corner as they are smooth and have higher entry and exit speeds, and even return better fuel economy, it’s just how we were taught and how we learned to drive with cars that were prone to failure.

  4. Not sure about ACC, but I disagree with your comment that Cruise Control may contribute to fatigue – on the contrary, I have found when energy reserves are low after a long day on the Hume Highway (or even after just a few hours), trying to maintain focus on vehicle speed can be enough to exhaust a tired driver. Cruise Control has been a safety net for me on many long-haul trips, giving that little extra freedom to enjoy the surroundings, select good music, etc, and generally stay more energized and alert..
    I do share the sentiments of Julian above on the importance to understand your car, how it works, and its limitations. (My old ’68 Datsun 1600 was known to spin 180 degrees on a slightly damp road if you pushed too hard on the brake pedal.) But, there’s a lot of great safety innovations built into modern vehicles and I’d much prefer my kids to be driving a safer vehicle than I did.

  5. Shouldn’t this post be titled “Crash Avoidance Technologies”. Most NSW drivers don’t seem to need any extra assistance in crashing, they manage that all by themselves.

  6. Tried this out last weekend by taking a Mitsi Outlander for a test drive through Perth rush hour traffic. It’s since moved from my list of interesting gimmicks to something that I loved and would really like to have in my next car if at all possible.

    The Outlander managed to keep a generous 2+ seconds behind the car in front (I kept it on the medium distance setting) and reacted very smoothly to it’s changing speed, even when a car merged between us on the freeway the deceleration was smooth and comfortable.

    Far from finding that it took away from the experience of driving (I mean if you feel like keeping pace with your foot just don’t switch it on) I found it took away the irritation I normally feel driving in a line of traffic that is constantly changing speed. My only problem now is that it’s availability is still pretty limited.

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