What Are Active Safety Features for Cars?


If you’re shopping for any type of new or used car, SUV, truck or van these days and you’re dutifully doing your research to decide what you want, if you’re looking at something new or relatively new, you’re going to hear a lot about active safety features. You’ll also hear about passive safety features too, but not as much as you’ll hear about active safety features. But what are active safety features for cars, do you need them, and are they worth paying extra for? And if you do like the idea of them, which ones should have and why?

Active safety features are computer-controlled electronic vehicle systems that work continually while you’re driving to help prevent accidents. Active safety features range from relatively simple systems such as traction control, electronic stability control and electronic braking systems to advanced driver-assist features that use sensors such as adaptive cruise control, automatic emergency braking and lane departure warning.

What’s the difference between active and passive safety features?

The difference between active and passive safety features is active systems work continually to prevent accidents while passive features are there to mitigate the damage when an unavoidable accident happens and to keep the vehicle occupants as safe as possible.

Passive safety features have been around almost as long as we’ve had cars, but that’s not to say they haven’t advanced and improved over time and they continue to do so. Passive safety features include things like pre-tensioner seat belts, airbags and crumple zones. Passive safety features are designed to reduce the consequences of a vehicle accident on the driver and passengers but they cannot prevent the accident from happening in the first place.

Common active safety features

Which features are common will inevitably change over time. The newest, most advanced features inevitably cost a lot of money when they first emerge and they’re often only found on the most expensive, high-end vehicle to begin with. However, over time they get cheaper to produce and fit and they start to filter their way down to cheaper mass-market vehicles.

Although it’s now hard to believe, even something as obligatory today as airbags started off as a very high-end feature only found in the most expensive luxury sedans. A good example of an active safety feature that’s gone from exclusive to common and now to compulsory in most cases is ABS (Anti-Lock Braking System).

As I write this list of today’s common active safety features, my definition of “common” is where they are regularly standard or available in small, affordable vehicles such as a Chevy Trax or a Ford EcoSport.

Today’s common active safety features include:

  • ABS
  • Lane departure warning
  • Blind-spot monitors
  • Parking sensors
  • Electronic stability control
  • Electronic brakeforce distribution
  • Tire pressure monitors
  • Cross-traffic alert
  • Automatic emergency braking
  • Forward collision alert
  • Auto high-beams

ABS

ABS is an acronym for anti-lock braking system and you’re not going to find a brand-new vehicle these days that doesn’t have it, although the system has only been mandatory for a few years now. ABS works by repeatedly applying and releasing or ‘pumping’ a vehicle’s brakes under heavy braking situations. Sensors on each wheel are used to detect ‘locking,’ which is a wheel stops moving and starts to skid along the surface.

Lane departure warning

Lane departure warning uses sensors that detect your position on the road and an audible alert is sounded when the system detects that the vehicle is veering out of its lane without the turn signal being activated. This feature is often combined with lane-keep assist (some manufacturers have their own proprietary names for it), which is a more advanced system that physically helps to keep the vehicle in its lane without any driver input.

Blind-spot monitors

Blind-spot monitoring systems use a vehicle’s cameras, radar, and/or ultrasonic sensors to detect vehicles in your blind spots, which are areas you can’t see that are next to or behind your car. The simpler systems just give a visual warning such as a light on your wing mirror, but some also give an audible alert too. More advanced systems can provide an additional warning if the turn signal is activated when the system considers that it’s unsafe at that moment to merge or change lanes.

Parking sensors

Parking sensors, or as proximity sensors as they’re sometimes referred to, are extremely useful devices integrated into vehicle bumpers to assist the driver when parking with audible alerts that get faster as you get closer to an object and emit a constant beep when you need to go no further.

Rear parking sensors are increasingly common these days, but front sensors are less common and they’re often an available option or a feature that comes with a higher trim level. You will often get front and rear sensors or just rear sensors on their own but you won’t come across a vehicle with sensors on the front but not at the rear.

Electronic stability control

Electronic stability control works with a vehicle’s ABS system to help prevent a loss of control in bends and sharp turns using emergency steering maneuvers to stabilize a vehicle when it begins to veer from its intended path. It’s an automatic system for helping the driver maintain control of the car during hard steering maneuvers.

Electronic brakeforce distribution

Electronic brakeforce distribution is a subsystem of a vehicle’s anti-lock braking and electronic stability control systems that stabilizes the amount of braking force that’s applied to each wheel of a vehicle. The system works on the premise that the same amount of braking force doesn’t need to be applied to every wheel, so when the vehicle brakes and its weight shifts across the wheels, each wheel isn’t always supporting the same amount of weight. As the name suggests, the system distributes the amount of braking force required as required.

Tire pressure monitors

As the name suggests, tire pressure monitoring systems constantly monitor the pressure in each tire and alerts the driver if any tire is under or overinflated. These systems are now widely available and the more advanced examples tell the driver exactly what the current pressure is in each tire without you having to get out and check them with a gauge. This might not be the sexiest or most advanced safety feature on this list, but I absolutely love them and I’d take tire pressure monitors over a lot of the more intrusive and more advanced safety features that are now available.

Cross-traffic alert

Cross-traffic alert is another system that comes in rear and front versions. Rear cross-traffic alert tells the driver if another vehicle is approaching from either side when the vehicle is in reverse gear and is backing out of somewhere like a parking space or a garage.

Front cross-traffic alert is effectively the same thing but for the front of the vehicle instead of the rear. Front versions are more advanced systems that in some cases are linked to a head-up display. The system alerts the driver if a vehicle they may not be able to see is pulling out on them, such as when approaching a cross junction. Like parking sensors, rear versions are more common and if a vehicle has front cross-traffic alert it will almost certainly also have rear cross-traffic alert too.

Automatic emergency braking

Automatic emergency braking (AEB) is an active safety system that a lot of people believe should be standard on all new vehicles today, but I’m not so keen myself. The system is designed to automatically activate a vehicle’s brakes when a potential collision is detected. This all happens without the driver actually having to touch the brake pedal at all themselves, and while all AEB systems detect vehicles, the more advanced systems can also sense pedestrians and cyclists.

My issue with these systems is they can lull a driver into a false sense of security where they come to rely on the system more and more and on themselves less and less. In my experience so far, these systems are some way away from being 100 percent reliable yet so I prefer to rely on myself to do the braking.

Forward collision alert

Forward Collision Alert probably sounds like it might be the same as forward cross-traffic alert, but it is different. This system has been designed to warn a driver if a potential front-end collision is detected with the vehicle they’re following so they can swiftly take appropriate action. The system can also work as a tailgating alert if it senses that you’re following the vehicle in front far too closely.

Auto high beams

Auto high beams or auto high beam assist as Chevy calls it, is basically a system that dips and raises your headlights without you having to do it yourself. When you’re driving in the dark, a sensor detects the lights of oncoming vehicles and dips your headlights accordingly, and when nothing is oncoming it puts your lights back on high beam for you. These systems also dip your headlights when you drive into a well-lit area such as an urban environment or a gas station at the side of a dark road.

I’ll admit to being extremely skeptical about this feature before I had it and I couldn’t imagine any way it could do the job better than I could myself. I thought that I’d end up being flashed by oncoming cars because the system didn’t dip my headlights as quickly as I would myself. But do you know what? Auto high beams operate my headlights much better and much quicker than I ever could. If you have this feature you really should use it and definitely look out for it when you’re buying your next new car.

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More advanced active safety features

A lot of the more advanced and high-end active safety features – as well as a few of the now common ones too – have come about as a result of the development of autonomous or self-driving vehicles. Although properly driverless cars are a long way from being sold for driving on public roads, automakers are adding a lot of the component parts that go towards making a vehicle autonomous to current cars, trucks and SUVs.

Some of the most advanced active safety features around right now include:

  • Intelligent speed assistance
  • Alcohol interlock devices
  • Drowsiness and attention detection
  • Advanced emergency braking
  • Adaptive cruise control
  • 360 camera systems
  • Rear camera mirror

Intelligent speed assistance

Intelligent speed assistance informs drivers of the speed limit in the current location and, as and when needed, effectively acts as a speed limiter by automatically reducing the speed of the vehicle by limiting the amount of power produced by the engine.

I can see a lot of resistance coming for this one in the US in particular, but also in Europe where it has already been decided that it will soon become a compulsory feature in all new vehicles. In truth, this is less to do with genuine safety and more to do with controlling.

For the moment at least, these systems can be overridden by pressing hard on the accelerator for overtaking. I also believe some of the early incarnations can even be turned off completely. However, the ramifications of these systems eventually being compulsory and it being illegal to remove or hack them to disable them are concerning, to say the least.

Tire pressure monitors

Alcohol interlock devices

Often also called an ignition interlock device or a breath alcohol ignition interlock device, these are fairly self-explanatory systems as they are effectively in-vehicle breathalyzers. When these systems are in place and activated they require that the driver blows into a mouthpiece connected to the device before they can start or continue to operate the vehicle.

My view on these is that they actually ENCOURAGE rather than discourage drunk driving and I think they are a really bad idea. Personally, if I’m going to be driving I do not have a drink at all. However, if you have one of these in your car you may think it’s okay to drive after having as much alcohol as you can get away drinking as long as the system says you are not over the limit. But with the way the western world is going increasingly nanny state on us these days I can see these becoming compulsory one day.

Drowsiness and attention detection

Drowsiness and attention detection systems are designed to assess by various means the driver’s alertness level and issue a warning if it senses that the driver ought to take a break. Some current systems work by monitoring how long someone has been driving, others work by analyzing the way the steering wheel is being operated, and the most advanced systems will use an increasingly varied and complex set of criteria to arrive at a conclusion.

These systems probably have a role to play in safety but you can imagine how annoying they could be if they’re too sensitive or they are malfunctioning.

Adaptive cruise control

Adaptive cruise control is a more advanced version of cruise control that uses a radar system to maintain a constant speed and a safe distance from the vehicle in front. When no vehicle is within a certain distance ahead of you the system will work like normal cruise control to maintain a constant speed set by the driver.

However, when something pulls in front of you or if you catch up with a vehicle ahead the system will reduce your speed automatically to maintain a safe distance from the vehicle in front. If the vehicle speeds up the system will accelerate as appropriate but it will not go above the speed you have set unless you choose to increase it.

360 camera systems

These systems use numerous cameras placed all around a vehicle to produce a 360-degree real-time view of the surrounding area. The 360-degree camera technology works cleverly to combine all the various perspectives from the video cameras located all around the vehicle into one image, typically a top-down view.

These are really great systems and I can’t think of anything negative to say about them whatsoever, well, apart from the fact you only find them on pretty high-end models at the moment. They can also be combined with autonomous parking systems that allow the driver to sit back and let the car park itself, and it’s easy to see that this kind of technology comes straight from the development of driverless vehicles.

Rear camera mirror

Rear camera mirrors are another feature I absolutely love and I can’t wait until they become a lot more common than they are right now. They make particularly good sense in vehicles with restricted views out of small rear windows like the Chevy Camaro. Instead of a regular rearview mirror, the mirror is actually a screen that shows a wide-angle image from the vehicle’s rearview camera.

This will give the driver a much better view of what’s going on behind them, but the downside is they won’t be able to see anything if the camera lens gets covered with dirt. Even so, I’d much prefer a camera mirror to a conventional mirror, even though I don’t have that feature in my current vehicle.

Do you need active safety features?

I’m going to part company with a lot of other automotive writers here because I’m not a huge fan of some active safety features for the reason I stated earlier. If a vehicle is going to be fully autonomous then fair enough, but this halfway house could easily lead to some people relying too heavily on systems that could let them down at some point.

It would be difficult for me to make a case against active safety technology as a whole, but I wouldn’t base my buying decision on whether a vehicle had automatic emergency braking or not. However, I would definitely think twice about buying any vehicle with a lane-keep-assist or lane departure warning system that couldn’t be turned fully off.

I had a Kia Sportage a few years ago that had lane-keep-assist and it drove me mad until I worked out how to turn it off. There’s a road near my house I drove along several times per day and it had cars parked on either side. This meant you had to drive straddling the white line down the middle and the system kept warning me and trying to move me to the side. It was a very happy day for me when I finally gave in and consulted the manual to find out how to turn the annoying feature off.

On the other hand, a lot of people could feel much better about buying a vehicle if it is bristling with active safety tech, so it’s up to you. I would suggest that some of these features only do what you should be doing already as a driver, but that obviously doesn’t apply to things like ABS, EBD and electronic traction control.

Do active safety features bolster residual values?

I cover in another article how some features can enhance a vehicle’s residual value or at least help to maintain it a little better, but most of the time adding features from the options list doesn’t actually help at all.

If you had two identical used cars for sale and one had automatic emergency braking and the other didn’t, it might mean the one with the feature sold a little easier, but I sincerely doubt whether it would justify a higher asking price. If you’re buying a used car and you want to pay extra for some additional active safety tech because you think it will be safer for you and your passengers then go right ahead. But don’t expect spending $3,000 extra on active safety tech to mean your trade-in price will be any more than an identical model without those features.

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Which active safety features should be standard?

I’d say any unobtrusive active safety technology should be standard with all new cars and much of it is. Every car you buy today will have ABS, traction control and similar systems. I’ve noticed that even some very modest vehicles now also come standard with tire pressure monitors. But for me, systems such as automatic emergency braking don’t need to be standard, and even if a vehicle has it you should always be able to turn it off if you don’t want to use it.

I’m going to make an admission here about something that shows I could end up changing my mind eventually and embracing all these features and any future ones that those clever auto engineers come up with.

The first job I got in the retail auto business was as a trainee sales exec and I got a Land Rover LR1 as my company car that had rear parking sensors. I joked at the time that they were only for women who couldn’t parallel park, but how that sexist view changed once I started using them.

I still don’t like parking sensors at the front and I dearly wish I could turn them off on my current SUV. But if there’s one thing that would categorically put me off buying a vehicle today it would be no rear parking sensors. I can do without heated seats, I’m not bothered about a power liftgate, but no rear parking sensors is a deal-breaker for me these days.

Maybe I’ll feel like that about automatic emergency braking and lane-keep-assist one day? I doubt it though.

Sean Cooper

Former retail auto industry professional for almost a decade and an automotive writer and journalist for the last 8 years

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