Does Adaptive Cruise Control Work in Stop-and-Go Traffic?

Adaptive cruise control (ACC) is part of the Advanced Driver Assistance Systems (ADAS) that improve driver safety and comfort while on the road. And as the name implies, the system maintains a set speed and distance to the car that’s directly ahead. 

Maintaining a set speed is possible at highway speeds as there’s less deceleration and acceleration. 

So, you may be wondering if the same can work in stop-and-go traffic. 

Adaptive cruise control (ACC) does work in stop-and-go traffic because it uses sensors to detect the positioning and movement of the car ahead. If the lead car stops, the ACC will bring your car to a complete stop. If it starts moving, your car will automatically follow and match its pace without having you press the gas pedal. 

It’ll then maintain a safe distance between the two cars while accelerating or decelerating to match the speed of the lead car. 

If you’ve been wondering how the ACC works in stop-and-go traffic, you’re in the right place. 

Today’s article looks at ACC systems in stop-and-go traffic, times when you should avoid it, and how it works in a manual transmission.

How Does Adaptive Cruise Control Work in Stop-and-Go Traffic?

Unlike the traditional cruise control that keeps a car at a constant cruising speed, you can use the adaptive cruise control in stop-and-go traffic. Here’s how it works. 

Let’s say that the road ahead is clear of obstacles or other vehicles and you’re cruising at a set speed. If you come up to slow traffic, your ACC will detect the presence of slow-moving vehicles in your lane and apply automatic braking to ensure that you don’t rear-end the car ahead. 

If the traffic isn’t stationary and is moving every one or two seconds, your ACC will stop your car temporarily and follow the lead car once it starts moving without needing human effort. And hence the name stop-and-go assist. 

Your car will emulate the lead car’s braking and acceleration for the entire duration while keeping a preset gap distance constant. 

However, the stop-and-go feature can only work if your car doesn’t come to a standstill for longer than three seconds in built-up areas and 30 seconds on the motorways (this may vary depending on the manufacturer). 

The adaptive cruise control will deactivate for more extended standstill periods, and you will need to press the resume button to reactivate the system. 

Manually reactivating the system ensures that you’re still paying attention and are fully aware of the surrounding traffic flow. 

You can also pair the adaptive cruise control with a stop and go feature and a lane-centering assist technology to prevent your vehicle from drifting out of your lane while in traffic. 

Lane centering technology utilizes a camera to identify lane markings on the road and provide minor wheel corrections to keep your car in its lane. It’s a feature that helps drivers who might lose concentration when the traffic is too slow or when cruising at highway speeds. 

When Does Adaptive Cruise Control With the Stop and Go Feature Fail?

As much as adaptive cruise control is an excellent driver-assist feature, we’re still lagging in terms of appreciating how important it is to many drivers. 

A reason is that you’ll need to pair your ACC system with other driver-assist technologies such as lane centering assist and front collision avoidance systems to maximize the technology. 

Additionally, below are situations when adaptive cruise control may fail.

Offset Cars

The ACC system may fail to detect a car that’s offset in your lane. It can be because it wants to shift out or into your lane. Such a vehicle that’s out of line will cause your car to detect an opening ahead, accelerate, but end up breaking on, realizing that there’s part of the car still in your lane. 

ACC systems may struggle with offset cars, often resulting in the jerky movement you’ll often see in traffic jams. 

Driving on Hilly Grounds

The ACC is different from the standard cruise control as it detects and responds to cars in your lane. On steep roads, your car’s ACC radar may fail to detect a car that’s just past the crest and cruising downhill on the other side. 

The result is that your car will assume that the lane is clear, and it may start accelerating. If you’re in slow traffic in an area with steep hills, turn off your cruise control.

Driving on Winding Roads

Adaptive cruise control sensors detect a vehicle that’s directly ahead of you. On winding roads, depending on the curve and the distance to the car ahead, a lead car will drive through the curve sometime before you do. In such a case, your car may decelerate to improve its cornering stability. 

Additionally, your radar may fail to detect the offset in the lead car’s positioning while cornering. Turn off your adaptive cruise control to avoid unnecessary acceleration and deceleration when taking sharp corners. 

Stationary Cars

A massive limitation of adaptive cruise control is that it may fail to detect a stationary object that’s blocking your lane. The system is more suited to detecting moving objects, and some struggle to detect slow-moving cars. 

In most cases, other advanced driver assistance systems such as front collision avoidance systems (CAS) will kick in and prevent you from rear-ending the vehicle ahead. Actually, radar-based ACC systems pick up moving objects but struggle to detect stationary ones due to their low resolution. 

Furthermore, emergency braking systems work best at lower speeds. However, if you’re cruising at 75 miles per hour and you suddenly notice that there’s an obstacle on the road, the 

ACC will warn you to apply brakes but may fail to brake in time. It’s therefore imperative to be attentive while your ACC system is activated, as taking evasive action is better than hard braking. 

Pedestrians, Cyclists, or Motorcycles 

Adaptive cruise control systems may also fail to spot pedestrians, cross-traffic, red traffic lights, and approaching traffic. Consult with your car’s manufacturer to ensure if it has additional ADAS features that may aid in overcoming these radar-based ACC shortcomings. 

Does Adaptive Cruise Control in Manual Transmission Work in Stop-and-Go Traffic?

Unlike an automatic transmission, manual transmission cars don’t support the low-speed follow feature that suits ACC-equipped cars in low-speed traffic. To drive a manual transmission car smoothly requires manual shifting of gears. 

You can only drive in low gears and shift up as the traffic opens up and your car begins accelerating in low-speed traffic. Therefore, since you’ll have to press the clutch pedal and shift the gears constantly, a stop-and-go or low-speed follow feature doesn’t suit manual transmission cars.   

Final remarks

Adaptive cruise control doesn’t substitute but complements your driving. As much as your vehicle can cruise while using the lead car as a guide, it would help if you were fully attentive while on the road. 

Driver-assist technology is a safety feature that can fail; hence you shouldn’t allow your car to cruise without your attention. 

Furthermore, if you’re driving a manual transmission car, the ACC will automatically deactivate itself in low-speed traffic. 

You still have to shift gears, and failure to match your car speed with an appropriate gear will stall it.