Traffic Jam Assist (TJA): Understanding This Advanced ADAS Feature

You begin to slowly take your foot off the brake, and the car inches ever so slightly forward. Stop. Again, you think the traffic begins to lighten, you let the car creep. Stop. Aggravated, you throw it into park and wait for more space, only to be reprimanded with angry honks behind you.

Who’d have thought that we’d finally have found a way to escape the antagonizing monotony of traffic? With Traffic Jam Assist (TJA) this advancement, your shop has added responsibility: learn how to service, calibrate, and document any work done related to TJA. .

Read on to learn how TJA functions, how it integrates with other ADAS features, and how to calibrate and document this new feature properly.

How traffic jam assist transforms stop-and-go driving

Traffic Jam Assist operates similarly to Adaptive Cruise Control (ACC). Designed for speeds under 40 mph, TJA uses front-mounted radar and/or camera sensors to detect the speed of vehicles ahead and automatically controls acceleration, braking, and steering. This means that in heavy-traffic scenarios, TJA takes control of steering, accelerating, and braking without driver intervention.

While TJA can fully stop the car, recenter it in the lane, and resume driving when necessary, the driver must maintain attention. If the driver fails to hold the steering wheel for a specific amount of time, TJA will disengage. This design intends to maintain driver focus on overall traffic conditions.

At any time, the driver’s input overrules TJA, meaning that the driver still has autonomy of lane changing and other decisions while TJA is operating.

TJA sensor integration and dependencies

TJA is a finely tuned and highly integrated ADAS feature with many moving parts. This system utilizes front-facing radars, cameras, and other lane marking detection sensors.

Front-mounted radar sensors help the vehicle’s computer determine the speed and distance of the vehicle ahead, whereas camera sensors can identify objects, road signs, and lane markings. Some manufacturers may use side-equipped infrared sensors that can identify lane markings.

The input from each sensor is vital to the proper function of the TJA system. To work as intended, the sensors must be able to measure and identify many variables and thus act accordingly.

TJA vs. other automated driving features 

As TJA is highly integrated and dependent on numerous sensors, it seemingly acts as a coordinated conglomerate of other ADAS features. Let’s compare TJA to other ADAS systems so we have a better idea of how TJA is unique.

Comparing TJA to Adaptive Cruise Control (ACC)

TJA and Adaptive Cruise Control (ACC) are often regarded as two sides of the same coin, yet there are important distinctions to be made. While the main difference is that TJA only functions below 40 mph and ACC at higher speeds, TJA offers a higher level of automation. 

While TJA is operating, the driver does not need to intervene after a stop; the car can control itself completely. When the driver brakes while using ACC, they must manually reengage the ACC system. 

It is also a standard that TJA maintains control of steering, whereas ACC does not always integrate Lane Keep Assist (LKA). TJA can even steer to avoid a collision, while ACC is not equipped with this feature. While these two ADAS features are similar, understanding the key differences is important for your shop when knowing their specific service needs.

The relationship between TJA and Lane Keep Assist (LKA)

TJA and LKA go hand-in-hand, yet are also distinct ADAS features. Typically, LKA utilizes side-mounted radar or camera sensors to identify lane markings and warn the driver if the vehicle begins to veer. If the driver does not heed the warning, LKA can control the car and re-center it in the lane.

TJA integrates with LKA at low speeds by operating in sync. Instead of a warning while the driver is in control, when TJA is operating, LKA can maintain the car in the center of the lane. This is a crucial role in Traffic Jam Assist.

Semi-autonomous vs. fully autonomous operation

It is important to understand that TJA is a Level 2 driver assistance system. This means that it is only semi-autonomous, requiring the driver to keep alert and maintain their hands on the wheel. 

This differs from Level 3 driving systems, in which the car is fully autonomous, not needing the driver to have any input. TJA will turn off if it senses that the driver has taken their hands off the wheel for too long, whereas a fully autonomous vehicle would not require this level of driver contribution.

Repair and calibration implications

Because TJA has so many moving parts, your shop has its hands full when calibrating this important system. Each sensor utilized in the overall TJA system requires unique care and its own calibration.

Front-mounted sensors, such as radars or cameras, rely on specific vehicle geometry to function properly. They both require an accurate reading of a “zero angle” to reference which direction is straight ahead. This zero angle applies both horizontally and vertically, meaning your technicians must pay close attention to these sensors when any work is done that may impact ride height or vehicle geometry, for example, suspension work, wheel alignments, or bumper repair.

Side-mounted sensors also rely on accurate readings of vehicle geometry. Sensor bracket angles, ride heights, and a correct reading of a zero angle are key to accurate sensor function.

These sensors do not work in isolation, and therefore they cannot be calibrated in isolation. Even with correct OEM procedure, your techs must verify that their work has been successfully completed. 

This system complexity can present some challenges for your technicians as the numerous sensors must correctly communicate with the car’s computer, and also properly take control of steering, brakes, and acceleration. Verifying this is a must and requires both static and dynamic testing to ensure the job has been correctly completed.

Industry adoption and market trends

Manufacturers are rushing to get a foothold in a TJA market that’s expected to balloon to a global market size of $7.17 billion by 2028. With this industry-wide adoption of TJA systems, it will be important to note the key differences between manufacturer-specific features. 

While most manufacturers design their TJA to work under 40 mph, Honda has engineered their system to work up to 45 mph and is integrated with their Lane Keeping Assist System (LKAS).

Some manufacturers boast a true hands-off experience, such as Ford’s BlueCruise, while Chevrolet’s Super Cruise detects head and eye positioning, reminding the driver to stay alert.

Other manufacturers that have integrated TJA systems include Mazda, Audi, and Acura, while Tesla and Mercedes are working towards completely autonomous TJA systems.

Traffic Jam Assist is here to stay. With a forecasted compound annual growth rate of 11.5%, it is vital that your shop stays in the know when it comes to servicing these complex systems.

Ensuring proper TJA repair with Revv

This tedious process of identifying, calibrating, and verifying TJA systems can leave your technicians overwhelmed and overworked. It truly is numerous jobs wrapped into a single system. Luckily for you and your technicians, Revv is here to relieve that stress and lighten the workload.

Instead of wasting time with diagnosing, searching for OEM requirements, and documenting by hand, Revv offers a streamlined process powered by AI that meets you in your workflow. This reduces time and eliminates steps for your techs. Revv offers:

• Instant identification of vehicles equipped with TJA and its specific features
• Detailed OEM procedure on how to calibrate each related sensor
• Automatically generated documentation that speeds up insurance claims and prevents liability issues
• Quicker jobs, more vehicle turnover, and increased revenue

TJA systems are complex but important to give adequate care to. Malfunctions could cause thousands in repair costs, and even bodily harm to your customers, situations in which you could be held liable if you fail to properly complete service.

Learn more about how Revv can vastly improve your shop’s TJA calibration experience by setting up a call with one of our experts. Don’t let TJA calibration be rocket science when Revv is here to simplify the process.