ADAS Under The Hood: Rear Cross Traffic Alert

Automobile accidents involving at least one vehicle driving in reverse account for a large share of collisions in the US. Over the past few years, auto manufacturers have increasingly adopted Rear Cross Traffic Alert (RCTA), an Advanced Driver Assistance System (ADAS), to thwart this issue.

A 2018 study found that RCTA reduced overall reversing-related accidents by 22%, a significant figure highlighting that RCTA is here to stay. In fact, market forecasts estimate that RCTA in the US will balloon from $478.9 million in 2024 to $812.3 million by 2030.

With the increasing prevalence of these systems, understanding and correctly servicing these systems is vital for safety, following manufacturer requirements, and as an added bonus, additional revenue.

Read on to find all of the relevant information that your shop will need to know about RCTA systems: how they function, their calibration requirements, potential Rear Cross Traffic Alert malfunctions, and how to equip your shop to offer this service.

What is a Rear Cross Traffic Alert (RCTA) system

Rear Cross Traffic Alert (RCTA) is an Advanced Driver Assistance System (ADAS) that assists the driver in detecting cross traffic when reversing. RCTA aims to make reversing safer and is especially useful in settings with limited visibility, such as a busy parking lot.

RCTA promotes situational awareness, contributing to safer maneuvers, and is integrated with other ADAS features to reduce collisions and increase driver safety.

How does an RCTA system work?

While Rear Cross Traffic Alert systems may vary slightly based on manufacturer, they all perform the basic function of using radar sensors to detect approaching traffic from the rear while the vehicle is in reverse. 

When the car is shifted into reverse, RCTA systems automatically activate. If an oncoming object is detected, the system alerts the driver with audio and visual alerts, such as a small beep and flashing indicator. 

Rear Cross Traffic Alert vs Rear Collision Warning (RCW)

While Rear Cross Traffic Alert (RCTA) and Rear Collision Warning (RCW) are both designed to reduce collisions from the rear, they vary in their specific purpose.

Rear Cross Traffic Alert (RCTA)

• Detects oncoming perpendicular traffic from behind only while in reverse
• Uses radar sensors on the sides of the rear bumper

Rear Collision Warning (RCW)

• Constantly monitors for rear-end collisions from directly behind at all times
• Uses radar, ultrasonic, camera, or Light Detection and Ranging (LIDAR) sensors on the center rear of the car

While it may be easy to confuse these two ADAS features, it is vital to know their difference. These systems require calibration to different sensors and need unique care.

Below, you will find the specific care needed for RCTA systems, including manufacturer-specific RCTA functions, triggers for calibration, and solutions to ensure you properly service your customers.

RCTA differences by manufacturer

Much like other ADAS features, RCTA is treated slightly differently manufacturer by manufacturer. Here are a few examples:

Chevrolet Rear Cross Traffic Alert

Red flashing triangles will appear in the upper-left or upper-right corners of the RearVision Camera display when traffic is detected. Arrows indicate from which side the traffic is coming. Some Chevrolet models also integrate RCTA with Rear Cross Traffic Braking that applies hard braking if the driver does not quickly respond to the RCTA Alert. If the radar sensor(s) are obstructed, not properly cleaned, or not properly calibrated, the system may not perform as expected.

Toyota Rear Cross-Traffic Alert (RCTA)

Toyota integrates its Rear Cross-Traffic Alert (RCTA)  with the Blind Spot Monitor (BSM) system. When in reverse, radar sensors begin to detect approaching rear traffic. Audio alerts and a flashing indicator on the side mirrors warn the driver of traffic, while the multimedia display may show directional arrows. RCTA works when the reversing vehicle is under 5 mph, and when crossing traffic travels between 5 and 18 mph.

Ford Cross Traffic Alert Systems

The RCTA system activates when the vehicle is in reverse and is designed to detect vehicles approaching at high speeds. When traffic is detected, an indicator illuminates in the exterior rear-view mirror, a tone sounds, and a message appears on the information display. If the driver reverses too quickly (greater than 6 mph), the RCTA system can malfunction. 

Volkswagen Rear Traffic Alert

Volkswagen claims they offer a “greater degree of awareness” with a wider than average monitoring area behind the vehicle. If oncoming traffic is detected while the vehicle is in reverse, a chime and warning indicator alert the driver of the direction of the crossing traffic. In some models, the system can also apply automatic braking to help avoid a collision.

While there may be slight nuances between manufacturers, RCTA systems all function virtually the same way. They facilitate radar sensors in the rear bumper and alert drivers when cross traffic is detected while reversing.

How Rear Cross Traffic Alert works with other ADAS features

Rear Cross Traffic Alert systems rarely operate in isolation. Most modern vehicles integrate various ADAS features that promote increased safety. In terms of RCTA, the rear-mounted radar sensors are often shared with:

•  Automatic Emergency Brake (AEB)
• Lane Departure Warning (LDW)
• Blind Spot Monitor (BSM) 

Due to the depth of integration, improper calibration can impact other ADAS features. For example, unsuccessful calibration of a Toyota’s rear radar sensors will have negative impacts on not only the RCTA system, but also the BSM system.

Other manufacturers such as Volkswagen, Hyundai, and GMC pair the feature with Rear Cross Traffic Braking. This enhancement aids the driver who does not respond quickly enough to the warnings by automatically applying the brakes to avoid a collision. 

What Does This Mean for Your Shop

Because of the degree these ADAS features are integrated, improper calibration of just one component can cause a chain reaction that compromises a whole network of ADAS features. 

You and your technicians must know which systems share which sensors, when to calibrate these sensors, and how to follow the correct OEM procedure for calibrating them.

This avoids any chance of being held liable for RCTA malfunction or failure of the entire ADAS system of the car you serviced. However, the correct procedure will ensure you have returning customers for years to come. 

Common calibrations needed for RCTA systems

If service is needed on the rear bumper due to a collision or even cosmetic work, proper calibration is critical to ensure the performance of the system is not compromised.

RCTA radar sensors are delicate and require precise calibration. Here are a few things to consider:

• Specific height and angle measurements of the sensors are vital to maintain to ensure accuracy
• RCTA systems are typically integrated with other ADAS sensor points that need to work in sync
• The bracket that holds the sensor also needs to be correctly adjusted

To ensure the RCTA system is working properly, it is important to note the triggers for RCTA calibration. These may not seem obvious, so let’s look at some considerations that warrant calibration. 

Common calibration triggers

While it’s obvious that bumper repair and replacement require RCTA calibration, other routine services impact these systems.

There are static and dynamic RCTA calibration processes that follow manufacturer-specific procedures. Your shop should thoroughly document and perform quality control checks before the car leaves the shop.

Collision-related Triggers

Other than fender benders, other collisions that impact the geometry of the vehicle, wheel alignment, or height of the vehicle may require RCTA sensor calibration.

Why?

Think about this: collision-related repairs to the suspension system, wheels, or a service that changes the weight of the car can alter the height and angles of the RCTA sensors.

Even a change in ride height or load balance due to heavier wheels or new parts can affect the sensor performance.

Play it safe and ensure your shop calibrates RCTA or any other ADAS feature with Revv’s ADAS calibration checklist.

Non-collision triggers

Some services that warrant RCTA sensor calibration aren’t obvious but still warrant consideration:

• Rear bumper removal and reinstallation
• Suspension modifications
• Wheel alignments are tire changes

It is important to note that minor services can trigger RCTA sensor calibration, even when no service to the rear bumper is completed. Overlooking a required calibration is not worth the risk to your shop or customers.

The Future of RCTA Systems

While only 38% of new cars in 2015 were equipped with RCTA sensors, the total number of ADAS-equipped cars has continued to climb. By 2021, A 2018 study found that RCTA reduced overall reversing-related accidents by 22%, a significant figure highlighting that RCTA is here to stay. In fact, market forecasts estimate that RCTA in the US will balloon from $478.9 million in 2024 to $812.3 million by 2030. were equipped with rear radar sensors. This number is expected to rise to 60% by 2026, bringing with it a surge in demand for accurate ADAS calibrationA 2018 study found that RCTA reduced overall reversing-related accidents by 22%, a significant figure highlighting that RCTA is here to stay. In fact, market forecasts estimate that RCTA in the US will balloon from $478.9 million in 2024 to $812.3 million by 2030.

RCTA systems and related features are becoming the norm and not just a luxury. Therefore, your shop must be prepared to address the challenges and opportunities that this presents. 

Instead of spending valuable hours searching endlessly for OEM requirements, Revv ADAS has already done this research for you. With Revv ADAS, you can instantly get:

• Instant identification of required calibrations
• Detailed OEM procedures 
• Comprehensive documentation tools
• Integrations with existing shop systems

Since Revv has already done the heavy lifting, your shop can focus on calibrating with confidence and getting the job done right the first time.

Are you looking to enhance your RCTA calibration process? Set up a call with our team and see how Revv ADAS can improve your shop by capturing more revenue and keeping your customers safe.