Highway Assist (HWA)

Highway Assist (HWA) is a Level 2 advanced driver assistance system engineered for structured roadways such as highways and expressways. Building upon Adaptive Cruise Control (ACC) and Lane Centring Control (LCC), it incorporates stalk-activated automatic lane changing, marking a vital step forward in the evolution of Level 2 driving assistance toward higher levels of autonomy.

Positioning: A Benchmark for Level 2+

Essentially, HWA represents an extension and functional upgrade of Traffic Jam Assist (TJA) into medium-to-high speed driving scenarios. While TJA is tailored for low-speed congestion between 0 and 60 km/h, HWA operates across higher speed bands, typically kicking in from 40 km/h or 60 km/h and extending all the way up to highway speed limits.

Both systems share the same longitudinal and lateral control foundation of ACC and LCC. However, what sets HWA apart is the introduction of active lane-changing capability—the defining hallmark of its leap from standard Level 2 to "Level 2+" status.

Key Features

On top of ACC and LCC, HWA incorporates the following core capabilities:

• Stalk-Activated Automatic Lane Change: Once the driver flicks the indicator stalk, front-side and rear-side radars assess the surrounding traffic. After verifying the target lane is clear with no collision risk, the system completes the lane change automatically without any steering input required from the driver.

• Lane Centring and Departure Correction: Utilizing a front-facing camera to detect lane markings, the system continuously applies steering torque to keep the vehicle centred within its lane, actively intervening if the vehicle begins to drift out inadvertently.

• Driver Monitoring System: The system monitors driver attentiveness in real time and triggers phased alerts if hands are taken off the steering wheel; certain systems allow brief periods of hands-off driving (such as up to two minutes), provided the driver remains fully attentive.

• Low-Speed Faded-Marking Following: In heavy traffic where lane markings are worn or indistinct, the system can track the trajectory of the vehicle ahead to maintain its path.

Hardware Configuration

Relative to entry-level Level 2 systems, HWA demands a more sophisticated sensor suite. A standard HWA setup employs a 5R1V architecture, comprising five millimetre-wave radars (one front forward-facing radar plus four corner radars) and one front camera. This hardware layout is largely identical to TJA, underscoring their shared hardware platform—the true differences lie in activation speed thresholds and lane-change software algorithms.

Distinction from Higher-Tier Systems

HWA, NOH (Navigation on Highway assist), and HWP (Highway Pilot) operate on a progressive hierarchy:

• HWA: Driven by sensor inputs; the driver triggers lane changes via indicator stalk inputs

• NOH: Driven by high-definition mapping and satellite navigation data; the system autonomously executes lane changes as well as highway on- and off-ramp transitions

• HWP: A higher-tier piloted driving system offering comprehensive, full-scenario highway driving capability

It is worth emphasising: HWA remains a driver assistance feature, not a self-driving system. Its performance can be limited by factors such as faded road markings and sharp cornering radiuses. Drivers must stay fully engaged and prepared to resume manual control at all times. Risky driving behaviours like speeding or erratic lane-swapping may trigger an automatic disengagement of the system, requiring the vehicle to be brought to a complete stop before it can be reactivated.