Tested: 'Lane Keeping Assist' system steers Acura ever closer to self-driving cars

I was driving with one finger on the steering wheel. The 2014 Acura RLX that I was barely controlling remained centered in its lane, even around a slight bend in the road, as if guided by an invisible force. I turned to my wife: “Look, no hands!” She smiled—and winced. She wasn’t sharing my appreciation of the Lane Keeping Assist System (LKAS) that makes the Acura RLX one of the most intelligent cars on the road.

The new lane-keeping approach: steering not braking

Lane-keeping isn’t really a new feature: Mercedes-Benz and Infiniti already offer an intervention system that puts you back in the lane. However, these earlier systems corrected you, usually by applying slight side braking.

Along with the 2013 Audi S6, the 2014 Infiniti Q50, and the Mercedes-Benz S550 and C-Class, the 2014 Acura RLX is one of the first cars to use electronically controlled steering that can maintain lane centering. (It’s also available in the 2014 Acura MDX.) Acura’s LKAS uses a camera mounted above the rear-view mirror to watch the lane markings on the road, and adjusts the steering to maintain a center position in the lane. You turn it on by pressing two buttons on the steering wheel, and it operates at highway speeds of 45 to 90 mph. (The Mercedes-Benz S550’s system works at speeds from 0 to 124 mph.)

Acura’s LKAS is a helpful aid for everyday driving at present, and it offers a tantalizing glimpse at how close we’re getting to a car that can steer itself. Although self-driving or autonomous cars remain many years away, many of the basic technologies required for these vehicles have been available for a while. “Lane assist is absolutely another step towards fully autonomous driving,” Ed Kim, vice president of industry analysis at AutoPacific, told TechHive.

The Acura RLX is one of the first cars with a lane-keeping system that guides by steering, not braking.

While Kim calls technology like LKAS a bridge between past tech and future tech, he also cautions that it’s mostly a safety feature. Systems like Acura’s LKAS are designed to supplement your own steering, making gentle nudges that you can always override.

After using it for a little while, however, you feel as though the car might just be ready to take over for you. And let’s admit it: The interesting—and fun—part is doing what you’re not really supposed to do, which is to take your hands off the wheel completely and see how the car will manage on its own.

“Lane-assist technology is a critical element in realizing self-driving capabilities and automated steering in particular,” Thilo Koslowski, vice president and lead automotive analyst at Gartner, told TechHive. “Having the car understand what lane you are in and staying in that lane is a big safety accomplishment and crucial for self-driving.”

Hands on, hands off

The lower-left button on the right side of the steering wheel enables lane keeping.

I tried the Lane Keeping Assist System on the RLX, both with hands on the wheel, and—briefly, carefully—hands off. Conditions varied. I drove during both day and night. I covered ground on major highways, but also ventured on an old country road.

The Acura LKAS needs clear lane markings to work. On a country road where the lane markings are not as pronounced, LKAS will actually turn itself off. And during one test with light rain, the RLX sometimes had trouble seeing markings and veered to the side.

At one point, with my hands on the wheel, I found myself on a stretch of road that narrowed suddenly for a construction zone. As I was driving, the RLX automatically kept me centered—there was little chance I’d brush against a pylon. In another case, a long trailer truck was inching into my lane from the right. The RLX didn’t move to the left, but kept me well centered. Wind was not a problem: Slight gusts simply caused the RLX to correct the centering a bit. On tight curves, the lane-keeping system actually made my own steering easier, keeping me on course.

Hands-off on the highway, I was impressed that the LKAS could handle slight curves on major highways on its own. It actually seemed to work best in this situation, as though the system were rising to the challenge.

I timed how long the Lane Keeping Assist System could maintain the lane for me. In most cases, the car stayed the course for about 15 seconds. The top time was 45 seconds. Even if the LKAS didn't veer, it would inevitably detect that my hands weren’t there to help. With a flashing steering icon and a beep, it would threaten to turn itself off unless I put my hands back on the wheel.

When Acura’s Lane Keeping Assist System is turned on, an image of lane markings appears in the center of the instrument cluster. The lane markings turn white when LKAS is actively operating.

One surprise: I activated the car’s turn signal, and the LKAS tried to keep me centered even as I tried to change lanes. Most lane-keeping systems I’ve used will notice your signal and not resist the lane change. Acura confirmed that its LKAS remains active even if you signal. As noted before, the gentle nudges of the LKAS are very easy to override.

Recently, I tested a 2013 Audi S6 under similar hands-off conditions on the same road. The S6 also maintained proper lane centering for long stretches—in my tests, about 20 seconds or so. But other automakers are more conservative: When I tried the lane-keeping feature on the 2013 Lexus LS, a sensor checked whether my hands were on the wheel and disabled lane-keeping when I wasn’t in direct control.

Who or what will be driving in the future?

Lane-keeping is as close as we’ll get to autonomous cars for a few years. Ford has experimented with a technology called Traffic Jam Assist, announced last summer. Cadillac announced a technology called Super Cruise last year as well. Both automakers have trumpeted tests of these systems, which allow hands-off driving for long stretches, but neither company has provided clear information on when they’d ever be deployed in production cars.

In the meantime, we still have the Lane Keeping Assist System, which accurately maintained its lane centering, even with my hands off the wheel for brief periods. In fact, the lane-keeping system worked so subtly and helpfully that I missed it when it was disabled at lower speeds.

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