Lane Keeping Assist

We have just replaced our 15 year old VW Touran diesel with a T-Cross 1.0 TSi. This is, as all new cars, fitted with lane keeping assist. I was wondering what would happen if it got confused? Could I, or my wife, fight it and win. Looking at the Bosch variant it either uses the electric power steering, if fitted, or brakes individual wheels using the ESP.

“Lane keeping assist uses a video camera to detect the lane markings ahead of the vehicle and to monitor the vehicle's position in its lane. If the vehicle’s distance to the lane markings falls below a defined minimum, the system steps in. In vehicles with electric power steering, it gently, but noticeably countersteers in order to keep the vehicle in the lane. In vehicles without electric power steering, it achieves the same effect by utilizing the electronic stability program (ESP®) to brake individual wheels.

Drivers can override the function at all times, so they retain control of the vehicle. If they activate the turn signal in order to intentionally change lanes or turn, the system does not intervene.”

I am fairly happy with these various assist systems so long as the appropriate risk assessment and performance level calculations have been carried out, so not designed like the Boing anti stall system.


Some while ago I started a thread on EVs apparently becoming immobilised due to battery or other failures.

The new car has a DSG transmission and the selector lever is locked in Park when the ignition is switched off. It requires 12V to be available to release it, so flat battery and the car is immobilized. Reading deeply in the handbook it can be released with a screwdriver (supplied with the car but buried under the spare wheel) by opening a flap in front of the (conventional) hand brake lever. Who, other than an Aspergers spectrum engineer, would actually look that up?

  • Lane keeping assist is a good idea but is surely dependant on there being legible road markings on the road for the cameras to identify? 

    What happens if the markings are worn out or not maintained? Who would then take responsibility if a car veers out of lane and causes an accident? Thinking

    My neighbours and I have been engaged over the last 6 years in an argument with our local council on the matter of missing carriageway markings along a 2 mile stretch of road exiting the village and out to a major A road. The road is a 60 mph limit road and is the main route out of the village and also acts as the shortcut for a number of villages surrounding us too.  After being resurfaced around 6 years ago, the Council are still refusing to reinstate the carriageway markings along the centre of the road citing some research undertaken along the lines of 'if you remove the carriageway markings on roads drivers will drive slower' 

    So how would a car fitted with Lane Assist stay on the correct side of the road if there are no markings on the road whatsoever? 

  • Your comment links interestingly with this article from E&T,

    New legislation to hold carmakers responsible for self-driving vehicle crashes | E+T Magazine (

    I can see some interesting discussions about the influence of road markings and road signs on the various driver assist/self driving systems Thinking

  • The joys of the modern world!

    Recently I had to go with my fifty year old jump leads in my eleven year old diesel van and jump start a hybrid petrol/electric car that always starts in electric mode, but would not start because the 12 volt battery was discharged. So we put the jump leads on and waited a few minutes, then it started and I followed it to the garage in my van with the jump leads, just in case it "stalled".

    I have also bought myself a new petrol car with various gizmos, including automatic slow speed braking, not something  I can actually be confident enough to try out by driving at something on purpose.

  • Interesting feeling going from a car with lane assist to a car without it.  My own car does not have lane assist and I always seems to stay in my lane but on a few recent works visits across Scotland in several different hire cars were involved.which some had lane assist.

    The steering wheel vibrates on some modles and then tries to get the car back in lane and on others you can just feel the wheel wanting to move slightly.  On long drives on A roads and motorways it really does help espcially if you are unfamiliar with the car and helps to counter act cross winds.

    A few point worth of note.

    Some single tracks in the Isle of Islay and on the Isle of Sky cuased a lot of vibration and movement.  I assume this is to do with the lack of road marking in some areas and I turned it off for some journeys.  Motorway contra flows seems also to upset the system while your lane changes even more so when there are lots of cats eyes that don't line up but settles down when the lane straightens.

    Long term I think lane assist is a good thing in a car, I think it should also be used in conjuction with Blind Spot Assist.  I strongly suggest that Lane assist must be able to be turned off for certain road conditions in the same manner as traction control. 

  • That is interesting legal idea . I can imagine there being very many real life situations confusing a self driving car.
    This one is a roundabout near me - which lanes are going and which stopping ? Ignoring for now the lanes that spiral out...
    Routinely confuses human drivers as well so perhaps its OK for the machine to get it wrong - personally I think the lights need shades or hoods of some sort but there aren't. Just in case you ever drive it, the red light on the right is for traffic joining from the left , not straight on  - that's the green light on the left...


    The lights at the next roundabout along are better though the white paint is a bit wild.


  • Ooh heck. Seconded for hoods, or a set of lights per lane.

    I've had some similar exciting moments from speed limiters (which normally-helpfully overrides the cruise control) causing brakes to slam on for non-existent 20/30mph zones when cruising a dual carriageway. Quite recoverable but something of a surprise to the drivers behind no doubt (to say nothing of any passengers).

    Both map-based and "visual"sign recognition modes are quite capable of being flummoxed, but the visual one is notorious for spotting signs for relating to local lanes running alongside the main road, or for slip roads off it.

    Don't get me wrong, the systems are quite clever and have a lot of utility particularly when tired on long journeys. But that's when they catch you out!

  • I don't like the idea of the lane keeping assist trying to steer. My other half's car has lane departure warning system (just flashes a light and buzzes but doesn't try to do anything else) but it's got it wrong plenty of times - often on motorway roadworks with a mix of original and temporary lane markings partly visible, especially when wet; on narrow winding roads it doesn't seem to fully understand that the position the car is in isn't entirely the same as the view from the front facing camera, and as for situations where driving deliberately close to the edge to allow space for a wide oncoming vehicle, it could be disastrous if it tweaked the steering to the right even for a moment.

    And don't get me going about the automatic sign reading ... the number of times it's missed signs completely ,or even funnier, reported a 30 sign as 80...

       - Andy.

  • I tried it out this afternoon on a straight dual carriageway that was clear of traffic. 

    If you are going fairly fast and start changing lanes without using the turn signal indicators it will turn you back into your lane.

    If you are driving slowly and/or using your turn signal indicators it will not do anything. 

    It feels a bit like kerbing the wheels, but you can just steer through it.

  • Yes that is my experience too. It is only active above a certain speed (about 30mph I think) and nudges rather than forces. Of course if you have your hands on the wheel, no problem. If you indicate, it cancels. It is a little strange at first but you soon get used to it. Doesn't always activate, possibly because it can't detect the edges/lanes so appears to be a little cautious.

    Other systems are looking ahead with the intention of preventing a crash. One pops up a little symbol that you are too close. Another actually slams the brakes on if an obstacle is detected. The first time this happened was a shock. I knew the car ahead was turning off, I was slowing, my foot was over the brake but the car decided a crash was imminent! Another car close behind me would have had a shock.... It's a bit "trigger happy".

  • Ha!

    I have had a funny with this sort of thing in a hire car - cruise control set to full legal (+) on a dual carriageway ,but the forward radar maintained a safe distance to chap in front. And keeps doing so as the traffic slows in a jam as the exit approaches,  and then slower still as we pull off into town. At about this point the cruise control setting is forgotten about.
    After a few mins of following on at 25-30mph the car in front turns off, and the car I'm in takes off like Niki Lauder - presumably trying to re-attain the now highly inappropriate cruise control setting.... A few moments  of ' what the !"£?' and braking before regaining composure.