I’m just wondering if anyone else has had this:

The car, unexpectedly applying its brakes when in ACC. The car is the Mk4 L&K 190 dsg 4x4 estate 

In both cases the car falsely thought it was approaching a hazard/characteristic which did not exist on the road I was travelling on.

Case 1: On a clear straight motorway, the car braked and displayed the message…..” bend in road”

This was when going under a motorway bridge so maybe the car thought it was on the road above which happened to have a bend.

Case 2: On a clear straight section of A road, the car braked with the message….”junction ahead”

It was where a minor road crossed the A road.

So yes it was a junction, but only relative to the minor road not the A road.

In both cases I quickly overrode it, and luckily, no one was close behind, but the implications do not bear thinking about.

If it had only happened on the A road then I’d not be too worried as I rarely use ACC there. But on a motorway, I do, and so this is a big worry.

I’ve called Skoda, and may take the car in. Strange one 🤔

In the first instance, your radar possibly mistakenly identified the bridge abutments as a bend in the road ahead.

In the second, I'd suggest it was operating correctly, as, although only a minor one, there was actually a junction there.

Possibly not an issue on motorways due to more open space to either side and no cross-junctions - but maybe your radar is a little oversensitive.

The ACC system takes account of the steering angle so if on the motorway you are changing lane and the system thinks you could be heading for the bridge abutments it will warn and brake.

Good points but no, the motorway was straight and unobstructed. The bridge was one of the many I had already gone under. The traffic in front had not braked. I don’t know whether the car logged these alleged hazards via its sensors or via its road database.

Every A road has countless examples of where minor roads cross but they are not junctions as far as that A road is concerned. The car wanted to come to a complete stop because it incorrectly thought it was on a minor road, coming to an A road junction, where in fact it was the other way round.

I think this is possibly inaccurate/incorrect mapping data in the car, and the ACC thinking that it needs to make adjustments for road features which don't exist (or aren't as mapped).

Poor-quality map data is the main reason that I've found Travel Assist mode to be virtually unusable, certainly around my local area - there are so many incorrect speed limits on the map for roads in my part of north Wales and Cheshire that it's actually unsafe to use ACC - the car will 'read' a speed limit sign and adjust its speed accordingly, only to have this overridden by incorrect map data a short distance later.

Someone did kindly give me the link a while back for submitting updates to mapped speed limit data, which I tried on a few local roads - it made absolutely no difference, the submitted changes seem to have been completely ignored and remain incorrect.

Have you tried disabling speed limit response and/or road layout response in ACC settings? Worth a try to help narrow down if it is a camera or mapping issue.

I suspect this behaviour is a "feature" of VAG cars. My Mk4 Octy does exactly the same thing - it seems to sometimes incorrectly attribute the speed limit of any parallel roads/roundabouts/bridges that you happen to be passing on the motorway at that time. It's almost as if the nav doesn't know your lateral position on the road.

I did as Ccc1 suggested and turned off the speed limit/road layout ACC settings and it's been fine since then. Basically a case of having to make your "smart" ACC dumb to avoid being rear-ended. It was quite alarming when it first happened to me on a busy M4 just after I got the car.

Map data is really ****e. It's the worst navigation system I've seen in the past few years.

I'm experiencing the same issues. "Bend ahead" on a highway (where there is none) and the car wants to slow down to 40 km/h. Luckily, it's never that dramatic, so you can take over control without any problems, but it's fairly annoying. Consider turning off road layout response. I did that and while sometimes I miss it, overall I'm more satisfied.

I found that for the month I was trialling traffic sign recognition on my 2023 Octavia, I was getting lots of phantom 50 mph warnings popping up (also mainly on M4) even though there were no such signs. Presumably it was remembering where roadworks were. But now the trial has expired, the speed indication on the satnav is correct.

My conclusion is that 'traffic sign recognition' is doing more than just looking for signs. It seems to be accessing some static GPS-based dataset, separate from normal satnav one.

The trial wasn't very effective for picking up variable speed limits on the overhead gantries. It only got about half correct.