Automatic Braking Feature

I agree with you. The lane tracing should keep the car in the middle of the lane, instead, the car will often get almost out of the lane then correct.

 

Is this the Lane Trace Assist (which only works when dynamic radar cruise control is operating and suggested to only use on major highways) or the Lane Departure Assist, used at speeds of over 25 mph? I do find that it takes some getting used to having the car steer itself back toward the center although I have not experienced the oversteering, probably because when I feel the feature I override it with my own steering. I've usually only felt it when I was trying to make it react. I have left it enabled, for now.

 

I don't believe that. TSS 2.0 is quite precise, and I don't expect TSS 3.0 to be worse.

Most drives think that LTA is not centering the car properly but toward one side, but in reality the car is in the center of the lane with LTA and the driver would normally drive closer toward one side without LTA.

 

LTA takes a while to get used to because the whole feeling of collaborative steering is new to you, but once you are used to it, you feel more confident with it than without it.

It is remarkable that Tesla does not have collaborative steering—it is either the car or the driver who can steer but not together. This is one reason why I would never buy a Tesla. Tesla has never improved their automatic driving assistance systems after introduction rather than minor incremental updates. It has been now surpassed by other OEMs. @bwilson4web is still happy with his though.

 

Both, really. Lane Departure Assist is kinda flaky, and either activates at seemingly random moments or doesn't activate at all. Better than nothing though, I suppose.
The issues with Lane Trace Assist are deeper than just "driving off-center", though. With enough of a grade combined with curve on the road you're traversing, it will misjudge what it sees and just casually plow right over the line on one side or the other with gusto, which you will have to actively work to steer against in order to stay in the lane. It's honestly pretty jarring when it happens.

On large highways with shallow grades/curves, it has no real trouble, but on main roads in any kind of terrain with lots of hills, it's actively dangerous, and you really do just have to avoid using it altogether -- but those kinds of roads are just 'highway' enough that people will end up using it anyway. Not everyone is going to have the same awareness or regard toward Toyota's recommendations, and the issue itself is indicative of inherent flaws in the design of LTA itself that I believe could be corrected to make it less of an active risk for such people (especially given that there are third-party aftermarket solutions which do a better job at performing the same task, though they're not compatible with the Prius thanks to the new security mechanisms in place within the steering control system).

Another part of the issue with LTA/LDA is that, depending on the road, sometimes it's just outright bad at keeping track of lines. I've had times when I was driving along and everything was fine, and suddenly it's beeping at me because it lost track of the lines, despite them still being clearly visible and more or less straight, and the car being perfectly between them. It also happens consistently, in the same spots. It's pretty bizarre. I've also found that, when LTA is engaged, it marks both sides' lines as green, as though it's actively tracking them both -- but if you turn off LTA so it marks them white/gray based on presence, it appears as though it's often only able to track one or the other.

At any rate, this thread isn't really about LTA/LDA -- I just felt that it's a good example of a bit of tech they're including in cars that I definitely wouldn't consider up to their usual standards in terms of safety. I think it's fine to have a feature that you can't rely on in all situations, but I don't think it's quite so fine to have a feature that's so half-baked that in the right situation it will try to outright yeet you into oncoming traffic or off the road.

 

Again, I don't know what is going here.

I had both TSS 1.0 and TSS 2.0, and LDA (lane-departure assist) in TSS 1.0 was not great, but LDA in TSS 2.0 was perfected, gluing the car into the lane at tricky forks and ramps even if you are not paying attention to the lane mark. Why would Toyota ruin LDA all of a sudden in TSS 3.0?

 

I find that LTA works well under most driving conditions but is not built for canyon carving or negotiating tight curves like cloverleaf interchanges. Haven’t really driven on very hilly roads yet but I suspect that has its grade change limitations too. By now I’ve used it enough to know its limits and when to take off the ankle weight and start steering her manually.

 

According to the techpaper for 3.0 it should even keep more distance while passing objects (similar to Autopilot in Tesla) - but who knows what works in practice:

https://www.toyota.com/content/dam/toyota/brochures/pdf/tss/CFA_TSS_3.pdf

 

It definitely doesn't do that to the extent that I would prefer, at the very least. I often feel like it's keeping me too close to vehicles I'm driving past on the parkway, and usually I find myself applying some steering force in the opposite direction just in case.

 

I do that in the Outback when passing a truck. Then when I ease up on the wheel, system may strongly over correct, and swerve towards the neighboring lane.

 

I'll update my statement. When we do the cruise control, the car keeps the lane very well. Without cruise control, still with lane tracing on, the car moves from one side to another, will not keep in the middle of the lane.

 

Sounded like their is actually two closely related systems; like with Subarus. The full lane keeping with cruise control, and a lesser lane tracing, which mostly gives alerts and nudges the steering wheel, without it. The thinking for this is likely based upon assumptions of the type of road cruise will be used on or not.

A highway where CC use is likely will tend to have well marked lines for the system to see. On surface streets where CC use isn't likely, even if the lines are properly marked, there is regular intersections where the car can lose sight of them. This leads to more alerts about the system disabling. Plus, you don't want to be fighting the steering wheel if a kid comes out from behind a parked car.

In an Acura, it was possible to use lane keeping without CC. Well, the CC was turned on, but it was possible to turn on the lane keeping without having to set a speed.

 

Correct. LTA(Lane Tracing Assist - keeping the car centered in the lane)) only works with DRCC(Dynamic Radar Cruise Control) engaged. Under manual control, it goes back to just LDA(Lane Departure Alert - keeping you from the edges).

I believe the problems with the LTA system not shifting over enough while passing are because it only works when you are the one passing, and only if both vehicles are traveling in the same direction. Against oncoming traffic, I don't think the system can detect oncoming vehicles accurately and quickly enough for the system to safely shift you over. And I don't think the system is tied into the back parking sensors to sense when a vehicle is coming up behind you. I think it only works if you are approaching a car from behind and the system can tell you're passing due to both vehicle's positioning in relation to the lines, as well as the relatively slow closing speed.


People who are confused about the different TSS 3.0 systems should watch this:

 

> it only works when you are the one passing, and only if both vehicles are traveling in the same direction

This is the exact scenario under which I notice that it doesn't give enough space. Actually I was just on the parkway just yesterday, with LTA engaged, in the left lane passing a car who was in the right lane. It kept me so far to the right in my lane that my sitting position was crossing over the center of the lane, and I had to force it over. That was probably the most severe instance I've noticed so far, but yeah in general it doesn't really seem to make any serious attempt to keep the car centered, nevermind keeping a safe distance with the car in the next lane.