Bumpy track at COTA: how serious is the problem?

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wesley123
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Joined: 23 Feb 2008, 17:55

Re: Bumpy track at COTA: how serious is the problem?

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El Scorchio wrote:
27 Oct 2021, 13:26
Did the bumps cause many accidents or damage to cars/DNFs?

Only the Alpines and Gasly didn't finish the race, so perhaps there was a weakness in the Alpine car that the track revealed, (so if their cars aren't well equipped enough to survive a track then it's on them rather than the track) but I wouldn't say it was a problem for the 2021 cars at all. Had you had 6-8 cars minimum all breaking because of the track then you'd have to look into it a bit more but ultimately it's on the teams trading off strength for speed. The could absolutely build a car to easily survive any track but it wouldn't be as fast. All about risk management.

For 2022, the teams need to make sure they engineer the cars and components well enough to take what all the tracks throw at them, including COTA.
You could add the Mercedes' to the list, as they had to raise their ride height(and subsequently had to slow themselves down) because of the bumps.
"Bite my shiny metal ass" - Bender

Edax
47
Joined: 08 Apr 2014, 22:47

Re: Bumpy track at COTA: how serious is the problem?

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tdshimo wrote:
28 Oct 2021, 23:32

<snip>
Edax wrote:
27 Oct 2021, 20:34
But I think COTA is a bit too much. The problem is not the severity of the isolated bumps, but that they seem to form in resonance structures. I don’t think getting over them fast is a sign of skill, more of car characteristics and a bit of luck. So if something is a risk for the drivers / cars and not a promotor of driving skill, it probably doesn’t belong on a track.
Yes, this is at the crux of my argument: that COTA's bumps are uniquely bad/dangerous, because of the nature of the bumps themselves, and the cars' overall design formula. It's how big the bumps are, combined with the rate they hit the cars at speed, and then, the sheer number of them. The "resonance structures" are absolutely something I was looking for, wondering if one car would have the a natural frequency align and hit a bad harmonic and *really* get crossed-up. In the end, I determined that the cars would only hit that harmonic if they were going much, much faster... but then I started thinking about the 2022 cars' length and tire sidewalls, so the question remains open (perhaps). And haha on digging potholes in Montreal. Does it need any more character than it already has :) ?

Thanks, all, for your perspective!
I am not sure about asphalt and cars, but with bikes we have this thing called braking bumps. If a track is getting worn out you get these washboard structures in the braking zones formed by many bikers braking in that area. Actually it is not really bumps but it is a succession of depressions since every bike bounces with similar frequency and where the rear wheel lands it starts producing holes.

These are pretty unpredictable when they get worse. If your bike falls out of the “rhythm” of the bumps it can produce some surprisingly hard hits.

Some of the footage of COTA reminds me of that effect. I understood that the main issue is the is the soft subsurface, but seeing how violently these cars react I wonder whether the cars actually play a role in producing those bumps. If so it could be that the frequency is naturally matched.

PhillipM
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Joined: 16 May 2011, 15:18
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Re: Bumpy track at COTA: how serious is the problem?

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F1 cars actually make those ripples a lot on tracks, part of the reason MotoGP stopped using the same tracks was the sheer force the F1 cars generate under braking puts ripples in the tarmac and makes it a nightmare for bikers.

hairy_scotsman
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Joined: 13 Nov 2010, 22:47

Re: Bumpy track at COTA: how serious is the problem?

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tdshimo wrote:
26 Oct 2021, 23:11
My view is that the bumps at COTA, particularly those in the esses complex into T6, and T10, are a serious problem that needs to be addressed before racing there again. I think it's a major safety issue (to say nothing of DNFs), one that will only get worse as time passes, and will be exacerbated by the dimensions of the 2022 cars. I'm in a debate with others who disagree. So, I thought I'd come here for a more reasoned discussion of the technical elements, and ask: how serious is the problem? Am I exaggerating the issue? Am I missing something in my reasoning?

My argument, in bullet points:
...
Given this, I think COTA's bumps are a big - and worsening - problem, and they need to be fixed before F1 races there in 2022. But am I exaggerating the problem? Am I wrong on my points? Am I missing something? ("Unless I'm very much mistaken, I am very much mistaken.")
I've been away from the forum for some time, but with the USGP at COTA coming up soon, I thought I'd bump this thread.

No, you are not exaggerating the issue. The bumps are a big problem at COTA. The track constantly changes, not just through normal settling, but because of the kind of soil upon which it sits. COTA has done some superficial work on it over the years, but no actual serious repair efforts. The most recent MotoGP outing there in April was a disaster, with riders falling 69 times during the weekend, and renewed calls for COTA to fix the surface.

It's a bit more complex of a problem than mere settling, and it's not because of F1 braking, as some have suggested, because we see it throughout the track, not just in braking zones. For anyone who's curious about how these conditions came about at COTA, here's what I posted in 2021 that explains what's happening out there. Sorry, it's rather long, but there's no quick way to explain it.
Full disclosure: I'm not an engineer, but over time I’ve gathered this info from several engineers, construction personnel, and others who were involved in the design, construction, and later the maintenance of the facility ... and one track design and repair specialist who is considered to be on the cutting edge of this field. I’m sure some of you have seen his recent work. I first posted this years ago, and we've seen it validated ever since.

"Yes, it's bumpy af, even after they resurfaced 40% of the circuit in 2019-20. The soil is constantly shifting and heaving, laterally and vertically.

The roads all around the circuit go through the same problems. They're like rollercoasters. The county comes out and levels & resurfaces them every few years, but within a few months they're crazy rollercoasters again. Hell, the utility poles in the area won't even stay vertical and have to be re-installed every few years. They install them nice and plumb, but in a year or two they need to be reset because they're leaning badly. They replace them over and over.

COTA Blvd is a great example, too. It was billiard table smooth in 2012 when it was built. It quickly became so bumpy that you can't drive even close to the speed limit on it without catching air in several places. These bumps are not because of F1 downforce. There are no F1 cars driving out there.

Short version: COTA is very bumpy at racing speeds, especially along the east side. It’s cracking/coming apart, and they aren't doing anything serious to fix the underlying problem.

Long version: The ground is not very stable (putting it kindly). Really, it just never stops moving. The black clay around and under COTA is extremely porous and expansive, expanding like a sponge in wet weather and shrinking in dry, hot weather. When it expands, it heaves, moving vertically and laterally. When it shrinks, it moves again and cracks.

Remember a couple of years ago when Jennie Gow reported that the teams take scans of the track on every visit, and it had moved as much as 1.5 meters in places just since the previous GP there? Think about that for a second. Holy crap. That led to the all-night bump grinding ops on both Friday and Saturday nights of the GP weekend. Seriously, after FP2 and after Qualifying? Wtf COTA? There have been other bump grinding ops done prior to that as well. That helps only marginally, and it thins & weakens the track surface, accelerating the appearance of new bumps & cracks in the future.

Here's the deal, in a nutshell. Without PROPER repairs, unlike many other tracks COTA will never get to a point where it's 'finished settling' and then be relatively stable. This isn't normal settling that can be remedied by repaving every few years until the ground finally stops settling, as at other circuits. There are massive problems with shifting soil/clay there, which was known even before they took the first core samples. The soil in that area basically never stops moving. COTA's track surface is not going to eventually settle and be stable going forward.

The engineers knew about the dynamic soil conditions and put an engineering solution in place to limit the issues. They dug down as much as 20 feet in places and laid an impermeable polymer barrier, then refilled it all with prescribed, imported road base aggregates, then paved on top of that, in a highly-specialized process that used imported, high-precision paving equipment.

The track is built along the side of a hill. A drainage solution was designed to divert rain runoff down the hill - around and under the track and under the water barrier. This way, the engineers sought to create an isolated 'tube' on which the track would rest and which would be made more stable than the surrounding soil by controlling the water content inside it .

The robust drainage system they designed was a critical component of the system. I’ve been told by multiple people involved that COTA brass canceled periodic maintenance of the drainage system, to save money. Then when big rain events predictably occurred in 2015, the unmaintained drainage system was overwhelmed. Water is always going to find a way downhill, no matter what, so it ran across, under, and even through the now-damaged subsurface barrier ‘tube’.

The water moving inside the 'tube' weakened the track base and caused subsidence. That created bumps and cracks in the surface. You can see evidence of this during any significant rain at COTA, as water weeps up from the track base (where it’s not even supposed to be) and out through cracks in the track surface (which also allow water into the substrate, and that’s very bad).

I've taken photos the last few years of water weeping up from under the asphalt, through cracks in the track. Last night, I was texted another such photo by a buddy who was out there yesterday. The photo shows water weeping up & out through cracks in the asphalt at one of the problem areas, between turns 9 and 10, and on the exit of 10. The last rain out there was over a week ago and water was still weeping out onto the track yesterday.

That area is one of the segments that was resurfaced in January 2020. Other areas where we've noticed such weeping are downhill of turn 1, all along the esses, at turn 10, around turn 11, along the back straight, and around turns 17-20.

In January 2020, they did some work on the deteriorating track surface. A lot of people think they resurfaced the whole thing, but they actually only resurfaced about 40% of the track, inexplicably ignoring some of the roughest areas (as noted by Tony Kanaan during IndyCar 'spring training). It's still very bumpy along the east side of the circuit (T2-11).

Edited for typos and clarity.

Oh, and the bumps and cracks are only part of the problem. After the latest round of bump grinding, COTA will have large areas that have just been ground and will have a different texture and roughness compared to other areas. On top of that, the two recent stints of resurfacing have left COTA with 3 different kinds and ages of surfaces. The MotoGP riders talked about problems from the constantly changing grip levels from one section to the next. So when F1 gets there, there will be 3 different surfaces, likely with portions of all three having been ground down.
Last edited by hairy_scotsman on 03 Oct 2023, 08:53, edited 4 times in total.
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hairy_scotsman
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Joined: 13 Nov 2010, 22:47

Re: Bumpy track at COTA: how serious is the problem?

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The engineers' soil mitigation plan was very clever imho. It worked very well and kept the track very smooth until 2015, when poor or nonexistent maintenance led to failure of the drainage system that's a key component of the soil mitigation solution. Now, the drainage system needs to be repaired to help stabilize the track's substrate, but in short that's very expensive and is not happening, so the cheaper, superficial fixes (patchwork grinding and lower-grade repaving only portions of the track) only last months rather than years.

They resurfaced about 40% of the track in January 2020, followed by the reappearance of bumps and weeping in the track surface just a few months later. Then they did about 40% again in early 2022 (a different 40% of the track, with some overlap on the previous 2020 resurfacing). That was only done because MotoGP (Dorna and the riders) said in October 2021 that the track was unsafe and COTA had to resurface it or they wouldn't return to COTA in 2022. Epstein asked them what was the minimum they'd accept. They replied that the whole track needs meaningful repair, but the minimum acceptable resurfacing would be T2-10. They got the minimum.

Remember when I told you about the highly specialized and precise paving operation that was done for the initial paving at COTA? Specialized, hand-picked imported materials, very precise machinery, a detailed layering process overseen by a pavement specialist chosen by Tilke, etc. They haven't bothered with any of that since then, using local paving crews and equipment, with common materials and techniques and no supervision by a racing pavement specialist. That's probably one reason we saw a recently re-surfaced area of the track surface actually breaking up during this year's MotoGP weekend.

T10 was the first turn to be resurfaced, by itself in late 2019 and then again during the first 40% resurfacing just a couple of months later in early 2020. It was also resurfaced again in the second 40% resurfacing in 2022. It's been resurfaced 3 times that I'm aware of, but it still has problems on the apex. Some of the resurfaced areas were ground and resurfaced multiple times, as the bumps kept reappearing within a month or two. T10 is one of the areas where we see the most weeping in the days after rain showers.

In October 2021 the dangerous T10 problems were still a major concern for the MotoGP riders. Fast forward to 2022 ... more complaints on MotoGP weekend, leading to their demand that the track be resurfaced. Then this past April 2023, the MotoGP riders yet again talked at length about the continuing track problems throughout a crash-filled weekend that culminated in 10 crashes in the GP alone, with riders crashing out of the race in 9 of them. There were 69 falls across all classes & all 3 days. Bad bumps. Track actually breaking up in places, etc. Crazy.

Many of the problems we're seeing now at COTA are in areas that have already been resurfaced, most notably the mess at T9, T11, T12, T10, T2, the back straight, the front straight, the T1 braking zone,T18-19, and more. Some of the most recently repaved areas have already had to be ground again, and there are now at least 5 or 6 different ages and types of asphalt on the racing surface as a result of the low-bid, piecemeal approach being taken to deal with the issues.

They claimed at the time of the different partial resurfacing ops that they were going to address the underlying drainage system deficiencies that are a big part of the problem. True to form for COTA, they ignored the drainage system and, as we predicted, the newly-resurfaced areas soon had big new bumps and cracking problems (which are actually just continuations of the same problems they've always had and have never addressed in any serious way). They ended up resurfacing some of those newly-paved areas once and even twice more in the following months, because the bumps & cracks kept coming back so quickly.

The track is a shambles. Incredibly bumpy, cracking up, and just falling apart at T12 and 11. The BT Sport guys in April pretty much couldn't stop talking about how bad it was. They said that if you walked out to your driveway and saw it in Turn 12's condition, "you'd find it appalling".

I think there were 15+ MotoGP riders down just at Turn 12 this year ... and 10 crashes in the MotoGP race is just crazy. Then there's the suspicion of the bumps causing numerous bikes to shut off and causing the ride-height issues that caused some crashes. What I also found interesting was the number of incidents at multiple different places on the circuit where the riders said they were doing everything normally and wham, front end just washed out, or the back end uncharacteristically broke loose suddenly, etc, and the riders were at a complete loss to explain what happened. Usually they know, and aren't too shy to say what it was.

In F1, the bumps have caused retirements due to broken suspensions (Vettel), electronic failures both Williams iirc, in different races, the Alpines recently, the Mercs, etc.

The track ownership has the money to repair the track properly, but despite having received more than $350 Million from the State of Texas subsidy so far, they're not interested in a proper repair of the track. They just keep rolling out the same old half-assed, piecemeal approach with low-bid local contractors, and keep having the same problems, over, and over. They aren't racing people, and as weird as it sounds, the quality of the racing surface is the absolute lowest priority at COTA.

Tavo's layout is awesome, but the track needs a lot of work and then a full resurfacing. Sadly, all the current management ever does is grind some bumps and do partial resurfacing, which leads to what we have now - a complete mess. I have no doubt that Tavo would want the track to feature the best surface in racing, but to the current idiots running the COTA show, the track surface is the absolute lowest priority.

The simple truth is that COTA boss Bobby Epstein will never do anything more than the absolute minimum to the track that he has to do to keep F1 and MotoGP coming back.

Edited for typos & clarity.
Last edited by hairy_scotsman on 03 Oct 2023, 08:55, edited 5 times in total.
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hairy_scotsman
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Joined: 13 Nov 2010, 22:47

Re: Bumpy track at COTA: how serious is the problem?

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tdshimo wrote:
28 Oct 2021, 23:32
I also remember, in 2012 standing with tickets in hand, two months before the race, praying that the FIA inspection would succeed... and then, praying that Tavo Hellmund would actually finish the facility in time for the race. Dude pulled it off, but it seemed like only just.
The reason the completion of the circuit came down to the wire the way it did is that construction came to a screeching halt after Epstein stole the F1 race rights from Hellmund and booted him from his own project. In short, it led to a lawsuit, and problems with Bernie. Hellmund was out months before the track was completed. Epstein basically took away the project to which Hellmund had dedicated a large financial investment and more than a decade of his life. Hellmund sued and won an undisclosed settlement. I've been told it was substantial, but I'll bet Hellmund would rather have been running the track all this time, and hates the sad state it's been allowed to fall into. It was his baby, and he's an ex-racing driver who has relationships all over the sport, and has race promoting in his blood.

Yes, this is at the crux of my argument: that COTA's bumps are uniquely bad/dangerous, because of the nature of the bumps themselves, and the cars' overall design formula. It's how big the bumps are, combined with the rate they hit the cars at speed, and then, the sheer number of them. The "resonance structures" are absolutely something I was looking for, wondering if one car would have the a natural frequency align and hit a bad harmonic and *really* get crossed-up. In the end, I determined that the cars would only hit that harmonic if they were going much, much faster... but then I started thinking about the 2022 cars' length and tire sidewalls, so the question remains open (perhaps). And haha on digging potholes in Montreal. Does it need any more character than it already has :) ?
The harmonics are a big deal for MotoGP, causing 'head shake' along the straights. The big bumps, which are scattered all around the track and change from season to season, are a big problem both for the bikes and the cars. For example there's the big bump between 9 and 10. In recent years, you can see the cars going off track, outside the line to avoid it. It was so bad that race control allowed them to exceed track limits there because that was the least severe route. I.E. staying on track was too jarring, with the cars completely bottoming out across the bump even outside the line. The sound of it was sickening if you were there. An extremely loud smack followed by the cars hitting the rev limiter because of the loss of traction caused by bottoming out.

The big bumps cause some big problems for the bikes as well, with the bikes' power management electronics sensing the rear wheel bouncing off the ground and as a result cutting power at top speeds on the straight. Quite disconcerting at best, and quite dangerous.
Last edited by hairy_scotsman on 03 Oct 2023, 08:39, edited 4 times in total.
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hairy_scotsman
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Joined: 13 Nov 2010, 22:47

Re: Bumpy track at COTA: how serious is the problem?

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noname wrote:
29 Oct 2021, 08:56
COTA is used not only by F1. MotoGP is racing there as well, and MotoGP riders were very vocal of COTA's shortcomings. Even track boss, Bobby Epstein, admitted bumps are an issue for bikes.
That's a nice way of saying it. On more than one occasion, he essentially said it's not a big deal (as if he would have even the slightest clue what's a big deal to a racer), and told them to 'shut up and race'.
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hairy_scotsman
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Joined: 13 Nov 2010, 22:47

Re: Bumpy track at COTA: how serious is the problem?

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basti313 wrote:
29 Oct 2021, 14:05
SiLo wrote:
29 Oct 2021, 10:29
I think the bumps are extreme, and should be remedied, but only the major ones. Seeing cars have stress failures or even retire is not what I want to see, as much as these teams are meant to be the best of the best.
Well, if you want to see bullet proof go to Indy car. They have no issues since the big bump at T10 was repaved. This was the only safety issue.
The big-ass bump on the apex and beyond the apex of 10 has been repaved at least 3 times in just 11 years ... and it's still there. That should tell us everything we need to know about how seriously COTA takes the 'repairs' they've done. And T10 is really not the only safety issue.
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