Challenge Questions

Concur with stevem. Using Torricelli's Equation, one can solve for the deceleration from the first scenario. Using Torricelli's equation again, one can solve for the distance using the deceleration from the first scenario. Assuming constant braking between the two scenarios, no reaction time and no brake fade this will give us a minimum distance (ideal case). The resulting distance is 175.8 foot which is greater than 150 foot. If the traffic light has been timed for the road speed limit, the driver is speeding.

Again, assuming an ideal case, one's speed would have to be below 69.3 mph to stop in 150 foot.

".....would you stop or get a speeding ticket...."

Better add to that.... have a crash!!

That would be a coefficient for friction of at least 1.1, so the first distance must have been measured from when the brakes were actually applied. SteveM is right - you would overshoot by at least 26-ft (at what point do old Camaro brakes fade??).

As to personal consequences, that depends. If the other road was clear and someone with similarly bad habits accelerated when they saw the lights change, you could both be badly hurt. If you avoid accident but are caught, you should be taken to court for dangerous driving; if there was a speed limit below 75 mph on that section of road that would be a subsidiary offence (names etc. of offences may vary).

75 MPH = 110 FPS (feet per second)

Reaction time = 1.5 second (The state of Oregon says it varies from .75 to 2 seconds)

No way you can stop in time.

A speeding ticket would depend on the speed limit.

I've seen 70 mph on many an interstate, but where can you drive 75?

In the UK, the Highway code doesn't seem to apply to many motorcycles....

Or BMW drivers, come to think of it...

... or "White Van" drivers ...

I suppose if the sat. nav. had told him to put his head in a fire.....

http://uk.news.yahoo.com/5/20090325/tuk-driver-led-to-100ft-cliff-edge-by-sa-45dbed5.html

75 in Colorado . . . but you would not encounter a traffic light!

Last time I was through there, Interstate 70 in eastern Colorado, the speed limit was 75. :)

All states I have been in East of the pacific coast states aka Idaho, Wyoming, Utah, Colorado, New Mexico, Arizona. Not sure about Nevada. It has been many years since I have been to that state.

Bill

Texas. -- JHF

Actually, there may be a bit more to it than simple braking.

In the first instance of a 'normal' stop from a moderate speed (40 mph), the driver applies the brake and waits to engage the clutch only as the car comes to a stop, assuming the car has a manual transmission. If the car had an automatic (yeah, there might be some guys who'd drive a Camaro with a automatic) the drivetrain remains engaged as the transmission downshifts during the braking. In either case, no (or very little) dynamic braking is used.

In the second instance of a 'panic' stop from a high speed (75 mph), a smart driver could quickly downshift to 3rd or 2nd gear while braking, making the engine 'rev' and absorb some of the kinetic energy, again assuming the car had a manual transmission. Or, if the car had an automatic transmission, the selector could be shoved into 3rd or 2nd gear, forcing the transmission into a lower gear to use engine braking, then slipping the car into neutral at the end to ensure there is no power sent to the drive wheels.

Dynamic braking only needs to remove 1 mph from his initial speed to stop within the remaining distance: (69/40)² * 50 = 148.8 feet.

If it were a matter of simple braking, then NO, the driver would not have time to stop and he could get a ticket for a 'failure to yield' when he ran through the red light (but NOT for speeding.)

With dynamic braking an experienced driver should be able to stop in time to avoid running the light.

No wonder there are so many accidents when so many people believe this sort of thing.

With 1.1 g deceleration, your limit is the tyres, not the brakes. If there is a limit from the brakes themselves (fading?), it will be much worse braking from 75 than it was from 40.

Slowing using the engine on just two wheels will make the braking load more uneven between front and rear, so it will be even less effective to stop you than using just the brakes.

Kinsale,

Guest is correct.

Actually including 'downshifting as a braking means' causes a counter-productive scenario:

much more braking potential added to the drive axle compromising the braking compensation mechanisms - resulting in probable loss of control; especially if any debris or slick spot.

Guest and bwire -

You're both answering problems that were not part of the original scenario. There was no mention of slick spots or debris. There was no mention of the brakes fading or the tires (or tyres) slipping.

If these were part of the original question your points might be valid. One could take these discussions far afield discussing, say, the stopping ability of front disk/rear drum vs all-disk brakes on car and the differences in handling for older rear-wheel drive cars (like old Camaros) vs most newer front-wheel drive cars, and so forth.

But taking the scenario as it is given, the point I'm making is that using the engine to absorb enough energy to reduce the speed by as little as 1 mph allows the car to stop within the required distance. (The only assumptions I make are the non-complicating ones of dry pavement, uniform road surface, no obstacles, etc.)

Experienced drivers who understand the technique know that it can work under similar circumstances of dry pavement, uniform road surface, etc.

There is no mention of the brake system being a limit either. So you only have the numbers to guide you. These give a deceleration of 1.1 g. That tells that the braking is already close to the limit set by the tyres, and that the braking had to be well balanced between front and back. Anything you do that unbalances the effect of the brakes between front and back can only make matters worse. The only conditions under which engine braking can reduce braking distances on a two-wheel-drive vehicle are either where the brakes are incapable of providing as much deceleration as the tyres (or tires), or where the brakes apply a disproportionate force to the non-driven wheels (so braking using the engine improves the balance). Neither of these is likely if the brakes worked this well in the first instance.

(It is possible the engine would help if the brakes on the driven wheels fade when used from 75 mph, but the best you could hope for would be to restore performance equivalent to the original, not to improve on it.)

Kinsale,

It was my way of expressing disagreement of your assertion specifically as the nature of your statement had veered slightly off subject I hadn't corrected your bent.

I appreciate your implication, though your assertion is inaccurate.

If you take note when professional drivers reduce speed they use the brakes only; no downshifting (romanticising) until after the controlled speed reduction need has passed, then downshift to accelerate.

Actually downshifting is a form of engine brake which most certainly is an effective means of shedding forward momentum. This coupled with judicious use of the brakes will certainly allow stopping in the required distance. As a motorcyclist, dirt track race car driver and hauling heavy loads, I have first hand experience.

The engine can be an effective form of braking. And it can allow the friction brakes to be used for longer without fading. But engine braking is not magic; so when the stopping distance is limited by the adhesion of the tires rather than by fading brakes there is no way it will reduce the distance - and the unevenness of the engine force as the engine speed changes and/or you change gear plus the fact that the engine must unbalance the distribution between front and rear wheels can only increase the overall stopping distance (as compared with optimally applied friction brakes).

If you can't believe this, try experimenting somewhere that there is no other traffic - but not on a motorbike. Attain a known steady speed and try stopping in as short a distance as possible using your brakes only. If you have done this well the wheels should never lock but there should be continuous rubber-marks from the point at which you started to brake. Then repeat it with the addition of engine braking, if you do this really well you may again achieve continuous rubber marks (though I think you will find that it is much more difficult, and the marks will probably be due to the driven wheels only) - now measure the distance from the point at which you started to brake.
(Even better, get two friends to help in the test, one to drive alongside you, and the other to signal when you should brake. First time, you use the brakes only, friend uses the engine as well; second time, you swap methods (but not vehicles). As you start side by side, all you need to look at is the finishing positions.

Truckers use a form of dynamic braking called 'jake braking' that uses the engine and exhaust system to slow down their trucks. Some truckers will use it instead or, or in addition to, regular braking, but it is a noisy system and is banned in many cities due to this noise.

(Professional drivers, such as NASCAR or Indy car drivers don't use this for the simple reason that it's hard on the engine and transmission and brake pads are cheaper than engines or transmissions.)

Would it stop a truck in an emergency situation better than just using the brakes alone? Under most real-world situations, with the brakes, tires, and road all in good conditions, no. In a case where the brakes have failed, it would at least slow down the truck to minimize an impending crash. A trucker that has to use an emergency stopping ramp on a mountain road uses this system to reduce his speed.

I suggested using dynamic braking to knock-off one or two miles per hour, to allow the stopping distance to get under 150 feet. If one assumes the brakes and tires are already at their maximum limits under the first condition of stopping in 50 feet from 40 mph (which is unrealistic, since this means the tire rolling friction constant has to be around 1.08, whereas it is typically around 0.8) then dynamic braking would do no good. But since the value of 1.08 is unrealistic, then one can assume any value for the tire rolling friction, so say it's closer to 1.27 (granted this is even more unrealistic). This means that the original scenario was not a panic stop. In which case, dynamic braking could be used to slow the car down by a few miles an hour as the braking commences, and the car could stop within 150 feet.

If you believe the Camaro could achieve shorter stopping distance by using "dynamic braking", I am going to state that the Camaro could stop, if he used his parachute.

You've said the same thing many times, but not apparently taken the trouble to answer the points made in the posts that were addressed to you. Specifically, they have shown that the braking rates must have been at or very close to (possibly even beyond) the limits of a Camaro's tyre adhesion, making it a reasonable assumption that the challenge intended the reference to the shortest stop possible from 40 mph with the specific vehicle. Clearly engine (or dynamic) braking acts through the tyres, so it can at best do the same job that perfect brakes would do. If there is a problem with the brakes fading when braking from 75-mph (it's an old Camaro, after all), engine braking could reduce the overshoot; but it can't improve on the capability of the tyres.

I'm probably being unfair, but your contribution reads as if you are expecting to knock-off the first couple of miles per hour using dynamic braking without the truck covering any ground while you are doing this.

Well, there's no question that the braking system was already beyond its realistic limits. The stopping distance is given by d= v² / (2 μ g). For a v of about 59 ft/sec, g of 32ft/sec² and using a realistic μ value of 0.8 (for brand-new tires) the original stopping distance should have been 68 feet, not 50 feet. And in the second scenario the true stopping distance would have been 236 feet, not 176 feet.

So given that the original value for μ was unrealistic, it is improper to conclude that the tires and brakes were already at their limits. I chose to address the problem from a different viewpoint, to let the engine absorb some of the energy. Certainly, if the tires were at their stopping limits, downshifting would have caused them to skid, and the situation wold have worsened; but they were already past this point in the first situation of stopping from 40 mph; yet magically the car stopped.

Must have been that parachute that bob c deployed! (Good comment, bob c. I like your sense of humor.)

but they were already past this point in the first situation of stopping from 40 mph; yet magically the car stopped.

If only that were true, but of course it is not. The Ferrari from the test for which I provided the link does not stop by magic.

As a European who frequently drives in Essex, I wouldn't feel safe driving a vehicle that was incapable of stopping from 40-mph in less than 50-ft in dry conditions (both the family cars will do this). However, neither is an elderly Camaro - but you could doubtless fit tyres to the Camaro that would stop in that distance (the spelling is to emphasise that standard European ones are more likely to do this than US ones).

Naturally, I have no objection to unconventional takes on these topics, provided that any improbable assumptions are explicit from the beginning. In this case they would need to be that the tyres have an coefficient of friction with the ground of 1.7, but that the initial information was not the shortest stop possible. Of course, that is equivalent to a 139 foot stopping distance using the brakes, but you have allowed extra distance to allow for the problems associated with "dynamic" braking.

N.B. I agree that dynamic braking has its place - on very long downhills it will reduce the load on the braking system without stressing anything else, and it is useful if the brakes fade (more applicable to trucks - never yet a problem with my cars). I also use it when coming up to roundabouts - not because it is an effective way to brake*, but easing off early is an economical way to drive, and it leaves the car in the correct gear for leaving the roundabout.
*It's actually very ineffective with any engine management system that times the valves so the cylinders are maintained empty.

If you had zero reaction time you could not stop before you got to the light. I agree that 75 MPH equals 110 feet per second and your reaction time would also keep you from getting stopped before going through the RED light. However, you might get a ticket for speeding if your speed was picked up by radar. However, the most likely ticket that you would not be able to get out of would be a ticket for running a red light.

I had a 1967 Camero. The only way I could have stopped it in 50 feet from 40 mph would have been to hit a solid wall. Stopping that fast would appear to require decelleration at over 3 g's. I don't think there is any car that could do that without retrorockets.

Hi Jim - you had me worried, but I think:

Start speed = 40-mph ≈ 59-ft/sec
Constant deceleration to zero → average speed ≈29.33-ft/sec
Time to stop = distance/average_speed ≈1.7-sec
Acceleration = original_speed/time ≈34.4-ft/sec² ≈1.1-gn

Still better deceleration than I would anticipate from an unmodified early Camero - but that is without any specific knowledge of the breed.

Regards

Fyz

I sure hate it when my errors show up for all to see. Your right. 1.1 g's is way to much for my old Camero.

Thanks,

Jim

Hi Jim

We all make slips. Credit is due to those who can admit to them.
BTW, the reason for my incredulity was that a current BoxsterS (which is reputed to have the shortest braking distances of any standard road car) requires about 48-ft to decelerate from 40mph to zero.

I think your answer was just fine, as it was. The cognoscenti all know that today is "divide by 2.73 day" (a.k.a. "divide by (1+ (3^.5)) day".)

There is nothing to say that the speed limit is not 75mph in the question even so they don't give tickets for speeding for running a red light.

Yes, more likely 'failure to maintain control due to excessive speed for the conditions' greater fine that way

Is this a level road? As others have suggested, it's unlikely that the Camaro could stop in anything like 50' on the flat - but suppose it was on a 1 in 8 (12.5%) incline?

[And would it manage 75mph up the same incline? Maybe, with a run-up.]

Haven't done any sums, just thinking aloud.

Depends on age and engine of old Camaro. I once had a 1978 Z-28 up to 160 mph on a level stretch of highway. I took a couple of miles to get it wound up that high, and I confess I did not check the accuracy of the speedometer, . . .

Is this a level road?

Interesting point. Only that it wouldn't change the final outcome, which is that the car will either crash or cross a red light (whether the driver will receive a ticket is a more complex problem!) I did some school-level maths for the case of an inclined road at angle θ, and if I haven't made a mistake, it holds:

m.g.s.(n.cosθ + 2.sinθ) = ½.m.v²

for both cases. This means that still, the distance is proportional to the square of the velocity.

"This means that still, the distance is proportional to the square of the velocity."

But now g is different - consider the difference in stopping distance between going downhill and uphill. (If downhill & very steep, good brakes would be needed to stop at all, uphill (& steep enough) lots of engine power + a good clutch are needed to even move).

But now g is different - consider the difference in stopping distance between going downhill and uphill.

g cannot be different. We may consider roads with different inclinations if you like, but this is another problem. In this particular problem it is stated that we are talking about the same road.

Moreover, I take for granted that the driver uses the same effort to stop the car in both cases, and that the wheels do not skid dissimilarly, therefore, the friction force is the same.

Good point - you got me !

Hi tkot:

I believe that JohnDG is correct that the incline would affect the stopping distance, not because g is different but because g is now calculated in accelerating the car in the opposite direction. If a car travelling 5 mi/hr on a level surface stops accelerating, it will eventually stop due to rolling friction. If the same car is on an incline it will stop sooner as the the rolling friction force and the force the incline provides by acceleration in the opposite direction to the travel combine to stop forward motion.

Cheers

mechtech

I don't doubt that an inclined road would help the car to break faster. I think that JohnDG was puzzled about whether a car like that would ever stop after such a short distance, and proposed that the road might be an uphill. This thought is quite valid.

My intervention had only to do with the fact that in the context of the quiz at hand, the inclination of the road is irrelevant. That's because the kinetic energy (which is proportional to the square of the velocity) has to equal the work of the friction (proportional to distance) plus the gain (or loss for that matter) of dynamic energy, which again is proportional to the distance, given that the inclination is constant. Therefore the distance covered will still be proportional to the square of the velocity.

you will get a speeding ticket

You will get hit as your vehicle can come to halt at distance of 175.78 feet.

I cannot comprehend the question, feets and miles? what are those in the metric system

But ignoring the the feet & miles i guess we have an accident at the intersection

Assuming you're in the US...are there any roads with a speed limit as high as 75mph? I suspect not?

So ? Yes you'd get a speeding ticket... but also you would not stop in time.

Tony

are there any roads with a speed limit as high as 75mph?

I-10 in Texas west of about Ozona to El Paso, I-80 in Wyoming and Nebraska, a few others, mainly in the Western States

Uh... why would I get a speeding ticket for running a red light? Is this a trick question or am I the only one paying attention?

Nope, you would get a ticket for speeding and running a red light, and for the car chase up to this point, and robbing the bank and stealing the car and so on.....

You beat me to the punch!

After the LEO see you skidding through the intersection and he measures the skid marks and does some math you will get a speeding ticket if the speed limit is less than 75mph.

You will also get a failure to maintain proper control of your vehicle and running a red light. Also one for no seatbelt if you were not wearing it. one for not having insurance an or proper registration if thats not correct. Also one for the broken tail light or cracked window or any other violation they can find or think up etc etc....

Best just drive slow enough and pay attention to job of driving. BUT where the FUN in that driving an old Camaro!

For perspective let's say your camaro may stop from 40 mph in about 165-210 feet.

If your camaro is traveling at 75 mph and the signal changes you will need pull the rip cord to stop shorter than about 625 feet. You have apparently neglected to add reaction time to the distance; your reaction to the signal change 1-2 seconds, plus your reaction to apply brakes 1-2 seconds, plus the brake system reaction time before controlled braking is evident 1-2 seconds.

No ticket just 30 days unless some injury is incurred then you get an extended stay

This stuff about reaction times is getting ridiculous. To quote Wikipedia "Mean RT for young adults is approximately 190 milliseconds to detect a visual stimulus". If you are watching the traffic light and prepared for the need to brake then you will be on the brake after a similar interval, and another similar period should be enough for the brake pedal and brake pad movement - a total of well under a second, not up to 6 seconds. You could never drive in town traffic without hitting the car in front if the braking time was in seconds.

UK motorway signs recommend a 2 second separation for safety, and you can bet that has been chosen to give a big safety margin.

JayGeeBSE,

You have some merit in that statement however detection of a visual stimulus (perception time) is just one property in the evolution of driver reaction time:

Marc Green

Seminar Available on this topic.

1. Mental processing time

a. Sensation

b. Perception/recognition

c. Situational awareness

d. Response selection and programing

2. Movement time

3. Device response time "a quote" read the article

Mechanical devices take time to actuate, even after the responder has acted. For example, a driver stepping on the brake pedal does not stop the car immediately. Instead, the stopping is a function of physical forces, gravity and friction.

Here's a simple example. Suppose a person is driving a car at 55 mph (80.67 feet/sec) during the day on a dry, level road. He sees a pedestrian and applies the brakes. What is the shortest stopping distance than can reasonably be expected? Total stopping distance consists of three components:

1. Reaction Distance. First. Suppose the reaction time is 1.5 seconds. This means that the car will travel 1.5 x80.67 or 120.9 feet before the brakes are even applied.
2. Brake Engagement Distance. Most reaction time studies consider the response completed at the moment the foot touches the brake pedal. However, brakes do not engage instantaneously. There is an additional time required for the pedal to depress and for the brakes to engage. This is variable and difficult to summarize in a single number because it depends on urgency and braking style. In an emergency, a reasonable estimate is .3 second, adding another 24.2 feet.
3. Physical Force Distance. Once the brakes engage, the stopping distance is determined by physical forces (D=S²/(30*f)) as 134.4 feet.

Total Stopping Distance = 120.9 ft + 24.2 ft + 134.4 ft = 279.5 ft

Almost half the distance is created by driver reaction time.

****************************************************

bwire remembers the incredulation he observed when conducting evasive driving courses and the measured reaction time of the average entrant in actual driving conditions; with all the normal distractions we take for granted generally

****************************************************

Other factors: Expectation [expected, unexpected and surprise]. Urgency, Cognitive load, Stimulus-Response compatibility, Psychological refractory period, Age, Gender, Nature of the signal [estimated-time-to-collision] a.k.a. TTC, Visibility, Response complexity, Reaction time at night.

Case Study

The ensuing example is taken from a real case. It demonstrates how "standard" reaction time estimates must be adjusted to situation-specific conditions.

A 73 year old male driver, Mr. Smith, broad-sided another car crossing his path from a side road in good daylight visibility. Mr. Smith stated that he had approached the intersection cautiously because he had had several close calls with vehicles cutting across that intersection. He also stated that the possible danger caused him to drive more cautiously than normal as he approached the intersection. This was confirmed by forensic reconstruction showing that he was traveling well under the speed limit at the time of the accident. Moreover, Mr. Smith stated that he approached the intersection with his foot hovering over the brake pedal. A hundred feet before the intersection he saw a car from the side road. What is his expected reaction time?

A typical reaction time for responding to this type of lane incursion would be 1.5 seconds. However, the circumstances in this example alter the "typical value."

First, expectation has a large effect on reaction time. Since Mr. Smith was aware of previous accidents at the intersection and had experienced close calls himself. Given Mr. Smith's heightened alertness and his expectation that a dangerous situation might arise, a more reasonable reaction time estimate would be 1.0-1.1 seconds, not the 1.5 of a totally surprised driver.

Next, Mr. Smith had his foot was on the brake as he approached the intersection. The time required to move foot from the accelerator to the brake pedal is about 0.2 seconds. Since Mr. Smith already had his foot at the brake pedal, the normal braking movement time would be reduced significantly. A conservative estimate would be that the normal 0.2 second movement time would be cut by at least half to 0.1 second. This reduces expected reaction time to 0.9-1.0 second

Lastly, Mr. Smith was 73, and aging slows reaction time 0.2 to 0.3 seconds. This would increase expected reaction times to a range of 1.1 - 1.3 seconds.

Complex reaction times

If you read the article you quote (and thought about it) you would realize that this reaction time would only apply if one were driving along a closed road with their foot hovering over the brake pedal, waiting for the light to turn red. Under real life conditions, the driver would be looking for all manner of stimuli (like police cars) thus, according to the article, RT would be increased.

I don't think I could get my foot off the gas and onto the brake pedal, full pressure, in 190 ms but my leg may be heavier than yours.

bwire

I'll tell you what Mate, that sounds more like bloody space travel. I used to drive the Autobahns of Germany and I know what it feels like when every thing turns Grey left and right because of the speed. Ones eye is to slow for the "side ways", if you know what I mean. Reaction time at those speeds can be a lottery (not in a 928 S Porsche) but at speeds like 75 mph one has quiet a bit of instinct that can set in.

If a rip cord is a hand break (you do have a funny language you guys) I would agree. It should be trained in driving school and not on the roads! If one can't control a tonne or 2 don't get in it. And they bloody well all do. Open slather, never mind the physics of it all.

I'm on my desk top while driving so I better leave you with the academic stuff. We have a speed limit here that is not recordable on any Richter scale. Slow down, the lot of you and not only the Camaro's. Oh, Ohh, her's bad blood!

If in doubt, steer like hell!

I think he was referring to the ripcord for a parachute, like the top fuel dragsters use to stopquick.

yeper

Thanks, rip cord Eh...

I'd take the exit just before the lights.
(OK... with tyre/passenger squeal)

Del

At 75mph require 176 ft to stop hence I will get a speeding ticket.

Regards,

lashsd@yahoo.com

Better to accelerate and get it all over with. Finding out by seeing what happens is the best school of science and probably cheaper in the long run. We could solve our prison over population by getting the inmates to volunteer for projects with the prospect of an early release if they survive

Too many variables.....no one mentioned the temp of the tires or road, what the road is made of, size of the tires, weight of the car with driver and fuel. Too many variables to accurately equate.....did anyone even check the weight of the car? What size engine, convertable top or hardtop.

Yes & Yes & what's the speed limit on this road??????

ANSWER the question

No you would not stop in time if the lights stayed red

or get a speeding ticket if there was no authority to book you.

The ticket would be for going through a red light, not for speeding.

Colin

You will get speeding ticket.

This site has a discussion on the same subject by some serious drivers and competent mathematicians.

http://www.advanced-driving.co.uk/bb/viewtopic.php?f=1&t=2381

They conclude that the figures for stopping distances in the UK highway code assume a reaction time + action time of 0.7 seconds ( I guesstimated 0.6 earlier in this discussion) and a deceleration of 25 feet per second squared = 0.77g.

It is rumoured that this stopping performance was based on a Ford Anglia (1958 - 1968) with unassisted drum brakes on cross-ply tyres. Probably similar to the old Camaro but not similar to a modern car.

Incidentally, there seems to be a belief that anti-lock brakes reduce the braking distance. Not true, they can extend it. It depends on how skilled you are at braking without ABS. The ABS is designed to leave some grip available for steering.

A GT2 class Porsche can stop like that but a Camaro would need to be tied to something heavy. Besides where are you goinfg to fins a dumbass to writw a speeding ticket for running a red light " on an interstate?" So the answer:

You wont get a speeding ticket for running a red light

unless your brakes failed and you got a speeding ticket and a ticket for running the red light, after all you are driving a Camaro.

No, the camaro had rather shitty brakes that would fade on you when braking from high speed.

Chances are the posted speed wouldn't be any more then 55 MPH if it has intersections governed by traffic lights.

My guess would be a Reckless Driving Ticket.

That would be my guess as well.