Stock Car Science

Sometimes, life isn’t content with just kicking you.  It insists on running you over a couple of times and then spitting on you for good measure.  Just in case you had an inkling of getting up again.

The last twelve months have been very rough for me.  Lots of broken dreams, lots of challenges to my deeply held belief that, when given a choice, most people will do the right thing, and than a lot more time spent on medical issues that are probably a by-product of the stress.  So I have great empathy for Brian Vickers just wanting some answers.  I am betting that Brian is also finding, as I did, that you learn a lot about other people during times of challenge like this.  Sometimes it’s information you really rather would have not known, but sometimes you find out that there are some amazing people in the world that teach you things about yourself you wouldn’t have known otherwise.

Brian Vickers is out for the remainder of the season due blood clots in his lungs and legs.  See Marty Smith’s excellent article for details.  Hopefully one of the things Brian has learned is that you should always listen to what your body is telling you – especially when it is shouting.  A recent study showed that married men live longer than single or divorced men, with one of the hypotheses being that married men are nagged more by their wives to do routine medical checkups and to see a doctor when they start to hurt.  So guys, don’t take our nagging lightly!  We nag because we care.

In general, clotting is good and one of the most important things blood does.  The particulars of when and where are the issue.  You’d like your blood to flow freely when everything is normal; however, a ruptured blood vessel should stimulate the formation of a clot to cover the hole and keep the rest of the blood inside.

Blood, it turns out, is pretty complicated.  If you think there’s just red blood cells running around, you’re not giving blood its due.  Blood is blood cells suspended in blood plasma.  Blood plasma is 90% water - the other 10% are dissolved proteins, sugars, mineral ions, hormones, oxygen on its way into the body, carbon dioxide on it’s way out of the body, etc.  Then there are red blood cells and white blood cells, which include leukocytes and platelets.  In the scaning electron microscope picture below, the thing on the left is the red blood cell, the middle object is a platelet and the right-most object is a white blood cell.  (Yes, the same type of cell that tried to extravasate Raquel Welch in Fantanstic Voyage .) A red blood cell is about 6-8 micrometers, where a micrometer is one millionth of a meter.  A single strand of your hair is about 70 micrometers, so ten blood cells would just about fit across the diameter of your hair.

Platelets (the smaller, middle cell in the picture) are tiny cells from the bone marrow.  They normally wander about the blood freely; however, any type of rupture in a blood vessel signals the platelets to start a series of chemical reactions that make the platelet surfaces near the breach very sticky. The sticky platelets start to adhere to the blood vessel wall at the place where bleeding is occuring.

Among the many proteins dissolved in your blood is a protein called fibrin, which is shown below.  Proteins are very complicated molecules - so complicated that biologist don’t even draw every molecule.  There are a couple hundred thousand of them there.  Fibrin is made from a protein made in the liver called fibrogen.  Lots of little fibrin pieces start to join together to form long protein strands.  These long strands bind to the platelets and form a mesh that acts like a bandage.  In the process of linking, the fibrin usually catches up red blood cells and that is why scabs are red.  (There are two phases to clotting - the platelets gathering in the area form a whitish cover.  You know that the fibrin has gotten into the act when the red color appears.

Clotting becomes a problem when it hapens in places it is not supposed to happen.  When clots form in the deep veins of the leg (fermoral vein, for example), it blocks blood flow, creating pain in the leg.  Of more concern is what can happen when the blood clot loosens - if it travels to the lungs, it can cause a pulmonary embolism, which is blockage of an artery in the lung.  This can lead to complications like not being able to breathe and death.  Clots that work their way loose and travel to the lungs (or brain) can cause death in a matter of minutes.  Brian is extremely lucky that, despite his ignoring the warning signs for a couple of days (!), the clots didn’t do major damage.

The question remains as to why a very healthy 26-year old would have blood clots.  One theory floated around that the blood clots may be due to increased carbon monoxide levels in the blood.  Carbon monoxide (CO) is produced by incomplete combustion of gasoline. About 2 percent of the average car exhaust is CO, but the figure is higher for racecars, as they have no catalytic converter.  Damange to the racecar can also open a hole in the cockpit that allows CO into the cockpit.

One of the things the blood does is provide taxi service for other molecules.  Hemoglobin moves oxygen from the lungs to places like the heart, brain, and muscles. When the hemoglobin reaches its destination, the oxygen hops off and the hemoglobin goes back to the lungs for more oxygen. Carbon monoxide also likes the hemoglobin taxi, but once it gets in, the CO doesn’t want to get out again. CO binds to hemoglobin 240 times more strongly than does oxygen, which leaves fewer opportunities for oxygen to get to other parts of your body.  You have less oxygen in your blood and that leads to nausea, weakness and other impairments.

CO, like most poisons, can affect you acutely or chronically. Acute exposure is exposure to a high level over a short time while chronic exposure is small doses over long periods of time. Neither is good, but chronic CO exposure is more of a problem for drivers. Each successive exposure further impairs their body’s ability to distribute oxygen throughout their body. Driver Rick Mast ended his career in 2002 because of chronic carbon monoxide exposure. He became so sensitive to CO that he couldn’t even bear to be around lawnmowers.

Carbon monoxide is tasteless, odorless and invisible, so how do you know when your driver is being exposed? Ray Evernham, when he was crew chiefing for Jeff Gordon, said that he could tell immediately,

“by the way Jeff answers me on the radio, when the carbon monoxide is getting to him. He becomes a smart-ass. When I started working with him, I thought he was a smart-ass. But the more I got to know him, and the more I learned about carbon monoxide, the more I realized what was happening.”

Other crew chiefs have said that drivers start to delaying answering questions, ignore instructions or make irrational decisions.  Of course, a number of crew chiefs also noted that their drivers were that way most of the time and this was not a good metric for establishing exposure.

Breathing pure oxygen, which increases the number of oxygen molecules in the lungs, is the primary treatment for CO exposure. More severe cases sometimes use hyperbaric oxygen therapy. The driver is placed in a sealed pressure chamber, similar to those used for treating decompression sickness in divers, and exposed to high-pressure oxygen. Advocates claim greater penetration of oxygen at tissue level, and that oxygen displaces the carbon monoxide-laden hemoglobin from red blood cells more quickly; however, there is disagreement in the medical community about the efficacy of this treatment.  It may be that repeated exposure permanently elevates your CO levels, or CO levels may be reversible over time.  It’s sort of an important thing to know if you want to make intelligent decicison about hanging around the track.

We do know that different people react very differently to CO exposure.  It’s easy to measure the amount of CO exposure:  you can track how much CO a driver exhales, or measure the ratio of carbon to hemoglobin molecules in the blood. A 2001 study reported blood levels of carboxyhemoglobin (carbon monoxide bound with hemoglobin) between 15 percent and 18 percent immediately after short-track races and 8-10 percent on superspeedways. A 5 percent concentration is enough to decrease motor skills. CO also exacerbates heat stress and decreases driving accuracy.  NASCAR drivers have the option of implementing a filter that filters the air before it reaches the driver to remove much of the CO.

Aside:  if Brendan Gaughan had to get out of his car at Charlotte due to carbon monoxide fumes, how bright do you have to be to volunteer to step in for him?  If you were a car owner and you knew CO was getting into the cabin, don’t you have a moral obligation to pull the car and fix it before you ask someone else to get in?  I know, there were only 50 laps to go, but you still have to wonder if Mrs. Green was asking Mark what the heck he was thinking doing that when he got home.  I don’t understand why the drivers don’t insist on CO sensors in their helmets so that at least have some idea of the CO levels of CO to which they are exposed.

What does CO have to do with blod clots?  There are three primary factors in blod clots:  how fast the blood flows, the thickness of the blood and the nature of the blood vessels.  These factors are affected by a number of other factors:  sitting for long periods of time slows down blood flow (bad).  Carbon monoxide depletes the blood of oxygen and slows down blood flow.  Usually, the people who are most at risk for blood clots are the elderly and the infirm, people suffering from cancer, or having had recent surgery, and people with genetic predisposition to developing blood clots.  Interestingly enough, there are some researchers who think that endurance athletes may actually have a higher risk of certain types of blood clots because they have slower blood flows.

Most NASCAR drivers have been exposed to plenty of CO in their careers.  If that’s the important factor, why don’t more drivers have blood clots?  As with most things in medicine, everything is so interrelated that you can’t point to a single factor.  Brian may just have exceptionally slow moving blood that is prone to clotting.  Thrombophilia is a genetic predisposition to blood clotting that is inherited. Factor V Leiden is a syndrome in which the clotting process is enhanced (the blood is “hypercoagulant").  About 5% of Caucasians in North America have Factor V Leiden, with less prevalence (1-2%) in Hispanics and African-Americans and very rare cases in people of Asian descent.  Women with Factor V Leiden have a much higher chance of miscarrying and having blood clots form during pregnancy.  You can be tested for Factor V Leiden and I’m sure Brian is looking into all of these options.  If the clotting is a genetic predisposition, it is a very different problem than if the clots he experienced last month were due to circumstances that are unlikely to be repeated.

The standard treatment for blod clots is blood thinner, which makes the blood thinner (duh) and can incrtease the rate of flow.  Another treatment is wearing anti-embolism compression stockings.  Not the old-lady hose your grandmother used to wear for her varicose veins.  They actually make compression stockings specifically for preventing embolisms and they exert significantly more pressure on your legs than the ones you can buy at the drugstore.  The stockings don’t do much for people who are immobile and stuck in bed, but there is some evidence that they are effective for airline flyers.

I wonder if they make Nomex nylons?

Kidding aside, the blood thinner treatments are generally aggressive in the first week and then taper down, depending on whether the origin is situational or genetic.  People with a strong pre-disposition to blood clots can be stuck taking blood thinners their entire life.  Obvious, Brian’s personal life is just that and we have no business asking him about the details of his condition (although I would like to see one of the ever-so-serious NASCAR press members ask him if he’s taken to wearing nylons!).

For Brian, all I can say is that I’ve found in my life that disruptions that initially seem to tear apart my world almost always end up with new revelations.  Even if there is no change in your situation, you learn important things about yourself and the people around you.  Sometimes you find out that it is possible for you to do things you didn’t even know you were interested in doing.  I hope for you that this episode is short and resolved quickly, but even if it isn’t, I hope that you find as many answers as you can.  Take care of yourself and, as I’m sure you already know, there are lots and lots of people out here cheering for you to have the best possible outcome.

Last week at Texas Motor Speedway was not fun because of the rain.  There were short periods of downpour and then just moisture hanging in the air that would not go away.

But we didn’t have to deal with severe storms and tornadoes.  Having spent 14 years in Nebraska and 16 in Wisconsin, I am more familiar with tornadoes than I would like to be.  The words that are most worrisome in the forecast are “tornado outbreak".  If you have a short attention span, scroll down to the last section of the article, which tells you what you should be doing if you are out at the track or planning on coming out.

Tornadoes are a primarily North American phenomenon, with the U.S. having about four times as many tornadoes as all of Europe (excluding waterspouts and if you ever lived in Nebraska, you know why).   North America stretches a long way North to South and there aren’t any major east-west mountain ranges that block the flow of air all the way from Canada to Mexico, so much larger fronts can form than in areas with more mountainous regions.

The Midwest has a lot of tornadoes – as you can see from the figure at right – because the Rockies block moisture and cause the atmospheric flow to buckle, forming low-pressure, dry areas to the east of the mountains.  The Gulf of Mexico is a great provider of moisture, which makes for ideal conditions for tornado formation.  The U.S. averages about 1,200 tornadoes per year.  Most happen between 3 p.m. and 7 p.m., but they can occur at any time of the day.

The worrisome thing this weekend is the prediction of a tornado outbreak, but let’s look at one tornado at a time.

Tornadoes form in boundary areas, like those between hot, dry air in the West and warm, moist air in the East.  The Central Plains states, like Nebraska, frequently experience strong storms this time of year.  Those storms move East and, depending on their North/South extent, can cause storms and tornadoes throughout a wide swatch of the country.

The worst tornadoes are spawned by thunderstorms called supercells, which contain mesocyclones.  ‘Meso’ means ‘mid’, so a mesocyclone is a medium-sized rotating air mass and, in meteorological terms, that means from a mile to five miles across.  Supercells also have very heavy rain, lots of lightening, strong winds and hail.

When it starts raining really hard, the rainfalll drags air down with it toward the back of the supercell.  The downdraft accelerates as it nears the ground, and drags the supercell’s mesocyclone down with it.  If you see a cloud that shows any sign of rotation, that’s time to start being concerned.  The mesocyclone approachs the ground, and a condensation funnel forms.  The condensation in the storm is the same thing as steam forming water droplets on the lid of a pot of boiling water.  The coolness of the downdraft condenses water from the air, and that forms the condensation funnel.  The rear downdraft keeps moving downward, which creates a very strong wind capable of causing damage well away from the funnel cloud.  A funnel is a rotating structure descending from the clouds, while a tornado is a funnel that has reached the ground.  The funnel cloud can become a full-fledged tornado within minutes of the rear wind gust hitting the ground.

Tornadoes are powered by warm, moist air.  The more air, the more energy the tornado has, and the tornado will keep growing as long as it has access to warm, moist air.  Tornadoes with diameters of more than a mile have been reported.  At some point, the cool rear downdraft will wrap around the tornado and prevent more warm air from reaching it.  The vortex, deprived of energy, begins to weaken, the size decreases and the tornado can be dispersed by the straight-line winds from the storm.  Don’t let the size of a tornado fool you.  Even what appears to be a small tornado is capable of causing a lot of destruction due to conservation of angular momentum.  When an ice skater is spinning, she spins more slowly when her arms are out, creating a larger effective diameter.  When she pulls her arms in, she spins faster.  A thin tornado can still feature very strong winds.

Once the original tornado is gone, it’s entirely possible for the cycle to repeat again, with a new mesocyclone descending.  Tornadoes are good in that they have a limited lifespan (you won’t see three-day tornadoes, like you would a hurricane), but unlike hurricanes, we still don’t have the technology to predict where and when a tornado will pop up.

“Tornado outbreak” doesn’t have a specific scientific meaning - it mostly means a lot of tornadoes are spawned from a single storm.  The worst outbreak on record was the “Super Outbreak” in April 1974.  There were 148 tornadoes in 18 hours, with six being classed as F5 (the most destructive) and 24 classed as F4.  About 315 people were killed in the U.S. and Canada and over 5000 people were injured.  This history is one of the reasons that people are so concerned about tomorrow’s weather.  The storm that is headed to Alabama passed through Texas earlier in the week and produced the largest tornado outbreak of 2010 to date - 32 tornadoes.

Tornadoes must have two fundamental ingredients:  wind shear and some instability, like the aforementioned hot/cold and dry/wet condition along a front.  Most of the time, you have some combination, like a little of one and a lot of the other.  Meteorologists start getting worried when there is a lot of both.  NOAA predictions are interesting to read, but you need a little background.  There are multiple weather models because weather is fundamenteally difficult to predict.  (Very much like the results of a Talladega race.)  Meteorologists run several scenarios with the different models and try to figure out which one is most accurate for the particular situation.  Our local meteorologist talks about ‘one model shows this and others show that, but I think the first one is right’.  The closer the weather system gets to actually spawning a tornado, the more confidence we have that one or more of the models are accurate.  Here’s part of the NOAA forecast with my comments.

SEVERAL FACTORS APPEAR TO BE COMING
   TOGETHER FOR A TORNADO OUTBREAK ACROSS THE REGION SATURDAY WITH A
   WIDESPREAD SEVERE THREAT CONTINUING THROUGH SATURDAY EVENING. THE
   KEY TO A TORNADO OUTBREAK SHOULD BE THE POSITION OF THE LOW-LEVEL
   JET. THE GFS AND NAM SOLUTIONS (GFS and NAM are two different models) VARY, WITH THE GFS FOCUSING THE
   LOW-LEVEL JET ACROSS NE LA (Northeast Louisiana) AND NW MS (Northwest Mississippi)SATURDAY MORNING WITH THE NAM
   FOCUSING THE LOW-LEVEL JET FURTHER SOUTHEAST IN SCNTRL (South Central) MS. AT THIS
   POINT...HAVE TAKEN A COMPROMISE BETWEEN THE TWO SOLUTIONS BUT AM
   FAVORING THE GFS SOLUTION WHICH IS SUGGESTING THE POTENTIAL FOR
   TORNADOES WILL BE GREATEST ACROSS NRN (Northeastern) LA...SRN/ERN (Southern/Eastern) AR AND WRN/NRN MS
   SATURDAY MORNING THROUGH EARLY AFTERNOON. 
Here's the important part for us:
A POTENTIAL FOR TORNADIC
   SUPERCELLS SHOULD ALSO EXIST EWD (Eastward) ALONG A WARM FRONT INTO NRN AL (Northern Alabama) AND
   SWD (Southward) ACROSS THE WARM SECTOR ACROSS MS AND AL SATURDAY AFTERNOON. ANY
   SUPERCELLS THAT DEVELOP ACROSS THE REGION SHOULD ALSO HAVE A THREAT
   FOR LARGE HAIL AND WIND DAMAGE.
   
   THE SETUP COULD BE FAVORABLE FOR STRONG TO VIOLENT TORNADOES AND A
   LONG-TRACK TORNADO WILL BE POSSIBLE. AN OUTLOOK UPGRADE TO HIGH RISK
   MAY BE NEEDED ACROSS PARTS OF THE REGION AS CONFIDENCE INCREASES
   CONCERNING THE MODEL SOLUTIONS. ALTHOUGH THE BRUNT OF THE OUTBREAK
   IS EXPECTED DURING THE MORNING AND EARLY AFTERNOON...SUPERCELLS AND
   WELL-DEVELOPED LINE-SEGMENTS SHOULD BE CAPABLE OF PRODUCING
   TORNADOES...LARGE HAIL AND WIND DAMAGE THROUGH SATURDAY EVENING. 

As the figure at left indicates, the area with the highest probability of severe weather includes the Talladega racetrack. This is a prediction from NOAA, which is about as good as it gets when it comes to weather

For every Jim Cantore you see standing out in the middle of a tornado or hurricane showing people how bad the conditions are and why no one should be outside, there are a hundred meterologists at federal agencies and TV stations poring over the output of their models, trying to figure out which model is most correct so that they can give the maximum amount of warning to the areas that are in danger.  Even though we can’t pin down the location, if you are or are planning on being out at the track, take this seriously and be careful.

Some Myths Debunked

• Opening windows does nothing.  Yes, the pressure may drop outside, but it is almost impossible for the pressure differential to be so great as to cause the house to “explode".  There is actually evidence that opening windows is worse in terms of damage to the house.  If it’s a really serious tornado, it is going to do some damage and it is not going to care whether your windows are open.  (A tornado also can’t lift up your house and deposit it in Oz, but it gave me an idea for a funny story that involves Kevin Harvick as Dorothy and the media as the Munchkins.)
• Highway overpasses are not safe places during a tornado.  Steel-reinforced concrete is strong, but not stronger than a tornado.  If the overpass is hit by a tornado, it can fall and anyone in the vicinity is in danger of being hit by debris.  If you think about it, the area underneath an overpass basically funnels all the wind through that area, so you are in much more danger being under an overpass than you are in your house.
• No geographical feature protects you from a tornado.  They go over the river and through the woods, through cities, over hills, and basically wherever they care to go. Lying in a ditch is the best thing to do if you’re outside, but it is much better not to be outside.
• Motorhomes and RVs do NOT cause tornadoes; however, you are much more likely to be injured by a tornado or high winds in a RV or motorhome than you are in a permanent structure.

What to Do

What you SHOULD DO, especially if you are out at the racetrack:

• If you’re at home and planning on heading for the track, listen to the radio to make sure activities haven’t been delayed or cancelled because of the weather.
• Have a weather radio with fresh batteries and spares.  Listen to the weather, watch it on TV, and be aware that you may need to take action on short notice.
• If you’re camping or RV’ing, have a flashlight and emergency kit that includes the basics, like bandages, antiseptic, etc.
• Make an emergency plan for your group - identify two places to meet if something happens and you are separated.  One place should be near your campsite or seats and another should be a little further away, to be used if there is damage to the first area.  Cell phone lines often become overloaded during emergencies, so don’t count on being able to reach each other on the phone.
• Don’t get falling down stupid drunk.  You may need to think quickly.  Wait until after the storm warnings have expired to enjoy the special pleasures of Talladega.
• If you hear sirens or radio/television reports that a storm is coming, get into a permanent structure if at all capable.  My guess is that the safest place at Talladega if you’re out camping is in a ground-floor bathroom in a concrete structure.   Like being on an airplane, identify two such structure because there are likely to be a lot of people with the same idea you have.  If you can get underneath something heavy, like a sturdy table, a workbench, or anything else that would protect your head from falling debris, that’s even better.
• Remember that NASCAR fans share a unique bond that makes us more like family than strangers, even if we’ve just met.  If someone needs help, help them – even if they are wearing a xx t-shirt (where xx is your least favorite driver’s car number).

I do not envy the folks at Talladega trying to guess the best way to proceed.  I was at Richmond two years ago when there was a hurricane.  The race was cancelled the day before.  It was beautiful in Richmond that Sunday, but there was a lot of damage on most of the routes leading to the racetrack.  NASCAR will probably get criticized no matter what they do, but I liked Jim Hunter’s attitude.  “There’s a chance of bad storms, but there’s also a chance of Sun."  Let’s hope for the Sun this weekend.

I’ve gotten a couple questions about why it takes so long for a track to dry and why humid weather should make a difference, so here’s a short explanation.

Air is a mix of gas molecules:  mostly (78%) nitrogen, about 21% oxygen, the rest misc. gases.  The composition is pretty uniform with the exception of how much water there is in the air.   The absolute humidity is the amount of water in some chosen volume of air, for example, how much water vapor is in one cubic meter of air.  Air can only hold so much water vapor and that amount depends on the temperature and pressure.  Dry air would be no ounces of water in a cubic foot of air.  If the vapor is saturated at 30 degrees centigrade (86 degrees Fahrenheit), then the amount of water could be up to three one-hundredths of an ounce of water per cubic foot.

The mechanisms we use to get rid of water on the track are evaporation and possibly boiling.  Evaporation is the same mechanism we use to dry dishes, or even ourselves when we get out a pool and just let the sun dry us.  Evaporation is a liquid changing into a gas.  Boiling is also changing a liquid from a vapor to a gas, but there’s a difference.  Evaporation happens at the surface of a water drop.  Only the outermost few water molecules change from liquid to gas.  Boiling affects the bulk of the water drop.

Regardless of whether we’re talking evaporation or boiling, the water on the track doesn’t exist in a vacuum.  There’s that water vapor in the air.

Nature likes equilibrium.  Equilibrium is when things are equal and concentration is one property that can be equal.  If you pour a glass of red dye into a fish tank full of clear water, the red dye molecules will spread out and uniformly distribute themselves throughout the fish tank.  (Don’t try this if there are fish in the tank, please…)

So we have water molecules in the water drop – a lot of water molecules – and water molecules in the air.  The concentration of water molecules in the air is smaller than the concentration of molecules in the water droplet, but it can vary depending on how humid it is.  The picture below schematically shows three situations in which there are increasing amounts of water vapor in the air surrounding the water drop. The darker the green, the higher the concentration of water molecules.

Nature likes equilibrium, so it would like to have the same concentration of water molecules everywhere.  The rate at which it can move water molecules from the water drop to the air is proportional to the difference in concentrations.

If you have really dry air, there is a big difference in concentrations, and the water from the droplet moves into the air faster.  Have you ever hung your swimsuit out to dry on the balcony of a Florida hotel in July?  It takes forever to dry because the air is so moist.  There isn’t a huge difference between the concentration of water in the air and the concentration of water in the water drop.  If it were relatively dry and we had a rainfall, the track would dry much more quickly than it would with the current conditions:  the humid air is already pretty saturated - relative humidity is how close we are to totally saturated and the numbers have been around 90%.  100% relative humidity means that you absolutely can’t put any more water vapor in the air, so it would take a very, very long time to dry the track.

The jet dryers are literally jet engines trained on the track to speed up evaporation.

The heat from combusting jet fuel is used to dry the track.  The temperature of the combustion fuel is on the order of 1100 degrees F, but it cools pretty quickly as it leaves the dryer (that’s why the jets are so close to the track surface.)  I was trying to get a good number for the temperature of the exhaust, but I haven’t had luck with that.

The numbers I did get (thanks to Jeff Gluck and Nate Ryan) are that they have eight jet dryers.  Each dryer will operate for 50 minutes on 175 gallons of fuel, so if you had all eight jet dryers and it takes 150 minutes to dry the track, we’re talking about

They have over 20,000 gallons of jet fuel available at TMS, which is really good because it looks like they are going to need it.  I noted in a previous post that the Cup race uses somewhere around 5,700 gallons of fuel.  By the time we’re done with the races Monday I suspect we will have used at least double that in jet fuel just trying to dry the track.

I’ve been looking in to why it is so hard to make asphalt that dries faster and it looks like there are some physical laws that make it difficult - more on that after I get in touch with some sources Monday.