GROUND MATTERS: GOD'S DIRT VERSUS MAN-MADE SYNTHETIC
Part 3 - Synthetics versus Dirt: The Pros and Cons
The advent of synthetic or “all-weather” track surfaces first appeared in Europe where they have long been used for training purposes as well as selected racing events.
Ironically, in North America the first synthetic track to be used for thoroughbred racing was not a replacement for traditional dirt but rather turf (grass) in 1966 at Tropical Park in Miami Fla. 
Over the ensuing years and up until the 2006 directive of the CHRB (California Horse Racing Board) only a single track in NA was converted from dirt to synthetic.
In 1988 Remington Park in Oklahoma City installed a surface called “Equitrack” yet this proved to be unsatisfactory and was replaced with a conventional dirt surface in 1991 due to maintenance issues and criticism from those in the racing circuit. 
In less than three years the polymer-based Equitrack began to disintegrate or “melt” creating considerable maintenance difficulties while the loosened track base was easily kicked up during races and subsequently inhaled by the horses causing respiratory illnesses. 
While there are many notable races held on turf (grass) tracks in NA the heated topic of traditional dirt versus synthetic all-weather track surfaces is the focal point of much controversy amongst disgruntled players in the industry.
Despite the fact that a synthetic track is alleged to confer a more forgiving surface in the interest of equine safety, many believe this is simply a hoax to divert suspicion away from the causal rationalization for the unacceptably high number of catastrophic breakdowns witnessed on NA tracks each and every year; most notably inbreeding and drugs.
Then again some are fervently convinced of their attributes and still others simply despise them as they factor into how a horse runs and ultimately displace customary betting methodologies.
Insofar as the number of tracks in NA that have installed synthetic surfaces it is, to date, only a scant handful compared to the total number of tracks in the whole of North America. A search on the Internet of the estimated 100 or more tracks in NA in operation pins the number of synthetic tracks at a paltry nine.
Moreover, one of these tracks (Santa Anita) has returned to dirt after issues encountered with two different types of synthetics. How representative or enabling of a true assessment of positive contributions is this given that these tracks characteristically are noted for “prominent” racing events?
TABLE 1. NORTH AMERICAN RACE TRACKS WITH SYNTHETIC SURFACES
Potentially it follows that because they are under the microscope, and the whole racing world is watching, the efforts to maintain these tracks may surpass those taken for their dirt counterparts at other racing venues. In consideration of the propaganda surrounding catastrophic injuries and the stigma attached to the perceived inability of the racing industry to address the concerns of the public’s opinion and overall negative assessment of the integrity of its intentions this only adds to the complexity of sifting out the pros and cons of synthetic over dirt surfaces.
In any case, differences between the two surfaces are numerous from a consistency perspective as well as the mechanics and interaction of the horse’s hoof with the track. Overall dirt tracks are the preferred economic option, relatively easy to maintain and provide more slip and slide such that races tend to be faster compared to a turf or synthetic surface which tends to “grab”. In other words dirt equates to speed.
The negative aspect of dirt lies in its failure to “give” and subsequent lack of shock absorption which puts tremendous stress and strain on a horse’s legs. Given that horses can reach speeds of up to almost 40 mph during a race together with the fragile structure of their distal limbs any stress exceeding a critical threshold may result in catastrophic injury. Apart from acute overload which results in abrupt traumatic failure, injuries can also occur as a result of chronic repeated minor overload. 
However, as the Jockey Club “Racing Surfaces” White Paper clearly underscores, the factors contributing to risk of injury are numerous, complicated and span across several intervening categories as shown in Figure 1.
A pathway from track properties as a risk factor to the desirable outcome of prevention of injury, via the postulated mechanical underpinnings of the causes of injury, and relevant feature of injuries once they occur.
“Optimization of surfaces alone will never eliminate catastrophic injuries, and may not even be a primary factor in most injuries. However, the absence of well accepted characterization methods and basic science of racing surfaces is a significant obstacle to improved performance and safety. A critical aspect of the effort to improve surfaces is looking at the factors of which control the performance of racing surfaces in the context of the relevant biomechanics, the different types of surfaces, and potential testing and maintenance strategies.” 
In contrast to dirt, synthetic tracks or “engineered surfaces” were designed to allow for improved shock absorption and “give” which in theory translates to diminished trauma to the distal limbs and overall reduction in catastrophic injuries. Apart from the objective of decreasing the risk of injury, synthetics were also predicted to eradicate some of the persistent issues that beleaguer dirt surfaces such as compaction, inadequate drainage, irregular surfaces and variations involving weather and temperature.
Currently there are several types of synthetic surface materials (refer to Table 1) all essentially combinations of sand, polymer oils, plastics in various forms, fibers of varying types, rubber compounds as well as waxes and binding agents. 
Designed with a base of gravel and porous asphalt the drainage system helps repel water and decreases the amount of rainwater held within the track surface which typically plagues dirt tracks during intense periods of rain. A cross section of a typical synthetic track surface and drainage system is shown in Figure 2.
FIGURE 2: Cross Section of Typical Synthetic Track Surface
There appears to be no skepticism that synthetic tracks have a clear advantage in terms of drainage. Since water is drained vertically downward from the surface, sloppy conditions are avoided allowing the track to remain open for scheduled training and racing venues. Consequently field size and handle are largely unaffected. By contrast it is often necessary to “seal” conventional dirt tracks by packing the surface down with heavy rolling equipment to prevent water from penetrating the surface.  This influences track consistency and has the potential to decrease field size which affects the betting handle negatively. The norm is that more money is wagered on races when the field size is larger hence the dryer synthetic surfaces decrease the number of horses scratched under inclement weather and track conditions.
“California racing figures to be the biggest benefactor of increased field sizes, because of anemic numbers over the past decade, seasonal considerations, and the artificial surfaces that now make it a much more attractive winter destination for East Coast trainers, who previously shunned sending horses out west because of California’s reputation for hard, fast racing surfaces.” 
However, whatever positives the dryness factor contributes, synthetic surfaces are not without other climate–related issues, principally temperature fluctuations.
The cold . . .
“But as we got to October and cool weather, we started to see some separation of the sand away from the rubber and fiber, and the wax away from the sand. The fiber began balling up and the surface could not be compressed. It was like pushing down on a bag of feathers. We had trouble working the track, and it began behaving like a cuppy dirt track, which was not as advertised.”
The heat . . .
“Then, in the hot weather, we had to fight it from being too hard. The wax seems to get more viscous in hot weather and the track presses down, and you have to dig it up and roto-till it enough to keep some give in it.
Changing seasons . . .
“It requires attention to the elements, especially temperature and moisture. We race in 95-degree weather with 90% humidity in September, and in five-degree weather with blowing winds in the winter, so you must take steps to anticipate what’s coming and keep track of how the surface behaves. We’ve had to modify the surface from its original mix toward that end, laying down more of an oil-based wax” to keep the ingredients from sticking, or balling up, in horses’ hooves.” 
Clearly synthetic tracks are a work in progress nevertheless the anathema expressed by some in the industry often defies logic.
Synthetics are also proving to be a steep learning curve for many track superintendents where promise of less maintenance and consistency was originally acknowledged. Not only are these engineered surfaces prone to seasonal changes in the quality of the surfaces but also daily fluctuations in temperatures. 
Disparities in surface conditions between morning training and work-out sessions and races in the afternoon can negatively alter a horse’s performance simply due to the fact that essentially they are running on two different tracks – horses thrive on consistency just as their owners, trainers, jockeys, bettors and fans do.
Furthermore, many believe that a properly maintained dirt track can be equally as safe and consistent as the synthetics and vehemently communicate this conviction in their eagerness to convert back to conventional dirt. The conversion of Santa Anita’s dirt to Cushion Track to ProRide then back to dirt in late 2010 serves as a prime example.
"The study indicated the Pro-Ride surface in three years had developed a hard pan layer on top and that rocks were protruding the upper layer. The track also lost 16 days of racing over the last two winters because the synthetic surface didn’t properly drain.
"Worse, the synthetic track became a polarizing subject in the industry. Owners and trainers with talented horses refused to train or race their horses on it. Hollywood Park and Del Mar will continue racing on their synthetic tracks, but the return to dirt — actually 86 percent sand, 8 percent clay and 6 percent silt — at Santa Anita has owners, trainers and jockeys excited. They’re all hoping the betting public embraces it." 
The new dirt track at Santa Anita consists of less clay than the original “hard” surface that races took place on prior to the installation of the synthetics and very similar to the dirt tracks at venues such as Churchill Downs, Gulfstream, and Saratoga giving rise to greater safety for the horses. Dr. Mick Peterson and Santa Anita Park track superintendent Richard Tedesco both suggest that consistency and maintenance are of greater consequence than the type of surface.
“Injuries to horses can be reduced on dirt and synthetic surfaces, they said, if tracks can use data to assess their surfaces and keep them consistent through weather changes and amount of traffic.” 
Other recurring issues with synthetics are the tendency to wear out very quickly and the difficulties related to restoring them to their original condition. Besides the high price tag of initial installation, the outlay of upkeep over the longer haul may prove costlier than traditional dirt. Moreover, how does a degrading synthetic track bode in terms of safety to both horse and jockey alike?
“The problem is that the early promises of minimal maintenance have proved to be a little too rosy, and the cost of $6 million to $10 million for tearing out dirt and replacing it with the artificial surface can be prohibitive.” 
In the end, as with anything novel, there is a wealth of information regarding the shortcomings of these all-weather tracks as a result of the North American insular mindedness and steadfast conviction that dirt tracks are paramount to maintaining tradition. Or perhaps more intuitively it is fear of the unknown.
And, while it is true that synthetics were promoted as the panacea for the NA horse racing industry’s woes but have not lived up to this lofty claim, recent data from the NA Equine Injury Database show promising trends. The question is whether these data are statistically significant, whether they are collected without bias and whether they are free of confounding factors that may host a flawed representation of the facts.
A look at the latest safety statistics, methods of collection and current opinions from those within the North American racing community will offer some compelling insight.