The Science of Horse Racing: Track Surfaces

October 19th, 2022

Ah, the racetrack. As fans gather on the apron and in the grandstand, checking out the day’s entries and preparing for more visits to the betting window, they tick through their list of considerations for the entries they may wager their dollars on. One factor lays before them as they plan: the racetrack.

Whatever the surface, understanding what that track is made of can add to your toolbox as you plan your next day at the windows. This month’s Science of Horse Racing considers the three types of surfaces and how weather and geography play into our understanding of how horses race over those tracks.

Dirt, America’s First Surface

The United States is home to more than seventy racetracks from coast to coast, with many featuring more than one type of running surface, usually dirt and turf. Most of the country’s famed stakes races are contested over dirt, which has long been the surface of choice for Americans. The composition of dirt tracks, though, varies from region to region.

Dirt has long been the preferred surface because it is easier to maintain and tends to be more predictable in terms of performance and pace. It is also friendlier to speed and produces faster times than other surfaces. However, if the dirt surface is not properly treated, if it is too loose or too compacted, that can factor into a horse’s performance. Fast means fast, right? A track can be fast, but moisture composition can affect how the surface gives under a horse’s hoof. If it is too loose, it can become cuppy and slow down the field. If it is too compact, it can become slick and hard to grip, increasing wear and tear on horses.

Rainfall can change the track surface quickly and racetracks must take care to keep their dirt courses usable while also considering long-term upkeep. On especially wet days, you might hear that a track has decided to seal its dirt surface; when they do, maintenance crews will compact the top layer, which allows water to skim off the top instead of soaking into the dirt. This prevents the track from becoming soupy and difficult to navigate. What that dirt track is made of, factors, into the decision racetracks make whenever inclement weather is in the forecast.

At California’s Del Mar, for example, the dirt track starts with a sub-base with drainage system running through it, overlayed with a compacted and decomposed granite base, and then a 10” layer of El Segundo sand. At Keeneland in Lexington, Kentucky, the track is laid over buried drainage pipe with a layer of dense-graded aggregated base, 2” of drainage stone, porous asphalt, limestone screenings, and then 6” of dirt surface comprised of sand, silt, and clay. Their respective compositions differ because of their geographical locations, which influence not only available materials but also weather conditions.

Alongside their dirt courses, many American racetracks also have a turf course, offering owners and trainers more than one option for their horses. 

Canterbury Park dirt horse racing scene (Photo by Coady Photography/Canterbury Park)

The Green, Green Grass

As with dirt, turf tracks have a basic composition: base, subsurface, and then the layer of grass on top. The type of grass each track uses differs based on location and climate. Del Mar uses Bermuda grass over a 9” sand base with a fiber-reinforced subsurface and a compacted sub-base while Churchill Downs’s new turf course is a mixture of fescue and bluegrass over topsoil and grit sand with a six-inch layer of masonry sand. Keeneland uses a rye, bluegrass, and tall fescue combination for their inner turf track.

Turf tracks require more maintenance than dirt or synthetic. If the surface is wet or yielding, a horse’s hooves dig deeper into the course, which can chop up the grass and make the surface uneven. Some tracks do not run turf races during the winter months; in New York, snow and cold temperatures can make it difficult to control the turf’s condition, limiting their ability to use those tracks during that season.

As turf courses absorb moisture, their conditions change from firm, or dry, to good, yielding, or soft. Racetracks use tools like a penetrometer to assess a course’s current state. That tool measures the firmness of the ground underneath the grass to grade its status. If the surface is carrying a lot of moisture, the grass will yield more easily than a drier track. Hooves will dig into the turf, causing divots and other irregularities. Tracks will move their turf course’s rail in or out to help with maintenance, keeping horses off sections which need time to recover from previous races.

Turf courses tend to be easier on horses physically, with the grass cushioning the impact of their footfalls and generally causing less kickback than on a dirt surface. Because of this cushion, turf races tend to be somewhat slower than dirt by comparison, with this surface friendlier to come-from-behind running styles. Additionally, some horses who perform well on the grass can also take that form to our last type of racing surface, synthetic.

Churchill Downs turf racing (Coady Photo/Churchill Downs)

Tapeta, Polytrack, Synthetic, Oh My!

The term synthetic or all-weather encompasses more than one type of track: Polytrack and Tapeta are two options, offered by private companies like Martin Collins and Michael Dickinson’s Tapeta Footings. Synthetic had its heyday in the mid-2000s, but tracks like Santa Anita and Keeneland have returned to dirt after trying an all-weather surface for a few years. However, Woodbine, Gulfstream Park, and Turfway Park are among those that still use a Tapeta surface while Polytrack is more commonly found in England.

The top layer of all-weather tracks is layered over a porous asphalt or geotextile membrane with a gravel base laid on top of a drainage system. The difference between these tracks lies in their surface composition. Polytrack is made up of silica sand and fibers comprised of recycled carpet, spandex, and rubber while Tapeta is a sand and rubber fiber mixture. Both surfaces are then coated with wax. Synthetic surfaces are made up of porous substances that allow water to drain more easily than dirt or turf might, making these types of tracks ideal for climates which get a lot of rain or harsher winters, which would exclude turf for a portion of the year.

Each surface has a different affect on a horse racing over it. Dirt might have a harder impact on the hooves and legs while turf might tire a horse faster because of the give in the surface. All-weather racetracks do have their detractors: some trainers complained that the tracks clumped too much during the heat of summer and became waxy during the winters, with kickback that their horses did not like.

Souper Sensational winning the Glorious Song S. at Woodbine (Michael Burns Photo)

Thinking Tracks

As bettors, you might be more accustomed to wagering on dirt and turf than on synthetic. Some horses like Caravel, a stakes winner on both turf and synthetic, can transition between those two surfaces with little change in form. Occasionally, you will find a dual surface horse that can race and win over both dirt and turf, as both Yoshida and Catholic Boy did. If you are wagering on a track with a synthetic surface, researching what to expect for horses making the change from dirt to synthetic or from synthetic to turf will be an asset to your wagering day.

Understanding not just the track's conditions, but what the tracks themselves are made of can also become an asset to your handicapping. Tapeta or turf, California or Kentucky, this kind of knowledge can help you capitalize on your bankroll next time you place that big bet at the windows.

Image Gallery: Wise Dan won on every surface, from both Poly Track and Tapeta synthetic to both turf and dirt - including the Clark Handicap at Churchill Downs.