Author ORCID Identifier

Date Available


Year of Publication


Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation


Agriculture; Engineering


Biosystems and Agricultural Engineering

First Advisor

Dr. Michael L. Peterson


Minimizing catastrophic injuries to racehorses, which also protects the riders, is critical for the future of the Thoroughbred racing industry. While the causes of catastrophic injuries are multifactorial, the condition of the racing surface is one of only a few factors that affects all horses in competition. Horse racing surfaces must retain enough shear strength to support the hoof of a Thoroughbred at a gallop. Turfgrass racing surfaces also require healthy turf to reinforce the footing while also achieving a high infiltration rate to allow races to run on the turf soon after or even during rain. This research is an investigation of current and potential future turfgrass soils at North American racing surfaces. The goal is to provide a consistent surface to support the horse and to help protect the horse and rider.

Laser diffraction was used to determine the particle size distribution of soils at 23 turf racing surfaces in North America. Laser diffraction was able to characterize the mean values of a racing surface’s particle size distribution and detect differences between racetracks with samples as small as 0.25g. The use of small samples minimizes safety concerns since removal of the sample causes minimal disturbance of the racing surface. This research can help select topdressing and divot mix materials. Potential problem areas in active turf racing surfaces can be investigated with samples as small as aeration cores removed as a part of normal maintenance. Baseline data has already been used to help guide profile selection for construction and renovation projects.

Simple tools suitable for daily use were evaluated against the Orono Biomechanical Surface Tester (OBST). Analysis was performed on test plots which simulate current and potential future fiber reinforced North American racetracks. The study establishes correlations between simple tools and the biomechanically based OBST measurements used for pre-meet inspections. Volumetric moisture content is the most important simple tool and it is well suited for daily measurements at racetracks. The Longchamp Penetrometer, which has an established correlation to horse performance and injuries, can be used to supplement the moisture meter. The inclusion of surface data in epidemiological models has the potential to increase our understanding of the contribution of the racing surface to the risk of injury as well as guide racetrack personnel and regulator decisions on race days.

Soil meeting the recommended profile for golf course greens was tested using triaxial shear. Three different types of fiber reinforcement were considered: no reinforcement, synthetic fiber reinforcement, and natural fiber reinforcement. Fiber reinforcement is the most promising method of modifying soils of this type to produce the shear strength required while maintaining a free draining racing surface. Natural fibers are a promising alternative to the synthetic fibers currently used. These materials avoid the introduction of microplastic into the environment and could reduce the need for aeration of older turf surfaces. Natural fibers are also promising for use in divot mixes in surfaces without fibers since the fibers decompose as the turf root system develops. Both synthetic polypropylene as well as jute and sisal natural fiber reinforcement increase the friction angle and reduce cohesion which makes the free draining soils more suitable for Thoroughbred racing surfaces.

This dissertation provides a better understanding of current and potential future soils used in turfgrass Thoroughbred racing surfaces. Methods which can be used to monitor surfaces both with and without fiber on a daily basis have also been established. The effect of appropriate fiber reinforcement is that even free draining soils may provide sufficient shear strength for Thoroughbred racing which will allow more races to be held on turfgrass racetracks.

Digital Object Identifier (DOI)

Funding Information

This research was supported by the Central Appalachian Regional Education and Research Center through the National Institute for Occupational Safety and Health/US Centers for Disease Control (NIOSH/CDC) Grant 6T42OH010278. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIOSH/CDC.