Proceedings of the Institution of Mechanical Engineers,Part P: Journal of Sports Engineering and Technology

The majority of outdoor sports surfaces are natural turf and they remain the elite-level standard for a number of sports. A natural turf surface is susceptible to environmental and physical stress and has a limited resistance to wear. A number of technological advances have increased the quality and durability of natural turf surfaces including: sand rootzones; drainage; irrigation; agrochemicals; turfgrass breeding; turf reinforcement; supplementary lighting; ventilation; and advanced stadium architecture. These advances have resulted in an increase in resource consumption and where resources are restricted natural turf viability, performance, and safety is limited. This paper examines these challenges and others facing natural turf by reviewing the state of the art and signposting future research required to ensure performance, safety, and sustainability from natural turf surfaces. More development is required for lower-cost technologies for recreational-level facilities. Synthetic turf surfaces can be used to reduce the intensity of use of natural turf but sustainable natural turf construction and management must focus on resource consumption reduction and resilience to climate change for the continued provision of high performance, safe surfaces for sport. Furthermore, greater user-awareness of resource consumption and the consequences of reduced consumption are important for adoption in the future of more sustainable practices.

The aim of this paper is to report the inter-rater reliabilities and intra-rater reliabilities of the Clegg hammer, penetrometer, and studded-boot apparatus used for measuring the mechanical properties of natural turf, and to determine whether the level of experience influences the reliability. Three experienced and three novice testers measured the surface hardness and rotational traction at nine locations on a community-level Australian football oval. A repeated-measures analysis of variance tested for significant differences between the six testers for all equipment, and intra-class correlation coefficients (ICCs) were calculated to determine the inter-rater reliabilities and intra-rater reliabilities. The ICCs for the reliability between the six testers ranged between 0.77 and 0.87 for the Clegg hammer, ranged between 0.55 and 0.73 for the penetrometer, and equalled 0.51 for the studded-boot apparatus. The inter-rater reliabilities and intra-rater reliabilities were greater for the experienced testers than for the novice testers for the Clegg hammer and penetrometer but the novice testers produced greater inter-rater reliabilities for the studded-boot apparatus. This study highlights the potential variability that can exist between testers using the ground hardness and traction equipment, which has implications for future research involving multiple testers both in agronomic-based studies and in linking the surface properties to the injury risk across multiple venues.

As the popularity of infilled synthetic turf continues to increase, concerns over potentially negative impacts on the health of field users have arisen. One of the main health issues on synthetic turf fields is high surface temperature, which can contribute to physiological stress of athletes and can cause serious heat-related illnesses. At The Pennsylvania State University, various methods to reduce surface temperatures have been evaluated including irrigation, covering the surface with a tarpaulin, and amending infill with calcined clay. Many of the regimes tested were initially successful in lowering the surface temperature to that of natural turf grass; however, these low temperatures could not be maintained for periods of time equal to the length of standard sporting events. Another issue that has received attention is the possibility of athletes contracting bacterial skin infections, specifically those caused by Staphylococcus aureus bacteria. Infilled synthetic turf has been targeted as a potential source for harbouring S. aureus bacteria. A survey of 20 infilled synthetic turf fields was conducted to determine microbial population and presence of S. aureus bacteria. S. aureus colonies were not found to be present on any field; however, S. aureus colonies were found on other tested surfaces, including blocking pads, used towels, and weight equipment.

The traction forces produced between an athlete’s footwear and the playing surface are a crucial factor influencing a player’s performance. Four primary factors affecting traction have been identified from literature: the sports specific movement, the footwear, the playing surface, and the environment. Many authors have investigated traction behaviour mechanically, using a variety of shoe and surface types, concluding that the traction generated at the shoe–surface interface is dependent on each shoe–surface combination (see work by Gheluwe et al., Cawley et al., and Villwocket et al., details given in main text). There has been little attempt in the literature, however, to try and explain the behaviour of the surface from the traction resistance measurements that were observed, perhaps owing to the complex number of variables involved. Furthermore, the variety of methodologies used in past research makes it difficult directly to compare datasets. This paper presents datasets comparing the traction behaviour of several carefully prepared surface systems and states, using three mechanical test procedures, and investigates the factors influencing traction resistance. Results highlight that properties of synthetic turf carpets (fibres and tuft spacing) and the density state of the crumbed rubber infill component and the stud size and configuration influence the maximum traction forces generated at the shoe–surface interface. The magnitude of stud penetration under controlled vertical loading is also presented. The findings of this study further demonstrate the importance of understanding the detail of the surface system under test, and that the infill state has a measurable effect. The design and operation of mechanical traction measurement equipment also demonstrates influences on the traction values measured, and the largest influence is the normal load applied. The FIFA standard test is shown to be less sensitive to infill state than other tests. Recommendations are made for more robust testing methods for future research.

This paper sets out to capture the recent discussions on maintenance ‘best practice’ for artificial turf surfaces and some related research. The information presented comes partly from a seminar in 2009, providing a mix of quantitative and qualitative information and opinions from a range of contributors both academic and industrial organized by the research network SportSURF (based at Loughborough University), and is supplemented with a case study of practices at Loughborough University on three different outdoor synthetic surfaces. The best practice information is further enhanced with recent research findings from a study investigating damage to artificial carpet fibres caused by power brushing.

The outcomes of the maintenance seminar showed a good consensus for aspects of the most relevant type and frequency of maintenance tasks, with a useful rule of thumb for pitch managers of one hour of maintenance for every 10 hours of use of the surface system. Maintenance costs for artificial turf has traditionally been marketed as being ‘low’, but the data show costs per annum should be expected to be similar to natural turf but when expressed as a cost ‘per hour of use’ then the relative cost to be much lower for artificial turf than natural turf. Damage caused by power brushing, from a short laboratory study, was found to be minimal in terms of fibre splits or breaks for three (standard) brush systems of varying stiffness and for three different carpet systems (both sand and rubber infill systems).

This paper collectively provides an advance in the knowledge and debate for the specialist practice of artificial surface maintenance, currently under-researched and poorly disseminated.

Third-generation artificial-turf pitches are often criticized because of their high abrasiveness when athletes fall on the surface, the high temperatures recorded in summer periods, and their unpleasant rubber odour. On the other hand, natural-turf pitches are not able to withstand the high play volumes currently associated with modern high-profile and community sports pitches. Hybrid systems with a varying presence of artificial fibres and reinforcements have long been tested and installed, without providing a definitive answer to the above-mentioned problems of natural turf.

The aim of this study was to evaluate the playing characteristics and the wear resistance of a newly patented hybrid natural-artificial sports pitch construction system after rugby and football play for 2 months and 5 months. This hybrid system consists of a modified third-generation artificial grass with organic infill, on which natural grass was allowed to grow.

A 11300 m² experimental pitch was constructed in Pisa (Italy) in the summer of 2007 and tested during 2007–2008 following football and rugby union play for an average of 8–9 h/week. The hybrid pitch showed a total absence of rubber odour, summer temperatures similar to those of natural-turf pitches, wear resistance superior to that of natural-turf pitches, abrasiveness similar to that of natural-turf pitches, and good infill particle size stability. Most playing-quality parameters fell within both the Fédération Internationale de Football Association (FIFA) Recommended 2-Star Standard requirements for artificial turf and generally accepted playing-quality parameters for natural turf. Since then more pitches as described herein have been constructed and witnessed international match play, while FIFA has classified the system as a reinforced natural-grass pitch.