Football Field

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Football & Rugby Field Design

Survey and Layout
The basic design process for a football field is obviously simpler than that encountered in baseball; the field is a rectangle, either 120 yards long (in the United States), or 160 yards long (in Canada). Field widths vary somewhat, but the official size for American high school, college, and professional football is 160 feet, and Canadian fields are 195 feet (65 yards) wide. In thinly-populated areas of the West and Southwest, many high schools play six and eight-man football, with the standard field size of 100 yards long (80 yard playing area plus two 10-yard end zones) and 40 yards wide.
 
The majority of football fields are laid out along a north-south axis, and crowned longitudinally down the center of the field, to promote surface drainage toward the sidelines and away from the part of the field subject to the greatest mechanical stresses. However, there are many fields in use which are flat and sloped to one side so that the entire playing field drains in a single direction. If the topography of the area lends itself better to a flat field sloped in one direction, such a field can be perfectly serviceable. A problem with this type of field is that someone may get the idea of "increasing the crown" on a field to improve drainage, not realizing that there is no crown there in the first place. Under these circumstances, raising the center of the field has the same effect as building a dam down the middle of the field. By restricting the flow of water, crowning an uncrowned field can turn the uphill half of the playing surface into a swamp.
 
12.2b Design Criteria for New Construction
 
The degree of slope should be from 1% to 1.75%. Fields sloped at the low end of this range may also need installed drain systems to speed up the movement of water.
 
Another equally basic question which must be addressed before designing a football field is the way it will be used. Because of the stresses placed on the turf by football competition, nearly all teams maintain separate practice and game (or "stadium") fields. Game fields must be designed to be durable enough to support game competition (usually by one to three teams playing five or six games a season), plus a few practices held on the field to allow the team to become accustomed to the surroundings. Game fields are also meant to be as aesthetically pleasing as possible, since football is the leading outdoor spectator sport at most high schools, colleges, and universities.
 
Practice fields, on the other hand, are designed to be safe, durable, and economical to maintain. Under such circumstances, flat sloped designs may frequently prove to be a better choice than crowned facilities, and the natural slope is normally more economical than a crowned field with catch basins or other drainage structures in place. As with a game field, the degree of slope should be between 1% and 1.75%.
 
Ideally, of course, practice fields should be laid out and lined on the same dimensions as a game field, to allow players and coaches the advantage of practicing under the most realistic possible conditions.
 
Safety Issues
The violent, high-speed collisions characteristic of adult football raise several important safety concerns. First of all, because of the popularity of the sport with spectators, many fields have traditionally been built with some form of barrier between the playing area and the grandstands. If such barriers are necessary, they should be placed well back from the sidelines, at least 20 to 25 feet away. Even at that distance, athletes running across the sidelines at top speed on wet turf may be unable to stop before reaching the barrier, so player safety should be a major concern in barrier design.
 
Figure 12.1.
Crowned field with level sidelines--elevations noted in feet.
 
Player momentum can also be a concern at the end of the field, commonly referred to as the "back of the end zone." Particularly on passing plays, a receiver may be moving at top speed when he crosses out of the field of play, so allowance must be made for stopping room in that distance.
 
12.2c Field Designs with Preferred Contours
 
Generally, field designs for surface drainage fall into one of two categories: a crowned field with level sidelines (see Figure 12.1), or a flat field sloped side to side (see Figure 12.2).
 
(Flat and level fields, which are designed to drain internally, are discussed in Chapter 24, Sand and Sand-based Fields.)
 
Probably the most common type of field is a crowned field with level sidelines. While this is a relatively easy design to build, and one which drains fairly efficiently away from the center third of the playing area, it ha a couple of limitations. First of all, the area where the crowned field meets the level sideline can turn into a wet spot. That creates a hazardous area in exactly the spot where players may be trying to execute maneuvers that require good footing--like catching passes while keeping feet inbounds, or stopping quickly to avoid contact with players and coaches.
 
The second problem with the level sidelines arises from the increasing popularity of soccer as a high school and college sport. Many schools use one game field, and extend the width of the football field for soccer. Unless there is consistent slope through the sideline area--which tends to get badly torn up by foot traffic at the football field bench area--the outer edges of the soccer field can become a quagmire (Figure 12.3).
 
Figure 12.2.
Flat field sloped side-to-side--elevations noted in feet.
 
Figure 12.1 shows a contour plan for a crowned football field. (Note that this plan shows a field that is built by cutting at the top of the diagram and filling at the bottom, as when a field is built on terrain that originally sloped top-to-bottom. This design shows a swale at the top draining to right, with catch basins at the left and upper left.
 
The field could be built with either swales or catch basins around the entire upper side of the field.)
 
For a contour plan designed for a football field surrounded by a track, see Chapter 16, figure 16.1.
 
Side-to-side sloped fields tend to be built that way because of the demands placed on the field by the surrounding terrain. If it's impractical or too costly to build a crowned facility, the flat, sloped design can work very well. When this design is chosen, internal drainage should be installed, at least in the lower half of the field to prevent that lower portion of the field from becoming too wet.
 
Figure 12.2 shows a contour plan for a side-to-side sloped field. Like Figure 12.1, this plan assumes original terrain sloping from top to bottom of the drawing. (Note the use of catch basins outside the upper edge of the field to prevent runoff entering the field of play.)
 
Fields that are sloped end-to-end should be avoided, for much the same reason. The lower end of the field almost invariably becomes muddy as the water flows across the field to the lower end. Furthermore, the end-to-end slope tends to create the impression in players that they are running uphill in one direction and downward in the other.
 
12.2d Multiple Field Layouts
 
When laying out a complex that will have more than one football field, it's wise to leave 60 to 80 feet between fields that are laid out side-by-side, and 30 to 40 feet between fields laid out end-to-end. If there are grandstands between the fields, the distance should obviously be increased by the width of the grandstand structures.
 
Each field should be treated as an individual drainage unit, and should not be expected to perform acceptably with water running across it from adjacent fields. In laying out such fields, make sure to leave enough room outside the playing areas for cuts and fills, catch basins and swales.
 
12.2e Turfgrass Selection
 
Experience has shown that for most football fields in the warm season zone, bermudagrass is the turfgrass of choice. Bermudagrass can provide a fast, dependable surface, and tolerates close mowing favored by fast teams.
 
In the transitional zone, there is no such thing as a "best" turf choice for a football field. Bermudagrass, tall fescue, and Kentucky bluegrass can all be used, but each has obvious limitations.
 
The primary problems with bermudagrass are its winter dormancy period and the potential for winter-kill. If the turf is to be used for football only, then a cold-tolerant cultivar of bermudagrass can be used (see Chapter 1 for discussion of bermudagrass cultivars.) A bermudagrass field should maintain acceptable color in most parts of the transition zone at least through mid-October, and in some years there will be acceptable color into November. Field color can be further maintained through the use of turf paint or overseeding.
 
If the field is not overseeded, this will result in playing up to 1/3 of the schedule on dormant bermudagrass. The playing quality of dormant bermudagrass is fine, as long as the field has not receive excessive wear prior to the onset or dormancy. To promote winter hardiness, mowing height should be raised to at least 1½" prior to the first killing frost.
 
Bermudagrass fields overseeded with perennial ryegrass will maintain a green, actively growing playing surface throughout the season. To overseed a bermudagrass field in the transition zone, apply seed in early to mid-September, preferably during a break in the schedule when the field is not going to ge used because of an off-week. If there is no off-week on the field, seed right after a game and irrigate lightly and frequently to encourage rapid germination. Keep players off the field during germination (if possible), and be prepared to apply more seed the following week, particularly in the middle of the field. (Obviously, successful overseeding of transition zone bermudagrass fields requires special attention and a certain amount of good fortune regarding weather and field use.) For these reasons, overseeding is of questionable value in many situations, but if a football field will be used for spring soccer, overseeding might be the only way to have turf, rather than mud, to play on.
 
Tall fescue is also a popular choice for transitional zone fields, particularly in the northern sections of this region. The primary limitations of tall fescue are its bunch-type growth habit and the fact that it must be mowed at a height of at least 2". Tall fescue has a deep root system that allows it to come through periods of moisture stress during the summer months, but it requires supplemental irrigation to achieve its highest quality for the early season games. Tall fescue has acceptable wear tolerance, but once it is damaged it has virtually no recuperative potential and requires reseeding.
 
Kentucky bluegrass can also be used in the northern areas of the transitional zone. The biggest limitation of Kentucky bluegrass is its poor performance during the summer months. Supplemental irrigation is essential to maintain acceptable bluegrass turf for the early part of the football season. Kentucky bluegrass tolerates cutting heights as low as 1", but normally needs to be maintained closer to 2" in this area. The rhizomatous growth habit of Kentucky bluegrass results in good recuperative potential during the fall months, but reseeding will likely be needed each fall.
 
For all the difficulties in maintaining game fields in the transition zone, the problems are even greater for practice fields. The limitations of turfgrasses for the region and the great stress placed on practice fields result in even less likelihood of high turf density. Practices should be moved around the field, and the rotating use of a second practice field can spell the difference between practicing on grass or mud.
 
Maintain an aggressive N fertility program (one pound of N per 1,000 square feet per month) on bermudagrass practice fields up to the point of killing frost. Even so, heavy practice field use during bermudagrass dormancy can result in fields that are more mud than grass the by end of the season. Overseeding with perennial ryegrass can help, but it's hard to get the ryegrass established on a heavily-used field. Unless a second practice field is available to rotate practice onto during overseeding establishment, it is unlikely a dense stand of perennial ryegrass will ever be attained.
 
For cool season grasses like fescue and bluegrass, supplemental irrigation during the late summer and early fall is necessary to maintain adequate growth and development. Begin N application in late August and continue them through the football season as long as temperatures are suitable for turfgrass growth to encourage turf recuperation and increase wear tolerance. Again, an additional field to use for some practices can make a big difference.
 
In the cool season zone, Kentucky bluegrass is the preferred choice for nearly all football fields. The aggressive character of bluegrass allows the turf to recuperate strongly after stresses, and the thick thatch layer provides valuable mechanical protection for both the field and the players. From the field standpoint, bluegrass thatch prevents excessive tearing at the root structure. For the players, the thick thatch cushions falls better than other turfgrasses. In rainy weather, bluegrass thatch keeps the players up out of the mud, and allows competition to go on in relative safety.
 
Some of the more aggressive (and therefore superior) varieties of bluegrass for football fields include Princeton-104, A-34, touchdown, and Blacksburg.
 
In any part of the country, seeded fields should be allowed to establish themselves before being used for practice of football games. Despite its superior performance, bluegrass takes a year to mature. A good policy is to seed a field in the spring of the year for use in the fall of the following year. If this is not possible, it's important to allow at least one full year for the turf to establish itself before using the field.
 
Where budgets allow, of course, sodding is the best method of turfgrass installation in all parts of the country. Standard-cut sod (with ½" of soil), can be used six to eight weeks after installation; thick-cut sod (with 1½" or more of soil) can be used within a week, as long as the thickness of the product is uniform and the seams are tight. When choosing sod, specify a mature product that is held together by its own thatch layer, instead of by netting. Tall fescue sod usually needs netting to hold it together because tall fescue varieties don't produce lateral stems or a thatch layer substantial enough to hold the sod together on its own. When using tall fescue, look for the oldest, best established sod available, to ensure that the netting will be secured well into the soil.
 
Some sports turf managers in the northern zone routinely seed ryegrass into a 100% bluegrass turf before and during the football season. This practice is designed to reduce mechanical stresses on the bluegrass plants, and to take advantage of the rapid establishment rate of the ryegrass.
 
12.2f Installed Irrigation Systems
 
When designing an irrigation system for a football field, three important considerations must be kept in mind: The placement of sprinkler heads, the size of the exposed surface of the head, and the durability of the exposed components.
 
Placement of the heads should take into consideration the portions of the field where the largest number of players line up. Many designs show a five row system for football fields, with a row of heads directly down the center of the field. This design is not recommended unless the facility has sufficient maintenance resources to allow inspection of the center row of heads after every game. Figure 12.4 shows a football field with a four row irritation system, which is a better choice for fields with a limited maintenance staff. Since the area between the hash marks gets the most player traffic, the four-row design places the heads away from the heaviest foot traffic, which can damage them and create a safety hazard.
 
This design requires water pressure of 75 PSI at field edge and yields a pressure of 60 PSI at the base of the sprinkler heads. Average precipitation rate for this system will be .44 inches/hour for full circle heads, .88 inches/hour for half-circle heads, and 1.76 inches/hour for quarter circle heads. Running time for 1" watering will be 2 hours 16 minutes for full circle heads, one hour 8 minute for half-circle heads, and 34 minutes for quarter circle heads.
 
Many fields, especially in the North, have been built with two-row systems, but it should be noted that these systems will almost always require additional hand-watering at the edge of the field during dry weather. Two-row systems also have the additional drawback of watering unevenly, with the center of the field irrigated more heavily than the sides. Where two-row systems are used, the turf should also be mowed no shorter than 2" to protect the turfgrass from excessive drying.
 
Figure 12.4
Shows a four-row system, which the authors recommend to provide superior Irrigation on the entire field anywhere in the country.
 
The size of the exposed surface of the heads is also an important consideration, and smaller is obviously better. With good grass cover around the head, players should be able to step right on the sprinkler head without noticing a difference in traction.
 
In terms of durability, the heads should be designed to withstand foot traffic, and should be rated by the manufacturer as suitable for football. Heads used for football should always have a rubber cover.
 
Inspect the heads regularly (and especially those near the middle of the field) to check for damage and make sure they are seated properly.
 
12.2g Installed Drain Systems and Catch Basins
 
Most turf managers would probably agree that improved drainage would contribute more to the quality of their fields than any other factor. More than any other type of sports field, a heavily used football field with no installed drain system can quickly turn into a "mud bowl" during rainy weather.
 
Surface drainage is seldom adequate to quickly shed heavy rains. A field with a 1.5% crown takes four hours to move water from the center of the field across the sidelines. So, a driving rainstorm results in standing water--even on the crown itself.
 
Pipe Drains
The traditional type of drainage system for a football field is the pipe drain. In the past, this type of system was constructed of foot-long sections of clay tile pipe, either covered with felt paper or packed with coarse sand to prevent the system from filling up with silt and clay. The trenches in which the pipe drains are laid (usually 2 to 3 feet deep) are then filled in with gravel to a level about 6" beneath the surface.
 
Pipe drain systems with the greatest longevity seem to be the ones with a heavy layer of sand (typically 12" to 18") around the sides of the pipe. However, pipe drain systems have some inherent drawbacks that persuade the authors that they are not the ideal type for sports fields.
 
As mentioned in Chapter 8, unless they are filled to the surface with sand or gravel, pipe drain systems remove water from the subsoil at a slow, consistent rate, and may have little effect in draining the topsoil of a field. Pipe drains also have the disadvantage that soil above the gravel can become saturated before water begins to percolate into the gravel, creating a false (or "perched") water table on top of the subsoil. Pip drains also can dry out the soil immediately above the drain pipes in drought conditions. Because of the width of pipe drain trenches, filling them to the surface with sand would help drain the topsoil, but would adversely impact turf growth and traction.
 
Pipe drain systems installed today make use of more modern and more economical types of thermoplastic pipe, but work in about the same way (see Figure 12.5, traditional [pipe drain] football field drainage system.)
 
In planning and installing these drainage systems, two main problems need to be avoided: a heavily compacted sub-base that prevents water from getting to the system, and the destruction of the pipe by crushing when heavy equipment is being moved across the surface.
 
Although these problems are created by the excavating contractor, they most frequently result from faulty specifications provided by the field designer. For example, many plans and specifications call for a "compacted sub-base." To the excavator, this means that a sheepsfoot roller or vibrating roller should be used. When this sort of equipment is used, the sub-base becomes impervious to water, which passes through the topsoil but stops at the sub-base. The uncompacted topsoil will become fully saturated during a heavy rain, because the sub-base is so compacted there's nowhere for the water to go.
 
Actually, the solution to this problem is very simple. Adding the instructions, "Avoid overcompaction of the sub-base" and "scarify sub-base before installing topsoil" will alert the excavator to the drainage dynamics at work in the field system, and prevent nearly all of these problems.
 
Strip Drains
Modern technology is also providing some new solutions to the challenge of properly draining football fields. One of these new solutions is called strip drains. These are cloth-wrapped plastic or fiber structures about an inch wide and 4" to 6" deep. Strip drains are installed in the top 12" of the soil and require only a 3" to 4" wide trench. The strip drain is placed in the bottom of the trench and extends halfway to the surface. The trench is then filled with sand right up to the surface level.
 
Figure 12.5.
Traditional [pipe drain] football field drainage system.
 
Strip drains intercept and remove some of the surface water as it moves across the field. The best designs have strip drains at a 45 degree angle to the direction of the surface runoff. However, in order for strip drains to work as they are meant to, it's essential that the topsoil not be overcompacted. (And, of course, the system works better if the sub-base is not overcompacted either.)
 
An additional advantage of strip drain systems that are installed at a 45 degree angle to surface runoff is that the drains can be laid out a a consistent one-foot depth from the field surface. Pipe drains (as illustrated in Figure 12.5, where the pipe drain is installed along the long axis of the field that is level) must be laid out with a transit to ensure consistent downward slope, and will vary in depth from the field surface.
 
Figure 12.6.
A Crowned Football field strip drain system.
 
(Figure 12.6 shows a design for a crowned football field drainage system using strip drains. Figure 12.7 shows a strip drain system for a side-to-side sloped football field. Note that the only difference in the two designs is the location of collector drains.)
 
Figure 12.7.
A side-to-side sloped football field strip drain system.
 
Catch basins
Catch basins on the sidelines are another common drainage structure used for football fields. At least 20 feet of sideline clearance should be allowed when using catch basins, to avoid dangerous falls. For the majority of fields, four catch basins are sufficient to assist prompt drainage--one outside the end zone sideline at each corner of the field. Catch basins are the "junction boxes" of many installed drain systems, and generally are equally valuable in connecting laterals and drain lines as they are in removing surface water.
 
One common drainage system design (often used in a crowned field with level sidelines) uses a number of catch basins around the field, with swales from basin-to-basin to assist surface runoff. This approach has two drawbacks: it creates an awkward appearance of hills and valleys along the field edge, and the swales tend to stay wet for extended periods during wet conditions. When these two problems occur together the results can be a mess--muddy spots on the sideline which standing players then turn into mudholes.
 
When drainage from level sidelines is a concern, a good option combines both pipe drains and strip drains to avoid creating swales. For instance, lay out a trench 15" deep, sloping away from the 50-yard line, parallel to and 20 feet outside the sidelines, running to catch basins outside the end zones. Lay a ½" bed of pea gravel in the trench, then a 4: perforated pipe. Then fill pea gravel to within 5" of the surface, top with coarse sand and seed or install washed sod. The best sand has less than 5% passing a 100-sieve screen.
 
(A variation on this type of system can be found in Chapter 16, Track and Field Facilities [Figure 16.4]. This variation, called a "Trackside Sand Drain," works very well for the many fields that are crowned with level sidelines, and with a 400-meter running track around them. If the sand drain is placed next to the track, it will serve as an open catch basin draining water away from both field and track, and eliminating the annoying swales to catch basins.)