Stadium Bowl
Design

2.3 STADIUM BOWL

08 min. de tiempo de lectura

The design of the stadium bowl incorporates the areas from which spectators view the match or event. The term “bowl” is most applicable to continuous structures that “wrap” around the entire or only parts of the stadium. However, it can also be applied to a collection of individual stands on various sides of the pitch that provide spectator seating or standing accommodation. The design of the stadium bowl is fundamental to the safety and overall experience of the spectator. It should provide good sightlines to the field of play in a safe environment while also enhancing the atmosphere and enjoyment of the game.

2.3.1 BOWL LAYOUT

The starting point of any stadium bowl design is to define the stadium’s capacity, which should be reviewed in terms of both gross and net capacities. Further details on the calculation of stadium capacities is provided later in this section.

The optimum viewing distance for seats in the stadium bowl is within an arc of 150m from the far corner of the pitch, and the maximum distance is within an arc of 190m from the far corner of the pitch. Where possible, the footprint of the stadium bowl should not exceed the optimum or maximum viewing distances.

The configuration of the stadium bowl should be considered at an early stage. This will include deciding between using either independent stands or a continuous bowl configuration. These considerations may be driven by cost, spectator experience, security, site geometry or aesthetics.

Independent stands that run parallel to the pitch tend to be more cost-effective but can reduce the overall proximity of the spectators to the pitch by not utilising all available space in the corners. Some designers also view a non-continuous bowl as less effective in containing the atmosphere within the stadium by allowing some of the crowd noise to escape through the gaps between stands. Curved tiers tend to improve sightlines to the pitch, but by curving away from the touchlines and goal lines, spectator proximity is compromised to a degree. This can have potential consequences for the overall footprint of the stadium.

Figure 2.3.1
Optimum and maximum viewing distances for seating within various stadium bowl layouts

The positioning of general admission and premium seating within the stadium bowl can affect stadium revenue and atmosphere. It is generally accepted that the best seats in a stadium are located on the halfway line in the main stand, followed by those on the halfway line in the opposite stand, and then extending in those stands to encompass seating located between the two penalty areas. These seats can generate considerable added revenue, and it is common to locate a large proportion of the premium seating here.

It is recommended that the placement of general admission seating within the seating bowl should create a wide range of offers. In many stadiums, a large concentration of general admission seating behind the goals can help to generate atmosphere.

The positioning of designated seating for visiting (away team) supporters can also influence the atmosphere but should be directed primarily by safety and security considerations. Where possible, it is recommended to avoid locating opposing fans behind and/or above one another. Where such placement is unavoidable, mitigating elements should be identified to address any potential problems that may arise. The impact of these measures on available seating should be included when calculating a stadium’s net capacity.

The areas for visiting supporters may vary in capacity depending on the demand and/or competition regulations. The stadium bowl should be designed to allow the capacity of these areas to be adapted, with the ability to move segregation lines and barriers to ensure the safe segregation of fans.

The main stadium control room, often referred to as the Venue Operations Centre (see Sub-Section 5.4.3), should be located within the stadium bowl and offer a good view of the entire stadium bowl, especially for visiting supporters.

Figure 2.3.2
Accessible seating and viewing positions guide

When designing the stadium bowl, spectators with disabilities and/or limited mobility should be catered for in all areas. The number of positions for wheelchair users and ambulant disabled spectators that should be provided to achieve international best practice is set out in Figure 2.3.2. All accessible positions and seats should allow for a companion to sit beside the disabled spectator. The percentages outlined in Figure 2.3.2 should be proportional to each seating type, i.e. general admission and hospitality. These figures are guidelines and may need to be adapted in accordance with local, regional or tournament requirements.

The location of broadcast and media facilities within the bowl should be considered early in the design process, with the main media tribune commonly located centrally within the main stand. It is crucial to ensure that there are no sightline obstructions to areas such as the TV presentation studios. See Section 6.2 for further details on broadcast and media facilities.

The need for multiple tiers within the seating bowl is usually driven by the overall capacity of the stadium, with a single-tier arrangement often sufficient for smaller stadiums. Other factors influencing the number of tiers may include the site footprint, where multi-tier stadiums can maximise the seating capacity with overlapping tiers, and also the desire for premium lounges and suites to have views of the pitch.

The maximum rake of any tier should be considered in line with national regulations, and compensatory measures should be reviewed, such as grab rails on gangways and additional barriers to improve spectator safety where the tiers are at their steepest.

The “yellow wall” at Signal Iduna Park, Dortmund. This single block of spectators generates an intense atmosphere within the stadium.

The configuration of seating tiers can also impact the matchday atmosphere. Multiple tiers can bring more spectators closer to the action, while single-tier stands can help to generate noise and atmosphere by creating a large, uninterrupted block of spectators. This effect can be maximised through the careful design of the stadium bowl’s acoustics.

The design of the stadium bowl in terms of the choice of independent stands versus a continuous bowl and the position and height of the surrounding stands will influence the micro-climate within the bowl and the growing conditions for the grass on the pitch (see Section 2.4).

When designing the stadium bowl, the stadium’s internal layout and floor-to-floor heights should be considered to ensure good operational planning, vertical circulation, and well-proportioned internal spaces.

Another parameter to look at from both a safety and comfort point of view is the tread depth for spectators. This may vary around the bowl depending on the seat type and user group. It is important that spectators are easily able to pass each other along the row, particularly in steeper upper tiers, and therefore a minimum clearway between rows/seats should be ensured, in line with national regulations (see Sub-Section 5.2.1).

2.3.2 CIRCULATION

The good design of circulation spaces will ensure the efficient movement of spectators into the building, enhance the spectator experience, and enable the safe exit from and emergency evacuation of the stadium. This will determine the design and location of gangways both radial, where the gangway is perpendicular to or across the treads of the tier, and lateral, where the gangway is parallel to the treads and vomitories.

The spaces and routes should be designed to provide free movement within the stadium, both safely and intuitively. All designs should comply with local building codes and regulations relating to emergency evacuation. When reviewing local regulations regarding emergency evacuation, the fire strategy should also be developed. All elements in the bowl should be non-flammable, including the seats and all structural elements (see Sub-Section 5.4.2).

When calculating the dimensions for circulation routes, a safe width should be determined using the relevant methodology in the local codes – be it units of width per person or through the use of flow rates, where the width is equated per person per minute. Flow-rate system examples and methodologies can be found in the SGSA’s Guide to Safety at Sports Grounds (6th Edition).

A minimum width on all routes should be assessed and is generally set at 1.2m. The minimum head clearance should be set at 2.4m wherever possible – however, for transitional areas such as vomitories, this may be reduced locally. The minimum clearance height should consider all items on circulation routes and concourses such as wayfinding signage and TV screens to help avoid damage and injury. In larger spaces, heights greater than 2.4m may be required to enhance the spectator experience.

All areas within the stadium should be accessible by all spectators regardless of any disability, and provision for this should be made at an early stage in the design.

It may be desirable for different areas of the stadium to be segregated from other areas for operational and/or safety reasons. This should be included in any circulation design to avoid, wherever possible, the ability for spectators from different zones to mix on both ingress and egress. However, careful consideration should be given to the impact of segregation on emergency evacuation to ensure that it does not unduly extend evacuation times.

All routes should be designed to minimise the risk of fire and should be built to local building standards, fire codes and regulations. This work should incorporate, where possible, the use of fire-engineering solutions (see Sub-Section 5.4.1).

The circulation systems within a stadium fall into two prime categories: vertical circulation routes and horizontal circulation routes.

Vertical circulation within the stadium bowl

Vertical Circulation

Vertical circulation routes include stairways, ramps, escalators, lifts and gangways within the seating bowl. When choosing which of these routes to incorporate within a stadium, local regulations, space, site and cost have to be taken into account.

Moving large numbers of spectators into and out of the stadium will primarily require either or both stairways and ramps, as the use of escalators and lifts in achieving this is often prohibited by cost and spatial constraints. Stairs and ramps should be designed to local codes and regulations and be of the correct width for the number of spectators using these routes. When using flow rates for the methodology, it should be remembered that the speed of spectators on stairways is slower than on the flat, and therefore a stairway may need to be wider than the route serving it.

To improve the spectator experience for all, consideration should also be given to the provision of ramps or lifts to provide a step-free alternative to staircases, and where long access routes are necessary on the approach to or within the stadium, rest areas should be integrated. Ramps often take up more space than stairways.

Figure 2.3.3
Head-of-stair barriers splitting spectator flows into stair channels

The approach to stairways – particularly larger stairways – should be designed to mitigate the build-up of crowd pressure, which may result in spectators being injured. This can be done by directing crowd flow so that spectators do not arrive at the stairway head-on, or by the addition of head-of-stair barriers that run perpendicular to the flow of spectators (see Figure 2.3.3). Introducing these measures will slow spectators as they reach the top of the stairway and direct the flow into each of the channels created by the handrails. Long, straight runs of flights of stairs should be avoided, with a change of direction ideally after no more than 36 risers.

The design of gangways within the seating bowl should be considered as part of the bowl design. The regulations for these routes are usually different to those for stairways and are usually outlined in local building codes and regulations.

Escalators and lifts can be used for moving smaller numbers of people in egress. Escalators can also be useful in ingress for moving large numbers of people to higher levels in a large stadium – however, this should be supplemented by the incorporation of stairways or ramps for egress and emergency evacuation.

Lifts are crucial in most stadiums for operational reasons such as the movement of goods and waste from concourses, hospitality spaces and kitchens. They are also often required to give a wide range of spectator viewing positions for wheelchair users and ambulant disabled spectators, and therefore for access to all concourses and hospitality areas, as well as for egress and emergency evacuation. For further information, refer to Sub-Section 5.6.5 and Sub-Section 5.4.2.

Horizontal circulation within the stadium bowl

Horizontal Circulation

Horizontal circulation primarily looks at the movement of spectators through concourse areas, dedicated corridors, and premium hospitality spaces that are on the flat. If using a flow-rate methodology for calculating safe widths for circulation routes, spectators move at a faster rate on the flat than they do on stairways or gangways.

Horizontal circulation routes should allow for two wheelchair users to pass each other unimpeded and should therefore be a minimum of 1.8m wide. Routes should seek to provide level floor surfaces linked by appropriate vertical circulation. Where level changes are required on circulation routes inside and outside of the stadium, gradients should be as shallow as possible.

Figure 2.3.4
Width of access route used by wheelchairs

The design of horizontal circulation routes through concourse spaces should consider a number of factors to ensure the safety of spectators in egress and emergency evacuation. These factors include but are not limited to the following:

• Permanent and temporary facilities associated with commercial displays
• Food and beverage concessions
• Enhanced and pop-up spectator facilities and experiences that may create possible obstructions or fire risks

Figure 2.3.5
Calculating tier profiles

2.3.3 SIGHTLINES

The quality of spectator sightlines to the field of play is expressed as a C-value. For any given seat, this measurement represents the quality of view to the near side or goal line (or focal point), and the degree of obstruction caused by the spectator sitting in the row directly in front. A C-value is calculated as the vertical distance from the eyes of a spectator to where the sightline from the spectator sitting behind passes through or over the spectator’s head (see Figure 2.3.5). This dimension is usually measured in millimetres. A C-value of 120mm is regarded as optimal, with the dimension from the eyes to the top of the head specified as 120mm. A minimum recommended C-value is C=60.

In designing the stadium bowl, the C-value must first be set by the design team in order to calculate the profile of the tiers. The equation shown in Figure 2.3.5 should be used to calculate the riser height of each row required to achieve the desired C-value.

When setting out the sightlines within the stadium bowl, other considerations should include possible requirements for wheelchair users and ambulant disabled spectators, as well as the effect of possible obstructions such as advertising boards on spectator sightlines.

Figure 2.3.6
Considerations when placing advertising boards in setting out the front rows of seating

Advertising boards around the pitch should be considered in the design of the stadium bowl, with the front row of spectators being set out to see over the boards to the near side or goal line. It should be remembered that photographers often sit behind these boards, particularly in positions adjacent to the goal lines. To alleviate possible restriction to viewing, it is advised to set sightlines in the front row even higher above the boards to account for this.

When reviewing the effect of the advertising boards on sightlines in the front row, it may be necessary to slope the edge of the field of play so that the boards can be accommodated without raising the front row significantly. This should be done with an initial level run-off for player safety and in such a way that it does not compromise playing activity, such as the taking of corners and throw-ins. To achieve this, it is recommended that a minimum level run-off of 2m be in place and that any slope should not be steeper than 5° (see Section 5.3).

The positioning of the advertising boards should be reviewed in conjunction with the design of the main TV gantry to ensure clear views to the boards from the main cameras. This is particularly important when looking towards the goals, where the boards should be clearly visible below the crossbar.

Restriction to sightlines by structural elements within the stadium, such as columns and other elements like video screens, should be avoided. This should not only consider views of the entire field of play, but also the high-ball line over the centre of the pitch. Any restrictions caused by safety barriers within the bowl should be minimised and, where possible, mitigated by the installation of transparent barriers (subject to appropriate crowd-loading and non-reflective surface).

Figure 2.3.7
Changing C-values

Figure 2.3.8
Changing the height of the front row

Figure 2.3.9
Changing the distance of the front row from the pitch

When setting out the tier geometry of the bowl and assessing the C-values to be used, several parameters need to be decided upon, depending on the operational and aesthetic design aspirations for the stadium.

When increasing the C-value of a tier, its rake increases together with its overall height, as illustrated in Figure 2.3.7.

Raising the front row of the lower tier of a stadium in relation to the pitch will increase the rake of the tier together with the overall height of the tier, as illustrated in Figure 2.3.8.

Increasing the distance between front-row seating and the pitch will reduce the rake of the tier together with its overall height, as illustrated in Figure 2.3.9.

These parameters must all be considered in setting out the seating bowl to achieve the desired proximity between the pitch and the seating tier. The designated C-value of a tier will also influence the maximum rake it can be set at. It will have a bearing on the overall height of the stadium and also the ability of the venue to meet certain operational requirements, such as the need for sufficient space at pitch level for media and security staff.

The preferred C-value for stadiums is C=90, rising to C=120. Anything above C=120 is mathematically regarded as a perfect sightline with no theoretical obstructions caused by spectators sitting in front of the viewer. Stadium C-values can be reduced to a minimum of C=60 in specific areas, but this should be avoided in lower tiers wherever possible as it will degrade the spectator experience and may result in spectators choosing to stand for a better view.

The perceived quality of a sightline is greatly improved as the viewing position becomes more elevated, and this means that it is possible to lower the C-values in the upper tiers of larger stadiums without compromising the spectator experience. This ability to vary the C-value depending on the tier gives designers some flexibility to either bring spectators closer to the pitch, thereby enhancing the atmosphere, or to reduce the rakes (steepness) of the upper tiers, thereby enhancing safety.

Figure 2.3.10
Perceived quality of views from an upper tier and a lower tier with the same C-value

When setting out sightlines in multi-tier stadiums, a high-ball line should be considered, together with possible obstructions suspended from the roof such as large TV screens. For football stadiums, a minimum requirement should be for clear sightlines to 15m above the centre of the pitch and at least 5m above the far goal or touchline.

Figure 2.3.11
Wheelchair user and companion space requirements (denoted in millimetres)

Sightlines for wheelchair users

It should be ensured that in the areas in which wheelchair users are located within the bowl, their sightlines are not obstructed when other spectators stand. This can be done by placing wheelchair users at the front of tiers or by creating a super riser (as shown in Figure 2.3.12). A super riser elevates the viewing area for wheelchair users within the bowl so that when spectators in front are standing, the quality of sightline (C-value) remains, at least, comparable to those in the adjacent areas of seating.

Seating for a range of ambulant disabled spectators should be provided in a variety of locations around the stadium bowl. The range of accessibility seating that should be provided is outlined in Section 5.2.

The required dimensions for a wheelchair user position with sufficient space for a companion, who should sit beside the wheelchair user, are 1.4m x 1.4m (minimum), allowing a width of 900mm for the wheelchair user and 500mm (minimum) for the companion’s seat.

Consideration should be given to access to the wheelchair user viewing positions from circulation routes and spectator facilities within GA concourses and premium spaces. To avoid sightline restrictions to other spectators in seating areas adjacent to and behind the wheelchair viewing areas, sightlines need to be catered for with the raising of tiers and careful placement of these areas.

Figure 2.3.12
Sightlines for wheelchair users

2.3.4 CAPACITY

The overall stadium capacity should be developed in line with a business plan and local competition requirements and/or aspirations. The minimum capacities in terms of FIFA’s categories of stadiums are shown in Chapter 7.

There are two key aspects to the calculation of the total capacity of the stadium:

• Secondly, the capacity can be reduced if not all seats are available for sale (because they are required for other users or purposes such as segregation) or usable (for example because of restricted views). This concept is dealt with in this section.

• Firstly, the concept of maximum safe capacity, which not only considers the number of seats within the stadium bowl, but takes into account other factors including entry, exit and emergency evacuation.

Figure 2.3.13
The five steps to calculate maximum safe capacity

Calculation of safe capacity

The most important principle in safety management is to determine how many spectators can be safely accommodated in the stadium during a football match or other event. This is not necessarily the maximum number of spectators that can be accommodated in seats (or other viewing accommodation) but must also take account of the entry, exit and emergency evacuation capacities of the stadium. For further guidance, please refer to the FIFA Stadium Safety and Security Regulations, as well as the SGSA’s Guide to Safety at Sports Grounds (6th Edition).

The maximum safe capacity of a stadium should be determined using the five-step process outlined in article 23 of the FIFA Stadium Safety and Security Regulations and summarised in Figure 2.3.13.

For the majority of stadiums, each section or sector should be considered separately, particularly when calculating entry, exit and emergency evacuation capacities.

The relevant local authorities should approve the calculation and issue a formal safety certificate (or a local equivalent) that clearly states the stadium’s maximum safe capacity. This should also detail the capacities of individual sections or sectors of the stadium.

Gross and net capacity
Media seating is included in a stadium’s gross capacity but is excluded from the net capacity.

Gross and net capacity

The calculation of safe capacity determines how many spectators can safely be accommodated in a stadium. It does not mean that all of the seats or standing accommodation included within this safe capacity can or will be offered for sale.

The stadium capacity should be considered in terms of both gross and net capacity. The gross capacity of a stadium includes all seats within the stadium bowl, including those that do not directly produce potential income, such as seating for the media. The net capacity of a stadium is the total number of usable seats available for purchase (in both general admission and premium seating areas) with a clear view of the whole of the field of play.

In major tournaments such as the FIFA World Cup™, the net capacity may be reduced by specific overlay requirements for that tournament, such as a larger requirement for media seating. This net capacity is usually the key metric in terms of tournament capacity requirements, and should be considered at the concept design stage of a project if it is foreseen that the stadium will be used for such events.

In accordance with FIFA stadium category guidelines, standing sections should not be included in either the gross or net capacity of a stadium unless these sections can be converted to all-seated areas – in which case the seated capacity will form part of the overall capacity calculations. See Sub-Section 5.2.2 for information on the design of standing areas for spectators.