Appeal 33539

1028.5

The exit discharge is required to lead directly to a public way, unless a safe dispersal area is provided that complies with the following provisions:

1. Area shall be sized to accommodate not less than 5 square feet per person.
2. Area shall be located on the same lot not less than 50 feet away from the building.
3. Area shall be permanently maintained and identified as a safe dispersal area.
4. Area shall be provided a safe and unobstructed path of travel from the building.

This appeal is required because the proposed concert seating and standing area layouts and occupant loads, and the existing configuration of the stadium itself, are all considerably different in quantity and/or configuration than those approved in Appeal 7339 Item 1.
A safe dispersal area is proposed in accordance with OSSC 1028.5. However, it is not possible to fit the safe dispersal area between the fence and the enclosed areas of the stadium as required by OSSC 1010.4.1. Instead, the safe dispersal area is proposed to be located at the center of the playing field.

The purpose of this appeal it to update the previously approved appeal (#7339, Item 1) with the current Stadium design. This appeal proposes to continue using the safe dispersal area (SDA) located on the playing field, as described in Appeal #7339, which was approved in 2010. Appeal #7339 is attached for reference (see Appendix A). The location and operation of the SDA is not changing as part of this project. The location of the building structure and roof adjacent to the SDA is not changing. The SDA is still 50 feet away from the adjacent building structure and roof. The area and capacity of the SDA is not changing. However, the number of occupants using the SDA is changing from 3,368 to 10,719 occupants. The reason for the change is because the maximum permitted occupant load on the field during a concert event is increasing from 5,000 to 12,622 occupants.

The following changes to the Stadium since 2010 have an effect on Appeal #7339.

1. The maximum field occupant load has increased from 5,000 to 12,622.
2. The number of occupants exiting to the SDA has increased from 3,368 to 10,719.
3. The number of occupants exiting from the field up the West bowl aisles has decreased from 313 to 157. Note that one of the two exit stairs from the field has been relocated one aisle to the North but is the same size and does not affect how many occupants exit up the bowl aisles.
4. The number of occupants exiting through the West/North (original 1926 construction) exterior exit gates has decreased from 18,762 to 16,523. This is primarily due to the reduction in fixed seating in the West/North lower seating bowl when the seating was changed from bench seating to individual fixed seats.
5. The number of occupants exiting from the field up the East bowl aisles has decreased from 2,685 to 1,973.
6. The 2017 East Addition has affected the natural smoke ventilation along the egress path between the East lower bowl and East exterior exit gates. A smoke venting study was conducted in Appeal #7339 which calculated the amount of open area below the roof canopy to demonstrate that smoke would naturally vent and maintain smoke-free exit paths indefinitely. Since the roof canopy has been replaced with three levels of seating decks, this study will be re-assessed for this appeal.
7. The number of occupants exiting through the East exterior exit gates has increased from 6,685 to 9,352. This is primarily due to the 3-story addition, which includes occupants that egress at the same exterior gates. During this 2017 Addition project, the gates were also modified to increase the aggregate egress width from 55.4 to 82.7 feet.

The general arrangement of lower bowl aisles and exterior gates has not changed significantly, such that the common paths of travel and exit access travel distances are essentially unchanged.

There are three areas of interest when applying Appeal #7339 to the current Stadium design:

1. The natural smoke ventilation at the East Concourse (Section 1 of the appeal)
2. The egress times up the bowl aisles and through the exterior gates (Section 2 of the appeal)
3. How the stated maximum field occupant load of 12,622 will be maintained (Section 3 of the appeal)

Section 1 – Natural Smoke Ventilation
Appeal #7339 presented smoke venting calculations to demonstrate that smoke will naturally vent away from the egress paths along the Concourse Level (refer to Pages 9 of 76 through 14 of 76 of Appendix A). Based on a 5,000 kilowatt (kW) design fire, a total venting area of 344 square feet (free area) was determined to be required around the perimeter of the roof canopy above the Concourse Level. A total of 11,1119 square feet was provided.

With the removal of the roof canopy and addition of the three club levels, the horizontal obstruction above the Concourse Level is now lower in elevation and closer to the occupied height. As such, the overall venting area has decreased, but is still more than the minimum required 334 square feet. All other assumptions from the original calculations are maintained, including the 5,000 kW design fire.

The following images (Figure 1, Figure 2, and Figure 3) present the calculations for the current vent area. The total venting (free area) provided around the perimeter of the Club Level 1 floor above the Concourse Level is 10,536 square feet. Since this is more than the minimum required 334 square feet, smoke will naturally vent away from the egress paths.
Summary of Vent Area Calculations
• Total required: 334 square feet
• Total provided: 9,245 square feet (OK)
o West: 1,288 square feet
o East: 5,392 square feet
o South: 1,173 square feet
o North: 1,392 square feet

Figure 1: Vent Area Calculations – Plan View

Figure 2: Vent Area Calculations – Section View Looking North

Figure 3: Vent Area Calculations – Section View Looking West

Section 2 – Egress Times
Appeal #7339 presented timed egress calculations to demonstrate that occupants will be able to egress from the building in a timely manner (refer to Pages 27 of 76 through 42 of 76 of Appendix A). The same egress width factors are used for the current Stadium as were used in Appeal #7339. The general arrangement of lower bowl aisles and exterior gates has not changed significantly, such that the common paths of travel and exit access travel distances are essentially unchanged.

The timed egress analysis consists of calculating (1) the travel (walking) times from most remote portions of the building to the exterior exit gates and (2) the flow (queue) times at the egress elements along the path of travel (e.g. stepped aisles, exterior gates). The travel times will remain the same as Appeal #7339 since the travel distances are essentially the same. However, the flow times are different than Appeal #7339 since the occupant loads and egress widths of these elements have changed. In all cases, the flow times have decreased, as shown below in Table 1.
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Table 1: Egress Flow Time Comparison – Previous vs. Current

Refer to Appendix B for the 2010 Exit Study drawings (Permit #09-161349) and 2024 Exit Study drawings (this project, Permit #24-027519-CO) that shows the changes in number of occupants exiting and egress widths.

The flow time is found by dividing the occupant load by the total egress width, then dividing by the flow rate. For the four relevant scenarios, the flow times in the current condition are less than they were in the previous condition. Therefore, the overall egress times are less than what was previously presented in Appeal #7339, so the continued use of the safe dispersal area will not result in a greater hazard to the building and occupants.

Section 3 – Field Occupant Load
The maximum permitted field occupant load of 12,622 occupants will be limited by ticket sales and enforced by event staff, arranged in one of the following ways:

1. Seating areas, with a total of up to 12,622 non-fixed seats (including wheelchair spaces) in one or more seating areas having a combined floor area of not more than 88,354 square feet (based on 7 square feet per person), with a seating layout submitted for each event under a Special Event permit.
2. Standing room only (SRO) areas, with a total of up to 12,622 occupants in one or more SRO areas having a combined floor area of not more than 63,110 square feet (based on 5 square feet per person).
3. Any combination of the above arrangements, such that the total number of occupants in seating areas and SRO areas does not exceed 12,622.

Refer to the Concert Seating General Notes on Sheet ES-101.C (Appendix C) for additional information.

Maximum occupant load signage stating a maximum permitted occupant load of 12,622 on the field will be posted near the Southeast and Northeast field level vomitories. Refer to Sheets ES-101.C and G003 (Appendix C) for locations and details.

Historically, the existing Stadium has not had sufficient egress capacity at the perimeter gates during a concert event due to the additional occupant load on the field. Previous approved appeals have allowed occupants to egress to the field into a safe dispersal area. This is permitted by OSSC 1028.5 where direct access to a public way is not available for exit discharge. The previous and current appeals clarify that a safe dispersal area is permitted on the field since, like other exterior areas used as safe dispersal areas, the field is more than 50 feet away from enclosed portions of the Stadium. Another aspect noted in the appeals is the unique open-air condition of the Stadium construction that allows for an unlimited travel distance (OSSC 1030.7, Exception 3) since smoke and heat can naturally vent, as demonstrated by the smoke venting calculations. The proposed design provides an equivalent level of safety and meets the intent of the code.