Life Safety Designs for a Skybridge

A building-link, skyway, skybridge, skywalk or building connector is an intermediate passageway between buildings.? They can be underground, ground-level or can connect across streets.? Colder climates often use them to connect several buildings together to protect occupants from the harsh winter.? These connecting corridors are typically conditioned spaces and may have horizontal moving walkways.

For building-to-building connectors, utility service and fire sprinklers may be supported by one or both buildings.? HVAC may be provided from a dedicated unit or from ductwork from one of the buildings, which would require a fire/smoke damper.? The Life Safety egress plan may include these occupant pathways as part of a horizontal exit.? Consideration must be given for occupant notification during a fire alarm or mass notification event.? To permit normal occupant travel, the connector’s opening often have self-closing fire rated doors normal held open with magnetic door holders (24VDC or 120VAC) with NFPA 72 door release service.

For smaller connectors which are less than 100ft, typically each respective building extends the base building fire alarm to each side.? This includes:

1. Manual pull station, with protective cover if site standard.
2. An audio/visual notification appliance above the pull stations.? This will notify occupants as they approach each building.? Some designs may also use a LED sign at each entrance which reads ‘FIRE ALARM DO NOT ENTER’, powered by either 24VDC fire alarm power or 120VAC building power.? It would be controlled directly by the fire alarm from each building.
3. Magnetic smoke door holders, coordinate with architectural door schedule. A smoke detector on either side of the door, to initiate door release service.? An addressable control relay module from Building #1’s fire alarm system and relay module from Building #2’s fire alarm system.? Smoke door power wired N.C. thru both relays in series.? If either system detectors smoke, both sets of doors will close, but only the building which detected the smoke will activate its respective alarm signals.
4. For fire/smoke dampers, supply an induct smoke duct detector or supply area smoke detectors;? addressable relay to interface with the HVAC damper’s actuator.? If the skybridge utilizes only fire dampers operated by fusible link; smoke detection and fire alarm interface are not required.
5. For horizontal moving walkways, provide fire alarm shutdown.? An addressable control relay module from Building #1’s fire alarm system and relay module from Building #2’s fire alarm system.? Smoke door power wired N.C. thru both relays in series.? If either system detectors smoke, both sets of doors will close, but only the building which detected the smoke will activate its respective alarm signals.

Even if the buildings are networked with the same fire alarm manufacturers, most engineers and AHJs will have each building’s FACP provide a relay for interfaces. This method is beneficial for both installation phases and to ensure operations in the event of a network communication failure.

For larger connectors over 100ft or spaces, additional notification appliances would be required for proper coverage.?

Typically, an alarm event in one building only initiates the evacuation signals in the building associated with the fire event.? It is not necessary to evacuate both buildings due to either the horizontal separation distance or the rated-type of construction (FW or FB).