Means of Egress with NFPA 130
NFPA 130 is the Standard for Fixed Guideway Transit and Passenger Rail Systems. It contains requirements for train stations, subway stations, the trains or subway cars themselves, and the tracks or paths these vehicles travel on. While NFPA 130 covers a wide array of topics this blog is going to concentrate on the unique means of egress requirements for fixed guideway transit and passenger rail stations. Means of Egress First, what is the means of egress? In layman’s terms the means of egress is the pathway out of a building or structure that leads to a point of safety and is comprised of three parts, the exit access, exit and exit discharge. EXIT ACCESS - The exit access is the path that leads to the exit EXIT - The exit is the portion of a means of egress that is separated from all other spaces of the building or structure by construction, location or equipment as required to provide a protected way of travel to the exit discharge. Examples include an exit door that leads directly outside, an exit staircase, exit passageways, etc. EXIT DISCHARGE - Exit discharge is that portion of a means of egress between the termination of an exit and a point of safety. In NFPA 130 the point of safety can either be the concourse or a point of safety outside of the building. In general, the station needs to comply with the means of egress requirements in NFPA 101®, Life Safety Code®, for New Assembly Occupancies except where it is modified by NFPA 130. For more information on the means of egress check out this blog! The following sections discuss those modifications. Occupant Load Determining the occupant load is needed to figure out how quickly those occupants can egress the station. To determine the occupant load we need to assume that all of the trains are simultaneously entering the station full of passengers who need to disembark and that there is a full train’s worth of people waiting on the platform to enter the train. So, the occupant load includes both the people exiting the train as well as those waiting on the platform. This will give us a worst-case scenario of having all of the trains recalled to the station at once and having to evacuate both the vehicle and station. There is also the occupant load for each platform that must be calculated in order to make sure each platform can be evacuated in a timely manner. This number is based on peak ridership numbers, which can often require an analysis be done to determine peak ridership statistics. Similar to the station occupant load, the platform occupant load needs to assume a full train has pulled into the station and drops off an entire train load while there is another train load of people waiting on the platform. Evacuation Time When looking at evacuation times there are two main figures that must be considered. The first is the platform evacuation time which is required to be less than 4 minutes. The second is the station evacuation time, in which the occupant load needs to be able to reach a point of safety in under 6 minutes. Travel Distance There are also limitations on travel distances and common paths of travel for platforms. Travel distance is your natural path of travel measured from the most remote point on the platform to the where the means of egress path leaves the platform. NFPA 130 requires that the travel distance is 100m (325ft) or less. There is also the concept of a common path of travel which is measured in the same manner as travel distance but terminates at that point where two separate and distinct routes become available. The common path of travel is not allowed to exceed 25m (82ft) or one car length, whichever is greater. Platforms Corridors & Ramps Many of the requirements for platforms, corridors and ramps are summarized in the table below. In addition to those limitations, when calculating available egress capacity on platforms, corridors, and ramps, 12 inches must be subtracted from each wall and 18 inches subtracted from the platform edge. Capacity Travel Speed Minimum width Platforms 2.08 p/in.- min (0.0819 p/mm-min) 124 ft/min (37.7 m/min) 44 in. (1120 mm) Corridors 2.08 p/in.- min (0.0819 p/mm-min) 124 ft/min (37.7 m/min) 44 in. (1120 mm) Ramps 2.08 p/in.- min (0.0819 p/mm-min) 124 ft/min (37.7 m/min) 44 in. (1120 mm) Concourse 200 ft/min (61.0 m/min) Stairs 48 ft/min (14.6 m/min)* 44 in. (1120 mm) Escalators 1.41 p/in.-min (0.0555 p/mm-min) 48 ft/min (14.6 m/min)* Elevators carrying capacity for 30 minutes *Travel Speed for vertical component of travel Escalators NFPA 101 typically doesn’t allow escalators to be used as a component in the required means of egress but because of the short evacuation timeframe, NFPA 130 allows it. When determining egress capacity for escalators there are a few rules that need to be followed. One escalator at each level must be assumed to be out of service and escalators cannot account for more than 50% of the egress capacity for a level unless they meet additional criteria. Elevators Elevators are another unique component of the means of egress that is allowed to be used in fixed guideway and passenger rail stations, but they also come with additional rules. One elevator must be considered out of service, elevators can’t account for more than 50% of the egress capacity and one elevator must be reserved for the fire service. The capacity of elevators is determined by calculating the carrying capacity over a 30-minute timeframe. Elevators also must meet certain construction requirements and they need to be accessed through holding areas or lobbies. Exit Hatches Exit hatches are another unique component of the means of egress permitted for fixed guideway and passenger rail stations. Exit hatches must be manually opened from the egress side with only one releasing operation requiring less than 30lb (130N) of force and have a hold-open device. It also needs to be clearly marked on the discharge side to prevent blockage. Fare Barriers Fare barriers are typically gate type or turnstile type, each of which have additional requirements that must be met to be allowed in the means of egress. Fare barriers are a unique characteristic of a station and have unique requirements. For a fare barrier to be allowed in the means of egress it must either be designed to release in the direction of travel during an emergency or be able to open by providing 15lbf (66N) of force in the egress direction. Platform Edge Provisions Finally, the platform edge is another unique feature of a station. Guards are not required along the trainway side of the platform edge. Certain horizontal sliding platform screens or doors are permitted to separate the platform from the trainway, but the doors or screens must open with less than 50 lb (220N) of force at any stopping position of the train and it needs to be able to withstand the positive and negative pressures caused by the passing trains. There are many unique fire and life safety elements found in Fixed Guideway Transit and Passenger Rail Systems. This blog discussed some of the unique means of egress characteristics, but NFPA 101 contains many more requirements that must be followed.