| Layouts of transport system stations, like layouts of other buildings that serve large numbers of people, require careful planning that takes into account a number of technical issues. Station layouts are defined by platform layouts, staff and plant room requirements and the space needed for passengers entering and exiting the station. The size of many station facilities will be influenced by the numbers and types of passengers during normal operations, peak period operations, and emergency situations with the latter over-riding operational space utilisation.
Space Standards
Space standards are a determination of passenger comfort spacing or personal space envelopes combined with length of travel between internal elements, such as ticketing points and conc ourses; cross movements (alighting/boarding); vertical circulation; (stairs/lifts/escalators); and wait time based on train headway or frequency and missed headways. Should retail/commercial outlets be incorporated into the design, they will affect movement patterns and speed through the system.
The capacity and frequency of train arrivals at peak periods adds an operational surge movement that affects the space standards and capacity of circulation routes. Surge movements vary, depending upon their direction and the characteristics of the people being moved. For example, commuter movements result in a tidal effect, in particular, on vertical circulation arrangements and ticketing entry/exit points, while people with baggage, the elderly and disabled affect access arrangements and passenger flow timings. At interchange locations, the synchronisation of the two service provisions has a critical effect on the space standards to be provided, so a clear understanding of capacities and headways is essential to ensure a safe design solution.
For emergency situations, allowance for space has to be made to accommodate station evacuation, a missed headway and emergency de-training. The design sizing criteria are governed by the worst-case scenario of an emergency situation with the need to move large numbers of people to a place of safety quickly and expediently in panic conditions.
There are many methods of calculating/illustrating passenger flows. Ped-Route is one example and PB’s own programme, SIMULEX, is another. All are generated by the overall objective of meeting the demands of passenger usage. This passenger forecast demand is established as part of a strategic urban study, and should also take into account the generated economic growth brought about by the introduction of the station into the city environment.
Station Sizing
The principles established in John Fruin’s study on pedestrian behaviour devised “design bands” based upon the relationship between circulation conditions and walk/travel speeds.1 These band s identify passenger densities (crowding). When applied to permitted evacuation time principles and peak demand, these bands allow the station to be sized and space to be allocated on the basis of each functional area. In addition, space will be required for those elements unaffected directly by passenger movements, such as operational facilities and other service provisions.
Access
Access to the stations will, of course, vary dependant upon their locations. The numbers and form of each entrance will be dictated by the overall station passenger capacity, ticketing regime/security and the disposition of emergency egress points. Consideration must also be given to the station approach, its identity in the locality, the additional facilities available, e.g., park and ride, commercial opportunities, multi-modal interchange, etc.
Access for the disabled must be provided within the station and on station approaches, entry points and car parks. Emerge ncy vehicle access should be considered early in the design process.
Ticket Halls and General Concourse
The key factor within this element of a station is the ability of the user (passenger), who may be unfamiliar with the facility, to have a clear line of sight from point of access to ticketing and onwards to the platforms. Queues for ticketing should be segregated from passenger access movements. Ticketing gates should be located to prevent cross circulation whilst at the same time being capable of reverse flow to accommodate peak periods and emergency evacuations.
Commercial opportunities may be considered and can be served from this general circulation space. If implemented, retail units must conform to the guidelines attached to ticket vending and be clear of movement lanes/desire lines of travel.
In assessing the space standard for the overall area, peak passenger numbers must be identified together with a delay period assigned to allow for passengers making use of commercial outlets and emergency evacuation (or part thereof) from the platforms.
Passages and Routes To, From and Between Platforms
Passageways in normal use are sized on passenger flow rates in either a single direction or two ways, dependent upon the access configuration. The flow rates include known potential tidal and surge flows and allow for emergency use. As it is impossible to identify from which direction an emergency will arise, it must be assumed that all passageways will be used in any direction in such an event.
As a rule, single directional movements have a greater flow rate than two-way and, if there is a condition of particularly high tidal flow, this rate can be used in the design as a base case.
Platforms require multiple access points and, therefore, linked passages. This is the case for passenger distribution and to provide an alternative means of escape in an emergency. These passages should be at least 2 m (6.5 feet) wide to allow use by the mobility impaired.
Vertical Circulation
Vertical circulation within stations can take the form of ramps, stairs, lifts and escalators. In all cases, the provision for mobility impaired access dictates the base case. Standards followed in the UK are as follows:
- Ramps. Used for minor differences of level, the preferred grade for ramps is 1:20. All ramps should have a minimum width of 2 m (6.5 feet).
- Stairs. Used for rises up to 5 m (16.5 feet). Stairs must comply with MIP if no lift is available. The sizing of stairs uses the same principles as passageways allowing for lower flow rates.
- Lifts. These must be provided in all new developments and serve all public areas, including platforms, ticket halls and entry points
- Escalators. These have the greatest capacity to carry passengers and can be regulated as to speed of movement. They may be used for rises of 5 m (16.5 feet) or more and can be used in reverse mode to accommodate tidal passenger flows. Escalators may also be used as an emergency means of escape in static mode (with reduced capacity) but require specific fire protection and protection of their power supplies.
In all cases, space allowance should be made for circulation at entry and egress points. In the case of the escalator, this is calculated on the basis of the maximum travel speed.
Platforms
As a general principle, platforms must take account of line standards, which are a combination of safety feat ures related to structure gauge/dynamic envelope, line speed, and general clearances. These requirements limit the available space for passenger movements/standing (e.g., clearance at platform edge and platform obstructions). The sizing of platforms also needs to take account of the numbers of passengers waiting to board, those alighting, the number of access points and the travel distance of the platform length. In some instances, if the platforms may be used as an inter-destination change facility, allowance should be made for increased numbers for that purpose.
On commuter lines, tidal passenger flows also produce surge conditions and these are directly affected by train headways. Dependant upon their clearance rates, platform designs must take account of this either by adequate exit routes to clear the platform between headways or by increased platform sizing.
In calculating passenger loadings and, therefore, platform widths in an emergency situation, allowance must be made for a missed headway and an emergency de-training. The train numbers are based on the crush loading capacity of the train.
The mobility impaired, if unable to reach the lift exit in an emergency, require the provision of a safe refuge isolated from the platform from where they can be assisted to leave the station stair or other means. |
