Preparing stations for summer through step-by-step flow studies

In this article we deal with the importance of flow studies as a support to architectural and infrastructure work related to public access buildings (museums, stations, shopping centres, etc.) and how crowd management helps adapt routes in order to provide pedestrians with maximum comfort.
View over the escalators of the Saint Lazare station
Paris Saint-Lazare station, vertical flows | (c) Didier Boy de la Tour

While in public transport means you may have taken an alternative route, much longer and less comfortable, or boarded rail replacement buses hoping to get at your destination. As a driver of a private vehicle, you may have had to take diversion routes because of ongoing works, and this experience may have proved quite stressful. Those events are quite common around the world. Metro or rail line closures due to works, such as the Washington Red Line closure, have an impact on other stations. This is coherent with the idea of network.

During summer 2016, the closure of RER line A led to the increase in traffic at Saint-Lazare station, Europe’s second busiest station -after Paris-Nord-, with 450,000 travellers daily. In fact, part of the RER line A passengers had to modify their daily journey and get their train bound for the west suburbs at Saint-Lazare. Faced with such unusual passenger numbers (RER travelers were added to the regular ones), stations are most likely to see their spaces reaching maximum capacity.

Such exceptional disturbances can be studied in advance so that users can still benefit from convenient circulation routes in spite of the difficulties:

  1.  Summer is a good time to carry out rail network improvement works as fewer passengers tend to travel compared to other times of the year. In Paris Region, RER A tracks are scheduled to be upgraded during four weeks every summer, and therefore, until 2018, traffic will be completely stopped on the sections of the line running within Paris and through the inner suburbs. Between 2019 and 2021 traffic is scheduled to stop at night for seven to nine weeks.
  2.  Several months in advance, station operators provide users with tools allowing detailed information on partial station closures. Travellers are thus able to start planning ahead for an alternative journey.
  3.  Flow studies are carried out by AREP's team (a subsidiary of SNCF Gares & Connexions) specializing in Flow and Mobility in order to anticipate the increase in passenger numbers. These studies are aimed at organizing and facilitating pedestrian flow on a daily or occasional basis, and at accompanying the operator's decisions to make sure that both stations spaces and circulation routes remain unobstructed. They take into account users' needs, organizational constraints and safety rules.


Firstly, places likely to be overcrowded need to be identified. Secondly, appropriate solutions are implemented in order to deal with such unusual passenger volumes and provide users with uncongested and legible routes. Precisely, as passenger volumes increase at Saint-Lazare station, circulation routes between metro and rail lines get overcrowded. Queue locations, such as the top and bottom of escalators, become congested as users slow down, or even stand still, for several seconds to a minute. This seemingly short pause may appear very long if it is part of your daily commute.


In the video below you can see how interchange within a station is affected when RER line travellers are added to the regular SNCF travellers. We used a simulation software to model passenger movements, focusing on the interchange area between metro and rail lines at Saint-Lazare  station level -1, and noticed congestion and cross flows at the bottom of the escalators.


The recommendations of the flow study respond to several challenges, such as:

  1.  The timeline on which the event takes place,
  2.  The existing spatial organization of the metro and rail stations,
  3.  Passengers' practices and habits.


Infrastructure works are scheduled to take place every summer during the following four years and last four weeks in a row. Proposals need to be flexible and implemented quickly because they may be rescheduled the following years.


Given the ad hoc nature of the event, it is not worth considering to modify the station's layout by building additional stairs to reduce congestion. Cross flows causing congestion and pedestrian conflicts can be avoided by changing the direction of some escalators and separating circulation routes depending on the destination (metro lines or rail lines).


Last but not least, staff can provide guidance within the station while the new signing system provides directional information and helps passengers move comfortably and unobstructedly from one place to another.


The video below displays passenger flows when station's internal movement structure is redesigned to minimize conflicting flows, which extend time spent to move from one line to another.  


AREP is a multi-disciplinary engineering consulting firm and our teams' main task is both to guide operators and design mobility-related buildings. Flow studies may sometimes have surprising results -we have recently found out that standing-only escalators could contribute to reducing congestion. The expertise they provide, however, is a valuable resource for the transport industry in general, public access spaces and even large territories. Crowd management is intrinsically related to safety and comfort and may apply to several everyday situations, from daily waiting times in stations to museum queues or special events (accidents, works, cultural or sports events).

So next summer, whether in Paris or Washington, you'll certainly have to replan your regular journey and that may prove annoying. But it is certainly less irritating than being stuck at the bottom of an escalator!