Pedestrian Simulation with VISSIM
People affect traffic flows in many different ways: behind the wheel – and on foot. Previously, most of the traffic analyses only focused on vehicles; the pedestrians were an attractive sideshow. The new VISSIM module from the PTV Vision product line for traffic planning realistically simulates interactions between pedestrian and vehicle flows. You can now run analyses that encompass both types of traffic, as well as analyses specific to pedestrians.
The person as a factor can be given more effective consideration using the Social Force model developed by Professor Helbing. This greatly improves the planning results, which are now more realistic, and has particular benefits for users. This program lends itself to a host of applications in the area of urban, architectural, and traffic planning, evacuation simulation and animation.
Software
VISSIM is a microscopic simulation tool meaning that all vehicles and pedestrians are simulated individually. The behaviour of pedestrians can now be defined individually, in the same way as before with vehicles. With the speed distribution, the VISSIM user can allocate to each pedestrian their own individual maximum walking/running speed.
For the first time in the development of VISSIM, it is now possible to show entities, whether pedestrians or vehicles, who deliberately violate traffic regulations. This behaviour was incorporated into the software upon the request of many customers throughout the world.
Pedestrians and Vehicles – an Interactive Relationship
VISSIM is the first multi-modal microscopic simulation program to include real interaction between pedestrians and vehicles. Traffic lights, pedestrian crossings, and normal parts of streets can all be modelled and simulated in VISSIM.
The Social Force Model for pedestrian dynamic was first developed by Dirk Helbing and Peter Molnar in 1995. Based on Newton’s theory, pedestrian interaction is modelled considering different forces. This includes the driving force. Pedestrians move purposefully as a rule, i.e. they walk at a desired speed towards their destination. Various elements influence them when doing so. On the one hand, pedestrians always maintain a kind of "safety distance" or personal space, not only to other pedestrians but also to obstacles or buildings. On the other hand, they are distracted by various attractions, like shop windows, so that they may alter their course. When modelling, there are psychological (social force) and physical components which must be taken into consideration.
Since its publication in 1995, the Social Force Model has been enhanced several times and used in many projects. Its general approach is flexible and it has recently been demonstrated that it can easily be extended to simulate extreme situations, such as the Hajj in Mecca.
To create a new scenario, the editing process is based on three steps:
First, the population needs to be defined and pedestrians grouped into types, classes and compositions. Their properties, such as walking speed, model parameters, colour, and 3d models are to be configured.
Next, geometry using walking areas, obstacles, ramps, stairways, escalators, traffic lights and levels is to be specified.
Finally, the inputs and routes of pedestrians are added to the geometry.
VISSIM supports a number of image formats (among them jpg and dxf), which can be loaded as background images to assist in creating the geometry.
Evaluation and Measurement
Measurements such as density, speed, flow, travel time and lost time can be included in the simulation at arbitrary positions. For each measurement, raw data can be measured and aggregation time intervals can be defined freely.
Scope of Application
Traffic engineering and transportation planning
The influence that pedestrians have on vehicular traffic – particularly in special situations like complex intersections – can be realistically forecasted.
Typically, the role of traffic technicians and planners is to adapt the infrastructure to match the volumes of road and pedestrian traffic. First and foremost is the evaluation of differing traffic situations. This is of particular interest for situations with a high proportion of pedestrians, like airport terminals, bus and railway stations. In addition to the flow of pedestrians, connections can also be examined: How quickly and by what route can the next terminal or next level of the station be reached? How can the timetable or schedule be adapted to this?
The close interaction between simulation and traffic assignment proves to be an advantage here. For a complex like a railway station, the emerging traffic flows over a large area are initially calculated in the VISUM module, before the pedestrian flows are microscopically simulated with VISSIM.
Environmentally friendly approaches to urban planning and development
In terms of environmentally friendly conveyance, the requirements of the pedestrian are gaining increasing interest in modern urban planning. If these are already taken into consideration from the onset, the urban planners will achieve high-quality results, which allow development of pedestrian-friendly towns and cities.
Evaluation of evacuation measures
Evacuation simulation represents a special area of application. Safety experts examine various aspects and assess the alternatives. This is particularly important when planning event locations, high-rise buildings or tunnels. Specialists take various measures in the initial phase, which reduces and structures uncontrollable behaviour. If people in evacuation scenarios are given clear instructions, as to how to behave and where to go, they react in a quite rational and cooperative manner. This makes the flow of movement target orientated and controllable. With suitable structural and organisational measures, controlled evacuations can be planned and put into reality using VISSIM.
Manage attractive events safely
The simulation of the course of large-scale events, which are increasing in scope, is another area of application. Any serious event organisation must be in a position to evaluate the flow of traffic and pedestrians to be expected within the framework of the given infrastructure. With the aid of the simulation results, urban planners and event managers mutually can draw up attractive, environmentally and socially acceptable concepts for large-scale events.
Last but not least, VISSIM, with its visualisation capabilities, is a powerful tool for architects who participate in large scale design and urban planning, for presenting their plans graphically to the public. This builds the bridge between traffic engineers, architects, and decision makers, who have little or no traffic planning background. Moreover, citizens can more easily participate in discussions regarding the design of towns, cities and public places.
