The design of mass transit and public building spaces presents architects with big challenges when dealing with high capacities and emergency egress. To help designers Oasys, has embodied years of simulation knowledge into its software

Level Of Service (LOS) simulation of a transit hub

Billions of people travel about their daily business, moving through train and metro stations, as well as airports, ports and bus terminals. Football venues like Wembley Arena are built to cater to crowds of 90,000 people on a weekly basis, while concert venues such as the O2 Arena have capacities in excess of 20,000. Globally, events like the Muslim Hajj attract two million pilgrims over five days to circle one shrine seven times. The challenge for designers to safely cater to the needs of these huge flows of people is too big to be tackled with guesswork or gut feel. This is where simulation can play a key role in the conceptual and detailed decision-making process.

Oasys is the software arm of multi-disciplinary giant Arup. Creators of popular products such as Mail Manager, the company offers very targeted solutions to the building market, including vibration and seismic analysis, 3D linear and non–linear static and dynamic building analysis, concrete detailing, slope stability detailing as well as environmental and bridge design tools. As Arup develops bespoke solutions to solve its clients’ problems, that knowledge gets distilled and turned into products by the Oasys group, providing industry tested solutions to the mass market.

Arup’s work is well known in the world of mass transit, stadia design (Olympics) and its work on public spaces (Hajj). Oasys took some of the simulation software developed for the analysis of hundreds of thousands of moving ‘avatars’ in 3D spaces and built a product called MassMotion. Costing £20,000 for a perpetual license and requiring a copy of the now defunct Autodesk Softimage, usage was once reserved for the lucky few. In its latest reworking of the product, MassMotion Flow, Oasys has rewritten the product, removed the need for Softimage as a geometry engine, added new functionality and priced a very capable version at a much lower price of £5,000 for more widespread adoption.


We were very impressed with the previous version of MassMotion ( although getting the geometry imported and prepared for analysis via Softimage was a bit contorted. With the writing on the wall for Softimage, as Autodesk owned all its competitors (3ds Max and Maya), it was pretty obvious that Autodesk was not putting development effort into Softimage. Oasys needed to remove MassMotion’s reliance on the Autodesk geometry engine and with MassMotion Flow, the system features a brand new modelling space, which looks and feels very similar to the previous one.

The full version of MassMotion still exists and can be purchased, although, and by the time you read this, an updated version should be near shipping — obviously featuring all the graphics and new feature updates that the new MassMotion Flow has. As to the difference between MassMotion and MassMotion Flow, the full version allows for a greater capacity to include scheduled events and plug into databases to drive more complex simulations. Perhaps providing real world arrival and departure times of trains, or planes to drive even more realistic results.

In use

MassMotion Flow can run on a reasonable Windows laptop or desktop but, as you would expect, the bigger the crowds involved in each scenario, the longer each analysis takes. A typical starting point is to import geometry from a CAD or BIM system such as AutoCAD, MicroStation, SketchUp, Rhino or Revit. The system supports 3DS, DXF, FBX and IFC, which is a good lightweight format with building metadata so the software can automatically recognise walls, slabs, stairs, etc.

This imported geometry is reference geometry for MassMotion Flow to automatically generate floors, stairs, ramps, escalators, etc. Work may be required, especially when modelling might not actually be as precise as expected or there are no appropriate IFC definitions for elements, such as baggage handling machines or security devices. MassMotion Flow can also create new geometry and be used to edit the models and filter out modelling errors and hide reference geometry. For heavy users of MassMotion Flow, or those that regularly send models for simulation, it is possible to create custom routines to assist in the import automation and include MassMotion Flow elements. The software comes with a library of intelligent geometry components, such as escalators and stairs, which can be used to swap out non-functioning elements or unrecognised components in imported models. It is also possible to create new intelligent elements. MassMotion elements, like escalators, can be easily edited to set direction or logic, such as timed open and close or repetitive tasks. For scheduled ‘timetable’ events driven by a spreadsheet, or complex process chains/tokens, you will need the full version of MassMotion.

Portals are placed to spawn ‘agents’ over time, which are highly configurable, as to the number of agents, their timings of generation and egress. Agents are spawned with individual objective destinations and each one is a mathematical point with a radius and can be displayed as animated ‘walking’ people, or moving pegs, should processor power be limited.

Once the model is complete and directions set on components like escalator travel directions, barriers, security, the simulation can be run. It is often a good idea to test the model first as if not set up correctly, agents may get trapped or bypass planned filters such as security checks, should an escalator direction allow a faster route to their destination.

In terms of processing speeds, it does depend on the complexity of a model but typically 15,000 agents can be calculated in real time — that is to say one minute of simulation will take one minute of compute time.

The more congested a design, the more computationally intensive the scenario; as agents will interact more with each other if confined in crowded spaces. The software is fully multithreaded so the more cores you have, the faster it will run. At the moment all processing is done locally on the computer but Oasys is evaluating the benefits of cloud-based options.

Once the simulation has been processed it is possible to watch the agents move about the space, navigate crowds and reach their destination. The real feedback comes with MassMotion Flow’s wealth of report generation tools, agent density, level of service (how much space agents have around them), identifying points of maximum congestion, queuing level of service, traces of all agents pathways, vision maps to identify walls which are most viewed (for best advertising spaces) and many others. Reports can be graphs or agents can be coloured to indicate their level of service within the simulation. It is even possible to filter to just see one agent’s experience throughout the simulation.

Graphs and animations (at various quality) can be easily exported for including in reports or sharing with design teams over the web.

Typically, Oasys recommends two days training to use MassMotion Flow, dealing with import of geometry and creation of simulations. Although, it has to be said that the knowledge required to properly understand all the analysed output is still viewed as being a specialised skill.

Running multiple scenarios in both best and worst cases can quickly identify problem areas within a design and help designers understand the capacity and comfort levels of people using the spaces. The software has many uses away from obvious train stations and airports, and has even been used to assist in the mapping out of school timetables to limit the congestion in corridors and canteens.


MassMotion Flow is the next generation of pedestrian/crowd simulation tools on the market and brings Oasys’ previously high-end and relatively expensive solution to a much wider market. While still a specialist area and requiring some knowledge to drive and understand the results, it is now much more feasible for a practice that works on public spaces, schools or transport systems to get quantifiable feedback on the quality of design, starting at the concept stage and working through to retrofit and timetables.

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