Ants help build better infrastructure
Majid Sarvi from Monash University explains how experimenting with panicked ants can help build better infrastructure for crowded cities.PT2M40S http://www.smh.com.au/action/externalEmbeddedPlayer?id=d-2onq0 620 349 June 21, 2013
When a big building is burning down, how do you control the evacuation of a panicked crowd of people? Australian researchers have come up with some answers using the crowd flow of ants.
Lead researcher Majid Sarvi from the department of civil engineering at Monash University says engineers have done a good job designing large buildings to cope with the structural stress brought on by catastrophes such as fires, earthquakes and even terrorist attacks.
''But there is a lack of data on people's behaviour that would help … to design exits that function more effectively during evacuations of large buildings and sporting arenas,'' Dr Sarvi said. ''So we were looking for a way to simulate panicked behaviour.''
Pack mentality: Majid Sarvi in front of a video projection of his experiment with ants at Monash University. Photo: Paul Jeffers
Seven years ago, he and his team began experimenting with ants, ''as a proxy for humans''. The experiments, run dozens of times with increasing complexity, began by digging up ants in the garden, creating an artificial nest in the laboratory and leaving them for a week while they put down pheromones and settled into their food and water-gathering routine.
For the experiment, the ants were put in a rectangular chamber, and sent into a panic by exposing them to a chemical. Exits were placed in the middle of a wall and at the corner.
"We found the ants evacuated rooms faster when the exits were located in corners rather than in the middle of hallways," Dr Sarvi said.
The corner exit was almost twice as effective.
''We found it was 93.5 per cent more effective in reducing the evacuation time than when the exit was positioned in the middle of the wall."
Dr Sarvi said the corner exits may have worked better as a ''minimisation of conflict'' at the evacuation point. "With the middle exit, ants escaping along both sides of the wall had to change their direction at the exit in order to evacuate. This created conflict with the ants moving straight towards the exit," Dr Sarvi said.
The next step was to place a column near each exit. The result was ''counter-intuitive'' said Dr Sarvi - because the column actually helped organise the evacuation into a more orderly flow, in the way concrete barriers work on highways.
The team then simulated human evacuation scenarios and found that the ants had accurately predicted human traffic flow.
The ant experiments continue. The team had looked at what happens when two streams of traffic meet in a panicked or agitated situation, similar to two lines of people trying to get access to the escalators at a train station at peak hour. The challenge in a dangerous evacuation is how to get the streams to merge smoothly. ''We haven't found a solution to that one yet.''
The researchers are being dogged by other challenges. They want to use mice in their experiments, ''but we haven't found a way to consistently panic them. You can't use chemicals. And other methods tend to make them freeze on the spot,'' he said.
Dr Sarvi said that, given ''the global trend towards mass urbanisation, and increasing incidence of mega-events, terrorism and natural disasters'', it was important that public infrastructure was designed to facilitate smooth emergency evacuations.